- Email: [email protected]
Geochronology and geochemistry of the TTG and potassic granite of the Taihua complex, Mts. Huashan: Implications for crustal evolution of the southern North China Craton
Accepted Manuscript Geochronology and geochemistry of the TTG and potassic granite of the Taihua complex, Mts. Huashan: implications for crustal evolution of the southern North China Craton Guo-Dong Wang, Hao Wang, Hong-Xu Chen, Bo Zhang, Qing Zhang, ChunMing Wu PII: DOI: Reference:
S0301-9268(16)30573-3 http://dx.doi.org/10.1016/j.precamres.2016.11.006 PRECAM 4613
To appear in:
Precambrian Research
Received Date: Revised Date: Accepted Date:
18 February 2016 26 October 2016 30 November 2016
Please cite this article as: G-D. Wang, H. Wang, H-X. Chen, B. Zhang, Q. Zhang, C-M. Wu, Geochronology and geochemistry of the TTG and potassic granite of the Taihua complex, Mts. Huashan: implications for crustal evolution of the southern North China Craton, Precambrian Research (2016), doi: http://dx.doi.org/10.1016/ j.precamres.2016.11.006
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
1
An original manuscript submitted to Precambrian Research
2 3 4 5 6
Geochronology and geochemistry of the TTG and potassic granite of the Taihua complex, Mts. Huashan: implications for crustal evolution of the southern North China Craton
7 8
Guo-Dong Wang a,b*, Hao Wang b, Hong-Xu Chen b, Bo Zhang c, Qing Zhang d,
9
Chun-Ming Wu b
10
a
Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
11
b
College of Earth Science, University of Chinese Academy of Sciences, P.O. Box
12
4588, Beijing 100049, China
13
c
14
d
15
100081, China
China Corporation of Coal Geology Engineering, Beijing 100073, China
Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing
16 17 18 19 *
Corresponding author. Tel: +86 0532 82898035. E-mail address: [email protected] (G.-D. Wang). 1
20 21
ABSTRACT Tonalite-trondhjemite-granodiorite
(TTG)
suite
and
potassic
granite
22
volumetrically expose in the Neoarchean to Paleoproterozoic Taihua complex, Mts.
23
Huashan region, southernmost segment of the Trans-North China Orogen (TNCO).
24
Zircon U–Pb dating on the trondhjemite, granitic gneiss, K-feldspar granite and
25
coarse-grained granite samples show three episodes of magmatism (2.55–2.49 Ga,
26
2.33–2.25 Ga and 1.87–1.80 Ga) with distinct geochemical features in this area during
27
the Paleoproterozoic. The trondhjemite samples have high SiO2 (67.46–71.73 wt%),
28
Na2O (4.83–5.95 wt%), low Mg# (31–40) and HREE contents, with moderate
29
(La/Yb)N values (16.8 to 35.3) and Sr/Y ratios (15.8 to 34). The potassic granite
30
samples show high SiO2 (65.2–75.43 wt%), K2O (3.9–8.6), low Na2O (1.74–4.17
31
wt%), Mg# (2–46) and HREE contents, with moderate to high (La/Yb)N values (10.3
32
to 226) and Sr/Y ratios (12.8 to 208). All these granitoid samples are characterized by
33
high SiO2 and low Mg#, Cr, Ni with moderate to high (La/Yb)N values and Sr/Y ratios.
34
The absence of evidence of any pre-existing high Sr/Y and La/Yb sources in this
35
region led to that the granitoids probably generated from partial melting of hydrous
36
mafic rocks with garnet and amphibole in the residue. Therefore, partial melting of
37
thickened lower curst is the most likely origin. Combined with previous studies, the
38
first episodic magmatism (2.55–2.49 Ga) represented by TTG and granitic gneisses
39
with positive whole rock ƐNd(t) and zircon ƐHf(t) values is interpreted as melts from
40
partial melting of juvenile thickened lower crust. The second episodic magmatism
41
(2.33–2.25 Ga) represented by TTG, granitic gneisses and K-feldspar granite with
2
42
positive to negative whole rock ƐNd(t) and zircon Ɛ Hf(t) values is suggested as the
43
product of partial melting of both juvenile and pre-existing crustal material. The third
44
episodic magmatism (1.87–1.80 Ga) is represented by these potassic granites, which
45
is synchronism with the metamorphism recorded in this region and probably resulted
46
from partial melting of pre-existing crustal materials in a syn-orogenic or
47
post-orogenic setting during the collision between the Eastern and Western Blocks of
48
the North China Craton. Multistage continental accretion (at 2.84–2.72 Ga, 2.57–2.43
49
Ga and 2.36–2.25 Ga) and reworking (at 2.36–2.25 Ga, 2.19–2.07 Ga and 1.87–1.80
50
Ga) occurred in the southern segment of the TNCO from Neoarchean to
51
Paleoproterozoic. Transformation from an Andean-type continental margin arc setting
52
on the western margin of the Eastern Block to continent-arc-continent collision in the
53
southern TNCO during Late Neoarchean to Late Paleoproterozoic is suggested in this
54
paper.
55
Keywords:
56
Complex; North China Craton
TTG; Potassic granite; Geochronology; Geochemistry; Taihua
57 58
1. Introduction
59
Formation and evolution of the Precambrian continental crust is the archive to
60
explore the early history of our Earth. Tonalite-trondhjemite-granodiorite (TTG) suite,
61
metamorphosed supracrustal rocks and K-rich granite-granodiorite-monzonite suite,
62
volumetrically dominate the preserved Archean crust worldwide (Jahn et al., 1981;
63
Frost et al., 2006; Moyen, 2011). Extensive investigations on sodic TTG suite provide
3
64
great constrains for the origin and evolution of the Precambrian continental crust (e.g.,
65
Martin, 1994; Sylvester, 1994; Martin and Moyen, 2002; Martin et al., 2005; Condie,
66
2005; Smithies et al., 2009). Furthermore, the potassic granites are also widespread
67
and voluminous constituent of Archaean cratons (Sylvester, 1994), which can also
68
offer us opportunities to investigate the crustal evolution of the old terranes (e.g.,
69
Sutcliffe et al., 1990; Frost et al., 2006; Moyen et al., 2003).
70
The North China Craton (NCC) is one of the well known oldest and largest
71
cratons in the world (~3.8 Ga; Liu et al., 1992) with widespread Archean to
72
Paleoproterozoic basement, whose crustal evolution is still controversial (eg., Zhao et
73
al., 1998, 2000, 2012; Zhai et al., 2000, 2005, 2007, 2010, 2011; Kusky and Li, 2003;
74
Santosh et al., 2006; Faure et al., 2007; Trap et al., 2007, 2012; Santosh, 2010; Kusky,
75
2011; Peng et al., 2014). For example, one of the familiar debates is the timing of
76
final amalgamation of the NCC. Some researches believed the final amalgamation of
77
the NCC occurred at ~1.85 Ga by continent-continent collision along the Trans-North
78
China Orogen (TNCO) between the Eastern and Western Blocks (e.g., Zhao et al.,
79
1998, 2000, 2012; Guo et al., 2005; Kröner et al., 2005), whereas some others argued
80
the collision between the Eastern and Western Blocks occurred at ~2.5 Ga (Kusky and
81
Li, 2003; Kusky, 2011). Zhai et al. (2010) proposed that the NCC was cratonized
82
through amalgamation of several micro-continental blocks at ~2.5 Ga, followed by the
83
formation of oceanic basins which disappeared in the Paleoproterozoic through
84
subduction and collision. A number of other models are also argued (e.g., Faure et al.,
85
2007; Trap et al., 2007, 2012; Santosh, 2010).
4
86
The Taihua metamorphic complex, usually termed as the Taihua Group in the
87
traditional Chinese literature, exposing in the southernmost segment of the
88
Trans-North China Orogen (TNCO) (Zhao et al., 1998, 2000, 2012), consists of
89
Neoarchean
90
metamorphosed supracrustal rocks and K-rich granitic rocks (Sun et al., 1994). From
91
the west to the east, the Taihua complex exposed discontinuously in several areas, i.e.,
92
the Mts. Huashan area in the northwest, the Luoning (or Xiong’er) area in the middle
93
and the Lushan and Wugang area in the southeast. Although there are numerous
94
chronological and geochemical studies on the granitoids from the Lushan area (Xue et
95
al., 1995; Wan et al., 2006; Liu et al., 2009; Diwu et al., 2010, 2014; Huang et al.,
96
2010; Zhou et al., 2014), the Luoning area (Diwu et al., 2007; Huang et al., 2012). But
97
in contrast, fewer studies have been done on the granitoids from the Huashan area
98
(Huang et al., 2013; Yu et al., 2013), and no investigations were carried out on the
99
potassic granites from the Huashan area. Additionally, inconformity also existed
100
among these researches. For example, Huang et al. (2013) proposed the TTG gneisses
101
formed at ~2.5 Ga in Huashan and Dengfeng areas resulted from partial melting of
102
thickened lower crust, whereas Diwu et al. (2011, 2014) argued these rocks were
103
derived mainly from the partial melting of subducted oceanic crust and interaction
104
with mantle peridotite. In this paper, we present new LA-ICP-MS zircon U–Pb ages,
105
as well as whole-rock major and trace elements of the TTG gneisses and potassic
106
granites from the Mts. Huashan Taihua complex to infer their emplacement ages and
107
petrogenetic processes, and provide a better understanding on the crustal and tectonic
to
Paleoproterozoic
basement,
5
mainly
including
TTG
suites,
108
evolution of the southern margin of the TNCO in the Neoarchean to Paleoproterozoic,
109
which will provide important insights into understanding the formation and evolution
110
of the NCC.
111
2. Geological setting
112
Although controversies on the Precambrian crustal evolution of the North China
113
Craton still exist (eg., Zhao et al., 1998, 2000, 2012; Zhai et al., 2000, 2005, 2007,
114
2010, 2011; Kusky and Li, 2003; Santosh et al., 2006; Faure et al., 2007; Trap et al.,
115
2007, 2012; Santosh, 2010; Kusky, 2011; Peng et al., 2014), there is a great consensus
116
that the Precambrian basement of the North China Craton is a result of the
117
amalgamation of several micro-blocks. Zhao et al. (1998, 2000, 2012) proposed that
118
the North China Craton can be divided into the Eastern Block and the Western Block
119
separated by the N–S striking Trans-North China Orogen (TNCO). During 2200 to
120
1900 Ma, the Eastern Block underwent a Paleoproterozoic rifting event forming the
121
Longgang and Langrim Blocks, followed by the amalgamation of these two blocks
122
along the N–S- striking Jiao–Liao–Ji Belt (Zhao et al., 2005, 2012). The Western
123
Block can be subdivided into the Yinshan Block in the north and the Ordos Block in
124
the south, separated by the E–W striking Khondalite Belt, which formed at ~1.95 Ga
125
during the collision between these two blocks (Zhao et al., 2005, 2012). The
126
Tran-North China Orogen is the result of the amalgamation of the Eastern and
127
Western Blocks at ca. 1.85 Ga (Zhao et al., 1998, 2000, 2005, 2012).
128
As mentioned above, the Taihua complex is composed of Archean to
129
Paleoproterozoic basement, making it an ideal object to investigate the Precambrian
6
130
crustal evolution of the southern margin of the North China Craton. In the last few
131
years, some investigations were carried out on the metamorphism of the amphibolites
132
from the Taihua complex, and all of them recorded clockwise P–T paths containing
133
isothermal decompression (ITD) segments with metamorphism age being dated to be
134
ca. 1800–1960 Ma, which reflect the southern segment of TNCO was also involved in
135
the amalgamation of the Eastern and Western Blocks in the Paleoproterozoic (Jiang et
136
al., 2012; Wang et al., 2012, 2013a, 2014; Lu et al., 2013, 2014; Chen et al., 2015). In
137
addition, numerous chronological and geochemical studies on the granitoids from the
138
Taihua complex were performed. In the Lushan area, the protolith ages of TTG and
139
TTG-like gneisses were dated as 2.85–2.72 Ga (Liu et al., 2009; Diwu et al., 2010;
140
Huang et al., 2010; Zhou et al., 2014). According to the systematic chronological and
141
geochemical studies on the TTG and TTG-like gneisses, Huang et al. (2010) proposed
142
a model of late Archean crustal accretion from ocean crust to continental terrain in the
143
southern NNC. Zhou et al. (2014) dated TTG suite, sodic-potassic granite suite and
144
potassic granite at ~2840 Ma, ~2760 Ma and 2570 Ma, respectively, and proposed a
145
tectonic transition from a compressive to an extensional setting in the southern NNC
146
between 2.85 Ga and 2.50 Ga. In the Luoning area, Huang et al. (2012) obtained two
147
magmatic events from zircons collected from the TTG gneisses (2.32–2.30 Ga and
148
2.19–2.07 Ga) and proposed that there was a tectonic transformation from an
149
accretionary orogenesis to an extensional regime, as a consequence of post-collisional
150
uplift in the southern segment of the TNCO in the Early Paleoproterozoic. In the Mts.
151
Huashan area, Huang et al. (2013) reported three magmatic episodes in the TTG suit
7
152
(2.48 Ga, 2.31 Ga and 2.16 Ga), corresponding to the respective tectonic setting of
153
subduction, initial assembly of the NCC within the Columbia supercontinent cycle
154
and the orogenic collapse, respectively. Another chronological and geochemical
155
research on four granitic samples performed by Yu et al. (2012) revealed two
156
magmatic ages of 2328–2346 Ma and 1866–1881 Ma, and both of them were
157
connected with subduction settings.
158
The Taihua complex in the Mts. Huashan area is exposed on the southern and
159
northern slopes of Mts. Huashan in Shan’anxi and Henan Provinces in central China
160
(Fig. 1b) and is unconformably covered by the Tietonggou Formation at Bayuan,
161
which formed at 1.91–1.80 Ga (Diwu et al., 2013). Sodic TTG gneisses and potassic
162
granites are dominant in the Mts. Huashan Taihua complex. The potassic granites,
163
which are characterized by K-feldspar rich, mainly consist of granitic gneiss,
164
K-feldspar granite and coarse-grained granite according to their field and petrographic
165
characteristics. The TTG gneisses and granitic gneisses show typical fabrics with
166
parallel layering and alignment of plagioclase, quartz and biotite (Fig. 2a–d) and
167
spread widely in the study area. The amphibolites in the Taihua complex in this area
168
generally occur as enclaves in the TTG and granitic gneisses (Fig. 2b). Studies on the
169
amphibolites revealed a regional metamorphism of high-amphibolite to granulite
170
facies at 1.96–1.80 Ga (Wang et al., 2012, 2013a, 2014). On the contrary, the
171
K-feldspar granites and coarse-grained granites show weak (Fig. 2e) or no gneissic
172
foliation (Fig. 2f–h) and intrude into the gneissic rocks as small irregular stocks in
173
several locations.
8
174
3. Samples and Petrography
175
In this study, we collected three TTG gneiss samples (S147, S153 and S165),
176
five granitic gneiss samples (S144, S145, S148, S149 and S155), five K-feldspar
177
granite samples (S137, S140, S142, S143 and S151) and three coarse-grained granite
178
samples (S159, S160 and S163).
179
The TTG gneiss samples (Fig. 3a) are trondhjemite and mainly composed of
180
plagioclase (55–60%), quartz (25–40%), biotite (10–20%) and a few accessory
181
minerals (<5%). Magnetite or ilmenite, apatite and zircon are common accessory
182
minerals. Plagioclase is partly altered to sericite due to later hydrothermal alteration.
183
The granitic gneiss samples (Fig. 3b) are fine- to medium-grained. The mineral
184
assemblages mainly consist of K-feldspar (20–40%), plagioclase (25–45%), quartz
185
(30–40%) and biotite (5–10%). Magnetite or ilmenite and zircon are the common
186
accessory minerals (<5%). These rocks show typical gneissic layering similar to the
187
TTG gneisses, but are characterized by K-feldspar-rich, which is not found in TTG
188
gneisses.
189
The K-feldspar granite samples (Fig. 3c) are medium- to coarse-grained. These
190
rocks also chiefly consist of K-feldspar (30–50%), plagioclase (10–30%), quartz
191
(35–40%) and biotite (<5%) with minor accessory zircon, magnetite or ilmenite
192
(1–2%). These rocks show weak or no gneissic foliation and have more K-feldspar
193
relative to plagioclase.
194
The coarse-grained granite samples are characterized by coarse-grained with
195
massive textures. The mineral assemblages of these samples (Fig. 3d) are mainly
9
196
composed of K-feldspar (25–40%), plagioclase (25–35%), quartz (25–35%), biotite
197
(<5%) or amphibole (~10% in sample S160) and accessory minerals (<2%). Most of
198
the grain sizes of these rocks are in the range of 2–5 mm, and some crystals can reach
199
2 cm in length.
200
4. Analytical methods
201
4.1. LA-ICP-MS U–Pb dating method
202
In situ zircon LA-ICP-MS U–Pb dating were performed at the Institute of
203
Geology and Geophysics, Chinese Academy of Sciences using Agilent 7500a ICP-MS
204
instrument connected with Geolas-193 UV laser ablation system. The spot diameters
205
are 44 µm (for samples S137, S142 and S163) and 32 µm (for the rest samples) in this
206
study with a laser repetition rate of 10 Hz and the carrier gas was Helium. The
207
207
208
GLITTER 4.0 program (van Achterbergh et al., 2001). The Harvard zircon 91500 was
209
used as an external standard for age calculation with a recommended 206Pb/238U age of
210
1065.4 ± 0.6 Ma (2σ) (Wiedenbeck et al, 1995). The NIST SRM 610 was analyzed for
211
the calibration of U, Th and Pb concentrations. Concordia diagrams and weighted
212
mean calculations were made using the software Isoplot (version 3.75) (Ludwig,
213
2003).
214
4.2. Whole-rock major and trace elements
Pb/206Pb,
206
Pb/238U and
207
Pb/235U isotopic ratios were calculated using the
215
Whole-rock major elements were analyzed by X-ray fluorescence (XRF)
216
spectroscopy with a Philips PW1400 spectrometer at the Institute of Geology and
217
Geophysics (IGG), Chinese Academy of Sciences. Fused glass disks were used and
10
218 219
the analytical precision is generally ≤ 5%. Trace
elements
were
analyzed
using
a
Perkin-Elmer
ELAN-DRC-e
220
inductively-coupled plasma mass spectrometry (ICP-MS) at the State Key Laboratory
221
of Ore Deposit Geochemistry (SKLOG), Institute of Geochemistry, Chinese Academy
222
of Sciences (IGCAS). The powdered samples (50 mg) were dissolved in high-pressure
223
Teflon bombs using HF+HNO3 mixture for 48 h at ~195 °C, and other detailed
224
procedures are described by Qi et al. (2000). Rh was used as an internal standard to
225
monitor signal drift during counting. The international standards GBPG-1, OU-6, and
226
the Chinese National standard GSR-1 were used for analytical quality control. The
227
analytical precision is generally ≤ 5%.
228
5. Results
229
5.1. Zircon LA-ICP-MS U–Pb dating
230
The cathodoluminescence (CL) images of representative zircons are shown in
231
Fig. 4 and the U–Th–Pb analytical results are presented in Supplementary Table 1 and
232
Fig. 5. The detailed characteristics of zircons and dating results are described as
233
follows.
234
5.1.1. TTG gneiss
235
Most of the zircons from the TTG gneiss samples are columnar or elongated in
236
shape and about 100–300 µm in length. The majority of these zircon grains show
237
core-rim structures in CL images (Fig. 4a–c). The cores usually display
238
well-developed oscillatory zonings, indicative of magmatic origin. Around the cores
239
are homogeneous rims with higher or lower luminescence, indicative of metamorphic
11
240
origin. Some of the rest zircon crystals are anhedral and homogeneous with no
241
core-rim structures or magmatic rhythmic textures (Fig. 4a), which are considered to
242
be of metamorphic origin.
243
Twenty spot analyses were conducted on 15 zircon grains from sample S147. The
244
U, Th contents and the Th/U ratios of four valid spots on the rim or metamorphic
245
grains are in the range of 291–941 ppm, 83–250 ppm and 0.23–0.29, respectively. All
246
of these analytical spots are concentrated on or very close to the concordia and yield
247
207
248
time of one metamorphic event. The rest eleven valid spots analyzed on the magmatic
249
cores have higher Th/U ratios of 0.38–0.77, with Th and U contents of 48–215 ppm
250
and 85–270 ppm. All of these U–Pb results are also distributed on or very close to the
251
concordia and yield a weighted mean 207Pb/206Pb age of 2315±16 Ma (Fig. 5a), which
252
is interpreted as the crystallization age of this rock.
Pb/206Pb ages ranging from 1815±20 Ma to 1876±18 Ma (Fig. 5a), reflecting the
253
Thirteen zircon grains were selected from sample S153. Ten spots distributed on
254
the metamorphic rims give U, Th contents and the Th/U ratios of 835–1888 ppm,
255
15–197 ppm and 0.04–0.24, respectively. All of these analytical spots fall on the
256
concordia and yield a weighted mean
257
representing an age of one metamorphic event. Nine valid spots on igneous cores have
258
higher Th/U ratios of 0.24–16.95, with Th and U contents of 41–1307 ppm and
259
77–988 ppm, respectively. These U–Pb results define a linear array on the concordia
260
diagram and yield an upper intercept age of 2254±29 Ma (Fig. 5b), which is
261
considered as the crystallization age of this rock.
207
Pb/206Pb age of 1841±21 Ma (Fig. 5b),
12
262
Three spots on metamorphic rims (spots 4, 10, 14), fifteen spots on cores or
263
magmatic zircon grains and three spots on inherited zircons (spots 1, 7, 11) for sample
264
S165 were dated. Two valid spot analyses on the rims distributed on the concordia
265
and yield
266
representing the time of one metamorphic event, with U, Th contents and Th/U ratios
267
of 174–295 ppm, 91–124 ppm and 0.31–0.71, respectively. Fourteen valid spots on
268
cores or magmatic grains are also distributed on the concordia and give a weighted
269
mean
270
crystallization age of this rock, with U, Th contents and Th/U ratios of 195–872 ppm,
271
63–873 ppm and 0.05–0.85, respectively. Three spots on inherited zircons are
272
discordant due to varying lead loss (Fig. 5c) and yield
273
2588±21 Ma to 2709±21 Ma.
274
5.1.2. Granitic Gneiss
207
207
Pb/206Pb ages of 1950±21 Ma and 1968±24 Ma (Fig. 5c), probably
Pb/206Pb age of 2485±21 Ma (Fig. 5c), which is interpreted as the
207
Pb/206Pb ages ranging from
275
Most of the zircon grains from the granitic gneiss samples are euhedral to
276
subhedral and about 100–400 µm in length (Fig. 4d–h). Some of them show
277
oscillatory-zoned cores with/without homogeneous rims, and the others are anhedral
278
and homogeneous without core-rim structures or magmatic rhythmic textures,
279
reflecting metamorphic origin.
280
Fourteen spots on cores or zircon grains with magmatic rhythmic textures and six
281
spots on rims or grains with blurred oscillatory zoning (Fig. 4d) are dated for sample
282
S144, and give U, Th contents and Th/U ratios of 132–539/334–720 ppm,
283
162–2466/49–613 ppm and 1.12–2.62/0.13–0.87, respectively. These analyses yield
13
207
Pb/206Pb ages ranging from 1797±22 Ma to 1875±28 Ma and define an
284
similar
285
upper intercept age of 1829±10 Ma (Fig. 5d), which is interpreted as the emplacement
286
age of this rock.
287
Twenty spots were carried out on 19 grains from sample S145. Two of them on 207
Pb/206Pb ages of
288
metamorphic rims are distributed on the concordia and give
289
1915±18 Ma and 1963±17 Ma with U, Th contents and low Th/U ratios of 895–1561
290
ppm, 54–56 ppm and 0.04–0.06, respectively. Eleven spots on oscillatory-zoned cores
291
give U, Th contents and higher Th/U ratios of 140–568 ppm, 55–627 ppm and
292
0.41–1.10, respectively, and define an upper intercept age of 2293±28 Ma (Fig. 5e).
293
Ten concordant spots near the upper intercept yield a weighted mean
294
of 2286±11 Ma, which is interpreted as the crystallization age of this rock and
295
consistent with the upper intercept age within analytical uncertainties. The rest spots
296
are distributed on the rims or transitional area to the core (Fig. 4e), some of which are
297
slightly discordant and yield younger
298
meaningless and probably as the result of uncompleted recrystallization during the
299
metamorphic event or the mixture of several parts in different proportions of the
300
zircons by laser ablation.
207
207
Pb/206Pb age
Pb/206Pb ages (Fig. 4e). These ages are
301
Twenty spots were analyzed on 10 zircon grains from sample S148. Eight spots
302
on homogeneous rims fall on the concordia and yield a weighted mean 207Pb/206Pb age
303
of 1873±27 Ma (Fig. 5f), which is considered as the age of one metamorphic event,
304
with U, Th contents and Th/U ratios of 91–635 ppm, 35–193 ppm and 0.22–0.73,
305
respectively. Five spots on cores with magmatic rhythmic textures and six spots on
14
306
domains with blurred oscillatory zonings (Fig. 4f) are distributed on or very close to
307
the concordia and have U, Th contents and Th/U ratios of 91–635 ppm, 19–164 ppm
308
and 0.13–0.68, respectively. These spots define a linear array on the concordia and
309
yield an upper intercept age of 2502±49 Ma (Fig. 5f). Three concordant analyses near
310
the upper intercept yield a weighted mean
311
taken as the emplacement age of this rock.
207
Pb/206Pb age of 2551±11 Ma, which is
312
Twenty spot analyses were determined on 17 zircon grains from sample S149.
313
Three spots (spots 07, 10 and 13) on homogeneous rims or grains (Fig. 4g) give U, Th
314
contents and Th/U ratios of 371–443 ppm, 192–300 ppm and 0.51–0.81, respectively.
315
The 207Pb/206Pb ages range from 1794±20 Ma to 1848±19 Ma (Fig. 5g), indicating the
316
time of metamorphism. The rest seventeen spots distributed on the oscillatory-zoned
317
cores and grains with blurred oscillatory zoning (Fig. 4g) yield
318
ranging from 2414±17 Ma to 2513±17 Ma and give U, Th contents and Th/U ratios of
319
191–623 ppm, 70–265 ppm and 0.32–0.79, respectively. Ten of them are concordant
320
and yield a weighted mean
321
regarded as the emplacement age of this rock. The younger seven spots are mostly
322
distributed on domains with blurred oscillatory zoning or the transitional area between
323
core and rim, which are inferred as the results of uncompleted resetting of protolith
324
zircons during metamorphism or the mixture of different generation zircons by laser
325
ablation. In these cases, these results are meaningless.
207
207
Pb/206Pb ages
Pb/206Pb age of 2495±11 Ma (Fig. 5g), which is
326
Twenty-one spots were analyzed on 14 zircon grains from sample S155. Six spots
327
on rims and valid fourteen spots on cores and grains with/without magmatic rhythmic
15
207
Pb/206Pb ages on the concordia ranging from
328
textures (Fig. 4h) show similar
329
1807±30 Ma to 1864±22 Ma with U contents of 127–387/116–866 ppm, Th contents
330
of 59–200/63–814 ppm and Th/U ratios of 0.47–0.58/0.47–1.28, respectively. These
331
analyses yield a weighted mean
332
interpreted as the formation age of this rock.
333
5.1.3. K-feldspar granite
207
Pb/206Pb age of 1834±10 Ma (Fig. 5h), which is
334
Most of the zircons from the K-feldspar granite samples are columnar or rounded
335
in shape and about 100–400 µm in length (Fig. 4i–m). The characteristics of zircons
336
from each sample are described respectively below.
337
Most of the zircons from sample S137 show no rim-core structures but
338
well-developed oscillatory zonings in CL images, implying magmatic origin (Fig. 4i).
339
All of twenty analytical spots fall along a concordia or near-concordia and give Th/U
340
ratios of 0.24–0.87, with Th and U contents of 92–567 ppm and 200–651 ppm,
341
respectively. These results define a linear array on the concordia diagram and yield an
342
upper intercept age of 1834±10 Ma (Fig. 6a), which is considered as the emplacement
343
age of this rock.
344
Zircons from S140 are euhedral to subhedral and
characterized
by
345
core-mantle-rim and mantle-rim structures (Fig. 4j). The cores show obvious
346
oscillatory zoning indicating magmatic origin, while the dark mantles and luminous
347
rims are homogeneous indicative of metamorphic origin. Five analyses were carried
348
out on the rims. These results are distributed on the concordia and yield a weighted
349
mean 207Pb/206Pb age of 1834±22 Ma (Fig. 6b), which are interpreted as the age of one
16
350
metamorphic event, with U, Th contents and Th/U ratios of 149–1181 ppm, 53–69
351
ppm and 0.06–0.41, respectively. Four analyses (spots 04, 05, 09 and 16) were
352
performed on the dark mantle domains, three of which are concentrated on the
353
concordia and give a weighted mean
354
contents and Th/U ratios of 590–1415 ppm, 120–295 ppm and 0.19–0.21, respectively,
355
which probably represents one thermal event, although it cannot be explained now.
356
Nine of eleven analyses on the oscillatory-zoned cores are distributed on or close to
357
the concordia and define an upper intercept age of 2271±28 Ma (Fig. 6b). Seven of
358
them are concentrated on the concordia and near the upper intercept, and yield a
359
weighted mean
360
emplacement age of this rock and consistent with the upper intercept age within
361
analytical uncertainties.
207
207
Pb/206Pb age of 2040±20 Ma with U, Th
Pb/206Pb age of 2275±14 Ma, which is considered as the
362
Zircons from sample S142 are euhedral to subhedral in shape and show weak
363
magmatic rhythmic textures with low to medium luminescence (Fig. 4k), indicating
364
magmatic origin. Twenty spot analyses fall on or very close to the concordia and
365
define an upper intercept age of 1836±17 Ma (Fig. 6c) with Th, U contents and Th/U
366
ratios of 61–462 ppm, 223–1431 ppm and 0.11–0.64, respectively. These results yield
367
a weighted mean
368
emplacement age of this rock.
207
Pb/206Pb age of 1839±8 Ma (Fig. 6c), which is considered as the
369
Zircons from sample S143 are mostly euhedral to subhedral with magmatic
370
rhythmic textures implying magmatic origin, and some of them show inherited cores
371
with strong luminescence (Fig. 4l). Nineteen spot analyzes define a linear array on the
17
372
concordia and yield an upper intercept age of 1868±15 Ma (Fig. 6d) with Th, U
373
contents and Th/U ratios of 27–2840 ppm, 117–2746 ppm and 0.13–1.98, respectively.
374
Sixteen concordant spots near the upper intercept yield a weighted mean
375
age of 1864±10 Ma, consistent with the upper intercept age, and is taken as the
376
emplacement age of this rock. One spot analyze on the inherited core fall on the
377
concordia and yield a 207Pb/206Pb age of 2474±17 Ma.
207
Pb/206Pb
378
Most zircons from sample S151 are euhedral to subhedral and show core-rim
379
structures. The cores exhibit higher luminescence than the rims and show weak or
380
blurred oscillatory zonings, indicative of magmatic origin. The rims and some grains
381
are free of zonings, implying metamorphic origin. Twenty-one spots were analyzed on
382
15 zircon grains for sample S151. Eight spots on homogeneous rims or grains with
383
dark luminescence (Fig. 4m) fall on or very close to the concordia, and give U, Th
384
contents and low Th/U ratios of 702–993 ppm, 45–263 ppm and 0.05–0.28,
385
respectively. Seven of them yield a weighted mean
386
(Fig. 6e), which is considered as the age of one metamorphic event. Nine valid spots
387
on cores and grains with weak or blurred oscillatory zonings are concordant and yield
388
a weighted mean
389
age of this rock with U, Th contents and Th/U ratios of 179–557 ppm, 96–235 ppm
390
and 0.23–0.72, respectively.
391
5.1.4. Coarse-grained granite
207
207
Pb/206Pb age of 1840±14 Ma
Pb/206Pb age of 2326±12 Ma, which is taken as the emplacement
392
The zircon grains from the coarse-grained granite samples are euhedral to
393
subhedral and about 150–400 µm in length (Fig. 4n–p). The characteristics of zircons
18
394
from each sample are described respectively below.
395
Most of the zircon grains from sample S159 are euhedral to subhedral and show
396
weak or blurred oscillatory zonings, indicative of magmatic origin. Some of them
397
exhibit inherited cores (Fig. 4n). Twenty-two analytical spots in this sample give
398
similar
399
upper intercept age of 1802±13 Ma (Fig. 6f), with Th, U contents and high Th/U
400
ratios of 57–926 ppm, 95–990 ppm and 0.38–1.19, respectively. All of these
401
analytical spots fall on or very close to the concordia and yield a weighted mean
402
207
403
of this rock.
207
Pb/206Pb ages ranging from 1776±26 Ma to 1829±25 Ma and define an
Pb/206Pb age of 1801±10 Ma (Fig. 6f), which is considered as the emplacement age
404
Zircons from S160 are characterized by core-mantle-rim, mantle-rim and
405
core-rim structures (Fig. 4o). The cores are anhedral and show dark luminescence and
406
weak oscillatory zonings implying inherited origin, while the dark luminescence
407
mantles and the luminous rims exhibit obvious magmatic rhythmic textures indicating
408
magmatic origin. Some zircon grains show no structures but obvious oscillatory
409
zonings with strong luminescence implying magmatic origin. Fourteen analyses on
410
the luminous rims or grains with well-developed oscillatory zonings and five analyses
411
on the mantles with oscillatory zonings give similar
412
Ma to 1860±21 Ma with Th, U contents and Th/U ratios of 63–967 ppm, 88–502 ppm
413
and 0.22–1.93, respectively. These results define a linear array on the concordia and
414
yield an upper intercept age of 1829±12 Ma (Fig. 6g), which is interpreted as the
415
emplacement age of this rock. Seven of eight analyses on the inherited cores also
19
207
Pb/206Pb ages from 1799±23
416
define a linear array on the concordia diagram and yield an upper intercept age of
417
2326±46 Ma (Fig. 6g).
418
Zircons from sample S163 show no core-rim structures but weak oscillatory
419
zonings with dark luminescence implying magmatic origin (Fig. 4p). Twenty-one
420
spots were performed on 15 grains. Twenty of them are distributed on or close to the
421
concordia and give an upper intercept age of 1838±25 Ma (Fig. 6h), which is
422
considered as the emplacement age of this rock, with Th, U contents and Th/U ratios
423
of 50–358 ppm, 62–276 ppm and 0.63–1.21, respectively.
424
5.2. Whole-rock major and trace elements
425
The whole-rock major and trace element compositions of the TTG gneisses and
426
potassic granites are given in Table 1. Detailed characteristics of these results are
427
described as follows.
428
5.2.1. TTG gneiss
429
The samples of this group contain SiO2 from 67.46 to 71.73 wt%, K2O from 1.84
430
to 2.21 wt%, high Na2O from 4.83 to 5.95 wt%, Al2O3 from 15.55 to 16.98 wt%,
431
Fe2O3 from 2.40 to 3.27 wt% and MgO from 0.72 to 1.06 wt% with Na2O/K2O ratios
432
from 2.34 to 3.23, respectively. Their Mg# [Mg#=Mg/(Mg+Fe), Fe=0.8998FeT] range
433
from 31 to 40. In the Ab-Or-An diagram (Barker and Arth, 1976), all the three
434
samples are plotted in the field of trondhjemite (Fig. 7). In the plot of SiO2 vs.
435
Na2O+K2O (Fig. 8), they are in the fields of granodiorite-granite. These rocks have a
436
calc-alkaline property (Fig. 9a) with δ values (δ=[w(Na2O+K2O)2]/[w(SiO2)2-43])
437
from 1.61 to 2.48, and show weakly peraluminous feature with A/CNK ratios ranging
20
438
from 1.04 to 1.14 and A/NK ratios ranging from 1.43 to 1.55 (Fig. 9b).
439
On the chondrite-normalized REE patterns, all the samples show LREE-enriched
440
and HREE-depleted patterns (Fig. 10a) with moderate (La/Yb)N values (16.8 to 35.3)
441
(Fig. 11) and weakly negative or positive Eu anomalies (Eu/Eu*=0.79–1.18). The
442
rocks have high La (18.4–62.6 ppm) and low Yb (0.53–1.67 ppm) with low Dy/Yb
443
ratios ranging from 1.17 to 2.28. On the primitive mantle-normalized trace elements
444
spidergram, the rocks show negative Ta, Nb, Ti, Sr, P anomalies and positive K, Nd
445
anomalies with Nb/Ta and Sr/Y ratios of 28.1–34.1 and 15.8–34, respectively.
446
5.2.2. Granitic gneiss
447
The rocks of this type have SiO2 ranging from 65.20 to 73.70 wt%, low Na2O
448
from 2.39 to 4.17 wt%, Al2O3 from 13.29 to 17.71 wt%, Fe2O3 from 1.51 to 3.64 wt%
449
and MgO from 0.34 to 1.19 wt%. They show Na2O/K2O ratios ranging from 0.34 to
450
1.07 and high K2O from 5.03 to 6.95 wt%, except one sample has lower K2O of 3.90
451
wt% with low SiO2 content of 65.20 wt%. The Mg# of these rocks range from 21 to
452
31 with the exception of one sample having higher Mg# of 46. In the plot of SiO2 vs.
453
Na2O+K2O (Fig. 8), they are in the fields of granite and quartz-monzonite. These
454
rocks show high-K calc-alkaline to shoshonitic properties (Fig. 9a) with δ values from
455
2.24 to 2.93 and weakly peraluminous feature with A/CNK ratios ranging from 1.06
456
to 1.27 and A/NK ratios ranging from 1.16 to 1.60 (Fig. 9b).
457
The samples are also enriched in LREE relative to HREE on the
458
chondrite-normalized REE patterns (Fig. 10c) with moderate to high (La/Yb)N values
459
of 25.4–202 (Fig. 11). Two samples (S144 and S145) show negative Eu anomalies
21
460
(Eu/Eu*=0.49–0.50), while the other three samples show obvious positive Eu
461
anomalies (Eu/Eu*=1.47–2.94). The rocks show low Dy/Yb ratios of 1.29 to 3.43. On
462
the primitive mantle-normalized spidergram (Fig. 10d), the rocks show negative Ta,
463
Nb, Sr, P anomalies (slightly positive Sr anomaly in S155), negative Ti anomaly in
464
S145 and positive K anomalies with Nb/Ta and Sr/Y ratios of 24.0–33.1 and 12.8–119,
465
respectively.
466
5.2.3. K-feldspar granite
467
These rocks contain higher SiO2 (72.08 to 75.43 wt%), K2O (5.93 to 8.60 wt%)
468
but relatively lower Na2O (1.74 to 2.83 wt%), Al2O3 (12.60 to 14.13 wt%), Fe2O3
469
(0.83 to 2.62 wt%) and MgO (0.11 to 0.34 wt%) contents compared to the granitic
470
gneisses. In the plot of SiO2 vs. Na2O+K2O (Fig. 8), they plot in the field of granite.
471
Their Na2O/K2O ratios range from 0.20 to 0.47 with Mg# from 8 to 41. All the rocks
472
show a shoshonitic property (Fig. 9a) with δ values from 2.14 to 3.68 and weakly
473
peraluminous future with A/CNK ratios ranging from 1.07 to 1.20 and A/NK ratios
474
ranging from 1.13 to 1.29 (Fig. 9b).
475
All the samples of this group also exhibit a LREE-enriched and HREE-depleted
476
patterns (Fig. 10e). Two of them (S140 and S142) show weakly negative or positive
477
Eu anomalies (Eu/Eu*=0.77–1.19) with (La/Yb)N values of 6.5–10.3 (Fig. 11).
478
Another two samples (S137 and S151) show obvious negative Eu anomalies
479
(Eu/Eu*=0.34–0.42) with high (La/Yb)N values of 49.4–226, while the last one
480
sample (S143) show obvious positive Eu anomalies (Eu/Eu*=2.63) with moderate
481
(La/Yb)N values of 26.9. On the primitive mantle-normalized spidergram (Fig. 10f),
22
482
the rocks show negative Ta, Nb, Ti, P anomalies, negative to positive Sr anomalies
483
and positive K anomalies with Nb/Ta and Sr/Y ratios of 11.9–27.7 and 6.7–121,
484
respectively.
485
5.2.4. Coarse-grained granite
486
These rocks have SiO2 contents from 68.54 to 73.20 wt%, K2O from 4.03 to 7.20
487
wt%, Na2O from 2.73 to 4.00 wt%, Al2O3 from 13.89 to 16.18 wt%, Fe2O3 from 1.65
488
to 3.30 wt% and MgO from 0.02 to 0.64 wt% with Na2O/K2O ratios ranging from
489
0.43 to 0.99 and Mg# from 2 to 43, respectively. In the plot of SiO2 vs. Na2O+K2O
490
(Fig. 8), they plot naturally in the field of granite. All the rocks show a shoshonitic
491
property with δ values from 2.52 to 3.89 and weakly metaluminous-peraluminous
492
futures with A/CNK ratios ranging from 1.00 to 1.16 and A/NK ratios ranging from
493
1.13 to 1.48, respectively (Fig. 9).
494
These samples also have LREE-enriched chondrite-normalized patterns with
495
moderate (La/Yb)N values ranging from 17.3 to 33.3 (Fig. 11) and show no or positive
496
Eu anomalies (Eu/Eu*=0.82–3.03) (Fig. 10g). These rocks have high Sr/Y ratios
497
(22.1–208) and Nb/Ta ratios (12.3–31.7) with negative Nb, Ta, P anomalies and
498
positive K anomalies on the primitive mantle-normalized spidergram (Fig. 10h).
499
6. Discussion
500
6.1. Multistage magmatism and metamorphism
501
Zircons from the TTG gneiss samples in this study reveal two episodic magmatic
502
ages (2254±29 Ma to 2315±16 Ma, and 2485±21 Ma) and one episodic
503
metamorphism ages (1815±20 Ma to 1968±24 Ma), indicating the trondhjemite of the
23
504
Taihua complex in the Mts. Huashan area formed in the Early Paleoproterozoic and
505
underwent metamorphism in the Late Paleoproterozoic. These results are consistent
506
with Huang et al. (2013), in which three episodes of crystallizations of the TTG
507
gneisses in this area were recognized (~2.48 Ga, ~2.31 Ga and ~2.16 Ga).
508
Three episodes of magmatism and one episodic metamorphism were identified
509
by zircons from the granitic gneiss samples. The first episode of magmatism
510
(2495±11 Ma to 2551±11 Ma) was represented by the formation of samples S148 and
511
S149 during the Late Neoarchean to the Early Paleoproterozoic, while the second
512
episode of magmatism (2283±12 Ma) was reflected by the emplacement of sample
513
S145 in the Early Paleoproterozoic. The metamorphism (1794±20 Ma to 1963±17 Ma)
514
recorded by these pre-exist rocks occurred at the same time with the third episode of
515
magmatism (1829±10 Ma to 1834±10 Ma), represented by the formation of samples
516
S144 and S155, in the Late Paleoproterozoic.
517
Two magmatism episodes and one metamorphic episode were also recognized in
518
the K-feldspar gneiss samples. The first episode of magmatism is exhibited by the
519
emplacement of samples S140 and S151 in the Early Paleoproterozoic (2275±14 Ma
520
to 2326±12 Ma), and the episode of metamorphism in the Late Paleoproterozoic
521
(1834±22 Ma to 1840±14 Ma) was also recorded. The second episode of magmatism
522
is represented by the formation of samples S137, S142 and S143 in the Late
523
Paleoproterozoic (1834±10 Ma to 1868±15 Ma).
524 525
The emplacement age of the coarse-grained granite samples (1801±10 Ma to 1838±25 Ma) also reveal the episode of magmatism in the Late Paleoproterozoic.
24
526
6.2. Petrogenesis of the granitoids
527
The large ion lithophile elements (LILEs), such as K, Cs, Rb and Ba are
528
susceptible to high-grade metamorphism and not useful in determining the nature of
529
the protolith of rocks experienced high-grade metamorphism. But some rare earth
530
elements (REEs, e.g. La, Ce and Yb) and high field strength elements (HFSEs, e.g.
531
Nb, Zr and Hf) are less susceptible to high-grade metamorphism and could preserve
532
the original information of the rocks (Pearce, et al., 1992; Kerrich et al., 1998).
533
Therefore, in the petrogenetic discussion in this study, we primarily based on the
534
elements of Si, Mg, Al, REEs and HFSEs, which are reliable in determining the
535
nature of the protolith of these rocks.
536
6.2.1. TTG gneiss
537
The three TTG gneiss samples collected in this study all belong to trondhjemite
538
in the normalized plot of An-Ab-Or (Fig. 7) with moderate Sr/Y ratios (15.8–34.0)
539
and (La/Yb)N values (16.8–35.3), showing characteristics of TTGs and adakites (Fig.
540
11) (Martin et al., 2005; Condie, 2005). The absence of evidence of any pre-existing
541
high Sr/Y and La/Yb sources in the Huashan area (Huang et al., 2013) led to that
542
these TTGs probably generated from partial melting of hydrous mafic rocks with
543
garnet and amphibole in the residue (e.g., Smithies, 2000; Martin et al., 2005; Condie,
544
2005). Although debate still exists on the tectonic setting for the formation of the TTG
545
assemblage (e.g., Martin, 1999; Smithies and Champion, 2000; Foley et al., 2002;
546
Condie, 2005; Foley, 2008; Moyen, 2009), they are commonly considered as the
547
product of partial melting of subducting oceanic crust under eclogite facies conditions,
25
548
which are characteristic of high Mg# values and high Cr and Ni concentrations due to
549
the interaction of the partial melts with peridotitic mantle during its ascent (Defant
550
and Drummond, 1990; Kay et al., 1993; Martin, 1999; Rapp et al., 1999; Smithies and
551
Champion, 2000; Martin et al., 2005; Moyen, 2009). Another familiar formation
552
mechanism is partial melting of hydrous thickened lower crust, which would produce
553
melts with low Mg# values and low Cr and Ni concentrations (Atherton and Petford,
554
1993; Rapp et al., 1999; Smithies 2000, 2002; Condie, 2005). The Huashan TTG
555
samples in this study show high SiO2 concentrations, low Mg# values and low Cr and
556
Ni concentrations, implying that the trondhjemite samples are probably derived from
557
a hydrous thickened, basaltic lower crust.
558
Generally, plagioclase has excessively high positive Sr and Eu anomalies but
559
highly depletion of other REEs (McKay et al., 1994; Niu and O’Hara, 2009), so the
560
absence of obvious Eu anomalies and high Sr concentrations of these trondhjemite
561
samples possibly imply a plagioclase-free/poor source and the lack of plagioclase
562
either as obvious accumulation or fractionating phases. The HREE-depleted REE
563
patterns revealed in these rocks indicate the potential residual phases of garnet and/or
564
amphibolite during partial melting (e.g., Martin et al., 2005) or garnet and/or
565
amphibolite fractionation during ascent. Partial melting with garnet in the residue will
566
effectively increase Sr/Y, La/Yb, Gd/Yb and Dy/Yb ratios, while melts with
567
amphibole as a residual phase will have low Nb/Ta, Gd/Yb and Dy/Yb ratios
568
(Macpherson et al., 2006; Davidson et al., 2007). Positive correlation between the
569
Sr/Y and La/Yb ratios could be observed as the result of fractionation of amphibole
26
570
and/or garnet (Huang et al., 2012). The rocks show moderate (La/Yb)N values
571
(16.8–35.3), Sr/Y ratios (15.8–34.0) and low Gd/Yb (2.10–3.32), Dy/Yb (1.71–2.28)
572
ratios and no correlation relationship between Sr/Y ratios and (La/Yb)N values was
573
observed (Table. 1), probably suggesting the parental magma of these trondhjemite
574
samples derived from partial melting of a source with both garnet and amphibole in
575
the residue. Moreover, the absence of concave upward REE patterns (Fig.9a) indicates
576
garnet was the dominant residual phase, because amphibole has a higher KD for
577
medium REEs than those for HREEs (Rollinson, 1993). The negative Nb, Ta
578
anomalies, positive Zr, Hf anomalies and high Nb/Ta (28.1−34.1) ratios of these
579
trondhjemite samples maybe indicate a residual phase of rutile in the source (Klemme
580
et al., 2005). It is anticipated that the primary magmas of these trondhjemite rocks
581
were probably derived from partial melting of a plagioclase-poor garnet-rich
582
amphibolites or rutile-bearing eclogite source, similar to medium- or high-pressure
583
TTG groups (Moyen, 2011).
584
6.2.2. Granitic gneisses
585
Most of the granitic gneiss samples have high SiO2, K2O and low Na2O, MgO,
586
CaO contents. They also have LREE-enriched and HREE-depleted patterns similar to
587
those of the TTG samples except for the obvious positive/negative Eu anomalies (Fig.
588
10c). These REE patterns and high (La/Yb)N values (25.4–202), Sr/Y ratios (12.8–119)
589
and low Gd/Yb (2.70–11.1), Dy/Yb (1.29–3.43) ratios and the lack of Sr/Y ratios
590
correlation with (La/Yb)N values indicate the parental magma of these samples
591
perhaps were derived from partial melting of a source with garnet and amphibole in
27
592
the residue. Positive Eu anomalies in the samples S148, S149 and S155 can be
593
explained by plagioclase accumulation in the rocks, while negative Eu anomalies in
594
the other two samples S144 and S145 possibly suggest plagioclase existing in the
595
residue and/or plagioclase fractionation during magma ascent.
596
6.2.3. K-feldspar granites
597
Although different chemical affinities exist among these samples, which were
598
probably resulted from partial melting of different/heterogeneous source rocks,
599
melting conditions or interaction with hydrothermal fluids (Villemant et al., 1996; Wu
600
et al., 2003), they also show high SiO2 and K2O, low Na2O, MgO and CaO contents.
601
The HREE-depleted patterns with various (La/Yb)N values (6.5–226), Sr/Y ratios
602
(6.7–121) and low Gd/Yb (1.75–11.1), Dy/Yb (2.35–6.47) ratios and the lack of Sr/Y
603
ratios correlation with (La/Yb)N values probably imply the residual phases of garnet
604
and amphibole in different proportions. The absence of obvious Eu anomalies and
605
high Sr concentrations of samples S140 and S142 (Fig. 10e) possibly indicate a
606
plagioclase-free/poor source and the lack of plagioclase either as obvious
607
accumulation or fractionating phases. The obvious negative Eu anomalies in S137 and
608
S151 could result from plagioclase removal by fractional crystallization or as a
609
residual phase during partial melting, and plagioclase accumulation could account for
610
the positive Eu anomaly in S143. Depletions of Nb, Ta and Ti were probably resulted
611
from rutile fractionation or as a residual phase in the source (Ionov and Hofmann,
612
1995; Xiong et al., 2005; Coltorti et al., 2007).
613
6.2.4. Coarse-grained granites
28
614
The three coarse-grained granite samples collected in this study have moderate to
615
high Sr/Y ratios (22.1–208) and (La/Yb)N values (17.3–33.3) and show characteristic
616
of TTGs and adakites (Defant and Drummond, 1990; Martin et al., 2005; Condie,
617
2005). The HREE-depleted patterns with high Sr/Y, (La/Yb)N, Zr/Sm (44.8−379) and
618
low Gd/Yb (2.54−3.31), Dy/Yb (1.48−2.48) can be interpreted by amphibole and
619
garnet as residual phases during partial melting or as fractionating phases. Positive
620
correlation between the Sr/Y ratios and (La/Yb)N values can be found in these
621
samples (Table. 1), so fractionation of amphibole and/or garnet couldn’t be ruled out
622
for these rocks. The relatively low and limited Dy/Yb variations indicate that the
623
contribution of dominant amphibole with minor garnet during partial melting or
624
fractional crystallization could be the main mechanism for the moderate to high Sr/Y
625
ratios and (La/Yb)N values of these rocks, which is consisted with the relatively flat
626
HREE patterns except for sample S160 (Fig. 10g). Plagioclase accumulation could
627
account for the positive Eu and Sr anomalies in S159 and S163, which was not
628
observed in S160.
629
As mentioned above, the absence of evidence of any pre-existing high Sr/Y and
630
La/Yb sources in the Huashan area (Huang et al., 2013) suggested that these potassic
631
granites also probably generated from partial melting of hydrous mafic rocks with
632
garnet and amphibole in the residue (e.g., Smithies, 2000; Martin et al., 2005; Condie,
633
2005). In conclusion, the potassic granites are generally considered as the results of
634
partial melting of subducted slab with assimilation/interaction of mantle wedge
635
peridotite or the product of partial melting of lower crustal materials (Moyen et al.,
29
636
2003; Jayananda et al., 2006; Moyen, 2011), which is supported by experimental
637
studies (Skjerlie and Jonston, 1993; Wang et al., 2005; Watkins et al., 2007). Most of
638
the potassic granite samples in this study show high SiO2, K2O and low MgO, ruling
639
out of the basaltic oceanic crustal source (Smithies, 2000). Therefore, it is suggested
640
that most of the potassic granites in this area were derived from partial melting of
641
lower crustal sources, which is also sustained by inherited zircons from some of these
642
samples. As mentioned above, different chemical features among these samples were
643
probably resulted from partial melting of different/heterogeneous source rocks,
644
melting conditions or interaction with hydrothermal fluids (Villemant et al., 1996; Wu
645
et al., 2003). More detailed and meticulous studies are necessary on each kind of these
646
potassic granites in the future.
647
6.3. Episodic crustal growth and reworking in the southern TNCO
648
In the last decades, more and more accurate geochronological and isotopic data
649
were obtained from the Taihua complex and revealed several obvious episodic
650
magmatic activities occurred in the southern segment of the TNCO at 2.84–2.72 Ga,
651
2.57–2.43 Ga, 2.36–2.25 Ga, 2.19–2.07 Ga and 1.87–1.80 Ga (e.g., Wan et al., 2006;
652
Liu et al., 2009; Diwu et al., 2010, 2014; Huang et al., 2010, 2012, 2013; Jiang et al.,
653
2011; Wang et al., 2012, 2013a, 2014; Zhou et al., 2014).
654
The first episode of magmatic activity (2.84–2.72 Ga) is recorded in the
655
granitoids and amphibolites from Lushan area (Liu et al., 2009; Diwu et al., 2010;
656
Huang et al., 2010; Zhou et al., 2014), which can be subdivided into two groups. The
657
first subgroup is represented by the granitoids formed at 2.84–2.77 Ga, which are
30
658
predominantly composed of TTG gneisses. These granitoids are characterized by low
659
SiO2 and high MgO (Mg#) with positive whole rock ƐNd(t) and zircon ƐHf(t) values
660
and were interpreted as production of partial melting of subducted oceanic crust with
661
interaction with the mantle wedge in a subduction setting (Diwu et al., 2010; Huang et
662
al., 2010; Zhou et al., 2014). The second subgroup is represented by minor TTG
663
gneisses and other granites formed at 2.76–2.72 Ga, which exhibit high SiO2 and low
664
MgO (Mg#) with negative whole rock ƐNd(t) and zircon ƐHf(t) values and were
665
explained as the results of partial melting of thickened mafic lower crust (Huang et al.,
666
2010; Zhou et al., 2014), probably triggered by underplating of basaltic magmas
667
extracted from mantle wedge (Zhou et al., 2014). In consequence, crustal growth is
668
dominant in the southern segment of the TNCO in the Early Neoarchean,
669
accompanied by a small amount of crustal reworking, which is consistent to the major
670
period of juvenile crustal growth in the NCC at ca. 2.8–2.7 Ga (Wu et al., 2005; Sun
671
et al., 2012; Wang and Liu, 2012). Juvenile continental crust can be produced at
672
subduction settings or by mantle plumes (Condie, 1998). Although the partial melting
673
of ocean crust in subduction setting was favored in previous studies (e.g., Huang et al.,
674
2010; Zhou et al., 2014), which means the initial subduction developed in the
675
southern NCC in the Archaean. However, why is this episode of magmatic activity
676
only preserved in Lushan area in the Taihua complex adjacent to the Eastern Block?
677
Zhao et al. (2007, 2013) interpreted these 2.8–2.7 Ga rocks in the Trans-North China
678
Orogen as the remnants of old continental basement, which most likely represented
679
the western margin of the Eastern Block. Assuredly, Liu et al. (2009) obtained the
31
680
metamorphic ages of 2.77–2.79 Ga and 2.64–2.67 Ga for the 2.83–2.85 Ga TTG
681
gneisses and amphibolites from the Taihua complex in Lushan area, which are similar
682
to the rock-forming and metamorphic ages of the granite-greenstone belt in Western
683
Shandong in the Eastern Block (Wan et al., 2011). In that case, the geodynamic
684
setting and geological evolution history of this tectonothermal event during 2.8–2.7
685
Ga are still equivocal and prefer a mantle plume model (e.g., Polat et al., 2006; Wan
686
et al., 2011; Wang et al., 2013b). Therefore, extensive and intensive investigations are
687
still needed on this episode of magmatic activity to explore the Early Neoarchean
688
evolution of the NCC.
689
The second episodic magmatic event (2.57–2.43 Ga) is represented by the
690
granitoids from Huashan and Dengfeng areas (Wan et al., 2009; Diwu et al., 2011,
691
2014; Huang et al., 2013; Zhang et al., 2013; this study) and amphibolites from the
692
Dengfeng and Lushan areas (Diwu et al., 2011; Lu et al., 2013, 2014; Zhang et al.,
693
2013). This episodic magmatic rocks show dominantly positive whole rock ƐNd(t) and
694
positive zircon ƐHf(t) values, indicating juvenile compositions (Diwu et al., 2011,
695
2014; Huang et al., 2013). Therefore, another major crustal growth episode was
696
recorded in the southern segment of the TNCO from the Late Neoarchean to the Early
697
Paleoproterozoic, which was also universal in the NCC (Zhai et al., 2010; Zhao and
698
Zhai, 2013). Diwu et al. (2011) interpreted these TTGs in Dengfeng areas as results of
699
partial melting of subducted oceanic crust with interaction with mantle peridotite,
700
whereas Huang et al. (2013) suggested that these rocks in Dengfeng and Huashan
701
areas generated similarly through partial melting of thickened lower crust in a
32
702
subduction setting. In this study, the granitoids from Huashan area show high SiO2
703
and low MgO (Mg#) and are also conjectured as partial melting of lower thickened
704
crust. Minor TTG gneisses in Huashan and potassic granites in Lushan show negative
705
whole rock Ɛ Nd(t) and positive zircon Ɛ Hf(t) values and are interpreted as results from
706
partial melting of pre-existing crustal materials (Huang et al., 2013; Zhou et al.,
707
2014).
708
The third episodic magmatic event (2.36–2.25 Ga) is dominantly presented by
709
the emplacement of the granitoids and the protoliths of the amphibolites from the
710
Huashan and Luoning areas (Diwu et al., 2007; Jiang et al., 2011; Huang et al., 2012,
711
2013; Wang et al., 2012, 2014; Yu et al., 2013; this study). This episodic magmatic
712
rocks show negative to positive whole rock ƐNd(t) and positive zircon ƐHf(t) values
713
with low MgO (Mg#) (Diwu et al., 2011, 2014; Huang et al., 2013; Yu et al., 2013;
714
this study). Thus, both crustal growth and reworking occurred in the southern segment
715
of TNCO in the Early Paleoproterozoic. These granitoids were interpreted resulting
716
from the partial melting of both juvenile and pre-existing crustal materials in a
717
subduction tectonic setting (Huang et al., 2013) or have resulted from partial melting
718
of lower crust and interacted with peridotitic mantle (Diwu et al., 2014). Based on the
719
characteristic of high SiO2 and low MgO (Mg#) contents of the granitoids in this
720
study, we agree with Huang et al. (2013) that these rocks were produced by partial
721
melting of both juvenile and pre-existing crustal materials. And we propose that this
722
magmatism was probably triggered by underplated mantle-derived basaltic magma,
723
which was probably emerged as amphibolite enclaves in the metamorphic complex at
33
724
present with protolith age of ~2.3 Ga (Wang et al., 2014). The depositional age of the
725
meta-sedimentary rocks from Lushan area terrane was constrained between 2.3 Ga
726
and 2.0 Ga (Wan et al., 2006; Diwu et al., 2014), meanwhile our previous studies also
727
indicated the protolith of the meta-sedimentary rocks in the Huashan and Luoning
728
areas terranes also formed after ~2.3 Ga (Jiang et al., 2011; Wang et al., 2012, 2013a).
729
Therefore, a continental margin arc or island arc setting was suggested at this time,
730
and the volcanic-sedimentary rocks developed in the back-arc basins.
731
The fourth episode of magmatism (2.19–2.07 Ga) is revealed by the granitoids
732
from the Huashan and the Luoning areas (Huang et al., 2012, 2013), which were
733
interpreted as the results of crustal reworking in an extensional setting related to the
734
breakup of one supercontinent (Huang et al., 2013).
735
The last episode of magmatism (1.87–1.80 Ga) is represented by the formation of
736
the granitoids from Mts. Huashan area in this study, which is synchronism with the
737
metamorphism recorded not only in the pre-existing granitoids but also in amphibolite
738
and metasedimentary in this region (Wang et al., 2012, 2013a, 2014). This episodic
739
magmatic activity was never reported noticeably in the Taihua complex in previous
740
studies (e.g., Liu et al., 2009; Huang et al., 2010, 2012, 2013; Diwu et al., 2010, 2014;
741
Zhou et al., 2014) and is presented remarkably in this study. The P–T paths
742
reconstructed from amphibolites in this region imply a continent-continent collision
743
between the Eastern Block and the Western Block and followed by rapid uplift
744
process (Wang et al., 2014), indicating transformation of tectonic environment from
745
compression to extension during the Late Paleoproterozoic. The last episodic
34
746
magmatism was probably resulted from partial melting of pre-existing crustal
747
materials during this period of time in a syn-orogenic or post-orogenic setting.
748
Therefore, crustal evolution in the southern TNCO is dominant by reworking in the
749
Late Paleoproterozoic.
750
6.4. Implication for tectonic evolution in the southern TNCO
751
The Taihua complex can be divided into the Lower Taihua subgroup and Upper
752
Taihua subgroup. The former principally consists of TTG gneisses, granitic gneisses,
753
metabasite and minor meta-supracrustal rocks, whereas the latter is dominantly
754
composed of meta-supracrustal rocks including metapelite, marbles and BIF. The
755
protolith of this rock combination was preferred as a marine volcanic-sedimentary
756
formation (Sun et al., 1983; Qi, 1992; Chen et al., 1997; Zhou et al., 1997, 1998),
757
indicating an active continental margin or island arc setting. As we mentioned, more
758
extensive and intensive investigations are needed on the episode of magmatic activity
759
in the southern TNCO during the Early Neoarchean (2.8–2.7 Ga). From Late
760
Neoarchean to Late Paleoproterozoic, it is notable that the magmatic activities
761
preserved in the southern TNCO are characterized by continuity rather than episodes.
762
In addition, the ages of magmatic activities in the Taihua complex tend to be younger
763
from the eastern Lushan area to the western Huashan area. Therefore, transformation
764
from an Andean-type continental margin arc setting on the western margin of the
765
Eastern Block to continent-arc-continent collision in the southern TNCO during Late
766
Neoarchean to Late Paleoproterozoic is suggested in this paper.
767
From 2.57 Ga to 2.43 Ga, magmas produced by partial melting of subducted
35
768
oceanic crust interacted with the overlying mantle peridotite and formed the high
769
MgO (Mg#) rocks in Dengfeng area. Synchronously, subduction of the oceanic
770
lithosphere caused partial melting of the mantle wedge, which led to underplating of
771
basaltic magma in the lower crust and formed part of the protolith of the amphibolites
772
in Lushan and Dengfeng areas. These underplating mafic magma provided the
773
thermal flux needed to melt the juvenile and minor pre-existing materials in the lower
774
crust and produce the low MgO (Mg#) granitoids in Lushan and Dengfeng areas and
775
minor TTG gneisses in Huashan area.
776
From 2.36 Ga to 2.25 Ga, as subduction continued, extension driven by the
777
possible trench retreating caused by rollback of subducted plate because of gravity
778
(Niu, 2013) led to the development of back-arc basins. The continuous subduction
779
caused partial melting of the mantle wedge, which led to underplating of mafic
780
magma in the lower crust in Huashan and Luoning areas and formed part of the
781
protolith of the amphibolites. These underplating mafic magma further caused partial
782
melting of lower crust and form large amounts of granitoids in Huashan and Luoning
783
areas. Contemporary volcanic-sedimentary rocks formed in the back-arc basins.
784
From 2.19 Ga to 2.07 Ga, a small amount of magmatism occurred in Huashan
785
and Luoning areas in an extensional setting related to the breakup of one
786
supercontinent (Huang et al., 2013). Here we prefer the extensional setting related to
787
the extension of back-arc basin.
788
Before 1.87–1.80 Ga, the oceanic basin between the Eastern and Western Blocks
789
was completely closed by subduction and led to continent-arc-continent collision
36
790
followed by a rapid uplift process, which can be reflected commendably by the
791
metamorphism recorded in the metamorphic complex (Lu et al., 2013, 3014; Wang et
792
al., 2014; Chen et al., 2015). This magmatism probably resulted from partial melting
793
of re-existing crustal materials in a syn-orogenic or post-orogenic setting.
794
7. Conclusion
795 796
The lithological, geochronological and geochemical data of the granitoids from the Mts. Huashan Taihua complex, allow us arrive at the following conclusions:
797
(1) At least three episodes of magmatism (2.55–2.49 Ga, 2.33–2.25 Ga and
798
1.87–1.80 Ga) occurred in the southern segment of the TNCO during Neoarchean to
799
Paleoproterozoic.
800
(2) The first episode of magmatism (~2.5 Ga) is interpreted as melts from partial
801
melting of thickened juvenile lower crust. The second episodic magmatism (~2.3 Ga)
802
is suggested as the product of partial melting of both juvenile and pre-existing crustal
803
materials, which was probably triggered by underplated mantle-derived basaltic
804
magma. The third episode of magmatism (1.87–1.80 Ga), accompanied by the coeval
805
metamorphism recorded in the metamorphic complex, probably resulted from partial
806
melting of re-existing crustal materials in a syn-orogenic or post-orogenic setting
807
during the collision between the Eastern and Western Blocks.
808
(3) Multistage continental accretion (at 2.84–2.72 Ga, 2.57–2.43 Ga and
809
2.36–2.25 Ga) and reworking (at 2.36–2.25 Ga, 2.19–2.07 Ga and 1.87–1.80 Ga)
810
occurred in the southern segment of the TNCO from Neoarchean to Paleoproterozoic.
811
Transformation from an Andean-type continental margin arc setting on the western
37
812
margin of the Eastern Block to continent-arc-continent collision in the southern
813
TNCO during Late Neoarchean to Late Paleoproterozoic is suggested.
814
Acknowledgements
815
This work was supported by the National Natural Science Foundation of China
816
(41225007, 41130314). We are grateful to Prof. Jin-Hui Yang and Yue-Heng Yang
817
for the LA-ICP-MS U–Pb dating of zircons. Special thanks are due to Profs. Kai-Jun
818
Zhang and Dr. Hao Wang for their discussions and suggestions.
819
References
820
Atherton, M.P., Petford, N., 1993. Generation of sodium-rich magmas from newly
821 822 823
underplated basaltic crust. Nature 362, 144–146. Barker, F., Arth, J.G., 1976. Generation of trondhjemitic-tonalitic liquids and Archaean bimodal trondhjemite-basalt suites. Geology 4, 596–600.
824
Chen, H.X., Wang, J., Wang, H., Wang, G.D., Peng, T., Shi, Y.H., Zhang, Q., Wu,
825
C.M., 2015. Metamorphism and geochronology of the Luoning metamorphic
826
terrane, southern terminal of the Palaeoproterozoic Trans-North China Orogen,
827
North China Craton. Precambrian Research 264, 156–178.
828
Chen, L.G., Wang, B.Y., Xue, Y.Z., 1997. The reestablishment of Taihua Group in
829
Xiao Qinling, Shanxi. Geology of Shanxi 15, 20–30 (in Chinese with English
830
abstract).
831
Coltorti, M., Bonadiman, C., Faccini, B., Grégoire, M., O’Reilly, S.Y., Powell, W.,
832
2007. Amphiboles from suprasubduction and intraplate lithospheric mantle.
833
Lithos 99, 68–84.
38
834
Condie, K.C., 1993. Chemical composition and evolution of the upper continental
835
crust: contrasting results from surface samples and shales. Chemical Geology
836
104, 1–37.
837 838 839 840 841 842 843 844
Condie, K.C., 1998. Episodic continental growth and supercontinents: a mantle avalanche connection? Earth and Planetary Science Letters 163, 97–108. Condie, K.C., 2005. TTGs and adakites: are they both slab melts? Lithosphere 79, 33–44. Davidson, J., Macpherson, C., Turner, S., 2007. Amphibole control in the differentiation of arc magmas. Geochimica et Cosmochimica Acta 71, A204. Defant, M.J., Drummond, M.S., 1990. Derivation of some modern arc magmas by melting of young subduction lithosphere. Nature 347, 662–665.
845
Diwu, C.R., Sun, Y., Gao, J.F., Fan, L.G., 2013. Early Precambrian tectonothermal
846
events of the North China Craton: Constraints from in situ detrital zircon U–Pb,
847
Hf and O isotopic compositions in Tietonggou Formation. Chinese Science
848
Bulletin 58, 3760–3770.
849
Diwu, C.R., Sun, Y., Guo, A.L., Wang, H.L., Liu, X.M., 2011. Crustal growth in the
850
North China Craton at ∼2.5 Ga: evidence from in situ zircon U–Pb ages, Hf
851
isotopes and whole-rock geochemistry of the Dengfeng Complex. Gondwana
852
Research 20, 149–170.
853
Diwu, C.R., Sun, Y., Lin, C.L., Liu, X.M., Wang, H.L., 2007. Zircon U–Pb ages and
854
Hf isotopes and their geological significance of Yiyang TTG gneisses from
855
Henan province, China. Acta Petrologica Sinica 23, 253–262 (in Chinese with
39
856
English abstract).
857
Diwu, C.R., Sun, Y., Lin, C.L., Wang, H.L., 2010. LA-(MC)-ICP-MS U–Pb zircon
858
geochronology and Lu–Hf isotope compositions of the Taihua Complex on the
859
southern margin of the North China Craton. Chinese Science Bulletin 55,
860
2557–2571.
861
Diwu, C.R., Sun, Y., Zhao, Y., Lai, S.C., 2014. Early Paleoproterozoic (2.45–2.20 Ga)
862
magmatic activity during the period of global magmatic shutdown: Implications
863
for the crustal evolution of the southern North China Craton. Precambrian
864
Research 255, 627–640.
865
Faure, M., Trap, P., Lin, W., Monié, P., Bruguier, O., 2007. Polyorogenic evolution of
866
the Paleoproterozoic Trans-North China Belt, new insights from the
867
Lüliangshan–Hengshan–Wutaishan and Fuping massifs. Episodes 30, 1–12.
868
Foley, S., 2008. A trace element perspective on Archean crust formation and on the
869
presence or absence of Archean subduction. In: Condie, K.C., Pease, V.
870
(Eds.), When Did Plate Tectonics Begin? Geological Society of America
871
Special Paper 440, Colorado, pp. 31–50.
872
Foley, S., Tiepolo, M., Vannucci, R., 2002. Growth of early continental crust
873
controlled by melting of amphibolite in subduction zones. Nature 417, 837–840.
874
Frost,
C.D.,
Frost,
B.R.,
Kirkwood,
R.,
Chamberlain,
K.R., 2006. The
875
tonalite-trondhjemite-granodiorite (TTG) to granodiorite-granite (GG) transition
876
in the late Archean plutonic rocks of the central Wyoming Province. Canadian
877
Journal of Earth Science 43, 1419–1444.
40
878
Guo, J.H., Sun, M., Zhai, M.G., 2005. Sm–Nd and SHRIMP U–Pb zircon
879
geochronology of high-pressure granulites in the Sanggan area, North China
880
Craton: timing of Paleoproterozoic continental collision. Journal of Asian Earth
881
Sciences 24, 629–642.
882
Huang, X.L., Niu, Y.L., Xu, Y.G., Yang, Q.J., Zhong, J.W., 2010. Geochemistry of
883
TTG and TTG-like gneisses from Lushan-Taihua complex in the southern North
884
China Craton: Implications for late Archean crustal accretion. Precambrian
885
Research 182, 43–56.
886
Huang, X.L., Wilde, S.A, Yang, Q.J., Zhong, J.W., 2012. Geochronology and
887
petrogenesis of gray gneisses from the Taihua Complex at Xiong'er in the
888
southern segment of the Trans-North China Orogen: Implications for tectonic
889
transformation in the Early Paleoproterozoic. Lithos 134–135, 236–252.
890
Huang, X.L., Wilde, S.A, Zhong, J.W., 2013. Episodic crustal growth in the southern
891
segment of the Trans-North China Orogen across the Archean-Proterozoic
892
boundary. Precambrian Research 233, 337–357.
893
Ionov, D.A., Hofmann, A.W., 1995. Nb-Ta-rich mantle amphiboles and micas:
894
implications for subduction-related metasomatic trace element fractionations.
895
Earth and Planetary Science Letters 131, 341–356.
896
Jahn, B.M., Glikson, A.Y., Peucat, J.J., Hickman, A.H., 1981. REE geochemistry and
897
isotopic data of Archaean silica volcanics and granitoids from the Pilbara Block,
898
western Australia: implications for the early crustal evolution. Geochimica et
899
Cosmochima Acta 45, 1633–1652.
41
900
Jayananda, M., Chardon, D., Peucat, J.J., Capdevila, R., 2006. 2.61 Ga potassic
901
granites and crustal reworking in the western Dharwar craton, southern India:
902
Tectonic, geochronologic and geochemical constraints. Precambrian Research
903
150, 1–26.
904
Jiang, Z.S., Wang, G.D., Xiao, L.L., Diwu, C.R., Lu, J.S., Wu, C.M., 2011.
905
Paleoproterozoic metamorphic P–T–t path and tectonic significance of the
906
Luoning metamorphic complex at the southern terminal of the Trans-North
907
China Orogen，Henan Province. Acta Petrologica Sinica 27, 3701–3717 (in
908
Chinese with English abstract).
909
Kay, S.M., Ramos, V.A., Marquez, M., 1993. Evidence in Cerro Pampa volcanic
910
rocks for slab-melting prior to ridge-trench collision in southern South America.
911
The Journal of Geology 101, 703–714.
912
Kerrich, R., Wyman, D., Fan, J., Bleeker, W., 1998. Boninite series: low Ti-tholeiite
913
associations from the 2.7 Ga Abitibi greenstone belt. Earth and Planetary
914
Science Letters 164, 303–316.
915
Klemme, S., Prowatke, S., Hametner, K., Günther, D., 2005. Partitioning of trace
916
elements between rutile and silicate melts: implications for subduction zones.
917
Geochimica et Cosmochima Acta 49, 2361–2371.
918
Kröner, A., Wilde, S.A., Li, J.H., Wang, K.Y., 2005. Age and evolution of a late
919
Archaean to early Palaeozoic upper to lower crustal section in the
920
Wutaishan/Hengshan/Fuping terrain of northern China. Journal of Asian Earth
921
Sciences 24, 577–595.
42
922 923 924 925
Kusky, T.M., 2011. Geophysical and geological tests of tectonic models of the North China Craton. Gondwana Research 20, 26–35. Kusky, T.M., Li, J.H., 2003. Paleoproterozoic tectonic evolution of the North China Craton. Journal of Asian Earth Sciences 22, 23–40.
926
Liu, D.Y., Nutman, A.P., Compston, W., Wu, J.S., Shen, Q.H., 1992. Remnants of
927
≥3800 Ma crust in the Chinese part of the Sino-Korean Craton. Geology 20,
928
339–342.
929
Liu, D.Y., Wilde, S.A., Wan, Y.S., Wang, S.Y., Valley, J.W., Kita, N., Dong, C.Y.,
930
Xie, H.Q., Yang, C.X., Zhang, Y.X., Gao, L.Z., 2009. Combined U–Pb,
931
hafnium and oxygen isotope analysis of zircons from meta-igneous rocks in
932
the southern North China Craton reveal multiple events in the Late
933
Mesoarchean–Early Neoarchean. Chemical Geology 261, 140–154.
934
Lu, J.S., Wang, G.D., Wang, H., Chen, H.X., Wu, C.M., 2013. Metamorphic P–T–t
935
paths retrieved from the amphibolites, Lushan terrane, Henan Province and
936
reappraisal of the Paleoproterozoic tectonic evolution of the Trans-North China
937
Orogen. Precambrian Research 238, 61–67.
938
Lu, J.S., Wang, G.D., Wang, H., Chen, H.X., Wu, C.M., 2014. Palaeoproterozic
939
Metamorphic evolution and geochronology of the Wugang block, southeastern
940
terminal of the Trans-North China Orogen. Precambrian Research 251,
941
197–211.
942 943
Ludwig, K.R., 2003. Isoplot 3.0-A geochronological toolkit for Micro-soft Excel. Berkeley Geochronology Center, Special Publication 4, 1–70.
43
944
Macpherson, C.G., Dreher, S.T., Thirlwall, M.F., 2006. Adakites without slab
945
melting: high pressure processing of basaltic island arc magma, Mindanao, the
946
Philippines. Earth and Planetary Science Letters 243, 581–593.
947 948
Maniar, P.D., Piccoli, P.M., 1989. Tectonic discrimination of granitoids. Geological Society of America Bulletin 101, 635–643.
949
Martin, H., 1994. The Archean grey gneisses and the genesis of continental crust. In:
950
Condie, K.C. (Ed.), Archean Crustal Evolution. Developments in Precambrian
951
Geology, vol. 11. Elsevier, New York, pp. 205–258.
952 953 954 955 956
Martin, H., 1999. Adakitic magmas: modern analogues of Archaean granitoids. Lithos 46, 411–429. Martin, H., Moyen, J.F., 2002. Secular changes in TTG composition as markers of the progressive cooling of the Earth. Geology 30, 319–322. Martin, H., Smithies, R.H., Rapp, R., Moyen, J.F., Champion, D., 2005. An overview
957
of
958
relationships and some implications for crustal evolution. Lithos 79, 1–24.
959
McKay, G., Le, L., Wagstaff, J., Crozaz, G., 1994. Experimental partitioning of rare
960
earth elements and strontium: constraints on petrogenesis and redox conditions
961
during crystallization of Antarctic angrite Lewis Cliff 86010. Geochimica et
962
Cosmochima Acta 58, 2911–2919.
963 964 965
adakite,
tonalite-trondhjemite-granodiorite
(TTG)
and
sanukitoid:
Middlemost, E.A.K., 1994. Naming materials in the magma/igneous rock system. Earth Science Review 37, 215–244. Moyen, J.F., 2009. High Sr/Y and La/Yb ratios: the meaning of the adakitic
44
966
signature. Lithos 112, 556–574.
967
Moyen, J.F., 2011. The composite Archaean grey gneisses: petrological significance,
968
and evidence for a non-unique tectonic setting for Archaean crustal growth.
969
Lithos 123(1–4), 21–36.
970
Moyen, J.F., Mratin, H., Jayananda, M., Auvray, B., 2003. Late Archean granites: a
971
typology based on the Dharwar Craton (India). Precambrian Research 127,
972
103–123.
973
Niu, Y.L., 2013. Subduction initiation, trench retreat and global tectonic
974
consequences: The origin of back-arc basins in the western Pacific and effect on
975
eastern China geology since the Mesozoic. In: Zhai, M.G., Xiao, W.J. (Eds),
976
Plate Tectonics, Geological Events and Resources: New Advances in Geological
977
Sciences. Science Press, Beijing, pp. 1–25 (in Chinese).
978
Niu, Y.L., O’Hara, M.J., 2009. MORB mantle hosts the missing Eu (Sr, Nb, Ta and Ti)
979
in the continental crust: new perspectives on crustal growth, crust-mantle
980
differentiation and chemical structure of oceanic upper mantle. Lithos 112,
981
1–17.
982
Polat, A., Li, J., Fryer, B., Kusky, T., Gagnon, J., Zhang, S., 2006. Geochemical
983
characteristics of the Neoarchean (2800–2700 Ma) Taishan greenstone belt,
984
North China Craton: evidence for plume-craton interaction. Chemical Geology
985
230, 60–87.
986
Pearce, J.A., van der Laan, S.R., Arculus, R.J., Murton, B.J., Ishii, T., Peate, D.W.,
987
1992. Boninite and Harzburgite from Leg 125 (Bonin-Mariana Fore-arc): a case
45
988
study of magma genesis during the initial stage of subduction. In: Fryer, P.,
989
Pearce, J.A., Stokking, L.B. (Eds.), Proceedings for the Ocean Drilling Program.
990
Sci. Results, vol. 125, pp. 623–659.
991
Peccerillo, R., Taylor, S.R., 1976. Geochemistry of Eocene calc-alkaline volcanic
992
rocks from the Kastamonu areas, Northern Turkey. Contributions to Mineralogy
993
and Petrology 58, 63–81.
994
Peng, P., Wang, X.P., Windley, B.F., Guo, J.H., Zhai, M.G., Li, Y., 2014. Spatial
995
distribution of ~1950–1800 Ma metamorphic events in the North China Craton:
996
Implications for tectonic subdivision of the craton. Lithos 202–203, 250–266.
997
Qi, J.Y., 1992. Metamorphic rock series of Taihua Group and conditions for its
998
formation in eastern Qinling. Scientia Geologica Sinica 8 (Suppl.), 95–107
999
(in Chinese with English abstract).
1000 1001
Qi, L., Hu, J., Grégoire, D.C., 2000. Determination of trace elements in granites by inductively coupled plasma mass spectrometry. Talanta 51, 507–513.
1002
Rapp, R.P., Shimizu, N., Norman, M.D., Applegate, G.S., 1999. Reaction between
1003
slab-derived melts and peridotite in the mantle wedge: experimental constraints
1004
at 3.8 GPa. Chemical Geology 160, 335–356.
1005 1006
Rollinson,
H.R.,
1993.
Using
geochemical
data:
evaluation,
presentation,
interpretation. Longman Technical Press, London, pp. 352.
1007
Santosh, M., 2010. Assembling North China Craton within the Columbia
1008
supercontinent: the role of double-sided subduction. Precambrian Research 178,
1009
149–167.
46
1010
Santosh, M., Sajeev, K., Li, J.H., 2006. Extreme crustal metamorphism during
1011
Columbia supercontinent assembly: evidence from North China Craton.
1012
Gondwana Research 10, 256–266.
1013
Skjerlie, K.P., Johnston, A.D., 1993. Vapour-absent melting from 10 to 20 Kbar of
1014
crustal rocks that contain multiple hydrous phases: implications for anatexis in
1015
the deep to very deep continental crust and active continental margins. Journal
1016
of Petrology 37, 661–691.
1017
Smithies, R.H., 2000. The Archaean tonalite-trondhjemite-granodiorite (TTG)
1018
series is not an analogue of Cenozoic adakite. Earth and Planetary Science
1019
Letters 182, 115–125.
1020 1021
Smithies, R.H., 2002. Archaean boninite-like rocks in an intracratonic setting. Earth and Planetary Science Letters 197, 19–34.
1022
Smithies, R.H., Champion, D.C., 2000. The Archaean high-Mg diorite suite: links to
1023
tonalite-trondhjemite-granodiorite magmatism and implications for early
1024
Archaean crustal growth. Journal of Petrology 41, 1653–1671.
1025
Smithies, R.H., Champion, D.C., Van Kranendonk, M.J., 2009. Formation of
1026
Paleoarchean continental crust through infracrustal melting of enriched basalt.
1027
Earth and Planetary Science Letters 281, 298–306.
1028
Sun, S.S., McDonough, W.F., 1989. Chemical and isotopic systematic of oceanic
1029
basalts: implications for mantle composition and processes. In: Saunders, S.D.,
1030
Norry, M.J. (Eds.), Magmatism in Ocean Basins. Geological Society of London
1031
42, pp. 313–345.
47
1032 1033
Sun, Y., 1983. Rocks in the granulite facie of the Taihua Group at Lushan, Henan. Journal of Northwest University 1, 92–98.
1034
Sun, Y., Yu, Z.P., Kröner, A., 1994. Geochemistry and single zircon geochronology
1035
of Archaean TTG gneisses in the Taihua high-grade terrain, Lushan area, central
1036
China. Journal of Southeast Asian Earth Sciences 10, 227–233.
1037
Sutcliffe, R.H., Smith, A.R., Doherty, W., Bernett, R.L., 1990. Mantle derivation of
1038
Archean amphibole-bearing granitoids and associated mafic rocks: evidence
1039
from the southern superior Province, Canada. Contributions to Mineralogy and
1040
Petrology 105, 255–274.
1041
Sylvester, P.J., 1994. Archaean granite plutons. In: Condie, K. (Ed.), Archaean
1042
Crustal Evolution. Developments in Precambrian Geology. Elsevier, Amsterdam,
1043
pp. 261–314.
1044
Trap, P., Faure, M., Lin, W., Breton, N.L., Monié, P., 2012. The Paleoproterozoic
1045
evolution of the Trans-North China Orogen: Toward a comprehensive model.
1046
Precambrian Research 222–223, 191–211.
1047
Trap, P., Faure, M., Lin, W., Monié, P., 2007. Late Palaeoproterozoic (1900–1800 Ma)
1048
nappe stacking and polyphase deformation in the Hengshan–Wutaishan area:
1049
Implications for the understanding of the Trans-North China Belt, North China
1050
Craton. Precambrian Research 156, 85–106.
1051
Van Achterbergh, E., Ryan, C., Jackson, S., Griffin, W.L., 2001. In Sylvester, P. (Ed.),
1052
Appendix
3
Data
Reduction
1053
Laser-Ablation-ICPMS in the Earth Sciences, vol. 29. Mineralogical
48
Software
for
LA-ICP-MS
in
1054
Association of Canada Short Course, pp. 239–243.
1055
Villemant, B., Boudon, G., Komorowski, J.C., 1996. U-series disequilibrium in arc
1056
magmas induced by water-magma interaction. Earth and Planetary Science
1057
Letters 140, 259–267.
1058
Wan, Y.S., Liu, D.Y., Wang, S.J., Yang, E.X., Wang, W., Dong, C.Y., Zhou, H.Y.,
1059
Du, L.L., Yang, Y.H., Diwu, C.R., 2011. 2.7 Ga juvenile crust formation in the
1060
North China Craton (Taishan–Xintai area, western Shandong Province): further
1061
evidence of an understated event from U–Pb dating and Hf isotopic composition
1062
of zircon. Precambrian Research 186, 169–180.
1063
Wan, Y.S., Wilde, S.A., Liu, D.Y., Yang, C.X., Song, B., Yin, X.Y., 2006. Further
1064
evidence for ∼1.85 Ga metamorphism in the Central Zone of the North China
1065
Craton: SHRIMP U–Pb dating of zircon from metamorphic rocks in the Lushan
1066
area, Henan Province. Gondwana Research 9, 189–197.
1067
Wang, A.D., Liu, Y.C., 2012. Neoarchean (2.5–2.8) crustal growth of the North China
1068
Craton revealed by zircon Hf isotope: a synthesis. Geoscience Frontiers 3,
1069
147–173.
1070
Wang, G.D., Lu, J.S., Wang, H., Chen, H.X., Xiao, L.L., Diwu, C.R., Ji, J.Q., Wu, 40
Ar/39Ar dating of
1071
C.M., 2013a. LA-ICP-MS U–Pb dating of zircons and
1072
amphiboles of the Taihua Metamorphic Complex, Huashan, southern terminal of
1073
the Palaeoprotorozoic Trans-North China Orogen. Acta Petrologica Sinica 29,
1074
3099–3114 (in Chinese with English abstract).
1075
Wang, G.D., Wang, H., Chen, H.X., Lu, J.S., Wu, C.M., 2014. Metamorphic
49
1076
evolution and zircon U–Pb geochronology of the Mts.Huashan amphibolites:
1077
Insights into the Palaeoproterozoic amalgamation of the North China Craton.
1078
Precambrian Research 245, 100–114.
1079
Wang, G.D., Wang, H., Chen, H.X., Lu, J.S., Xiao, L.L., Wu, C.M., 2012. U–Pb
1080
dating of zircons from metamorphic rocks of the Taihua Metamorphic Complex,
1081
Huashan, Southern Margin of the Trans-North China Orogen. Acta Geologica
1082
Sinica 86, 1541–1551 (in Chinese with English abstract).
1083
Wang, Q., McDermott, F., Xu, J.F., Bellon, H., Zhu, Y.T., 2005. Cenozoic K-rich
1084
adakitic volcanic rocks in the Hohxil area, northern Tibet: lower-crustal
1085
melting in an intra-continental setting. Geology 33, 465–468.
1086
Wang, W., Yang, E.X., Zhai, M.G., Wang, S.J., Santosh, M., Du, L.L., Xie, H.Q., Lv,
1087
B., Wan, Y.S., 2013b. Geochemistry of ~2.7 Ga basalts from Taishan area:
1088
Constraints on the evolution of early Neoarchean granite-greenstone belt in
1089
western Shandong Province, China. Precambrian Research 224, 94–109.
1090
Watkins, J., Clemens, J., Treloar, P., 2007. Archean TTGs as sources of younger
1091
granitic magmas: melting of sodic metatonalites at 0.6–1.2 G pa. Contributions
1092
to Mineralogy and Petrology 154, 91–100.
1093
Wiedenbeck, M., Alle, P., Corfu, F., Griffin, W.L., Meier, M., Oberli, F., Vonquadt,
1094
A., Roddick, J.C., Speigel, W., 1995. Three natural zircon standards for
1095
U–Th–Pb, Lu–Hf, trace-element and REE analyses. Geostandards and
1096
Geoanalytical Research 19, 1–23.
1097
Whitney, D.L., Evans, B.W., 2010. Abbreviations for names of rock-forming minerals.
50
1098
American Mineralogist 95, 185–187.
1099
Wu, F.Y., Jahn, B.M., Wilde, S.A., Lo, C.H., Yui, T.F., Lin, Q., Ge, W.C., Sun, D.Y.,
1100
2003. Highly fractionated I-type granites in NE China (I): geochronology and
1101
petrogenesis. Lithos 66, 241–273.
1102 1103
Wu, F.Y., Zhao, G.C., Simon, A., 2005. Nd isotopic constraints on crustal formation in the North China Craton. Journal of Asian Earth Science24, 523–545.
1104
Xiong, X.L., Adam, J., Green, T.H., 2005. Rutile stability and rutile/melt HFSE
1105
partitioning during partial melting of hydrous basalt: implications for TTG
1106
genesis. Chemical Geology 218, 339–359.
1107
Xue, L.W., Yuan, Z.L., Zhang, Y.S., Qiang, L.Z., 1995. The Sm–Nd isotope age of
1108
Taihua Group in Lushan area and their implications. Geochimica 24, Suppl.,
1109
92–97 (in Chinese with English abstract).
1110
Yu, X.Q., Liu, J.L., Li, C.L., Chen, S.Q., Dai, Y.P., 2013. Zircon U–Pb dating and Hf
1111
isotope analysis on the Taihua Complex: Constraints on the formation and
1112
evolution of the Trans-North China Orogen. Precambrian Research 230, 31–34.
1113
Zhai, M.G., Bian, A.G., Zhao, T.P., 2000. The amalgamation of the supercontinent of
1114
North China Craton at the end of the Neoarchaean and its breakup during late
1115
Palaeoproterozoic and Mesoproterozoic. Science in China Series D: Earth
1116
Sciences 43, 219–232.
1117
Zhai, M.G., Guo, J.H., Liu, W.J., 2005. Neoarchean to Paleoproterozoic continental
1118
evolution and tectonic history of the North China Craton: A review. Journal of
1119
Asian Earth Sciences 24, 547–561.
51
1120
Zhai, M.G., Li, T.S., Peng, P., Hu, B., Liu, F., Zhang, Y.B., Guo, J.H., 2010.
1121
Precambrian key tectonic events and evolution of the North China Craton. In:
1122
Kusky, T.M., Zhai, M.G., Xiao, W.J. (Eds.), The Evolving Continents. Journal
1123
of the Geological Society, London, Special Publications 338, 235–262.
1124 1125 1126 1127
Zhai, M.G., Peng, P., 2007. Paleoproterozoic events in North China Craton. Acta Petrologica Sinica 23, 2665–2682 (in Chinese with English abstract). Zhai, M.G., Santosh, M., 2011. The early Precambrian odyssey of North China Craton. A synoptic overview. Gondwana Research 20, 6–25.
1128
Zhang, J., Zhang, H.F., Lu, X.X., 2013. Zircon U–Pb and Lu–Hf isotope constraints
1129
on Precambrian evolution of continental crust in the Songshan area, the
1130
south-central North China Craton. Precambrian Research 226, 1–20.
1131
Zhao, G.C., Cawood, P.A., Li, S.Z., Wilde, S.A., Sun, M., Zhang, J., He, Y.H., Yin,
1132
C.Q., 2012. Amalgamation of the North China Craton: Key issues and
1133
discussion. Precambrian Research 222–223, 55–76.
1134
Zhao, G.C., Cawood, P.A., Wilde, S.A., Sun, M., Lu, L.Z., 2000. Metamorphism of
1135
basement rocks in the Central Zone of the North China Craton: implications for
1136
Paleoproterozoic tectonic evolution. Precambrian Research 103, 55–88.
1137
Zhao, G.C., Kröner, A., Wilde, S.A., Sun, M., Li, S.Z., Li, X.P., Zhang, J., Xia, X.P.,
1138
He, Y.H., 2007. Lithotectonic elements and geological events in the
1139
Hengshan–Wutai–Fuping belt: a synthesis and implications for the evolution of
1140
the Trans-North China Orogen. Geological Magazine 144, 753–775.
1141
Zhao, G.C., Sun, M., Wilde, S.A., Li, S.Z., 2005. Neoarchaean to Palaeoproterozoic
52
1142
evolution of the North China Craton: key issues revisited. Precambrian Research
1143
136, 177–202.
1144
Zhao, G.C., Wilde, S.A., Cawood, P.A., Lu, L.Z., 1998. Thermal evolution of the
1145
Archaean basement rocks from the eastern part of the North China Craton and
1146
its bearing on tectonic setting. International Geology Review 40, 706–721.
1147
Zhao, G.C., Zhai, M.G., 2013. Lithotectonic elements of Precambrian basement in the
1148
North China Craton: Review and tectonic implications. Gondwana Research 23,
1149
1207–1240.
1150
Zheng, Y.F., 2009. Fluid regime in continental subduction zones: petrological
1151
insights from ultrahigh-pressure metamorphic rocks. Journal of the Geological
1152
Society 166, 763–782.
1153
Zhou, H.W., Li, X.H., Zhong, Z.Q., Liu, Y., Xu, Q.D., 1997. Geochemistry of
1154
amphibolites within the Taihua complex from the Xiao Qinling area, western
1155
Henan and its tectonic implication. Geochimica 26, 87–100 (in Chinese with
1156
English abstract).
1157
Zhou, H.W., Zhong, Z.Q., Ling, W.L., Zhong, G.L., Xu, Q.D., 1998. Sm–Nd isochron
1158
for the amphibolites within Taihua complex from the Xiao Qinling area, western
1159
Henan and its geological implications. Geochimica 27, 367–372 (in Chinese
1160
with English abstract).
1161
Zhou, Y.Y., Zhao, T.P., Zhai, M.G., Gao, J.F., Sun, J.Y., 2014. Petrogenesis of the
1162
Archean tonalite-trondhjemite-granodiorite (TTG) and granites in the Lushan
1163
area, southern margin of the North China Craton: Implications for crustal
53
1164
accretion and transformation. Precambrian Research 255, 514–537.
1165
Figure captions
1166 1167
Fig. 1. (a) Geological sketch map of the North China Craton (Zhao et al. 1998,
1168
2005) and (b) Geological sketch map of the Mts. Huashan metamorphic terrane,
1169
slightly modified after the 1:200000 Weinan and Luonan Geological Maps. Sample
1170
locations are depicted.
1171
Fig. 2. Field photographs. (a) trondhjemite intruded by dolerite dyke; (b)
1172
trondhjemite with amphibolite enclaves; (c and d) outcrops of granitic gneisses with
1173
typical fabrics; (e) outcrop of K-feldspar granite with weak gneissic foliation; (f)
1174
K-feldspar granitic stocks with no gneissic foliation intrude the gneissic rocks; (g and
1175
h) coarse-grained granite show no gneissic foliation.
1176
Fig. 3. Photomicrographs of the (a) TTG gneiss, (b) granitic gneiss, (c)
1177
K-feldspar granite and (d) coarse-grained granite in the Huashan area. The
1178
abbreviations of minerals are from Whitney and Evans (2010).
1179
Fig. 4. Cathodoluminescence (CL) images of zircons from (a–c) trondhjemite
1180
samples; (d–h) granitic gneiss samples; (i–m) K-feldspar granite samples; (n–p)
1181
coarse-grained granite samples.
1182
Fig. 5. Concordia diagrams of LA-ICP-MS zircon U–Pb geochronology. (a–c)
1183
trondhjemite samples; (d–h) granitic gneiss samples. The dotted circles correspond to
1184
the invalid data in Supplementary Table 1.
1185
Fig. 6. Concordia diagrams of LA-ICP-MS zircon U–Pb geochronology. (a–e)
54
1186
K-feldspar granite samples; (f–h) coarse-grained granite samples. The dotted circles
1187
correspond to the invalid data in Supplementary Table 1.
1188 1189 1190 1191
Fig. 7. An-Ab-Or classification diagram (Barker and Arth, 1976) of the granitoids of the Taihua complex in the Mts. Huashan. Fig. 8. SiO2 vs. (Na2O + K2O) diagram of the granitoids of the Taihua complex in the Mts. Huashan (after Middlemost, 1994).
1192
Fig. 9. (a) SiO2 vs. K2O diagram (after Peccerillo and Taylor, 1976); (b) A/CNK
1193
vs. A/NK diagram (after Maniar and Piccoli, 1989) for the TTG gneiss, granitic gneiss,
1194
K-feldspar granite and coarse-grained granite.
1195
Fig. 10. (a, c, e, g) Chondrite-normalized REE and (b, d, f, h) primitive
1196
mantle-normalized trace elements patterns of the granitoids of the Taihua complex in
1197
the Mts. Huashan area (normalization values after Sun and McDonough, 1989).
1198
Fig. 11. (a) (Yb)N vs. (La/Yb)N and (b) Y vs. Sr/Y diagrams for the granitoids.
1199
Fields of high-Al TTG, adakite and common island arc magmatic rocks are from
1200
Defant and Drummond (1990) and Martin et al. (2005).
Table caption
1201 1202 1203
Table 1. Major (wt%) and trace element (ppm) data of the granitoids of the Taihua complex in the Mts. Huashan area.
Supporting Information
1204 1205 1206
1207
Additional Supporting Information can be found in the online version of this article: Supplemental Table 1. Zircon LA-ICP-MS U–Pb data of the granitoids of the 55
1208
Taihua complex in the Mts. Huashan area. The data with strikethrough are invalid and
1209
meaningless, which probably come from the mixture of several parts in different
1210
proportions of the zircons by laser ablation.
1211
56
100°
105°
110°
115°
125°
120°
130°
Abbreviations for metamorphic complexes in Fig.1(a):
Changchun
(a)
SJ
0
200 400 km
Duolun
Bayan Obo WC
GY
40° AL
Yinshan Block HL
WL JP
NH
40°
WD JN XH MY HA Khondalite Belt EH Beijing QL HS WT FP
Xi ' An
SL
LG Pyeonrang
EASTERN BLOCK
WESTERN BLOCK LL Taiyuan ZH Ordos Block 35°
NL
Gyeonggi
ES 35°
TRANS - NORTH WS CHINA OROGEN ZT DF
TH Hidden basement in the Eastern and Western Block
Xinyang Shanghai
Exposed basement in the Eastern and Western Block Hidden basement in the Paleoproterozoic orogens
30°
Exposed basement in the Khondalite Belt in the Western Block
Wuhan
Exposed basement in the Trans-North China orogen Exposed basement in the Jiao-Liao-Ji Belt in the Eastern Block Major fault
115°
110° 10´
109° 45´
AL – Alashan; CD – Chengde; DF – Dengfeng; EH – Eastern Hebei; ES – Eastern Shandong; FP – Fuping; GY – Guyang; HA – Huai'an; HL – Helanshan; HS – Hengshan; JN – Jining; LG – Langrim; LL – Lüliang; MY– Miyun; NH – Northern Hebei; NL – Northern Liaoning; QL – Qianlishan; SJ – Southern Jilin; SL – Southern Liaoning; TH – Taihua; WD– Wulashan-Daqingshan; WL– Western Liaoning; WS – Western Shandong; WT – Wutai; XH – Xuanhua; ZH – Zanhuang; ZT – Zhongtiao.
125°
120°
110° 15´
110° 30´
N
Huayin
(b)
S165 S163
Huaxian
34° 30´
Tongguan
S145 S151 S137 S148 S144 S140 S149
Arth 1
Arth 2 S142
110° 45´ 0 10000m 34° 30´
S160 S159
S147
S155
S153
Arth 1
S143
Pt 1 xl 3
34° 00´
110°30´
110°15´ Lower Taihua Group (Arth 1)
Upper Taihua Group (Arth 2 )
Upper Xiong'er Group
Proterozoic granite
Μesozoic granite
Sample location
110°45´
34° 00´
(b)
(a) Dolerite dyke
Trondhjemite Amphibolites
Trondhjemite
Trondhjemite Trondhjemite
(d)
(c)
Granitic gneiss
Granitic gneiss
(e)
(f) Granitic gneiss K-feldspar granite K-feldspar granite
(g)
Coarse-grained granite
(h)
Coarse-grained granite
(b)
(a) Pl Bt
Kfs Kfs
Q
Kfs
Pl
Qz Kfs
Qz
Pl Pl
Bt 1000 µm
Pl
(c)
Qz Pl
Qz Bt
1000 µm
(d)
Kfs
Bt
Q
Qz Kfs Kfs Qz
Qz
Pl Kfs 1000 µm
Pl 1000 µm
(a) S147 1837±18 03 1861±20 04 16 2287±22
(b) S153 1824±18 02
2030±18 07
2305±20 01
01 2216±18
06 2307±20
02
(d) S144
2442±18
1968±24
100µm
02 1823±21
05 1825±20
1915±18
2275±18
03
2311±19
2092±18 20
19 17 2309±20 100µm
01
19 1843±30 100µm
(f) S148 04 1881±25 2488±18 09 03 2517±19
1822±22 08 06 07 1822±22 1822±35
(j) S140 2030±17 1849±18 06
1823±21 17
1826±26 08 07 2283±17
04
2318±18 07
2050±18
10
16
11
2278±18
2284±18 100µm
(k) S142
(m) S151
15 1854±21
1806±31
200µm
05 1829±19
1833±28 14
1828±29 09
200µm
(i) S137 02 1822±18
1845±25 20 1883±26 15 16 19 2523±20 2436±21
10 2548±19 100µm
(h) S155 1827±20 05
(g) S149 2430±17 03 2447±18 2508±17 06 10 02 11 1816±19 2430±17 07 100µm 1848±19
1858±22 20
15 1819±22
100µm (e) S145
1803±18 2215±25 14
1824±20 16
10
09 2427±18
2540±17 06
01 2709±24
15
11 10 2278±23
100µm (c) S165
1834±18
15
(l) S143 1844±18 08 1822±18 07
1833±18 11 10 2333±19
1834±20 13
15 1829±19
2474±17
1884±20 10
05
200µm
100µm
1837±19 1833±19
18
(n) S159
17 2320±20
16
11 1801±26
100µm 1824±22 (o) S160 1820±25 12 1813±26 04 24 13 2285±18 03 23 2345±17 2255±21
1840±25 29 1856±20
100µm
28
1888±23 1863±19 16 18
1797±27 1808±21 18 21 17 1798±22 1808±21 20 19 16 1810±19 1814±25 200µm
(p) S163 14 1819±28 1816±33 02 16 03 1809±29 15 1825±30 1797±25
1811±25 19
200µm
0.46
2450
(a) S147
2450
(b) S153
0.46
2350
2350 10
0.42
2250
20
2150
12 0.38
207
0.34
13
5.5
2050
upper intercept age： 2254±29Ma (MSWD = 0.73)
1950 0.34
1750 0.30 4.5
0.38
206
weighted mean Pb/ Pb age: 2315±16Ma (MSWD = 1.3, n=11)
19
07
05 1950 03 16 1850 15
2250
0.42
1850
207
206
weighted mean Pb/ Pb age: 1841±21Ma (MSWD = 2.7, n=10)
1750 6.5
7.5 207
8.5
9.5
10.5
0.30 4.5
5.5
6.5
7.5
235
207
Pb/ U
8.5
9.5
10.5
235
Pb/ U 2100
0.52
0.38
(c) S165
(d) S144 2000
2600
0.36 01
0.48
0.44
1900
0.34
11
2400 07
1800
0.32
12 2200 0.40
207
1700
0.30
weighted mean Pb/ Pb age： 2485±21Ma (MSWD = 4.2, n=14)
04
206
upper intercept age: 1829±10Ma (MSWD = 1.11)
1600
0.28 2000
0.36
14
1500
0.26
10 0.32 5
7
9
11 207
13
15
1400 0.24 2.5
3.5
4.5
235
207
Pb/ U
5.5
6.5
235
Pb/ U
0.46
2400
(e) S145
0.44
2300
upper intercept age： 2293±28Ma (MSWD = 0.75)
0.42
0.52
(f) S148
2600
0.48
upper intercept age： 2400 2502±49Ma (MSWD = 0.84)
14 0.44 0.40
14
2100 0.38
0.40
07
2000 0.36
207
207
03
2000
0.36
207
1900
15
0.34
0.32
0.32
206
weighted mean Pb/ Pb age: 2551±11Ma (MSWD = 1.0, n=3)
206
weighted mean Pb/ Pb age: 2283±12Ma (MSWD = 0.78, n=10)
206
weighted mean Pb/ Pb age: 1873±27Ma (MSWD = 2.1, n=8)
1800
1800 0.28 4.5
5.5
6.5
7.5 207
8.5
9.5
4
6
8
235
10 207
Pb/ U
0.52
12
14
235
Pb/ U
0.37 2600
(h) S155
(g) S149
0.48
1950
0.35
0.44
1850 0.33 2200
0.40 207
2000
0.36 10
0.31
07 0.29
1800
0.32
20
1750
206
weighted mean Pb/ Pb age: 2495±11Ma (MSWD = 0.51, n=10)
1650 207
0.28 4
206
weighted mean Pb/ Pb age: 1834±10Ma (MSWD = 0.44, n=20)
13
6
8 207
Pb/ 235U
10
12
0.27 3.6
4.0
4.4
4.8 207
5.2
Pb/ 235U
5.6
6.0
0.38
(a) S137
2350
(b) S140
0.44
2000
upper intercept age： 2271±28Ma (MSWD = 0.18)
0.36
18
12
0.40
1900
05
0.34 2050 0.36
1800
0.32
0.30
1850
upper intercept age： 1834±10Ma (MSWD = 0.22)
1700
0.32
weighted mean Pb/ Pb age： 2040±20Ma (MSWD = 0.36, n=3) 207
206
1750 weighted mean 207Pb/ 206Pb age： 1834±22Ma (MSWD = 0.41, n=5)
1650 1600 0.28 3.8
weighted mean 207Pb/ 206Pb age： 2275±14Ma (MSWD = 0.29, n=7)
1950
0.28 4.2
4.6
5.0 207
5.4
5.8
6.2
6.6
4
5
6
7
235
207
Pb/ U
0.37
8
9
10
235
Pb/ U
0.50 2000
(c) S142 1960 upper intercept age： 1836±17Ma (MSWD = 0.23)
0.35
2500
(d) S143
0.46
05 2300
1920
0.42
1880
2100
0.38 1840
0.33
1900
0.34
1800 1760 0.31
upper intercept age： 1868±15Ma (MSWD = 0.77)
1700
0.30
1720 weighted mean Pb/ Pb age： 1839±8Ma (MSWD = 0.34, n=20) 207
1680 0.29 4.0
4.4
4.8
5.2 207
206
5.6
6.0
weighted mean Pb/ Pb age： 1864±10Ma (MSWD = 0.46, n=16) 207
1500
0.26 1300 0.22 2
4
6
235
8 207
Pb/ U
206
10
12
235
Pb/ U
0.36
0.48
(e) S151
(f) S159
2400
1920
upper intercept age： 1802±13Ma (MSWD = 0.49)
0.44
0.34
2200
1880 1840
0.40
01
2100
1800 0.32
weighted mean Pb/ Pb age： 2326±12Ma (MSWD = 0.18, n=9) 207
15
12
0.36
206
1760 1720
04
1800
0.32
08 0.30
weighted mean 207Pb/ 206Pb age： 1840±14Ma (MSWD = 0.16, n=7)
1640
0.28 4
6
8 207
weighted mean 207Pb/ 206Pb age： 1801±10Ma (MSWD = 0.4, n=22)
1680
10
0.28 3.8
4.2
4.6
235
5.0 207
Pb/ U
5.4
5.8
235
Pb/ U
0.46 2000
(g) S160
0.36
2300
0.42
0.38
(h) S163 upper intercept age： 1838±25Ma (MSWD = 0.61)
upper intercept age： 1829±12Ma (MSWD = 0.75) 16 08
1900
0.34
1800 0.32
1900
0.34
upper intercept age： 2326±46Ma (MSWD = 1.4)
11
20 0.30
1500 0.26 3
1700
0.30
5
7 207
Pb/ 235U
9
0.28 3.8
1700
4.2
4.6
5.0 207
Pb/ 235U
5.4
5.8
6.2
An
TTG gneiss Granitic gneiss 80 30
K-felsdspar granite 70 Coarse-grained granite 50 40
60
30
70
20
80
Trondhjemite Granite
Or
Ab 30
40
50
60
70
80
90
16 TTG gneiss
14
Foid syenite
Granitic gneiss K-feldspar granite
12
Foid monzodiotite
Syenite
Coarse-graned granite
Foid monzosyenite
10 8
Quartzmonzonite Monzonite
Monzodiotite Monzogabbro
Foid gabbro
6
Granite
Granodiorite
4
Diorite
2
Peridetegabbro
Gabbroic diorite
Gabbro
0 35
40
45
50
55
SiO 2 (wt%)
60
65
70
75
80
3.00
13 12 11 10 9 8 7 6 5 4 3 2 1 0
(a)
(b) 2.50
TTG gneiss Granitic gneiss K-feldspar granite Coarse-grained granite
Peraluminous
2.00 1.50
Metaluminous
1.00 0.50
Peralkaline
0.00 0
20
40 60 SiO 2 (wt.%)
80
100
0.00
0.50
1.00 A/CNK
1.50
2.00
1000
1000
(a) TTG gneiss S147
100
(b) TTG gneiss S147
100
S165
S153
10
S165
10
S153
1
1 La Ce Pr Nd
Rb Ba Th U K Ta Nb La Ce Sr Nd P Zr Hf Sm Ti Y Yb Lu
Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 10000.
1000.
S145 S144
100.
(c) Granitic gneiss
1000.
(d) Granitic gneiss
S145 S144
S149 100.
S148 10.
S155
10.
S149 S148
1.
S155
1.
0. 1
0.1 La Ce Pr Nd
Rb Ba Th U K Ta Nb La Ce Sr Nd P Zr Hf Sm Ti Y Yb Lu
Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 1000.
1000.
S137
S137
(e) K - feldspar granite
(f) K - feldspar granite
S142
100.
100.
S151 S142
S140 10.
10.
S151
S140
S143
S143 1.
1.
0.1
0.1 La Ce Pr Nd
Rb Ba Th U K Ta Nb La Ce Sr Nd P Zr Hf Sm Ti Y Yb Lu
Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
10 00 .
1000.
(g) Coarse-grained granite 10 0.
(h) Coarse-grained granite 100.
S160
10 .
1.
S163 S160
S163
10.
S159 1.
0. 1
S159
0.1 La Ce Pr Nd
Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Rb Ba Th U K Ta Nb La Ce Sr Nd P Zr Hf Sm Ti Y Yb Lu
300
250
TTG gneiss (~2.5 Ga) TTG gneiss (~2.3 Ga) Granitic gneiss (~2.5 Ga) Granitic gneiss (~2.3 Ga) Granitic gneiss (~1.8 Ga) K-feldspar granite (~2.3 Ga) K-feldspar granite (~1.8 Ga) Coarse-grained granite
200 200 150 100 100 50
Island arc magmatic rocks
Island arc magmatic rocks 0
0
0
5
10
15 Yb N
20
25
30
0
10
20
30 Y
40
50
60
1212
Table 1
1213
Major (wt%) and trace element (ppm) data of the granitoids of the Taihua complex in the Mts.
1214
Huashan area.
1215 1216
57
S p o t
T T G
G r a n i t i c
g n e i s s
K f e l d s p a r
g n e i s s
C o a r s e g r a i n e d
g r a n i t e
S 1 4 7
S 1 5 3
S 1 6 5
S 1 4 4
S 1 4 5
S 1 4 8
S 1 4 9
S 1 5 5
S 1 3 7
S 1 4 0
S 1 4 2
S 1 4 3
S 1 5 1
S 1 5 9
S 1 6 0
S 1 6 3
g r a n i t e
S 6 7 6 7 7 6 7 7 7 7 7 7 7 7 7 6 i
7 1 8 1 3 5 0 0 3 5 3 2 4 0 3 8
O .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
2 4 7 7 7 7 2 4 7 1 4 2 0 3 4 2 5 6 3 6 0 0 0 8 8 1 3 3 8 2 5 0 4
T 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
i
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
6 5 5 4 3 7 4 4 3 2 4 3 3 4 3 6
O 5
3
3
3
1
4
2
3
2
1
1
2
1
1
2
4 .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
2 0
0
2
2
7
2
8
0
0
9
7
5
7
7
1
2 9 5 5 1 2 7 9 5 9 6 1 8 1 5 8 1 8 9 5 3 9 1 5 4 3 0 3 1 9 9 9 8 A l 2
O 3
T 3
2
3
2
1
3
2
2
2
1
0
2
2
1
1
3
F .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
e 2
4
2
9
5
6
7
8
6
1
8
3
3
8
6
3
7
0
1
8
1
4
5
0
2
6
3
1
7
5
5
0
M 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
n .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
O 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3
3
4
3
1
4
2
2
1
1
1
2
2
1
2
2
2
O 3
M 0
0
1
0
0
0
1
0
0
0
0
0
0
0
0
0
g .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
O 7
7
0
4
3
6
1
4
3
3
2
2
1
0
6
4
4
2
6
0
4
2
9
7
4
0
9
5
1
2
4
6
C
2
1
2
1
0
1
1
1
0
0
0
0
0
0
0
1
a
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
O
3
9
2
2
5
5
3
3
4
6
3
1
6
8
5
9
3
8
1
2
3
7
0
2
3
9
3
3
7
7
6
1
N 5
4
5
2
2 4 3 3 2 2 1 1 2 3 2 4
a .
.
.
.
.
9
8
1
9
3 1 2 1 6 3 8 7 8 1 7 0
O 5
3
7
1
9 7 7 2 7 4 2 4 3 3 3 0
2
.
.
.
.
.
.
.
.
K
1 1 2 5 6 3 5 5 5 6 8 8 5 7 6 4
2
.
O
8 9 2 1 9 9 0 7 9 0 5 6 9 2 0 0
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
4 8 1 1 5 0 3 6 3 0 3 0 8 0 0 3
.
.
.
P
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
2
.
O
1 0 1 0 0 1 0 1 0 0 0 0 0 0 0 2
5
4 6 4 8 2 3 8 0 4 1 4 7 2 2 4 2
L
1 1 0 0 0 2 0 0 0 0 0 0 0 0 0 1
O
.
I
0 0 8 8 3 9 9 6 7 6 4 5 4 6 6 1
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
6 6 4 6 8 8 8 2 8 6 4 8 4 6 8 4
T 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 O 7 8 6 6 7 6 7 7 7 8 8 7 7 7 7 6 T .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
A 0 2 3 7 7 7 5 0 4 2 9 5 7 1 9 9 L 4 7 1 6 8 4 8 3 4 4 9 2 5 3 7 2
M
3
3
4
2
3
2
4
2
2
3
4
1
g
1
7
0
1
1
5
6
5
0
4
1
8
8
2
4
2
3
2
# S
6
4
1
4
4
7
4
3
3
3
4 3
4
4
7
4
c
.
.
0
.
.
.
.
.
.
6
0 .
.
.
.
.
9
2
.
3
3
0
2
4
3
.
.
9
2
0
6
1
1
7
5
9
9
3
3
7
2
2
0 7
7
2
9
4
3
5
2
1 5
3
3
1
2
1
7
2
2
1
4
8
9
5
9
7 3
0
1
7
5
7
.
.
7
6
5
.
.
.
.
.
.
.
.
0
8
1
6
.
.
4
8
5
1
0 4
2
7
5
6
3
9
8
C
1
1
3
1
1
1
1
7
1
8
4
1
5
8
1
1
r
7
1
0
7
3
1
8
.
6
1
4
1
.
.
8
0
.
.
.
.
.
8
.
.
.
.
7
3
.
.
3
2
5
5
7
6
9
3
4
7
9
3
8
V
.
C
5
4
1
2
3
7
8
4
1
5
3
1
1
2
2
1
o
.
.
2
.
.
.
.
.
.
6
3
.
.
.
.
4
2
3
4
2
9
0
1
3
.
.
2
1
3
5
.
3
8
4
3
9
1
2
N
6 6 1 6 5 1 1 3 5 9 1 3 1 3 8 6
i
.
.
5 .
0 3 .
.
1 0 .
7 6 .
.
.
0 0 .
1 2 .
.
.
.
.
4
6
6
5
6
3
.
9 8 9 1 3
5 1 9 7 3 7 1 1 9 0 3 5 8 5 7 3
C
4
3
1
4
4
9
1
5
2
5
1
6
1 5
3
4
u
3
.
0
.
.
.
5
.
.
1
6
.
.
.
.
.
7
.
8
9
1
.
9
9
.
.
0
8 4
8
8
1
4
4
6
7
2
3
2
1
8
2
6
0 8
9
0
Z
3
2 5
2
4 6
5
2
1
1
2
1
2
1
2
2
n
6
7 7
6
1 7
1
6
7
7
1
8
4
0
2
8
.
.
.
.
.
.
.
2
9
.
.
.
.
.
6
0 5
1
0 9
4
5
7
9
7
5
8
6
.
.
.
G
2 1 1
1
2
2
1
1
2
2
2
1
1
1
1
2
a
0 7 9
8
3
0
8
6
0
2
2
2
7
4
4
3
.
.
.
0 0 7
.
.
.
.
.
.
.
.
.
.
.
.
7
3
7
7
6
1
6
1
5
4
7
2
R
4 5 9 2 1 1
1 1 1 4 8 2 2 2 1 9
b
0 3 1 4 9 1
4 7 7 7 5 0 0 0 5 5
.
9 2 3 .
.
.
6 5 2
7 2 8
.
5 7 0 6 .
1 9
6
S
2 2 3 7
2 9
2 3 1 5 3 1 8 2 2 6
r
6 3 1 4
3 3
9 3 4 0 8 8 9 6 2 2
5 4 4
3
4 3 7 2 5 9 .
0 3 3
6
Z
3
1
1
2
3
1
1
3
5
1
3
1 3
4
1
8
r
1
6
3
8
8
0
0
6
7
1
0
9 7
5
5
4
5
5
1
0
3
5
9
4
7
5
4
.
.
2
4
0
1
7
N
1
6
7
8
1
5
6
2 2
1
1 2
3
0
3
3
b
2
.
.
.
0
.
.
.
5
7 .
.
.
.
.
.
6
9
9
.
0
2
6 6
.
.
8
1
9
8
0
6
3
6
3
1
3
9
0 8
4
0 3
3
2
6
8
.
C
0 0 0 0 0 0 0 0 0 0 1
0 0 0 1 0
s
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
3 4 5 8 6 7 7 3 5 8 6
4 4 4 1 2
7 2 3 8 3 1 3 5 4 7 8
7 0 1 7 7
B
6 5 8 9 1 1 1 1 1 3 1 2 6 2 1 1
a
6 7 6 5 3 0 1 9 1 8 3 6 2 5 4 6 5 2 2 5 1 2 3 3 4 7 1 3 0 2 4 2 7 4 2 3 7
7 3
6 8 5
L
6 1 3 1 1 1 3 1 1 1 6 5 4 5 1 2
a
2 8 9 2 7 8 6 3 6 4 2 . .
.
.
3 8 .
.
.
3 .
.
2 .
0 .
8 4
3 .
.
6 4 2
.
8 7 5
8 2 8 8 1 1 2
0
C
1 3 6 1 3 3 6 2 3 3 1 8 7 6 3 4
e
0 1 7 8 1 2 0 0 0 0 2 . 7 .
.
6 4 .
1 3
.
.
0 .
1 0 1
1 .
4 2 .
9
5 0
9 .
.
3 4 6 8 4
P
1 3 7 2 3 3 5 2 2 3 1 1 8 0 4 4
r
2 . .
.
1 0 .
6 4 .
.
.
.
7 .
3 8 0 .
5 .
9 .
.
.
.
.
0 6 6 8 4
2 1 2 4 4 2 2 6 5 0 5 6 2 9 3 6
N
4 1 2 6 8 1 1 7 7 1 6 4 3 2 1 1
d
1 2 5 5 7 1 7 . .
.
.
.
.
.
.
4 6 1 .
2 .
.
.
0 .
1 .
9 6
3 .
.
1 6 4 4 5 8 5 2 4 6 9 0 4 3 0 0
S
5 2 4 8 9 1 1 1 6 3 1 0 4 0 3 2
m
.
.
.
.
.
.
.
.
.
.
1 .
9 0 2 2 1 7 9 0 5 8 .
.
.
.
.
6 8 3 3 2
7 8 2 3 8 4 1 5 0 9 4 6 3 7 9 2
E
1 0 1 1 1 0 0 1 0 1 2 0 0 0 0 1
u
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
3 7 0 1 2 7 8 0 7 5 7 5 4 3 8 2 6 4 2 2 1 4 6 1 2 6 8 0 7 3 2 7
G
4 1 3 4 5 1 1 1 3 4 1 0 3 0 2 1
d
.
.
.
.
.
.
.
.
.
.
0 .
2 6 5 8 1 2 1 0 3 0 .
.
.
.
.
4 3 2 4 5
2 4 0 7 9 3 5 3 6 6 2 7 9 9 8 9
T
0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0
b
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
5 2 5 5 6 1 1 1 3 6 4 0 4 0 3 2
6 3 1 1 3 5 2 0 3 3 8 6 5 4 5 0
D
2 1 2 1 2 0 0 0 0 3 8 0 1 0 1 0
y
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
9 2 8 5 3 7 4 4 9 7 6 2 9 2 8 8 0 0 6 0 5 2 7 9 1 8 7 8 8 0 6 6
H
0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0
o
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
5 2 5 2 4 1 0 1 1 7 7 0 3 0 3 1 2 0 8 0 0 3 7 0 4 1 3 5 0 4 3 6
E
1 0 1 0 1 0 0 0 0 2 4 0 0 0 0 0
r
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
4 5 7 5 2 3 2 3 5 0 9 1 7 1 8 4 7 5 5 8 3 5 0 0 5 3 4 4 5 1 9 9
T
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
m
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
1 0 2 0 1 0 0 0 0 2 6 0 0 0 1 0 9 8 4 6 5 4 2 5 6 7 8 2 9 2 2 7
Y
1 0 1 0 0 0 0 0 0 1 4 0 0 0 0 0
b
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
2 5 6 4 9 2 1 3 5 6 3 1 6 1 7 5 7 3 7 4 2 6 7 8 2 4 4 4 2 1 5 8
L
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
u
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
1 0 2 0 1 0 0 0 0 2 6 0 0 0 1 0 9 8 6 7 4 4 3 7 8 5 5 2 9 2 1 9
Y
1
6
1
5
1
3
2
3
4
2
5
1
8
1
1
5
6
.
9
.
2
.
.
.
.
3
7
.
.
.
0
.
.
8
.
7
.
7
4
3
3
.
.
5
5
2
.
4
4
8
9
8
7
4
8
7
7
5
7
6
7
5
1
7
H
8
4
3
6
9
2
2
7
1
2
6
0 8
0 4
1
f
.
.
.
.
.
.
.
.
3
.
.
.
.
7
0
4
3
6
1
5
5
6
.
6
2
5 8
9 1
.
1
1
6
8
1
1
8
7
3
3
9
6 7
8 2
7
2
2
T
0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0
a
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
3 2 2 2 3 1 2 1 1 2 9 1 1 0 1 1 7 4 8 7 4 9 6 0 6 9 0 6 1 7 2 1
P
5
4
7
9
2
4
4
7
5
3
1
5
9
4
9
7
b
.
.
.
.
0
.
.
.
.
.
5
.
.
.
.
.
8
1
0
0
.
1
2
0
7
5
6
0
8
2
2
8
2
1
9
2
9
6
2
8
5
9
5
1
9
9
T
1
5
1
4
8
0 6
0 5
1
5
0 1
0 1 0
h
7
.
0
3
7
.
.
.
.
.
.
.
2
.
.
.
4 3
5 .
1
1
7 .
3 8 8
2
6
6
5
1
0 8
3 9
3
1 8
9 1 1
.
1
2
.
.
4 U
0 0 0 0 1 0 0 0 0 0 1
0 1
0 0 0
.
.
.
.
.
.
.
.
.
.
.
.
.
.
1 2
1 4 4
3 0 2 6 0 3 0 7 3 0 8
1 4
4 0 9
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
/ 7 1 7 5 4 4 6 9 4 1 7 6 3 0 8 9 E 9 8 9 0 9 7 4 4 2 9 7 3 4 3 2 6 u *
(
3 2 1 2 1 5 1 2 2 6 1 2 4 3 1 2
L 5 5 6 0 3 1 5 5 2 . a .
.
.
/ 3 1 8 Y b
.
6 5 8 6 1 2 2 3 7 2 1
E 0 1 0 0 0 1 1 2 0 1 0 2 0 3 0 1 u .
.
2 9 . 1
7 . 4
0 6 9 3 7 9
6 4 .
.
.
.
.
.
9 3 9 4 3 3 9
) N
S
1 3 1 1 1 2 1
9 3 2 6
1 1 2 2 1
r
6 4 5 2 8 4 1
8 3 1 .
2 0 0 2 1
/
.
.
1 .
Y
2 0 8 8 4 9
.
.
.
.
.
9
.
.
7
9 6 4
5
D 2 2 1 3 2 2 2 1 1 2 2 2 3 1 2 1 y .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
/ 2 2 7 4 5 7 7 2 7 3 0 1 1 7 4 4 Y 8 8 1 3 6 1 8 9 5 1 0 1 9 3 8 8 b
R 0 0 0 3 0 1 0 0 1 0 0 1 2 0 0 0 b .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
/ 1 2 2 3 8 2 5 5 1 0 2 0 3 7 7 1 S 5 3 9 1 4 0 1 2 8 9 2 8 1 7 0 5 r
G 3 3 2 1 5 4 6 2 6 2 2 3 5 2 3 2
8 . 1
4
d .
.
.
1 .
/ 3 1 1 .
.
.
.
.
.
.
.
.
.
.
.
6 6 8 7 4 4 3 5 4 5 3 7
Y 2 2 0 1 7 3 2 0 7 7 5 0 5 4 1 3 b
1217
● Three episodic magmatism (2.55–2.49 Ga, 2.33–2.25 Ga
1218
and 1.87–1.80 Ga) were revealed from the Mts. Huashan
1219
granitoids.
1220
● The ~2.5 Ga rocks represent an episodic crustal growth,
1221
while the ~2.3 Ga rocks reflect both crustal growth and
1222
reworking.
1223
● The 1.87–1.80 Ga rocks probably resulted from crustal
1224
reworking during the collision between the Eastern and
1225
Western Blocks.
1226
● Transformation from an Andean-type continental margin
1227
arc setting to continent-arc-continent collision in the
1228
southern TNCO during Late Neoarchean to Paleoproterozoic
1229
is suggested.
1230
58
S0301-9268(16)30573-3 http://dx.doi.org/10.1016/j.precamres.2016.11.006 PRECAM 4613
To appear in:
Precambrian Research
Received Date: Revised Date: Accepted Date:
18 February 2016 26 October 2016 30 November 2016
Please cite this article as: G-D. Wang, H. Wang, H-X. Chen, B. Zhang, Q. Zhang, C-M. Wu, Geochronology and geochemistry of the TTG and potassic granite of the Taihua complex, Mts. Huashan: implications for crustal evolution of the southern North China Craton, Precambrian Research (2016), doi: http://dx.doi.org/10.1016/ j.precamres.2016.11.006
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
1
An original manuscript submitted to Precambrian Research
2 3 4 5 6
Geochronology and geochemistry of the TTG and potassic granite of the Taihua complex, Mts. Huashan: implications for crustal evolution of the southern North China Craton
7 8
Guo-Dong Wang a,b*, Hao Wang b, Hong-Xu Chen b, Bo Zhang c, Qing Zhang d,
9
Chun-Ming Wu b
10
a
Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
11
b
College of Earth Science, University of Chinese Academy of Sciences, P.O. Box
12
4588, Beijing 100049, China
13
c
14
d
15
100081, China
China Corporation of Coal Geology Engineering, Beijing 100073, China
Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing
16 17 18 19 *
Corresponding author. Tel: +86 0532 82898035. E-mail address: [email protected] (G.-D. Wang). 1
20 21
ABSTRACT Tonalite-trondhjemite-granodiorite
(TTG)
suite
and
potassic
granite
22
volumetrically expose in the Neoarchean to Paleoproterozoic Taihua complex, Mts.
23
Huashan region, southernmost segment of the Trans-North China Orogen (TNCO).
24
Zircon U–Pb dating on the trondhjemite, granitic gneiss, K-feldspar granite and
25
coarse-grained granite samples show three episodes of magmatism (2.55–2.49 Ga,
26
2.33–2.25 Ga and 1.87–1.80 Ga) with distinct geochemical features in this area during
27
the Paleoproterozoic. The trondhjemite samples have high SiO2 (67.46–71.73 wt%),
28
Na2O (4.83–5.95 wt%), low Mg# (31–40) and HREE contents, with moderate
29
(La/Yb)N values (16.8 to 35.3) and Sr/Y ratios (15.8 to 34). The potassic granite
30
samples show high SiO2 (65.2–75.43 wt%), K2O (3.9–8.6), low Na2O (1.74–4.17
31
wt%), Mg# (2–46) and HREE contents, with moderate to high (La/Yb)N values (10.3
32
to 226) and Sr/Y ratios (12.8 to 208). All these granitoid samples are characterized by
33
high SiO2 and low Mg#, Cr, Ni with moderate to high (La/Yb)N values and Sr/Y ratios.
34
The absence of evidence of any pre-existing high Sr/Y and La/Yb sources in this
35
region led to that the granitoids probably generated from partial melting of hydrous
36
mafic rocks with garnet and amphibole in the residue. Therefore, partial melting of
37
thickened lower curst is the most likely origin. Combined with previous studies, the
38
first episodic magmatism (2.55–2.49 Ga) represented by TTG and granitic gneisses
39
with positive whole rock ƐNd(t) and zircon ƐHf(t) values is interpreted as melts from
40
partial melting of juvenile thickened lower crust. The second episodic magmatism
41
(2.33–2.25 Ga) represented by TTG, granitic gneisses and K-feldspar granite with
2
42
positive to negative whole rock ƐNd(t) and zircon Ɛ Hf(t) values is suggested as the
43
product of partial melting of both juvenile and pre-existing crustal material. The third
44
episodic magmatism (1.87–1.80 Ga) is represented by these potassic granites, which
45
is synchronism with the metamorphism recorded in this region and probably resulted
46
from partial melting of pre-existing crustal materials in a syn-orogenic or
47
post-orogenic setting during the collision between the Eastern and Western Blocks of
48
the North China Craton. Multistage continental accretion (at 2.84–2.72 Ga, 2.57–2.43
49
Ga and 2.36–2.25 Ga) and reworking (at 2.36–2.25 Ga, 2.19–2.07 Ga and 1.87–1.80
50
Ga) occurred in the southern segment of the TNCO from Neoarchean to
51
Paleoproterozoic. Transformation from an Andean-type continental margin arc setting
52
on the western margin of the Eastern Block to continent-arc-continent collision in the
53
southern TNCO during Late Neoarchean to Late Paleoproterozoic is suggested in this
54
paper.
55
Keywords:
56
Complex; North China Craton
TTG; Potassic granite; Geochronology; Geochemistry; Taihua
57 58
1. Introduction
59
Formation and evolution of the Precambrian continental crust is the archive to
60
explore the early history of our Earth. Tonalite-trondhjemite-granodiorite (TTG) suite,
61
metamorphosed supracrustal rocks and K-rich granite-granodiorite-monzonite suite,
62
volumetrically dominate the preserved Archean crust worldwide (Jahn et al., 1981;
63
Frost et al., 2006; Moyen, 2011). Extensive investigations on sodic TTG suite provide
3
64
great constrains for the origin and evolution of the Precambrian continental crust (e.g.,
65
Martin, 1994; Sylvester, 1994; Martin and Moyen, 2002; Martin et al., 2005; Condie,
66
2005; Smithies et al., 2009). Furthermore, the potassic granites are also widespread
67
and voluminous constituent of Archaean cratons (Sylvester, 1994), which can also
68
offer us opportunities to investigate the crustal evolution of the old terranes (e.g.,
69
Sutcliffe et al., 1990; Frost et al., 2006; Moyen et al., 2003).
70
The North China Craton (NCC) is one of the well known oldest and largest
71
cratons in the world (~3.8 Ga; Liu et al., 1992) with widespread Archean to
72
Paleoproterozoic basement, whose crustal evolution is still controversial (eg., Zhao et
73
al., 1998, 2000, 2012; Zhai et al., 2000, 2005, 2007, 2010, 2011; Kusky and Li, 2003;
74
Santosh et al., 2006; Faure et al., 2007; Trap et al., 2007, 2012; Santosh, 2010; Kusky,
75
2011; Peng et al., 2014). For example, one of the familiar debates is the timing of
76
final amalgamation of the NCC. Some researches believed the final amalgamation of
77
the NCC occurred at ~1.85 Ga by continent-continent collision along the Trans-North
78
China Orogen (TNCO) between the Eastern and Western Blocks (e.g., Zhao et al.,
79
1998, 2000, 2012; Guo et al., 2005; Kröner et al., 2005), whereas some others argued
80
the collision between the Eastern and Western Blocks occurred at ~2.5 Ga (Kusky and
81
Li, 2003; Kusky, 2011). Zhai et al. (2010) proposed that the NCC was cratonized
82
through amalgamation of several micro-continental blocks at ~2.5 Ga, followed by the
83
formation of oceanic basins which disappeared in the Paleoproterozoic through
84
subduction and collision. A number of other models are also argued (e.g., Faure et al.,
85
2007; Trap et al., 2007, 2012; Santosh, 2010).
4
86
The Taihua metamorphic complex, usually termed as the Taihua Group in the
87
traditional Chinese literature, exposing in the southernmost segment of the
88
Trans-North China Orogen (TNCO) (Zhao et al., 1998, 2000, 2012), consists of
89
Neoarchean
90
metamorphosed supracrustal rocks and K-rich granitic rocks (Sun et al., 1994). From
91
the west to the east, the Taihua complex exposed discontinuously in several areas, i.e.,
92
the Mts. Huashan area in the northwest, the Luoning (or Xiong’er) area in the middle
93
and the Lushan and Wugang area in the southeast. Although there are numerous
94
chronological and geochemical studies on the granitoids from the Lushan area (Xue et
95
al., 1995; Wan et al., 2006; Liu et al., 2009; Diwu et al., 2010, 2014; Huang et al.,
96
2010; Zhou et al., 2014), the Luoning area (Diwu et al., 2007; Huang et al., 2012). But
97
in contrast, fewer studies have been done on the granitoids from the Huashan area
98
(Huang et al., 2013; Yu et al., 2013), and no investigations were carried out on the
99
potassic granites from the Huashan area. Additionally, inconformity also existed
100
among these researches. For example, Huang et al. (2013) proposed the TTG gneisses
101
formed at ~2.5 Ga in Huashan and Dengfeng areas resulted from partial melting of
102
thickened lower crust, whereas Diwu et al. (2011, 2014) argued these rocks were
103
derived mainly from the partial melting of subducted oceanic crust and interaction
104
with mantle peridotite. In this paper, we present new LA-ICP-MS zircon U–Pb ages,
105
as well as whole-rock major and trace elements of the TTG gneisses and potassic
106
granites from the Mts. Huashan Taihua complex to infer their emplacement ages and
107
petrogenetic processes, and provide a better understanding on the crustal and tectonic
to
Paleoproterozoic
basement,
5
mainly
including
TTG
suites,
108
evolution of the southern margin of the TNCO in the Neoarchean to Paleoproterozoic,
109
which will provide important insights into understanding the formation and evolution
110
of the NCC.
111
2. Geological setting
112
Although controversies on the Precambrian crustal evolution of the North China
113
Craton still exist (eg., Zhao et al., 1998, 2000, 2012; Zhai et al., 2000, 2005, 2007,
114
2010, 2011; Kusky and Li, 2003; Santosh et al., 2006; Faure et al., 2007; Trap et al.,
115
2007, 2012; Santosh, 2010; Kusky, 2011; Peng et al., 2014), there is a great consensus
116
that the Precambrian basement of the North China Craton is a result of the
117
amalgamation of several micro-blocks. Zhao et al. (1998, 2000, 2012) proposed that
118
the North China Craton can be divided into the Eastern Block and the Western Block
119
separated by the N–S striking Trans-North China Orogen (TNCO). During 2200 to
120
1900 Ma, the Eastern Block underwent a Paleoproterozoic rifting event forming the
121
Longgang and Langrim Blocks, followed by the amalgamation of these two blocks
122
along the N–S- striking Jiao–Liao–Ji Belt (Zhao et al., 2005, 2012). The Western
123
Block can be subdivided into the Yinshan Block in the north and the Ordos Block in
124
the south, separated by the E–W striking Khondalite Belt, which formed at ~1.95 Ga
125
during the collision between these two blocks (Zhao et al., 2005, 2012). The
126
Tran-North China Orogen is the result of the amalgamation of the Eastern and
127
Western Blocks at ca. 1.85 Ga (Zhao et al., 1998, 2000, 2005, 2012).
128
As mentioned above, the Taihua complex is composed of Archean to
129
Paleoproterozoic basement, making it an ideal object to investigate the Precambrian
6
130
crustal evolution of the southern margin of the North China Craton. In the last few
131
years, some investigations were carried out on the metamorphism of the amphibolites
132
from the Taihua complex, and all of them recorded clockwise P–T paths containing
133
isothermal decompression (ITD) segments with metamorphism age being dated to be
134
ca. 1800–1960 Ma, which reflect the southern segment of TNCO was also involved in
135
the amalgamation of the Eastern and Western Blocks in the Paleoproterozoic (Jiang et
136
al., 2012; Wang et al., 2012, 2013a, 2014; Lu et al., 2013, 2014; Chen et al., 2015). In
137
addition, numerous chronological and geochemical studies on the granitoids from the
138
Taihua complex were performed. In the Lushan area, the protolith ages of TTG and
139
TTG-like gneisses were dated as 2.85–2.72 Ga (Liu et al., 2009; Diwu et al., 2010;
140
Huang et al., 2010; Zhou et al., 2014). According to the systematic chronological and
141
geochemical studies on the TTG and TTG-like gneisses, Huang et al. (2010) proposed
142
a model of late Archean crustal accretion from ocean crust to continental terrain in the
143
southern NNC. Zhou et al. (2014) dated TTG suite, sodic-potassic granite suite and
144
potassic granite at ~2840 Ma, ~2760 Ma and 2570 Ma, respectively, and proposed a
145
tectonic transition from a compressive to an extensional setting in the southern NNC
146
between 2.85 Ga and 2.50 Ga. In the Luoning area, Huang et al. (2012) obtained two
147
magmatic events from zircons collected from the TTG gneisses (2.32–2.30 Ga and
148
2.19–2.07 Ga) and proposed that there was a tectonic transformation from an
149
accretionary orogenesis to an extensional regime, as a consequence of post-collisional
150
uplift in the southern segment of the TNCO in the Early Paleoproterozoic. In the Mts.
151
Huashan area, Huang et al. (2013) reported three magmatic episodes in the TTG suit
7
152
(2.48 Ga, 2.31 Ga and 2.16 Ga), corresponding to the respective tectonic setting of
153
subduction, initial assembly of the NCC within the Columbia supercontinent cycle
154
and the orogenic collapse, respectively. Another chronological and geochemical
155
research on four granitic samples performed by Yu et al. (2012) revealed two
156
magmatic ages of 2328–2346 Ma and 1866–1881 Ma, and both of them were
157
connected with subduction settings.
158
The Taihua complex in the Mts. Huashan area is exposed on the southern and
159
northern slopes of Mts. Huashan in Shan’anxi and Henan Provinces in central China
160
(Fig. 1b) and is unconformably covered by the Tietonggou Formation at Bayuan,
161
which formed at 1.91–1.80 Ga (Diwu et al., 2013). Sodic TTG gneisses and potassic
162
granites are dominant in the Mts. Huashan Taihua complex. The potassic granites,
163
which are characterized by K-feldspar rich, mainly consist of granitic gneiss,
164
K-feldspar granite and coarse-grained granite according to their field and petrographic
165
characteristics. The TTG gneisses and granitic gneisses show typical fabrics with
166
parallel layering and alignment of plagioclase, quartz and biotite (Fig. 2a–d) and
167
spread widely in the study area. The amphibolites in the Taihua complex in this area
168
generally occur as enclaves in the TTG and granitic gneisses (Fig. 2b). Studies on the
169
amphibolites revealed a regional metamorphism of high-amphibolite to granulite
170
facies at 1.96–1.80 Ga (Wang et al., 2012, 2013a, 2014). On the contrary, the
171
K-feldspar granites and coarse-grained granites show weak (Fig. 2e) or no gneissic
172
foliation (Fig. 2f–h) and intrude into the gneissic rocks as small irregular stocks in
173
several locations.
8
174
3. Samples and Petrography
175
In this study, we collected three TTG gneiss samples (S147, S153 and S165),
176
five granitic gneiss samples (S144, S145, S148, S149 and S155), five K-feldspar
177
granite samples (S137, S140, S142, S143 and S151) and three coarse-grained granite
178
samples (S159, S160 and S163).
179
The TTG gneiss samples (Fig. 3a) are trondhjemite and mainly composed of
180
plagioclase (55–60%), quartz (25–40%), biotite (10–20%) and a few accessory
181
minerals (<5%). Magnetite or ilmenite, apatite and zircon are common accessory
182
minerals. Plagioclase is partly altered to sericite due to later hydrothermal alteration.
183
The granitic gneiss samples (Fig. 3b) are fine- to medium-grained. The mineral
184
assemblages mainly consist of K-feldspar (20–40%), plagioclase (25–45%), quartz
185
(30–40%) and biotite (5–10%). Magnetite or ilmenite and zircon are the common
186
accessory minerals (<5%). These rocks show typical gneissic layering similar to the
187
TTG gneisses, but are characterized by K-feldspar-rich, which is not found in TTG
188
gneisses.
189
The K-feldspar granite samples (Fig. 3c) are medium- to coarse-grained. These
190
rocks also chiefly consist of K-feldspar (30–50%), plagioclase (10–30%), quartz
191
(35–40%) and biotite (<5%) with minor accessory zircon, magnetite or ilmenite
192
(1–2%). These rocks show weak or no gneissic foliation and have more K-feldspar
193
relative to plagioclase.
194
The coarse-grained granite samples are characterized by coarse-grained with
195
massive textures. The mineral assemblages of these samples (Fig. 3d) are mainly
9
196
composed of K-feldspar (25–40%), plagioclase (25–35%), quartz (25–35%), biotite
197
(<5%) or amphibole (~10% in sample S160) and accessory minerals (<2%). Most of
198
the grain sizes of these rocks are in the range of 2–5 mm, and some crystals can reach
199
2 cm in length.
200
4. Analytical methods
201
4.1. LA-ICP-MS U–Pb dating method
202
In situ zircon LA-ICP-MS U–Pb dating were performed at the Institute of
203
Geology and Geophysics, Chinese Academy of Sciences using Agilent 7500a ICP-MS
204
instrument connected with Geolas-193 UV laser ablation system. The spot diameters
205
are 44 µm (for samples S137, S142 and S163) and 32 µm (for the rest samples) in this
206
study with a laser repetition rate of 10 Hz and the carrier gas was Helium. The
207
207
208
GLITTER 4.0 program (van Achterbergh et al., 2001). The Harvard zircon 91500 was
209
used as an external standard for age calculation with a recommended 206Pb/238U age of
210
1065.4 ± 0.6 Ma (2σ) (Wiedenbeck et al, 1995). The NIST SRM 610 was analyzed for
211
the calibration of U, Th and Pb concentrations. Concordia diagrams and weighted
212
mean calculations were made using the software Isoplot (version 3.75) (Ludwig,
213
2003).
214
4.2. Whole-rock major and trace elements
Pb/206Pb,
206
Pb/238U and
207
Pb/235U isotopic ratios were calculated using the
215
Whole-rock major elements were analyzed by X-ray fluorescence (XRF)
216
spectroscopy with a Philips PW1400 spectrometer at the Institute of Geology and
217
Geophysics (IGG), Chinese Academy of Sciences. Fused glass disks were used and
10
218 219
the analytical precision is generally ≤ 5%. Trace
elements
were
analyzed
using
a
Perkin-Elmer
ELAN-DRC-e
220
inductively-coupled plasma mass spectrometry (ICP-MS) at the State Key Laboratory
221
of Ore Deposit Geochemistry (SKLOG), Institute of Geochemistry, Chinese Academy
222
of Sciences (IGCAS). The powdered samples (50 mg) were dissolved in high-pressure
223
Teflon bombs using HF+HNO3 mixture for 48 h at ~195 °C, and other detailed
224
procedures are described by Qi et al. (2000). Rh was used as an internal standard to
225
monitor signal drift during counting. The international standards GBPG-1, OU-6, and
226
the Chinese National standard GSR-1 were used for analytical quality control. The
227
analytical precision is generally ≤ 5%.
228
5. Results
229
5.1. Zircon LA-ICP-MS U–Pb dating
230
The cathodoluminescence (CL) images of representative zircons are shown in
231
Fig. 4 and the U–Th–Pb analytical results are presented in Supplementary Table 1 and
232
Fig. 5. The detailed characteristics of zircons and dating results are described as
233
follows.
234
5.1.1. TTG gneiss
235
Most of the zircons from the TTG gneiss samples are columnar or elongated in
236
shape and about 100–300 µm in length. The majority of these zircon grains show
237
core-rim structures in CL images (Fig. 4a–c). The cores usually display
238
well-developed oscillatory zonings, indicative of magmatic origin. Around the cores
239
are homogeneous rims with higher or lower luminescence, indicative of metamorphic
11
240
origin. Some of the rest zircon crystals are anhedral and homogeneous with no
241
core-rim structures or magmatic rhythmic textures (Fig. 4a), which are considered to
242
be of metamorphic origin.
243
Twenty spot analyses were conducted on 15 zircon grains from sample S147. The
244
U, Th contents and the Th/U ratios of four valid spots on the rim or metamorphic
245
grains are in the range of 291–941 ppm, 83–250 ppm and 0.23–0.29, respectively. All
246
of these analytical spots are concentrated on or very close to the concordia and yield
247
207
248
time of one metamorphic event. The rest eleven valid spots analyzed on the magmatic
249
cores have higher Th/U ratios of 0.38–0.77, with Th and U contents of 48–215 ppm
250
and 85–270 ppm. All of these U–Pb results are also distributed on or very close to the
251
concordia and yield a weighted mean 207Pb/206Pb age of 2315±16 Ma (Fig. 5a), which
252
is interpreted as the crystallization age of this rock.
Pb/206Pb ages ranging from 1815±20 Ma to 1876±18 Ma (Fig. 5a), reflecting the
253
Thirteen zircon grains were selected from sample S153. Ten spots distributed on
254
the metamorphic rims give U, Th contents and the Th/U ratios of 835–1888 ppm,
255
15–197 ppm and 0.04–0.24, respectively. All of these analytical spots fall on the
256
concordia and yield a weighted mean
257
representing an age of one metamorphic event. Nine valid spots on igneous cores have
258
higher Th/U ratios of 0.24–16.95, with Th and U contents of 41–1307 ppm and
259
77–988 ppm, respectively. These U–Pb results define a linear array on the concordia
260
diagram and yield an upper intercept age of 2254±29 Ma (Fig. 5b), which is
261
considered as the crystallization age of this rock.
207
Pb/206Pb age of 1841±21 Ma (Fig. 5b),
12
262
Three spots on metamorphic rims (spots 4, 10, 14), fifteen spots on cores or
263
magmatic zircon grains and three spots on inherited zircons (spots 1, 7, 11) for sample
264
S165 were dated. Two valid spot analyses on the rims distributed on the concordia
265
and yield
266
representing the time of one metamorphic event, with U, Th contents and Th/U ratios
267
of 174–295 ppm, 91–124 ppm and 0.31–0.71, respectively. Fourteen valid spots on
268
cores or magmatic grains are also distributed on the concordia and give a weighted
269
mean
270
crystallization age of this rock, with U, Th contents and Th/U ratios of 195–872 ppm,
271
63–873 ppm and 0.05–0.85, respectively. Three spots on inherited zircons are
272
discordant due to varying lead loss (Fig. 5c) and yield
273
2588±21 Ma to 2709±21 Ma.
274
5.1.2. Granitic Gneiss
207
207
Pb/206Pb ages of 1950±21 Ma and 1968±24 Ma (Fig. 5c), probably
Pb/206Pb age of 2485±21 Ma (Fig. 5c), which is interpreted as the
207
Pb/206Pb ages ranging from
275
Most of the zircon grains from the granitic gneiss samples are euhedral to
276
subhedral and about 100–400 µm in length (Fig. 4d–h). Some of them show
277
oscillatory-zoned cores with/without homogeneous rims, and the others are anhedral
278
and homogeneous without core-rim structures or magmatic rhythmic textures,
279
reflecting metamorphic origin.
280
Fourteen spots on cores or zircon grains with magmatic rhythmic textures and six
281
spots on rims or grains with blurred oscillatory zoning (Fig. 4d) are dated for sample
282
S144, and give U, Th contents and Th/U ratios of 132–539/334–720 ppm,
283
162–2466/49–613 ppm and 1.12–2.62/0.13–0.87, respectively. These analyses yield
13
207
Pb/206Pb ages ranging from 1797±22 Ma to 1875±28 Ma and define an
284
similar
285
upper intercept age of 1829±10 Ma (Fig. 5d), which is interpreted as the emplacement
286
age of this rock.
287
Twenty spots were carried out on 19 grains from sample S145. Two of them on 207
Pb/206Pb ages of
288
metamorphic rims are distributed on the concordia and give
289
1915±18 Ma and 1963±17 Ma with U, Th contents and low Th/U ratios of 895–1561
290
ppm, 54–56 ppm and 0.04–0.06, respectively. Eleven spots on oscillatory-zoned cores
291
give U, Th contents and higher Th/U ratios of 140–568 ppm, 55–627 ppm and
292
0.41–1.10, respectively, and define an upper intercept age of 2293±28 Ma (Fig. 5e).
293
Ten concordant spots near the upper intercept yield a weighted mean
294
of 2286±11 Ma, which is interpreted as the crystallization age of this rock and
295
consistent with the upper intercept age within analytical uncertainties. The rest spots
296
are distributed on the rims or transitional area to the core (Fig. 4e), some of which are
297
slightly discordant and yield younger
298
meaningless and probably as the result of uncompleted recrystallization during the
299
metamorphic event or the mixture of several parts in different proportions of the
300
zircons by laser ablation.
207
207
Pb/206Pb age
Pb/206Pb ages (Fig. 4e). These ages are
301
Twenty spots were analyzed on 10 zircon grains from sample S148. Eight spots
302
on homogeneous rims fall on the concordia and yield a weighted mean 207Pb/206Pb age
303
of 1873±27 Ma (Fig. 5f), which is considered as the age of one metamorphic event,
304
with U, Th contents and Th/U ratios of 91–635 ppm, 35–193 ppm and 0.22–0.73,
305
respectively. Five spots on cores with magmatic rhythmic textures and six spots on
14
306
domains with blurred oscillatory zonings (Fig. 4f) are distributed on or very close to
307
the concordia and have U, Th contents and Th/U ratios of 91–635 ppm, 19–164 ppm
308
and 0.13–0.68, respectively. These spots define a linear array on the concordia and
309
yield an upper intercept age of 2502±49 Ma (Fig. 5f). Three concordant analyses near
310
the upper intercept yield a weighted mean
311
taken as the emplacement age of this rock.
207
Pb/206Pb age of 2551±11 Ma, which is
312
Twenty spot analyses were determined on 17 zircon grains from sample S149.
313
Three spots (spots 07, 10 and 13) on homogeneous rims or grains (Fig. 4g) give U, Th
314
contents and Th/U ratios of 371–443 ppm, 192–300 ppm and 0.51–0.81, respectively.
315
The 207Pb/206Pb ages range from 1794±20 Ma to 1848±19 Ma (Fig. 5g), indicating the
316
time of metamorphism. The rest seventeen spots distributed on the oscillatory-zoned
317
cores and grains with blurred oscillatory zoning (Fig. 4g) yield
318
ranging from 2414±17 Ma to 2513±17 Ma and give U, Th contents and Th/U ratios of
319
191–623 ppm, 70–265 ppm and 0.32–0.79, respectively. Ten of them are concordant
320
and yield a weighted mean
321
regarded as the emplacement age of this rock. The younger seven spots are mostly
322
distributed on domains with blurred oscillatory zoning or the transitional area between
323
core and rim, which are inferred as the results of uncompleted resetting of protolith
324
zircons during metamorphism or the mixture of different generation zircons by laser
325
ablation. In these cases, these results are meaningless.
207
207
Pb/206Pb ages
Pb/206Pb age of 2495±11 Ma (Fig. 5g), which is
326
Twenty-one spots were analyzed on 14 zircon grains from sample S155. Six spots
327
on rims and valid fourteen spots on cores and grains with/without magmatic rhythmic
15
207
Pb/206Pb ages on the concordia ranging from
328
textures (Fig. 4h) show similar
329
1807±30 Ma to 1864±22 Ma with U contents of 127–387/116–866 ppm, Th contents
330
of 59–200/63–814 ppm and Th/U ratios of 0.47–0.58/0.47–1.28, respectively. These
331
analyses yield a weighted mean
332
interpreted as the formation age of this rock.
333
5.1.3. K-feldspar granite
207
Pb/206Pb age of 1834±10 Ma (Fig. 5h), which is
334
Most of the zircons from the K-feldspar granite samples are columnar or rounded
335
in shape and about 100–400 µm in length (Fig. 4i–m). The characteristics of zircons
336
from each sample are described respectively below.
337
Most of the zircons from sample S137 show no rim-core structures but
338
well-developed oscillatory zonings in CL images, implying magmatic origin (Fig. 4i).
339
All of twenty analytical spots fall along a concordia or near-concordia and give Th/U
340
ratios of 0.24–0.87, with Th and U contents of 92–567 ppm and 200–651 ppm,
341
respectively. These results define a linear array on the concordia diagram and yield an
342
upper intercept age of 1834±10 Ma (Fig. 6a), which is considered as the emplacement
343
age of this rock.
344
Zircons from S140 are euhedral to subhedral and
characterized
by
345
core-mantle-rim and mantle-rim structures (Fig. 4j). The cores show obvious
346
oscillatory zoning indicating magmatic origin, while the dark mantles and luminous
347
rims are homogeneous indicative of metamorphic origin. Five analyses were carried
348
out on the rims. These results are distributed on the concordia and yield a weighted
349
mean 207Pb/206Pb age of 1834±22 Ma (Fig. 6b), which are interpreted as the age of one
16
350
metamorphic event, with U, Th contents and Th/U ratios of 149–1181 ppm, 53–69
351
ppm and 0.06–0.41, respectively. Four analyses (spots 04, 05, 09 and 16) were
352
performed on the dark mantle domains, three of which are concentrated on the
353
concordia and give a weighted mean
354
contents and Th/U ratios of 590–1415 ppm, 120–295 ppm and 0.19–0.21, respectively,
355
which probably represents one thermal event, although it cannot be explained now.
356
Nine of eleven analyses on the oscillatory-zoned cores are distributed on or close to
357
the concordia and define an upper intercept age of 2271±28 Ma (Fig. 6b). Seven of
358
them are concentrated on the concordia and near the upper intercept, and yield a
359
weighted mean
360
emplacement age of this rock and consistent with the upper intercept age within
361
analytical uncertainties.
207
207
Pb/206Pb age of 2040±20 Ma with U, Th
Pb/206Pb age of 2275±14 Ma, which is considered as the
362
Zircons from sample S142 are euhedral to subhedral in shape and show weak
363
magmatic rhythmic textures with low to medium luminescence (Fig. 4k), indicating
364
magmatic origin. Twenty spot analyses fall on or very close to the concordia and
365
define an upper intercept age of 1836±17 Ma (Fig. 6c) with Th, U contents and Th/U
366
ratios of 61–462 ppm, 223–1431 ppm and 0.11–0.64, respectively. These results yield
367
a weighted mean
368
emplacement age of this rock.
207
Pb/206Pb age of 1839±8 Ma (Fig. 6c), which is considered as the
369
Zircons from sample S143 are mostly euhedral to subhedral with magmatic
370
rhythmic textures implying magmatic origin, and some of them show inherited cores
371
with strong luminescence (Fig. 4l). Nineteen spot analyzes define a linear array on the
17
372
concordia and yield an upper intercept age of 1868±15 Ma (Fig. 6d) with Th, U
373
contents and Th/U ratios of 27–2840 ppm, 117–2746 ppm and 0.13–1.98, respectively.
374
Sixteen concordant spots near the upper intercept yield a weighted mean
375
age of 1864±10 Ma, consistent with the upper intercept age, and is taken as the
376
emplacement age of this rock. One spot analyze on the inherited core fall on the
377
concordia and yield a 207Pb/206Pb age of 2474±17 Ma.
207
Pb/206Pb
378
Most zircons from sample S151 are euhedral to subhedral and show core-rim
379
structures. The cores exhibit higher luminescence than the rims and show weak or
380
blurred oscillatory zonings, indicative of magmatic origin. The rims and some grains
381
are free of zonings, implying metamorphic origin. Twenty-one spots were analyzed on
382
15 zircon grains for sample S151. Eight spots on homogeneous rims or grains with
383
dark luminescence (Fig. 4m) fall on or very close to the concordia, and give U, Th
384
contents and low Th/U ratios of 702–993 ppm, 45–263 ppm and 0.05–0.28,
385
respectively. Seven of them yield a weighted mean
386
(Fig. 6e), which is considered as the age of one metamorphic event. Nine valid spots
387
on cores and grains with weak or blurred oscillatory zonings are concordant and yield
388
a weighted mean
389
age of this rock with U, Th contents and Th/U ratios of 179–557 ppm, 96–235 ppm
390
and 0.23–0.72, respectively.
391
5.1.4. Coarse-grained granite
207
207
Pb/206Pb age of 1840±14 Ma
Pb/206Pb age of 2326±12 Ma, which is taken as the emplacement
392
The zircon grains from the coarse-grained granite samples are euhedral to
393
subhedral and about 150–400 µm in length (Fig. 4n–p). The characteristics of zircons
18
394
from each sample are described respectively below.
395
Most of the zircon grains from sample S159 are euhedral to subhedral and show
396
weak or blurred oscillatory zonings, indicative of magmatic origin. Some of them
397
exhibit inherited cores (Fig. 4n). Twenty-two analytical spots in this sample give
398
similar
399
upper intercept age of 1802±13 Ma (Fig. 6f), with Th, U contents and high Th/U
400
ratios of 57–926 ppm, 95–990 ppm and 0.38–1.19, respectively. All of these
401
analytical spots fall on or very close to the concordia and yield a weighted mean
402
207
403
of this rock.
207
Pb/206Pb ages ranging from 1776±26 Ma to 1829±25 Ma and define an
Pb/206Pb age of 1801±10 Ma (Fig. 6f), which is considered as the emplacement age
404
Zircons from S160 are characterized by core-mantle-rim, mantle-rim and
405
core-rim structures (Fig. 4o). The cores are anhedral and show dark luminescence and
406
weak oscillatory zonings implying inherited origin, while the dark luminescence
407
mantles and the luminous rims exhibit obvious magmatic rhythmic textures indicating
408
magmatic origin. Some zircon grains show no structures but obvious oscillatory
409
zonings with strong luminescence implying magmatic origin. Fourteen analyses on
410
the luminous rims or grains with well-developed oscillatory zonings and five analyses
411
on the mantles with oscillatory zonings give similar
412
Ma to 1860±21 Ma with Th, U contents and Th/U ratios of 63–967 ppm, 88–502 ppm
413
and 0.22–1.93, respectively. These results define a linear array on the concordia and
414
yield an upper intercept age of 1829±12 Ma (Fig. 6g), which is interpreted as the
415
emplacement age of this rock. Seven of eight analyses on the inherited cores also
19
207
Pb/206Pb ages from 1799±23
416
define a linear array on the concordia diagram and yield an upper intercept age of
417
2326±46 Ma (Fig. 6g).
418
Zircons from sample S163 show no core-rim structures but weak oscillatory
419
zonings with dark luminescence implying magmatic origin (Fig. 4p). Twenty-one
420
spots were performed on 15 grains. Twenty of them are distributed on or close to the
421
concordia and give an upper intercept age of 1838±25 Ma (Fig. 6h), which is
422
considered as the emplacement age of this rock, with Th, U contents and Th/U ratios
423
of 50–358 ppm, 62–276 ppm and 0.63–1.21, respectively.
424
5.2. Whole-rock major and trace elements
425
The whole-rock major and trace element compositions of the TTG gneisses and
426
potassic granites are given in Table 1. Detailed characteristics of these results are
427
described as follows.
428
5.2.1. TTG gneiss
429
The samples of this group contain SiO2 from 67.46 to 71.73 wt%, K2O from 1.84
430
to 2.21 wt%, high Na2O from 4.83 to 5.95 wt%, Al2O3 from 15.55 to 16.98 wt%,
431
Fe2O3 from 2.40 to 3.27 wt% and MgO from 0.72 to 1.06 wt% with Na2O/K2O ratios
432
from 2.34 to 3.23, respectively. Their Mg# [Mg#=Mg/(Mg+Fe), Fe=0.8998FeT] range
433
from 31 to 40. In the Ab-Or-An diagram (Barker and Arth, 1976), all the three
434
samples are plotted in the field of trondhjemite (Fig. 7). In the plot of SiO2 vs.
435
Na2O+K2O (Fig. 8), they are in the fields of granodiorite-granite. These rocks have a
436
calc-alkaline property (Fig. 9a) with δ values (δ=[w(Na2O+K2O)2]/[w(SiO2)2-43])
437
from 1.61 to 2.48, and show weakly peraluminous feature with A/CNK ratios ranging
20
438
from 1.04 to 1.14 and A/NK ratios ranging from 1.43 to 1.55 (Fig. 9b).
439
On the chondrite-normalized REE patterns, all the samples show LREE-enriched
440
and HREE-depleted patterns (Fig. 10a) with moderate (La/Yb)N values (16.8 to 35.3)
441
(Fig. 11) and weakly negative or positive Eu anomalies (Eu/Eu*=0.79–1.18). The
442
rocks have high La (18.4–62.6 ppm) and low Yb (0.53–1.67 ppm) with low Dy/Yb
443
ratios ranging from 1.17 to 2.28. On the primitive mantle-normalized trace elements
444
spidergram, the rocks show negative Ta, Nb, Ti, Sr, P anomalies and positive K, Nd
445
anomalies with Nb/Ta and Sr/Y ratios of 28.1–34.1 and 15.8–34, respectively.
446
5.2.2. Granitic gneiss
447
The rocks of this type have SiO2 ranging from 65.20 to 73.70 wt%, low Na2O
448
from 2.39 to 4.17 wt%, Al2O3 from 13.29 to 17.71 wt%, Fe2O3 from 1.51 to 3.64 wt%
449
and MgO from 0.34 to 1.19 wt%. They show Na2O/K2O ratios ranging from 0.34 to
450
1.07 and high K2O from 5.03 to 6.95 wt%, except one sample has lower K2O of 3.90
451
wt% with low SiO2 content of 65.20 wt%. The Mg# of these rocks range from 21 to
452
31 with the exception of one sample having higher Mg# of 46. In the plot of SiO2 vs.
453
Na2O+K2O (Fig. 8), they are in the fields of granite and quartz-monzonite. These
454
rocks show high-K calc-alkaline to shoshonitic properties (Fig. 9a) with δ values from
455
2.24 to 2.93 and weakly peraluminous feature with A/CNK ratios ranging from 1.06
456
to 1.27 and A/NK ratios ranging from 1.16 to 1.60 (Fig. 9b).
457
The samples are also enriched in LREE relative to HREE on the
458
chondrite-normalized REE patterns (Fig. 10c) with moderate to high (La/Yb)N values
459
of 25.4–202 (Fig. 11). Two samples (S144 and S145) show negative Eu anomalies
21
460
(Eu/Eu*=0.49–0.50), while the other three samples show obvious positive Eu
461
anomalies (Eu/Eu*=1.47–2.94). The rocks show low Dy/Yb ratios of 1.29 to 3.43. On
462
the primitive mantle-normalized spidergram (Fig. 10d), the rocks show negative Ta,
463
Nb, Sr, P anomalies (slightly positive Sr anomaly in S155), negative Ti anomaly in
464
S145 and positive K anomalies with Nb/Ta and Sr/Y ratios of 24.0–33.1 and 12.8–119,
465
respectively.
466
5.2.3. K-feldspar granite
467
These rocks contain higher SiO2 (72.08 to 75.43 wt%), K2O (5.93 to 8.60 wt%)
468
but relatively lower Na2O (1.74 to 2.83 wt%), Al2O3 (12.60 to 14.13 wt%), Fe2O3
469
(0.83 to 2.62 wt%) and MgO (0.11 to 0.34 wt%) contents compared to the granitic
470
gneisses. In the plot of SiO2 vs. Na2O+K2O (Fig. 8), they plot in the field of granite.
471
Their Na2O/K2O ratios range from 0.20 to 0.47 with Mg# from 8 to 41. All the rocks
472
show a shoshonitic property (Fig. 9a) with δ values from 2.14 to 3.68 and weakly
473
peraluminous future with A/CNK ratios ranging from 1.07 to 1.20 and A/NK ratios
474
ranging from 1.13 to 1.29 (Fig. 9b).
475
All the samples of this group also exhibit a LREE-enriched and HREE-depleted
476
patterns (Fig. 10e). Two of them (S140 and S142) show weakly negative or positive
477
Eu anomalies (Eu/Eu*=0.77–1.19) with (La/Yb)N values of 6.5–10.3 (Fig. 11).
478
Another two samples (S137 and S151) show obvious negative Eu anomalies
479
(Eu/Eu*=0.34–0.42) with high (La/Yb)N values of 49.4–226, while the last one
480
sample (S143) show obvious positive Eu anomalies (Eu/Eu*=2.63) with moderate
481
(La/Yb)N values of 26.9. On the primitive mantle-normalized spidergram (Fig. 10f),
22
482
the rocks show negative Ta, Nb, Ti, P anomalies, negative to positive Sr anomalies
483
and positive K anomalies with Nb/Ta and Sr/Y ratios of 11.9–27.7 and 6.7–121,
484
respectively.
485
5.2.4. Coarse-grained granite
486
These rocks have SiO2 contents from 68.54 to 73.20 wt%, K2O from 4.03 to 7.20
487
wt%, Na2O from 2.73 to 4.00 wt%, Al2O3 from 13.89 to 16.18 wt%, Fe2O3 from 1.65
488
to 3.30 wt% and MgO from 0.02 to 0.64 wt% with Na2O/K2O ratios ranging from
489
0.43 to 0.99 and Mg# from 2 to 43, respectively. In the plot of SiO2 vs. Na2O+K2O
490
(Fig. 8), they plot naturally in the field of granite. All the rocks show a shoshonitic
491
property with δ values from 2.52 to 3.89 and weakly metaluminous-peraluminous
492
futures with A/CNK ratios ranging from 1.00 to 1.16 and A/NK ratios ranging from
493
1.13 to 1.48, respectively (Fig. 9).
494
These samples also have LREE-enriched chondrite-normalized patterns with
495
moderate (La/Yb)N values ranging from 17.3 to 33.3 (Fig. 11) and show no or positive
496
Eu anomalies (Eu/Eu*=0.82–3.03) (Fig. 10g). These rocks have high Sr/Y ratios
497
(22.1–208) and Nb/Ta ratios (12.3–31.7) with negative Nb, Ta, P anomalies and
498
positive K anomalies on the primitive mantle-normalized spidergram (Fig. 10h).
499
6. Discussion
500
6.1. Multistage magmatism and metamorphism
501
Zircons from the TTG gneiss samples in this study reveal two episodic magmatic
502
ages (2254±29 Ma to 2315±16 Ma, and 2485±21 Ma) and one episodic
503
metamorphism ages (1815±20 Ma to 1968±24 Ma), indicating the trondhjemite of the
23
504
Taihua complex in the Mts. Huashan area formed in the Early Paleoproterozoic and
505
underwent metamorphism in the Late Paleoproterozoic. These results are consistent
506
with Huang et al. (2013), in which three episodes of crystallizations of the TTG
507
gneisses in this area were recognized (~2.48 Ga, ~2.31 Ga and ~2.16 Ga).
508
Three episodes of magmatism and one episodic metamorphism were identified
509
by zircons from the granitic gneiss samples. The first episode of magmatism
510
(2495±11 Ma to 2551±11 Ma) was represented by the formation of samples S148 and
511
S149 during the Late Neoarchean to the Early Paleoproterozoic, while the second
512
episode of magmatism (2283±12 Ma) was reflected by the emplacement of sample
513
S145 in the Early Paleoproterozoic. The metamorphism (1794±20 Ma to 1963±17 Ma)
514
recorded by these pre-exist rocks occurred at the same time with the third episode of
515
magmatism (1829±10 Ma to 1834±10 Ma), represented by the formation of samples
516
S144 and S155, in the Late Paleoproterozoic.
517
Two magmatism episodes and one metamorphic episode were also recognized in
518
the K-feldspar gneiss samples. The first episode of magmatism is exhibited by the
519
emplacement of samples S140 and S151 in the Early Paleoproterozoic (2275±14 Ma
520
to 2326±12 Ma), and the episode of metamorphism in the Late Paleoproterozoic
521
(1834±22 Ma to 1840±14 Ma) was also recorded. The second episode of magmatism
522
is represented by the formation of samples S137, S142 and S143 in the Late
523
Paleoproterozoic (1834±10 Ma to 1868±15 Ma).
524 525
The emplacement age of the coarse-grained granite samples (1801±10 Ma to 1838±25 Ma) also reveal the episode of magmatism in the Late Paleoproterozoic.
24
526
6.2. Petrogenesis of the granitoids
527
The large ion lithophile elements (LILEs), such as K, Cs, Rb and Ba are
528
susceptible to high-grade metamorphism and not useful in determining the nature of
529
the protolith of rocks experienced high-grade metamorphism. But some rare earth
530
elements (REEs, e.g. La, Ce and Yb) and high field strength elements (HFSEs, e.g.
531
Nb, Zr and Hf) are less susceptible to high-grade metamorphism and could preserve
532
the original information of the rocks (Pearce, et al., 1992; Kerrich et al., 1998).
533
Therefore, in the petrogenetic discussion in this study, we primarily based on the
534
elements of Si, Mg, Al, REEs and HFSEs, which are reliable in determining the
535
nature of the protolith of these rocks.
536
6.2.1. TTG gneiss
537
The three TTG gneiss samples collected in this study all belong to trondhjemite
538
in the normalized plot of An-Ab-Or (Fig. 7) with moderate Sr/Y ratios (15.8–34.0)
539
and (La/Yb)N values (16.8–35.3), showing characteristics of TTGs and adakites (Fig.
540
11) (Martin et al., 2005; Condie, 2005). The absence of evidence of any pre-existing
541
high Sr/Y and La/Yb sources in the Huashan area (Huang et al., 2013) led to that
542
these TTGs probably generated from partial melting of hydrous mafic rocks with
543
garnet and amphibole in the residue (e.g., Smithies, 2000; Martin et al., 2005; Condie,
544
2005). Although debate still exists on the tectonic setting for the formation of the TTG
545
assemblage (e.g., Martin, 1999; Smithies and Champion, 2000; Foley et al., 2002;
546
Condie, 2005; Foley, 2008; Moyen, 2009), they are commonly considered as the
547
product of partial melting of subducting oceanic crust under eclogite facies conditions,
25
548
which are characteristic of high Mg# values and high Cr and Ni concentrations due to
549
the interaction of the partial melts with peridotitic mantle during its ascent (Defant
550
and Drummond, 1990; Kay et al., 1993; Martin, 1999; Rapp et al., 1999; Smithies and
551
Champion, 2000; Martin et al., 2005; Moyen, 2009). Another familiar formation
552
mechanism is partial melting of hydrous thickened lower crust, which would produce
553
melts with low Mg# values and low Cr and Ni concentrations (Atherton and Petford,
554
1993; Rapp et al., 1999; Smithies 2000, 2002; Condie, 2005). The Huashan TTG
555
samples in this study show high SiO2 concentrations, low Mg# values and low Cr and
556
Ni concentrations, implying that the trondhjemite samples are probably derived from
557
a hydrous thickened, basaltic lower crust.
558
Generally, plagioclase has excessively high positive Sr and Eu anomalies but
559
highly depletion of other REEs (McKay et al., 1994; Niu and O’Hara, 2009), so the
560
absence of obvious Eu anomalies and high Sr concentrations of these trondhjemite
561
samples possibly imply a plagioclase-free/poor source and the lack of plagioclase
562
either as obvious accumulation or fractionating phases. The HREE-depleted REE
563
patterns revealed in these rocks indicate the potential residual phases of garnet and/or
564
amphibolite during partial melting (e.g., Martin et al., 2005) or garnet and/or
565
amphibolite fractionation during ascent. Partial melting with garnet in the residue will
566
effectively increase Sr/Y, La/Yb, Gd/Yb and Dy/Yb ratios, while melts with
567
amphibole as a residual phase will have low Nb/Ta, Gd/Yb and Dy/Yb ratios
568
(Macpherson et al., 2006; Davidson et al., 2007). Positive correlation between the
569
Sr/Y and La/Yb ratios could be observed as the result of fractionation of amphibole
26
570
and/or garnet (Huang et al., 2012). The rocks show moderate (La/Yb)N values
571
(16.8–35.3), Sr/Y ratios (15.8–34.0) and low Gd/Yb (2.10–3.32), Dy/Yb (1.71–2.28)
572
ratios and no correlation relationship between Sr/Y ratios and (La/Yb)N values was
573
observed (Table. 1), probably suggesting the parental magma of these trondhjemite
574
samples derived from partial melting of a source with both garnet and amphibole in
575
the residue. Moreover, the absence of concave upward REE patterns (Fig.9a) indicates
576
garnet was the dominant residual phase, because amphibole has a higher KD for
577
medium REEs than those for HREEs (Rollinson, 1993). The negative Nb, Ta
578
anomalies, positive Zr, Hf anomalies and high Nb/Ta (28.1−34.1) ratios of these
579
trondhjemite samples maybe indicate a residual phase of rutile in the source (Klemme
580
et al., 2005). It is anticipated that the primary magmas of these trondhjemite rocks
581
were probably derived from partial melting of a plagioclase-poor garnet-rich
582
amphibolites or rutile-bearing eclogite source, similar to medium- or high-pressure
583
TTG groups (Moyen, 2011).
584
6.2.2. Granitic gneisses
585
Most of the granitic gneiss samples have high SiO2, K2O and low Na2O, MgO,
586
CaO contents. They also have LREE-enriched and HREE-depleted patterns similar to
587
those of the TTG samples except for the obvious positive/negative Eu anomalies (Fig.
588
10c). These REE patterns and high (La/Yb)N values (25.4–202), Sr/Y ratios (12.8–119)
589
and low Gd/Yb (2.70–11.1), Dy/Yb (1.29–3.43) ratios and the lack of Sr/Y ratios
590
correlation with (La/Yb)N values indicate the parental magma of these samples
591
perhaps were derived from partial melting of a source with garnet and amphibole in
27
592
the residue. Positive Eu anomalies in the samples S148, S149 and S155 can be
593
explained by plagioclase accumulation in the rocks, while negative Eu anomalies in
594
the other two samples S144 and S145 possibly suggest plagioclase existing in the
595
residue and/or plagioclase fractionation during magma ascent.
596
6.2.3. K-feldspar granites
597
Although different chemical affinities exist among these samples, which were
598
probably resulted from partial melting of different/heterogeneous source rocks,
599
melting conditions or interaction with hydrothermal fluids (Villemant et al., 1996; Wu
600
et al., 2003), they also show high SiO2 and K2O, low Na2O, MgO and CaO contents.
601
The HREE-depleted patterns with various (La/Yb)N values (6.5–226), Sr/Y ratios
602
(6.7–121) and low Gd/Yb (1.75–11.1), Dy/Yb (2.35–6.47) ratios and the lack of Sr/Y
603
ratios correlation with (La/Yb)N values probably imply the residual phases of garnet
604
and amphibole in different proportions. The absence of obvious Eu anomalies and
605
high Sr concentrations of samples S140 and S142 (Fig. 10e) possibly indicate a
606
plagioclase-free/poor source and the lack of plagioclase either as obvious
607
accumulation or fractionating phases. The obvious negative Eu anomalies in S137 and
608
S151 could result from plagioclase removal by fractional crystallization or as a
609
residual phase during partial melting, and plagioclase accumulation could account for
610
the positive Eu anomaly in S143. Depletions of Nb, Ta and Ti were probably resulted
611
from rutile fractionation or as a residual phase in the source (Ionov and Hofmann,
612
1995; Xiong et al., 2005; Coltorti et al., 2007).
613
6.2.4. Coarse-grained granites
28
614
The three coarse-grained granite samples collected in this study have moderate to
615
high Sr/Y ratios (22.1–208) and (La/Yb)N values (17.3–33.3) and show characteristic
616
of TTGs and adakites (Defant and Drummond, 1990; Martin et al., 2005; Condie,
617
2005). The HREE-depleted patterns with high Sr/Y, (La/Yb)N, Zr/Sm (44.8−379) and
618
low Gd/Yb (2.54−3.31), Dy/Yb (1.48−2.48) can be interpreted by amphibole and
619
garnet as residual phases during partial melting or as fractionating phases. Positive
620
correlation between the Sr/Y ratios and (La/Yb)N values can be found in these
621
samples (Table. 1), so fractionation of amphibole and/or garnet couldn’t be ruled out
622
for these rocks. The relatively low and limited Dy/Yb variations indicate that the
623
contribution of dominant amphibole with minor garnet during partial melting or
624
fractional crystallization could be the main mechanism for the moderate to high Sr/Y
625
ratios and (La/Yb)N values of these rocks, which is consisted with the relatively flat
626
HREE patterns except for sample S160 (Fig. 10g). Plagioclase accumulation could
627
account for the positive Eu and Sr anomalies in S159 and S163, which was not
628
observed in S160.
629
As mentioned above, the absence of evidence of any pre-existing high Sr/Y and
630
La/Yb sources in the Huashan area (Huang et al., 2013) suggested that these potassic
631
granites also probably generated from partial melting of hydrous mafic rocks with
632
garnet and amphibole in the residue (e.g., Smithies, 2000; Martin et al., 2005; Condie,
633
2005). In conclusion, the potassic granites are generally considered as the results of
634
partial melting of subducted slab with assimilation/interaction of mantle wedge
635
peridotite or the product of partial melting of lower crustal materials (Moyen et al.,
29
636
2003; Jayananda et al., 2006; Moyen, 2011), which is supported by experimental
637
studies (Skjerlie and Jonston, 1993; Wang et al., 2005; Watkins et al., 2007). Most of
638
the potassic granite samples in this study show high SiO2, K2O and low MgO, ruling
639
out of the basaltic oceanic crustal source (Smithies, 2000). Therefore, it is suggested
640
that most of the potassic granites in this area were derived from partial melting of
641
lower crustal sources, which is also sustained by inherited zircons from some of these
642
samples. As mentioned above, different chemical features among these samples were
643
probably resulted from partial melting of different/heterogeneous source rocks,
644
melting conditions or interaction with hydrothermal fluids (Villemant et al., 1996; Wu
645
et al., 2003). More detailed and meticulous studies are necessary on each kind of these
646
potassic granites in the future.
647
6.3. Episodic crustal growth and reworking in the southern TNCO
648
In the last decades, more and more accurate geochronological and isotopic data
649
were obtained from the Taihua complex and revealed several obvious episodic
650
magmatic activities occurred in the southern segment of the TNCO at 2.84–2.72 Ga,
651
2.57–2.43 Ga, 2.36–2.25 Ga, 2.19–2.07 Ga and 1.87–1.80 Ga (e.g., Wan et al., 2006;
652
Liu et al., 2009; Diwu et al., 2010, 2014; Huang et al., 2010, 2012, 2013; Jiang et al.,
653
2011; Wang et al., 2012, 2013a, 2014; Zhou et al., 2014).
654
The first episode of magmatic activity (2.84–2.72 Ga) is recorded in the
655
granitoids and amphibolites from Lushan area (Liu et al., 2009; Diwu et al., 2010;
656
Huang et al., 2010; Zhou et al., 2014), which can be subdivided into two groups. The
657
first subgroup is represented by the granitoids formed at 2.84–2.77 Ga, which are
30
658
predominantly composed of TTG gneisses. These granitoids are characterized by low
659
SiO2 and high MgO (Mg#) with positive whole rock ƐNd(t) and zircon ƐHf(t) values
660
and were interpreted as production of partial melting of subducted oceanic crust with
661
interaction with the mantle wedge in a subduction setting (Diwu et al., 2010; Huang et
662
al., 2010; Zhou et al., 2014). The second subgroup is represented by minor TTG
663
gneisses and other granites formed at 2.76–2.72 Ga, which exhibit high SiO2 and low
664
MgO (Mg#) with negative whole rock ƐNd(t) and zircon ƐHf(t) values and were
665
explained as the results of partial melting of thickened mafic lower crust (Huang et al.,
666
2010; Zhou et al., 2014), probably triggered by underplating of basaltic magmas
667
extracted from mantle wedge (Zhou et al., 2014). In consequence, crustal growth is
668
dominant in the southern segment of the TNCO in the Early Neoarchean,
669
accompanied by a small amount of crustal reworking, which is consistent to the major
670
period of juvenile crustal growth in the NCC at ca. 2.8–2.7 Ga (Wu et al., 2005; Sun
671
et al., 2012; Wang and Liu, 2012). Juvenile continental crust can be produced at
672
subduction settings or by mantle plumes (Condie, 1998). Although the partial melting
673
of ocean crust in subduction setting was favored in previous studies (e.g., Huang et al.,
674
2010; Zhou et al., 2014), which means the initial subduction developed in the
675
southern NCC in the Archaean. However, why is this episode of magmatic activity
676
only preserved in Lushan area in the Taihua complex adjacent to the Eastern Block?
677
Zhao et al. (2007, 2013) interpreted these 2.8–2.7 Ga rocks in the Trans-North China
678
Orogen as the remnants of old continental basement, which most likely represented
679
the western margin of the Eastern Block. Assuredly, Liu et al. (2009) obtained the
31
680
metamorphic ages of 2.77–2.79 Ga and 2.64–2.67 Ga for the 2.83–2.85 Ga TTG
681
gneisses and amphibolites from the Taihua complex in Lushan area, which are similar
682
to the rock-forming and metamorphic ages of the granite-greenstone belt in Western
683
Shandong in the Eastern Block (Wan et al., 2011). In that case, the geodynamic
684
setting and geological evolution history of this tectonothermal event during 2.8–2.7
685
Ga are still equivocal and prefer a mantle plume model (e.g., Polat et al., 2006; Wan
686
et al., 2011; Wang et al., 2013b). Therefore, extensive and intensive investigations are
687
still needed on this episode of magmatic activity to explore the Early Neoarchean
688
evolution of the NCC.
689
The second episodic magmatic event (2.57–2.43 Ga) is represented by the
690
granitoids from Huashan and Dengfeng areas (Wan et al., 2009; Diwu et al., 2011,
691
2014; Huang et al., 2013; Zhang et al., 2013; this study) and amphibolites from the
692
Dengfeng and Lushan areas (Diwu et al., 2011; Lu et al., 2013, 2014; Zhang et al.,
693
2013). This episodic magmatic rocks show dominantly positive whole rock ƐNd(t) and
694
positive zircon ƐHf(t) values, indicating juvenile compositions (Diwu et al., 2011,
695
2014; Huang et al., 2013). Therefore, another major crustal growth episode was
696
recorded in the southern segment of the TNCO from the Late Neoarchean to the Early
697
Paleoproterozoic, which was also universal in the NCC (Zhai et al., 2010; Zhao and
698
Zhai, 2013). Diwu et al. (2011) interpreted these TTGs in Dengfeng areas as results of
699
partial melting of subducted oceanic crust with interaction with mantle peridotite,
700
whereas Huang et al. (2013) suggested that these rocks in Dengfeng and Huashan
701
areas generated similarly through partial melting of thickened lower crust in a
32
702
subduction setting. In this study, the granitoids from Huashan area show high SiO2
703
and low MgO (Mg#) and are also conjectured as partial melting of lower thickened
704
crust. Minor TTG gneisses in Huashan and potassic granites in Lushan show negative
705
whole rock Ɛ Nd(t) and positive zircon Ɛ Hf(t) values and are interpreted as results from
706
partial melting of pre-existing crustal materials (Huang et al., 2013; Zhou et al.,
707
2014).
708
The third episodic magmatic event (2.36–2.25 Ga) is dominantly presented by
709
the emplacement of the granitoids and the protoliths of the amphibolites from the
710
Huashan and Luoning areas (Diwu et al., 2007; Jiang et al., 2011; Huang et al., 2012,
711
2013; Wang et al., 2012, 2014; Yu et al., 2013; this study). This episodic magmatic
712
rocks show negative to positive whole rock ƐNd(t) and positive zircon ƐHf(t) values
713
with low MgO (Mg#) (Diwu et al., 2011, 2014; Huang et al., 2013; Yu et al., 2013;
714
this study). Thus, both crustal growth and reworking occurred in the southern segment
715
of TNCO in the Early Paleoproterozoic. These granitoids were interpreted resulting
716
from the partial melting of both juvenile and pre-existing crustal materials in a
717
subduction tectonic setting (Huang et al., 2013) or have resulted from partial melting
718
of lower crust and interacted with peridotitic mantle (Diwu et al., 2014). Based on the
719
characteristic of high SiO2 and low MgO (Mg#) contents of the granitoids in this
720
study, we agree with Huang et al. (2013) that these rocks were produced by partial
721
melting of both juvenile and pre-existing crustal materials. And we propose that this
722
magmatism was probably triggered by underplated mantle-derived basaltic magma,
723
which was probably emerged as amphibolite enclaves in the metamorphic complex at
33
724
present with protolith age of ~2.3 Ga (Wang et al., 2014). The depositional age of the
725
meta-sedimentary rocks from Lushan area terrane was constrained between 2.3 Ga
726
and 2.0 Ga (Wan et al., 2006; Diwu et al., 2014), meanwhile our previous studies also
727
indicated the protolith of the meta-sedimentary rocks in the Huashan and Luoning
728
areas terranes also formed after ~2.3 Ga (Jiang et al., 2011; Wang et al., 2012, 2013a).
729
Therefore, a continental margin arc or island arc setting was suggested at this time,
730
and the volcanic-sedimentary rocks developed in the back-arc basins.
731
The fourth episode of magmatism (2.19–2.07 Ga) is revealed by the granitoids
732
from the Huashan and the Luoning areas (Huang et al., 2012, 2013), which were
733
interpreted as the results of crustal reworking in an extensional setting related to the
734
breakup of one supercontinent (Huang et al., 2013).
735
The last episode of magmatism (1.87–1.80 Ga) is represented by the formation of
736
the granitoids from Mts. Huashan area in this study, which is synchronism with the
737
metamorphism recorded not only in the pre-existing granitoids but also in amphibolite
738
and metasedimentary in this region (Wang et al., 2012, 2013a, 2014). This episodic
739
magmatic activity was never reported noticeably in the Taihua complex in previous
740
studies (e.g., Liu et al., 2009; Huang et al., 2010, 2012, 2013; Diwu et al., 2010, 2014;
741
Zhou et al., 2014) and is presented remarkably in this study. The P–T paths
742
reconstructed from amphibolites in this region imply a continent-continent collision
743
between the Eastern Block and the Western Block and followed by rapid uplift
744
process (Wang et al., 2014), indicating transformation of tectonic environment from
745
compression to extension during the Late Paleoproterozoic. The last episodic
34
746
magmatism was probably resulted from partial melting of pre-existing crustal
747
materials during this period of time in a syn-orogenic or post-orogenic setting.
748
Therefore, crustal evolution in the southern TNCO is dominant by reworking in the
749
Late Paleoproterozoic.
750
6.4. Implication for tectonic evolution in the southern TNCO
751
The Taihua complex can be divided into the Lower Taihua subgroup and Upper
752
Taihua subgroup. The former principally consists of TTG gneisses, granitic gneisses,
753
metabasite and minor meta-supracrustal rocks, whereas the latter is dominantly
754
composed of meta-supracrustal rocks including metapelite, marbles and BIF. The
755
protolith of this rock combination was preferred as a marine volcanic-sedimentary
756
formation (Sun et al., 1983; Qi, 1992; Chen et al., 1997; Zhou et al., 1997, 1998),
757
indicating an active continental margin or island arc setting. As we mentioned, more
758
extensive and intensive investigations are needed on the episode of magmatic activity
759
in the southern TNCO during the Early Neoarchean (2.8–2.7 Ga). From Late
760
Neoarchean to Late Paleoproterozoic, it is notable that the magmatic activities
761
preserved in the southern TNCO are characterized by continuity rather than episodes.
762
In addition, the ages of magmatic activities in the Taihua complex tend to be younger
763
from the eastern Lushan area to the western Huashan area. Therefore, transformation
764
from an Andean-type continental margin arc setting on the western margin of the
765
Eastern Block to continent-arc-continent collision in the southern TNCO during Late
766
Neoarchean to Late Paleoproterozoic is suggested in this paper.
767
From 2.57 Ga to 2.43 Ga, magmas produced by partial melting of subducted
35
768
oceanic crust interacted with the overlying mantle peridotite and formed the high
769
MgO (Mg#) rocks in Dengfeng area. Synchronously, subduction of the oceanic
770
lithosphere caused partial melting of the mantle wedge, which led to underplating of
771
basaltic magma in the lower crust and formed part of the protolith of the amphibolites
772
in Lushan and Dengfeng areas. These underplating mafic magma provided the
773
thermal flux needed to melt the juvenile and minor pre-existing materials in the lower
774
crust and produce the low MgO (Mg#) granitoids in Lushan and Dengfeng areas and
775
minor TTG gneisses in Huashan area.
776
From 2.36 Ga to 2.25 Ga, as subduction continued, extension driven by the
777
possible trench retreating caused by rollback of subducted plate because of gravity
778
(Niu, 2013) led to the development of back-arc basins. The continuous subduction
779
caused partial melting of the mantle wedge, which led to underplating of mafic
780
magma in the lower crust in Huashan and Luoning areas and formed part of the
781
protolith of the amphibolites. These underplating mafic magma further caused partial
782
melting of lower crust and form large amounts of granitoids in Huashan and Luoning
783
areas. Contemporary volcanic-sedimentary rocks formed in the back-arc basins.
784
From 2.19 Ga to 2.07 Ga, a small amount of magmatism occurred in Huashan
785
and Luoning areas in an extensional setting related to the breakup of one
786
supercontinent (Huang et al., 2013). Here we prefer the extensional setting related to
787
the extension of back-arc basin.
788
Before 1.87–1.80 Ga, the oceanic basin between the Eastern and Western Blocks
789
was completely closed by subduction and led to continent-arc-continent collision
36
790
followed by a rapid uplift process, which can be reflected commendably by the
791
metamorphism recorded in the metamorphic complex (Lu et al., 2013, 3014; Wang et
792
al., 2014; Chen et al., 2015). This magmatism probably resulted from partial melting
793
of re-existing crustal materials in a syn-orogenic or post-orogenic setting.
794
7. Conclusion
795 796
The lithological, geochronological and geochemical data of the granitoids from the Mts. Huashan Taihua complex, allow us arrive at the following conclusions:
797
(1) At least three episodes of magmatism (2.55–2.49 Ga, 2.33–2.25 Ga and
798
1.87–1.80 Ga) occurred in the southern segment of the TNCO during Neoarchean to
799
Paleoproterozoic.
800
(2) The first episode of magmatism (~2.5 Ga) is interpreted as melts from partial
801
melting of thickened juvenile lower crust. The second episodic magmatism (~2.3 Ga)
802
is suggested as the product of partial melting of both juvenile and pre-existing crustal
803
materials, which was probably triggered by underplated mantle-derived basaltic
804
magma. The third episode of magmatism (1.87–1.80 Ga), accompanied by the coeval
805
metamorphism recorded in the metamorphic complex, probably resulted from partial
806
melting of re-existing crustal materials in a syn-orogenic or post-orogenic setting
807
during the collision between the Eastern and Western Blocks.
808
(3) Multistage continental accretion (at 2.84–2.72 Ga, 2.57–2.43 Ga and
809
2.36–2.25 Ga) and reworking (at 2.36–2.25 Ga, 2.19–2.07 Ga and 1.87–1.80 Ga)
810
occurred in the southern segment of the TNCO from Neoarchean to Paleoproterozoic.
811
Transformation from an Andean-type continental margin arc setting on the western
37
812
margin of the Eastern Block to continent-arc-continent collision in the southern
813
TNCO during Late Neoarchean to Late Paleoproterozoic is suggested.
814
Acknowledgements
815
This work was supported by the National Natural Science Foundation of China
816
(41225007, 41130314). We are grateful to Prof. Jin-Hui Yang and Yue-Heng Yang
817
for the LA-ICP-MS U–Pb dating of zircons. Special thanks are due to Profs. Kai-Jun
818
Zhang and Dr. Hao Wang for their discussions and suggestions.
819
References
820
Atherton, M.P., Petford, N., 1993. Generation of sodium-rich magmas from newly
821 822 823
underplated basaltic crust. Nature 362, 144–146. Barker, F., Arth, J.G., 1976. Generation of trondhjemitic-tonalitic liquids and Archaean bimodal trondhjemite-basalt suites. Geology 4, 596–600.
824
Chen, H.X., Wang, J., Wang, H., Wang, G.D., Peng, T., Shi, Y.H., Zhang, Q., Wu,
825
C.M., 2015. Metamorphism and geochronology of the Luoning metamorphic
826
terrane, southern terminal of the Palaeoproterozoic Trans-North China Orogen,
827
North China Craton. Precambrian Research 264, 156–178.
828
Chen, L.G., Wang, B.Y., Xue, Y.Z., 1997. The reestablishment of Taihua Group in
829
Xiao Qinling, Shanxi. Geology of Shanxi 15, 20–30 (in Chinese with English
830
abstract).
831
Coltorti, M., Bonadiman, C., Faccini, B., Grégoire, M., O’Reilly, S.Y., Powell, W.,
832
2007. Amphiboles from suprasubduction and intraplate lithospheric mantle.
833
Lithos 99, 68–84.
38
834
Condie, K.C., 1993. Chemical composition and evolution of the upper continental
835
crust: contrasting results from surface samples and shales. Chemical Geology
836
104, 1–37.
837 838 839 840 841 842 843 844
Condie, K.C., 1998. Episodic continental growth and supercontinents: a mantle avalanche connection? Earth and Planetary Science Letters 163, 97–108. Condie, K.C., 2005. TTGs and adakites: are they both slab melts? Lithosphere 79, 33–44. Davidson, J., Macpherson, C., Turner, S., 2007. Amphibole control in the differentiation of arc magmas. Geochimica et Cosmochimica Acta 71, A204. Defant, M.J., Drummond, M.S., 1990. Derivation of some modern arc magmas by melting of young subduction lithosphere. Nature 347, 662–665.
845
Diwu, C.R., Sun, Y., Gao, J.F., Fan, L.G., 2013. Early Precambrian tectonothermal
846
events of the North China Craton: Constraints from in situ detrital zircon U–Pb,
847
Hf and O isotopic compositions in Tietonggou Formation. Chinese Science
848
Bulletin 58, 3760–3770.
849
Diwu, C.R., Sun, Y., Guo, A.L., Wang, H.L., Liu, X.M., 2011. Crustal growth in the
850
North China Craton at ∼2.5 Ga: evidence from in situ zircon U–Pb ages, Hf
851
isotopes and whole-rock geochemistry of the Dengfeng Complex. Gondwana
852
Research 20, 149–170.
853
Diwu, C.R., Sun, Y., Lin, C.L., Liu, X.M., Wang, H.L., 2007. Zircon U–Pb ages and
854
Hf isotopes and their geological significance of Yiyang TTG gneisses from
855
Henan province, China. Acta Petrologica Sinica 23, 253–262 (in Chinese with
39
856
English abstract).
857
Diwu, C.R., Sun, Y., Lin, C.L., Wang, H.L., 2010. LA-(MC)-ICP-MS U–Pb zircon
858
geochronology and Lu–Hf isotope compositions of the Taihua Complex on the
859
southern margin of the North China Craton. Chinese Science Bulletin 55,
860
2557–2571.
861
Diwu, C.R., Sun, Y., Zhao, Y., Lai, S.C., 2014. Early Paleoproterozoic (2.45–2.20 Ga)
862
magmatic activity during the period of global magmatic shutdown: Implications
863
for the crustal evolution of the southern North China Craton. Precambrian
864
Research 255, 627–640.
865
Faure, M., Trap, P., Lin, W., Monié, P., Bruguier, O., 2007. Polyorogenic evolution of
866
the Paleoproterozoic Trans-North China Belt, new insights from the
867
Lüliangshan–Hengshan–Wutaishan and Fuping massifs. Episodes 30, 1–12.
868
Foley, S., 2008. A trace element perspective on Archean crust formation and on the
869
presence or absence of Archean subduction. In: Condie, K.C., Pease, V.
870
(Eds.), When Did Plate Tectonics Begin? Geological Society of America
871
Special Paper 440, Colorado, pp. 31–50.
872
Foley, S., Tiepolo, M., Vannucci, R., 2002. Growth of early continental crust
873
controlled by melting of amphibolite in subduction zones. Nature 417, 837–840.
874
Frost,
C.D.,
Frost,
B.R.,
Kirkwood,
R.,
Chamberlain,
K.R., 2006. The
875
tonalite-trondhjemite-granodiorite (TTG) to granodiorite-granite (GG) transition
876
in the late Archean plutonic rocks of the central Wyoming Province. Canadian
877
Journal of Earth Science 43, 1419–1444.
40
878
Guo, J.H., Sun, M., Zhai, M.G., 2005. Sm–Nd and SHRIMP U–Pb zircon
879
geochronology of high-pressure granulites in the Sanggan area, North China
880
Craton: timing of Paleoproterozoic continental collision. Journal of Asian Earth
881
Sciences 24, 629–642.
882
Huang, X.L., Niu, Y.L., Xu, Y.G., Yang, Q.J., Zhong, J.W., 2010. Geochemistry of
883
TTG and TTG-like gneisses from Lushan-Taihua complex in the southern North
884
China Craton: Implications for late Archean crustal accretion. Precambrian
885
Research 182, 43–56.
886
Huang, X.L., Wilde, S.A, Yang, Q.J., Zhong, J.W., 2012. Geochronology and
887
petrogenesis of gray gneisses from the Taihua Complex at Xiong'er in the
888
southern segment of the Trans-North China Orogen: Implications for tectonic
889
transformation in the Early Paleoproterozoic. Lithos 134–135, 236–252.
890
Huang, X.L., Wilde, S.A, Zhong, J.W., 2013. Episodic crustal growth in the southern
891
segment of the Trans-North China Orogen across the Archean-Proterozoic
892
boundary. Precambrian Research 233, 337–357.
893
Ionov, D.A., Hofmann, A.W., 1995. Nb-Ta-rich mantle amphiboles and micas:
894
implications for subduction-related metasomatic trace element fractionations.
895
Earth and Planetary Science Letters 131, 341–356.
896
Jahn, B.M., Glikson, A.Y., Peucat, J.J., Hickman, A.H., 1981. REE geochemistry and
897
isotopic data of Archaean silica volcanics and granitoids from the Pilbara Block,
898
western Australia: implications for the early crustal evolution. Geochimica et
899
Cosmochima Acta 45, 1633–1652.
41
900
Jayananda, M., Chardon, D., Peucat, J.J., Capdevila, R., 2006. 2.61 Ga potassic
901
granites and crustal reworking in the western Dharwar craton, southern India:
902
Tectonic, geochronologic and geochemical constraints. Precambrian Research
903
150, 1–26.
904
Jiang, Z.S., Wang, G.D., Xiao, L.L., Diwu, C.R., Lu, J.S., Wu, C.M., 2011.
905
Paleoproterozoic metamorphic P–T–t path and tectonic significance of the
906
Luoning metamorphic complex at the southern terminal of the Trans-North
907
China Orogen，Henan Province. Acta Petrologica Sinica 27, 3701–3717 (in
908
Chinese with English abstract).
909
Kay, S.M., Ramos, V.A., Marquez, M., 1993. Evidence in Cerro Pampa volcanic
910
rocks for slab-melting prior to ridge-trench collision in southern South America.
911
The Journal of Geology 101, 703–714.
912
Kerrich, R., Wyman, D., Fan, J., Bleeker, W., 1998. Boninite series: low Ti-tholeiite
913
associations from the 2.7 Ga Abitibi greenstone belt. Earth and Planetary
914
Science Letters 164, 303–316.
915
Klemme, S., Prowatke, S., Hametner, K., Günther, D., 2005. Partitioning of trace
916
elements between rutile and silicate melts: implications for subduction zones.
917
Geochimica et Cosmochima Acta 49, 2361–2371.
918
Kröner, A., Wilde, S.A., Li, J.H., Wang, K.Y., 2005. Age and evolution of a late
919
Archaean to early Palaeozoic upper to lower crustal section in the
920
Wutaishan/Hengshan/Fuping terrain of northern China. Journal of Asian Earth
921
Sciences 24, 577–595.
42
922 923 924 925
Kusky, T.M., 2011. Geophysical and geological tests of tectonic models of the North China Craton. Gondwana Research 20, 26–35. Kusky, T.M., Li, J.H., 2003. Paleoproterozoic tectonic evolution of the North China Craton. Journal of Asian Earth Sciences 22, 23–40.
926
Liu, D.Y., Nutman, A.P., Compston, W., Wu, J.S., Shen, Q.H., 1992. Remnants of
927
≥3800 Ma crust in the Chinese part of the Sino-Korean Craton. Geology 20,
928
339–342.
929
Liu, D.Y., Wilde, S.A., Wan, Y.S., Wang, S.Y., Valley, J.W., Kita, N., Dong, C.Y.,
930
Xie, H.Q., Yang, C.X., Zhang, Y.X., Gao, L.Z., 2009. Combined U–Pb,
931
hafnium and oxygen isotope analysis of zircons from meta-igneous rocks in
932
the southern North China Craton reveal multiple events in the Late
933
Mesoarchean–Early Neoarchean. Chemical Geology 261, 140–154.
934
Lu, J.S., Wang, G.D., Wang, H., Chen, H.X., Wu, C.M., 2013. Metamorphic P–T–t
935
paths retrieved from the amphibolites, Lushan terrane, Henan Province and
936
reappraisal of the Paleoproterozoic tectonic evolution of the Trans-North China
937
Orogen. Precambrian Research 238, 61–67.
938
Lu, J.S., Wang, G.D., Wang, H., Chen, H.X., Wu, C.M., 2014. Palaeoproterozic
939
Metamorphic evolution and geochronology of the Wugang block, southeastern
940
terminal of the Trans-North China Orogen. Precambrian Research 251,
941
197–211.
942 943
Ludwig, K.R., 2003. Isoplot 3.0-A geochronological toolkit for Micro-soft Excel. Berkeley Geochronology Center, Special Publication 4, 1–70.
43
944
Macpherson, C.G., Dreher, S.T., Thirlwall, M.F., 2006. Adakites without slab
945
melting: high pressure processing of basaltic island arc magma, Mindanao, the
946
Philippines. Earth and Planetary Science Letters 243, 581–593.
947 948
Maniar, P.D., Piccoli, P.M., 1989. Tectonic discrimination of granitoids. Geological Society of America Bulletin 101, 635–643.
949
Martin, H., 1994. The Archean grey gneisses and the genesis of continental crust. In:
950
Condie, K.C. (Ed.), Archean Crustal Evolution. Developments in Precambrian
951
Geology, vol. 11. Elsevier, New York, pp. 205–258.
952 953 954 955 956
Martin, H., 1999. Adakitic magmas: modern analogues of Archaean granitoids. Lithos 46, 411–429. Martin, H., Moyen, J.F., 2002. Secular changes in TTG composition as markers of the progressive cooling of the Earth. Geology 30, 319–322. Martin, H., Smithies, R.H., Rapp, R., Moyen, J.F., Champion, D., 2005. An overview
957
of
958
relationships and some implications for crustal evolution. Lithos 79, 1–24.
959
McKay, G., Le, L., Wagstaff, J., Crozaz, G., 1994. Experimental partitioning of rare
960
earth elements and strontium: constraints on petrogenesis and redox conditions
961
during crystallization of Antarctic angrite Lewis Cliff 86010. Geochimica et
962
Cosmochima Acta 58, 2911–2919.
963 964 965
adakite,
tonalite-trondhjemite-granodiorite
(TTG)
and
sanukitoid:
Middlemost, E.A.K., 1994. Naming materials in the magma/igneous rock system. Earth Science Review 37, 215–244. Moyen, J.F., 2009. High Sr/Y and La/Yb ratios: the meaning of the adakitic
44
966
signature. Lithos 112, 556–574.
967
Moyen, J.F., 2011. The composite Archaean grey gneisses: petrological significance,
968
and evidence for a non-unique tectonic setting for Archaean crustal growth.
969
Lithos 123(1–4), 21–36.
970
Moyen, J.F., Mratin, H., Jayananda, M., Auvray, B., 2003. Late Archean granites: a
971
typology based on the Dharwar Craton (India). Precambrian Research 127,
972
103–123.
973
Niu, Y.L., 2013. Subduction initiation, trench retreat and global tectonic
974
consequences: The origin of back-arc basins in the western Pacific and effect on
975
eastern China geology since the Mesozoic. In: Zhai, M.G., Xiao, W.J. (Eds),
976
Plate Tectonics, Geological Events and Resources: New Advances in Geological
977
Sciences. Science Press, Beijing, pp. 1–25 (in Chinese).
978
Niu, Y.L., O’Hara, M.J., 2009. MORB mantle hosts the missing Eu (Sr, Nb, Ta and Ti)
979
in the continental crust: new perspectives on crustal growth, crust-mantle
980
differentiation and chemical structure of oceanic upper mantle. Lithos 112,
981
1–17.
982
Polat, A., Li, J., Fryer, B., Kusky, T., Gagnon, J., Zhang, S., 2006. Geochemical
983
characteristics of the Neoarchean (2800–2700 Ma) Taishan greenstone belt,
984
North China Craton: evidence for plume-craton interaction. Chemical Geology
985
230, 60–87.
986
Pearce, J.A., van der Laan, S.R., Arculus, R.J., Murton, B.J., Ishii, T., Peate, D.W.,
987
1992. Boninite and Harzburgite from Leg 125 (Bonin-Mariana Fore-arc): a case
45
988
study of magma genesis during the initial stage of subduction. In: Fryer, P.,
989
Pearce, J.A., Stokking, L.B. (Eds.), Proceedings for the Ocean Drilling Program.
990
Sci. Results, vol. 125, pp. 623–659.
991
Peccerillo, R., Taylor, S.R., 1976. Geochemistry of Eocene calc-alkaline volcanic
992
rocks from the Kastamonu areas, Northern Turkey. Contributions to Mineralogy
993
and Petrology 58, 63–81.
994
Peng, P., Wang, X.P., Windley, B.F., Guo, J.H., Zhai, M.G., Li, Y., 2014. Spatial
995
distribution of ~1950–1800 Ma metamorphic events in the North China Craton:
996
Implications for tectonic subdivision of the craton. Lithos 202–203, 250–266.
997
Qi, J.Y., 1992. Metamorphic rock series of Taihua Group and conditions for its
998
formation in eastern Qinling. Scientia Geologica Sinica 8 (Suppl.), 95–107
999
(in Chinese with English abstract).
1000 1001
Qi, L., Hu, J., Grégoire, D.C., 2000. Determination of trace elements in granites by inductively coupled plasma mass spectrometry. Talanta 51, 507–513.
1002
Rapp, R.P., Shimizu, N., Norman, M.D., Applegate, G.S., 1999. Reaction between
1003
slab-derived melts and peridotite in the mantle wedge: experimental constraints
1004
at 3.8 GPa. Chemical Geology 160, 335–356.
1005 1006
Rollinson,
H.R.,
1993.
Using
geochemical
data:
evaluation,
presentation,
interpretation. Longman Technical Press, London, pp. 352.
1007
Santosh, M., 2010. Assembling North China Craton within the Columbia
1008
supercontinent: the role of double-sided subduction. Precambrian Research 178,
1009
149–167.
46
1010
Santosh, M., Sajeev, K., Li, J.H., 2006. Extreme crustal metamorphism during
1011
Columbia supercontinent assembly: evidence from North China Craton.
1012
Gondwana Research 10, 256–266.
1013
Skjerlie, K.P., Johnston, A.D., 1993. Vapour-absent melting from 10 to 20 Kbar of
1014
crustal rocks that contain multiple hydrous phases: implications for anatexis in
1015
the deep to very deep continental crust and active continental margins. Journal
1016
of Petrology 37, 661–691.
1017
Smithies, R.H., 2000. The Archaean tonalite-trondhjemite-granodiorite (TTG)
1018
series is not an analogue of Cenozoic adakite. Earth and Planetary Science
1019
Letters 182, 115–125.
1020 1021
Smithies, R.H., 2002. Archaean boninite-like rocks in an intracratonic setting. Earth and Planetary Science Letters 197, 19–34.
1022
Smithies, R.H., Champion, D.C., 2000. The Archaean high-Mg diorite suite: links to
1023
tonalite-trondhjemite-granodiorite magmatism and implications for early
1024
Archaean crustal growth. Journal of Petrology 41, 1653–1671.
1025
Smithies, R.H., Champion, D.C., Van Kranendonk, M.J., 2009. Formation of
1026
Paleoarchean continental crust through infracrustal melting of enriched basalt.
1027
Earth and Planetary Science Letters 281, 298–306.
1028
Sun, S.S., McDonough, W.F., 1989. Chemical and isotopic systematic of oceanic
1029
basalts: implications for mantle composition and processes. In: Saunders, S.D.,
1030
Norry, M.J. (Eds.), Magmatism in Ocean Basins. Geological Society of London
1031
42, pp. 313–345.
47
1032 1033
Sun, Y., 1983. Rocks in the granulite facie of the Taihua Group at Lushan, Henan. Journal of Northwest University 1, 92–98.
1034
Sun, Y., Yu, Z.P., Kröner, A., 1994. Geochemistry and single zircon geochronology
1035
of Archaean TTG gneisses in the Taihua high-grade terrain, Lushan area, central
1036
China. Journal of Southeast Asian Earth Sciences 10, 227–233.
1037
Sutcliffe, R.H., Smith, A.R., Doherty, W., Bernett, R.L., 1990. Mantle derivation of
1038
Archean amphibole-bearing granitoids and associated mafic rocks: evidence
1039
from the southern superior Province, Canada. Contributions to Mineralogy and
1040
Petrology 105, 255–274.
1041
Sylvester, P.J., 1994. Archaean granite plutons. In: Condie, K. (Ed.), Archaean
1042
Crustal Evolution. Developments in Precambrian Geology. Elsevier, Amsterdam,
1043
pp. 261–314.
1044
Trap, P., Faure, M., Lin, W., Breton, N.L., Monié, P., 2012. The Paleoproterozoic
1045
evolution of the Trans-North China Orogen: Toward a comprehensive model.
1046
Precambrian Research 222–223, 191–211.
1047
Trap, P., Faure, M., Lin, W., Monié, P., 2007. Late Palaeoproterozoic (1900–1800 Ma)
1048
nappe stacking and polyphase deformation in the Hengshan–Wutaishan area:
1049
Implications for the understanding of the Trans-North China Belt, North China
1050
Craton. Precambrian Research 156, 85–106.
1051
Van Achterbergh, E., Ryan, C., Jackson, S., Griffin, W.L., 2001. In Sylvester, P. (Ed.),
1052
Appendix
3
Data
Reduction
1053
Laser-Ablation-ICPMS in the Earth Sciences, vol. 29. Mineralogical
48
Software
for
LA-ICP-MS
in
1054
Association of Canada Short Course, pp. 239–243.
1055
Villemant, B., Boudon, G., Komorowski, J.C., 1996. U-series disequilibrium in arc
1056
magmas induced by water-magma interaction. Earth and Planetary Science
1057
Letters 140, 259–267.
1058
Wan, Y.S., Liu, D.Y., Wang, S.J., Yang, E.X., Wang, W., Dong, C.Y., Zhou, H.Y.,
1059
Du, L.L., Yang, Y.H., Diwu, C.R., 2011. 2.7 Ga juvenile crust formation in the
1060
North China Craton (Taishan–Xintai area, western Shandong Province): further
1061
evidence of an understated event from U–Pb dating and Hf isotopic composition
1062
of zircon. Precambrian Research 186, 169–180.
1063
Wan, Y.S., Wilde, S.A., Liu, D.Y., Yang, C.X., Song, B., Yin, X.Y., 2006. Further
1064
evidence for ∼1.85 Ga metamorphism in the Central Zone of the North China
1065
Craton: SHRIMP U–Pb dating of zircon from metamorphic rocks in the Lushan
1066
area, Henan Province. Gondwana Research 9, 189–197.
1067
Wang, A.D., Liu, Y.C., 2012. Neoarchean (2.5–2.8) crustal growth of the North China
1068
Craton revealed by zircon Hf isotope: a synthesis. Geoscience Frontiers 3,
1069
147–173.
1070
Wang, G.D., Lu, J.S., Wang, H., Chen, H.X., Xiao, L.L., Diwu, C.R., Ji, J.Q., Wu, 40
Ar/39Ar dating of
1071
C.M., 2013a. LA-ICP-MS U–Pb dating of zircons and
1072
amphiboles of the Taihua Metamorphic Complex, Huashan, southern terminal of
1073
the Palaeoprotorozoic Trans-North China Orogen. Acta Petrologica Sinica 29,
1074
3099–3114 (in Chinese with English abstract).
1075
Wang, G.D., Wang, H., Chen, H.X., Lu, J.S., Wu, C.M., 2014. Metamorphic
49
1076
evolution and zircon U–Pb geochronology of the Mts.Huashan amphibolites:
1077
Insights into the Palaeoproterozoic amalgamation of the North China Craton.
1078
Precambrian Research 245, 100–114.
1079
Wang, G.D., Wang, H., Chen, H.X., Lu, J.S., Xiao, L.L., Wu, C.M., 2012. U–Pb
1080
dating of zircons from metamorphic rocks of the Taihua Metamorphic Complex,
1081
Huashan, Southern Margin of the Trans-North China Orogen. Acta Geologica
1082
Sinica 86, 1541–1551 (in Chinese with English abstract).
1083
Wang, Q., McDermott, F., Xu, J.F., Bellon, H., Zhu, Y.T., 2005. Cenozoic K-rich
1084
adakitic volcanic rocks in the Hohxil area, northern Tibet: lower-crustal
1085
melting in an intra-continental setting. Geology 33, 465–468.
1086
Wang, W., Yang, E.X., Zhai, M.G., Wang, S.J., Santosh, M., Du, L.L., Xie, H.Q., Lv,
1087
B., Wan, Y.S., 2013b. Geochemistry of ~2.7 Ga basalts from Taishan area:
1088
Constraints on the evolution of early Neoarchean granite-greenstone belt in
1089
western Shandong Province, China. Precambrian Research 224, 94–109.
1090
Watkins, J., Clemens, J., Treloar, P., 2007. Archean TTGs as sources of younger
1091
granitic magmas: melting of sodic metatonalites at 0.6–1.2 G pa. Contributions
1092
to Mineralogy and Petrology 154, 91–100.
1093
Wiedenbeck, M., Alle, P., Corfu, F., Griffin, W.L., Meier, M., Oberli, F., Vonquadt,
1094
A., Roddick, J.C., Speigel, W., 1995. Three natural zircon standards for
1095
U–Th–Pb, Lu–Hf, trace-element and REE analyses. Geostandards and
1096
Geoanalytical Research 19, 1–23.
1097
Whitney, D.L., Evans, B.W., 2010. Abbreviations for names of rock-forming minerals.
50
1098
American Mineralogist 95, 185–187.
1099
Wu, F.Y., Jahn, B.M., Wilde, S.A., Lo, C.H., Yui, T.F., Lin, Q., Ge, W.C., Sun, D.Y.,
1100
2003. Highly fractionated I-type granites in NE China (I): geochronology and
1101
petrogenesis. Lithos 66, 241–273.
1102 1103
Wu, F.Y., Zhao, G.C., Simon, A., 2005. Nd isotopic constraints on crustal formation in the North China Craton. Journal of Asian Earth Science24, 523–545.
1104
Xiong, X.L., Adam, J., Green, T.H., 2005. Rutile stability and rutile/melt HFSE
1105
partitioning during partial melting of hydrous basalt: implications for TTG
1106
genesis. Chemical Geology 218, 339–359.
1107
Xue, L.W., Yuan, Z.L., Zhang, Y.S., Qiang, L.Z., 1995. The Sm–Nd isotope age of
1108
Taihua Group in Lushan area and their implications. Geochimica 24, Suppl.,
1109
92–97 (in Chinese with English abstract).
1110
Yu, X.Q., Liu, J.L., Li, C.L., Chen, S.Q., Dai, Y.P., 2013. Zircon U–Pb dating and Hf
1111
isotope analysis on the Taihua Complex: Constraints on the formation and
1112
evolution of the Trans-North China Orogen. Precambrian Research 230, 31–34.
1113
Zhai, M.G., Bian, A.G., Zhao, T.P., 2000. The amalgamation of the supercontinent of
1114
North China Craton at the end of the Neoarchaean and its breakup during late
1115
Palaeoproterozoic and Mesoproterozoic. Science in China Series D: Earth
1116
Sciences 43, 219–232.
1117
Zhai, M.G., Guo, J.H., Liu, W.J., 2005. Neoarchean to Paleoproterozoic continental
1118
evolution and tectonic history of the North China Craton: A review. Journal of
1119
Asian Earth Sciences 24, 547–561.
51
1120
Zhai, M.G., Li, T.S., Peng, P., Hu, B., Liu, F., Zhang, Y.B., Guo, J.H., 2010.
1121
Precambrian key tectonic events and evolution of the North China Craton. In:
1122
Kusky, T.M., Zhai, M.G., Xiao, W.J. (Eds.), The Evolving Continents. Journal
1123
of the Geological Society, London, Special Publications 338, 235–262.
1124 1125 1126 1127
Zhai, M.G., Peng, P., 2007. Paleoproterozoic events in North China Craton. Acta Petrologica Sinica 23, 2665–2682 (in Chinese with English abstract). Zhai, M.G., Santosh, M., 2011. The early Precambrian odyssey of North China Craton. A synoptic overview. Gondwana Research 20, 6–25.
1128
Zhang, J., Zhang, H.F., Lu, X.X., 2013. Zircon U–Pb and Lu–Hf isotope constraints
1129
on Precambrian evolution of continental crust in the Songshan area, the
1130
south-central North China Craton. Precambrian Research 226, 1–20.
1131
Zhao, G.C., Cawood, P.A., Li, S.Z., Wilde, S.A., Sun, M., Zhang, J., He, Y.H., Yin,
1132
C.Q., 2012. Amalgamation of the North China Craton: Key issues and
1133
discussion. Precambrian Research 222–223, 55–76.
1134
Zhao, G.C., Cawood, P.A., Wilde, S.A., Sun, M., Lu, L.Z., 2000. Metamorphism of
1135
basement rocks in the Central Zone of the North China Craton: implications for
1136
Paleoproterozoic tectonic evolution. Precambrian Research 103, 55–88.
1137
Zhao, G.C., Kröner, A., Wilde, S.A., Sun, M., Li, S.Z., Li, X.P., Zhang, J., Xia, X.P.,
1138
He, Y.H., 2007. Lithotectonic elements and geological events in the
1139
Hengshan–Wutai–Fuping belt: a synthesis and implications for the evolution of
1140
the Trans-North China Orogen. Geological Magazine 144, 753–775.
1141
Zhao, G.C., Sun, M., Wilde, S.A., Li, S.Z., 2005. Neoarchaean to Palaeoproterozoic
52
1142
evolution of the North China Craton: key issues revisited. Precambrian Research
1143
136, 177–202.
1144
Zhao, G.C., Wilde, S.A., Cawood, P.A., Lu, L.Z., 1998. Thermal evolution of the
1145
Archaean basement rocks from the eastern part of the North China Craton and
1146
its bearing on tectonic setting. International Geology Review 40, 706–721.
1147
Zhao, G.C., Zhai, M.G., 2013. Lithotectonic elements of Precambrian basement in the
1148
North China Craton: Review and tectonic implications. Gondwana Research 23,
1149
1207–1240.
1150
Zheng, Y.F., 2009. Fluid regime in continental subduction zones: petrological
1151
insights from ultrahigh-pressure metamorphic rocks. Journal of the Geological
1152
Society 166, 763–782.
1153
Zhou, H.W., Li, X.H., Zhong, Z.Q., Liu, Y., Xu, Q.D., 1997. Geochemistry of
1154
amphibolites within the Taihua complex from the Xiao Qinling area, western
1155
Henan and its tectonic implication. Geochimica 26, 87–100 (in Chinese with
1156
English abstract).
1157
Zhou, H.W., Zhong, Z.Q., Ling, W.L., Zhong, G.L., Xu, Q.D., 1998. Sm–Nd isochron
1158
for the amphibolites within Taihua complex from the Xiao Qinling area, western
1159
Henan and its geological implications. Geochimica 27, 367–372 (in Chinese
1160
with English abstract).
1161
Zhou, Y.Y., Zhao, T.P., Zhai, M.G., Gao, J.F., Sun, J.Y., 2014. Petrogenesis of the
1162
Archean tonalite-trondhjemite-granodiorite (TTG) and granites in the Lushan
1163
area, southern margin of the North China Craton: Implications for crustal
53
1164
accretion and transformation. Precambrian Research 255, 514–537.
1165
Figure captions
1166 1167
Fig. 1. (a) Geological sketch map of the North China Craton (Zhao et al. 1998,
1168
2005) and (b) Geological sketch map of the Mts. Huashan metamorphic terrane,
1169
slightly modified after the 1:200000 Weinan and Luonan Geological Maps. Sample
1170
locations are depicted.
1171
Fig. 2. Field photographs. (a) trondhjemite intruded by dolerite dyke; (b)
1172
trondhjemite with amphibolite enclaves; (c and d) outcrops of granitic gneisses with
1173
typical fabrics; (e) outcrop of K-feldspar granite with weak gneissic foliation; (f)
1174
K-feldspar granitic stocks with no gneissic foliation intrude the gneissic rocks; (g and
1175
h) coarse-grained granite show no gneissic foliation.
1176
Fig. 3. Photomicrographs of the (a) TTG gneiss, (b) granitic gneiss, (c)
1177
K-feldspar granite and (d) coarse-grained granite in the Huashan area. The
1178
abbreviations of minerals are from Whitney and Evans (2010).
1179
Fig. 4. Cathodoluminescence (CL) images of zircons from (a–c) trondhjemite
1180
samples; (d–h) granitic gneiss samples; (i–m) K-feldspar granite samples; (n–p)
1181
coarse-grained granite samples.
1182
Fig. 5. Concordia diagrams of LA-ICP-MS zircon U–Pb geochronology. (a–c)
1183
trondhjemite samples; (d–h) granitic gneiss samples. The dotted circles correspond to
1184
the invalid data in Supplementary Table 1.
1185
Fig. 6. Concordia diagrams of LA-ICP-MS zircon U–Pb geochronology. (a–e)
54
1186
K-feldspar granite samples; (f–h) coarse-grained granite samples. The dotted circles
1187
correspond to the invalid data in Supplementary Table 1.
1188 1189 1190 1191
Fig. 7. An-Ab-Or classification diagram (Barker and Arth, 1976) of the granitoids of the Taihua complex in the Mts. Huashan. Fig. 8. SiO2 vs. (Na2O + K2O) diagram of the granitoids of the Taihua complex in the Mts. Huashan (after Middlemost, 1994).
1192
Fig. 9. (a) SiO2 vs. K2O diagram (after Peccerillo and Taylor, 1976); (b) A/CNK
1193
vs. A/NK diagram (after Maniar and Piccoli, 1989) for the TTG gneiss, granitic gneiss,
1194
K-feldspar granite and coarse-grained granite.
1195
Fig. 10. (a, c, e, g) Chondrite-normalized REE and (b, d, f, h) primitive
1196
mantle-normalized trace elements patterns of the granitoids of the Taihua complex in
1197
the Mts. Huashan area (normalization values after Sun and McDonough, 1989).
1198
Fig. 11. (a) (Yb)N vs. (La/Yb)N and (b) Y vs. Sr/Y diagrams for the granitoids.
1199
Fields of high-Al TTG, adakite and common island arc magmatic rocks are from
1200
Defant and Drummond (1990) and Martin et al. (2005).
Table caption
1201 1202 1203
Table 1. Major (wt%) and trace element (ppm) data of the granitoids of the Taihua complex in the Mts. Huashan area.
Supporting Information
1204 1205 1206
1207
Additional Supporting Information can be found in the online version of this article: Supplemental Table 1. Zircon LA-ICP-MS U–Pb data of the granitoids of the 55
1208
Taihua complex in the Mts. Huashan area. The data with strikethrough are invalid and
1209
meaningless, which probably come from the mixture of several parts in different
1210
proportions of the zircons by laser ablation.
1211
56
100°
105°
110°
115°
125°
120°
130°
Abbreviations for metamorphic complexes in Fig.1(a):
Changchun
(a)
SJ
0
200 400 km
Duolun
Bayan Obo WC
GY
40° AL
Yinshan Block HL
WL JP
NH
40°
WD JN XH MY HA Khondalite Belt EH Beijing QL HS WT FP
Xi ' An
SL
LG Pyeonrang
EASTERN BLOCK
WESTERN BLOCK LL Taiyuan ZH Ordos Block 35°
NL
Gyeonggi
ES 35°
TRANS - NORTH WS CHINA OROGEN ZT DF
TH Hidden basement in the Eastern and Western Block
Xinyang Shanghai
Exposed basement in the Eastern and Western Block Hidden basement in the Paleoproterozoic orogens
30°
Exposed basement in the Khondalite Belt in the Western Block
Wuhan
Exposed basement in the Trans-North China orogen Exposed basement in the Jiao-Liao-Ji Belt in the Eastern Block Major fault
115°
110° 10´
109° 45´
AL – Alashan; CD – Chengde; DF – Dengfeng; EH – Eastern Hebei; ES – Eastern Shandong; FP – Fuping; GY – Guyang; HA – Huai'an; HL – Helanshan; HS – Hengshan; JN – Jining; LG – Langrim; LL – Lüliang; MY– Miyun; NH – Northern Hebei; NL – Northern Liaoning; QL – Qianlishan; SJ – Southern Jilin; SL – Southern Liaoning; TH – Taihua; WD– Wulashan-Daqingshan; WL– Western Liaoning; WS – Western Shandong; WT – Wutai; XH – Xuanhua; ZH – Zanhuang; ZT – Zhongtiao.
125°
120°
110° 15´
110° 30´
N
Huayin
(b)
S165 S163
Huaxian
34° 30´
Tongguan
S145 S151 S137 S148 S144 S140 S149
Arth 1
Arth 2 S142
110° 45´ 0 10000m 34° 30´
S160 S159
S147
S155
S153
Arth 1
S143
Pt 1 xl 3
34° 00´
110°30´
110°15´ Lower Taihua Group (Arth 1)
Upper Taihua Group (Arth 2 )
Upper Xiong'er Group
Proterozoic granite
Μesozoic granite
Sample location
110°45´
34° 00´
(b)
(a) Dolerite dyke
Trondhjemite Amphibolites
Trondhjemite
Trondhjemite Trondhjemite
(d)
(c)
Granitic gneiss
Granitic gneiss
(e)
(f) Granitic gneiss K-feldspar granite K-feldspar granite
(g)
Coarse-grained granite
(h)
Coarse-grained granite
(b)
(a) Pl Bt
Kfs Kfs
Q
Kfs
Pl
Qz Kfs
Qz
Pl Pl
Bt 1000 µm
Pl
(c)
Qz Pl
Qz Bt
1000 µm
(d)
Kfs
Bt
Q
Qz Kfs Kfs Qz
Qz
Pl Kfs 1000 µm
Pl 1000 µm
(a) S147 1837±18 03 1861±20 04 16 2287±22
(b) S153 1824±18 02
2030±18 07
2305±20 01
01 2216±18
06 2307±20
02
(d) S144
2442±18
1968±24
100µm
02 1823±21
05 1825±20
1915±18
2275±18
03
2311±19
2092±18 20
19 17 2309±20 100µm
01
19 1843±30 100µm
(f) S148 04 1881±25 2488±18 09 03 2517±19
1822±22 08 06 07 1822±22 1822±35
(j) S140 2030±17 1849±18 06
1823±21 17
1826±26 08 07 2283±17
04
2318±18 07
2050±18
10
16
11
2278±18
2284±18 100µm
(k) S142
(m) S151
15 1854±21
1806±31
200µm
05 1829±19
1833±28 14
1828±29 09
200µm
(i) S137 02 1822±18
1845±25 20 1883±26 15 16 19 2523±20 2436±21
10 2548±19 100µm
(h) S155 1827±20 05
(g) S149 2430±17 03 2447±18 2508±17 06 10 02 11 1816±19 2430±17 07 100µm 1848±19
1858±22 20
15 1819±22
100µm (e) S145
1803±18 2215±25 14
1824±20 16
10
09 2427±18
2540±17 06
01 2709±24
15
11 10 2278±23
100µm (c) S165
1834±18
15
(l) S143 1844±18 08 1822±18 07
1833±18 11 10 2333±19
1834±20 13
15 1829±19
2474±17
1884±20 10
05
200µm
100µm
1837±19 1833±19
18
(n) S159
17 2320±20
16
11 1801±26
100µm 1824±22 (o) S160 1820±25 12 1813±26 04 24 13 2285±18 03 23 2345±17 2255±21
1840±25 29 1856±20
100µm
28
1888±23 1863±19 16 18
1797±27 1808±21 18 21 17 1798±22 1808±21 20 19 16 1810±19 1814±25 200µm
(p) S163 14 1819±28 1816±33 02 16 03 1809±29 15 1825±30 1797±25
1811±25 19
200µm
0.46
2450
(a) S147
2450
(b) S153
0.46
2350
2350 10
0.42
2250
20
2150
12 0.38
207
0.34
13
5.5
2050
upper intercept age： 2254±29Ma (MSWD = 0.73)
1950 0.34
1750 0.30 4.5
0.38
206
weighted mean Pb/ Pb age: 2315±16Ma (MSWD = 1.3, n=11)
19
07
05 1950 03 16 1850 15
2250
0.42
1850
207
206
weighted mean Pb/ Pb age: 1841±21Ma (MSWD = 2.7, n=10)
1750 6.5
7.5 207
8.5
9.5
10.5
0.30 4.5
5.5
6.5
7.5
235
207
Pb/ U
8.5
9.5
10.5
235
Pb/ U 2100
0.52
0.38
(c) S165
(d) S144 2000
2600
0.36 01
0.48
0.44
1900
0.34
11
2400 07
1800
0.32
12 2200 0.40
207
1700
0.30
weighted mean Pb/ Pb age： 2485±21Ma (MSWD = 4.2, n=14)
04
206
upper intercept age: 1829±10Ma (MSWD = 1.11)
1600
0.28 2000
0.36
14
1500
0.26
10 0.32 5
7
9
11 207
13
15
1400 0.24 2.5
3.5
4.5
235
207
Pb/ U
5.5
6.5
235
Pb/ U
0.46
2400
(e) S145
0.44
2300
upper intercept age： 2293±28Ma (MSWD = 0.75)
0.42
0.52
(f) S148
2600
0.48
upper intercept age： 2400 2502±49Ma (MSWD = 0.84)
14 0.44 0.40
14
2100 0.38
0.40
07
2000 0.36
207
207
03
2000
0.36
207
1900
15
0.34
0.32
0.32
206
weighted mean Pb/ Pb age: 2551±11Ma (MSWD = 1.0, n=3)
206
weighted mean Pb/ Pb age: 2283±12Ma (MSWD = 0.78, n=10)
206
weighted mean Pb/ Pb age: 1873±27Ma (MSWD = 2.1, n=8)
1800
1800 0.28 4.5
5.5
6.5
7.5 207
8.5
9.5
4
6
8
235
10 207
Pb/ U
0.52
12
14
235
Pb/ U
0.37 2600
(h) S155
(g) S149
0.48
1950
0.35
0.44
1850 0.33 2200
0.40 207
2000
0.36 10
0.31
07 0.29
1800
0.32
20
1750
206
weighted mean Pb/ Pb age: 2495±11Ma (MSWD = 0.51, n=10)
1650 207
0.28 4
206
weighted mean Pb/ Pb age: 1834±10Ma (MSWD = 0.44, n=20)
13
6
8 207
Pb/ 235U
10
12
0.27 3.6
4.0
4.4
4.8 207
5.2
Pb/ 235U
5.6
6.0
0.38
(a) S137
2350
(b) S140
0.44
2000
upper intercept age： 2271±28Ma (MSWD = 0.18)
0.36
18
12
0.40
1900
05
0.34 2050 0.36
1800
0.32
0.30
1850
upper intercept age： 1834±10Ma (MSWD = 0.22)
1700
0.32
weighted mean Pb/ Pb age： 2040±20Ma (MSWD = 0.36, n=3) 207
206
1750 weighted mean 207Pb/ 206Pb age： 1834±22Ma (MSWD = 0.41, n=5)
1650 1600 0.28 3.8
weighted mean 207Pb/ 206Pb age： 2275±14Ma (MSWD = 0.29, n=7)
1950
0.28 4.2
4.6
5.0 207
5.4
5.8
6.2
6.6
4
5
6
7
235
207
Pb/ U
0.37
8
9
10
235
Pb/ U
0.50 2000
(c) S142 1960 upper intercept age： 1836±17Ma (MSWD = 0.23)
0.35
2500
(d) S143
0.46
05 2300
1920
0.42
1880
2100
0.38 1840
0.33
1900
0.34
1800 1760 0.31
upper intercept age： 1868±15Ma (MSWD = 0.77)
1700
0.30
1720 weighted mean Pb/ Pb age： 1839±8Ma (MSWD = 0.34, n=20) 207
1680 0.29 4.0
4.4
4.8
5.2 207
206
5.6
6.0
weighted mean Pb/ Pb age： 1864±10Ma (MSWD = 0.46, n=16) 207
1500
0.26 1300 0.22 2
4
6
235
8 207
Pb/ U
206
10
12
235
Pb/ U
0.36
0.48
(e) S151
(f) S159
2400
1920
upper intercept age： 1802±13Ma (MSWD = 0.49)
0.44
0.34
2200
1880 1840
0.40
01
2100
1800 0.32
weighted mean Pb/ Pb age： 2326±12Ma (MSWD = 0.18, n=9) 207
15
12
0.36
206
1760 1720
04
1800
0.32
08 0.30
weighted mean 207Pb/ 206Pb age： 1840±14Ma (MSWD = 0.16, n=7)
1640
0.28 4
6
8 207
weighted mean 207Pb/ 206Pb age： 1801±10Ma (MSWD = 0.4, n=22)
1680
10
0.28 3.8
4.2
4.6
235
5.0 207
Pb/ U
5.4
5.8
235
Pb/ U
0.46 2000
(g) S160
0.36
2300
0.42
0.38
(h) S163 upper intercept age： 1838±25Ma (MSWD = 0.61)
upper intercept age： 1829±12Ma (MSWD = 0.75) 16 08
1900
0.34
1800 0.32
1900
0.34
upper intercept age： 2326±46Ma (MSWD = 1.4)
11
20 0.30
1500 0.26 3
1700
0.30
5
7 207
Pb/ 235U
9
0.28 3.8
1700
4.2
4.6
5.0 207
Pb/ 235U
5.4
5.8
6.2
An
TTG gneiss Granitic gneiss 80 30
K-felsdspar granite 70 Coarse-grained granite 50 40
60
30
70
20
80
Trondhjemite Granite
Or
Ab 30
40
50
60
70
80
90
16 TTG gneiss
14
Foid syenite
Granitic gneiss K-feldspar granite
12
Foid monzodiotite
Syenite
Coarse-graned granite
Foid monzosyenite
10 8
Quartzmonzonite Monzonite
Monzodiotite Monzogabbro
Foid gabbro
6
Granite
Granodiorite
4
Diorite
2
Peridetegabbro
Gabbroic diorite
Gabbro
0 35
40
45
50
55
SiO 2 (wt%)
60
65
70
75
80
3.00
13 12 11 10 9 8 7 6 5 4 3 2 1 0
(a)
(b) 2.50
TTG gneiss Granitic gneiss K-feldspar granite Coarse-grained granite
Peraluminous
2.00 1.50
Metaluminous
1.00 0.50
Peralkaline
0.00 0
20
40 60 SiO 2 (wt.%)
80
100
0.00
0.50
1.00 A/CNK
1.50
2.00
1000
1000
(a) TTG gneiss S147
100
(b) TTG gneiss S147
100
S165
S153
10
S165
10
S153
1
1 La Ce Pr Nd
Rb Ba Th U K Ta Nb La Ce Sr Nd P Zr Hf Sm Ti Y Yb Lu
Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 10000.
1000.
S145 S144
100.
(c) Granitic gneiss
1000.
(d) Granitic gneiss
S145 S144
S149 100.
S148 10.
S155
10.
S149 S148
1.
S155
1.
0. 1
0.1 La Ce Pr Nd
Rb Ba Th U K Ta Nb La Ce Sr Nd P Zr Hf Sm Ti Y Yb Lu
Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 1000.
1000.
S137
S137
(e) K - feldspar granite
(f) K - feldspar granite
S142
100.
100.
S151 S142
S140 10.
10.
S151
S140
S143
S143 1.
1.
0.1
0.1 La Ce Pr Nd
Rb Ba Th U K Ta Nb La Ce Sr Nd P Zr Hf Sm Ti Y Yb Lu
Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
10 00 .
1000.
(g) Coarse-grained granite 10 0.
(h) Coarse-grained granite 100.
S160
10 .
1.
S163 S160
S163
10.
S159 1.
0. 1
S159
0.1 La Ce Pr Nd
Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Rb Ba Th U K Ta Nb La Ce Sr Nd P Zr Hf Sm Ti Y Yb Lu
300
250
TTG gneiss (~2.5 Ga) TTG gneiss (~2.3 Ga) Granitic gneiss (~2.5 Ga) Granitic gneiss (~2.3 Ga) Granitic gneiss (~1.8 Ga) K-feldspar granite (~2.3 Ga) K-feldspar granite (~1.8 Ga) Coarse-grained granite
200 200 150 100 100 50
Island arc magmatic rocks
Island arc magmatic rocks 0
0
0
5
10
15 Yb N
20
25
30
0
10
20
30 Y
40
50
60
1212
Table 1
1213
Major (wt%) and trace element (ppm) data of the granitoids of the Taihua complex in the Mts.
1214
Huashan area.
1215 1216
57
S p o t
T T G
G r a n i t i c
g n e i s s
K f e l d s p a r
g n e i s s
C o a r s e g r a i n e d
g r a n i t e
S 1 4 7
S 1 5 3
S 1 6 5
S 1 4 4
S 1 4 5
S 1 4 8
S 1 4 9
S 1 5 5
S 1 3 7
S 1 4 0
S 1 4 2
S 1 4 3
S 1 5 1
S 1 5 9
S 1 6 0
S 1 6 3
g r a n i t e
S 6 7 6 7 7 6 7 7 7 7 7 7 7 7 7 6 i
7 1 8 1 3 5 0 0 3 5 3 2 4 0 3 8
O .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
2 4 7 7 7 7 2 4 7 1 4 2 0 3 4 2 5 6 3 6 0 0 0 8 8 1 3 3 8 2 5 0 4
T 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
i
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
6 5 5 4 3 7 4 4 3 2 4 3 3 4 3 6
O 5
3
3
3
1
4
2
3
2
1
1
2
1
1
2
4 .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
2 0
0
2
2
7
2
8
0
0
9
7
5
7
7
1
2 9 5 5 1 2 7 9 5 9 6 1 8 1 5 8 1 8 9 5 3 9 1 5 4 3 0 3 1 9 9 9 8 A l 2
O 3
T 3
2
3
2
1
3
2
2
2
1
0
2
2
1
1
3
F .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
e 2
4
2
9
5
6
7
8
6
1
8
3
3
8
6
3
7
0
1
8
1
4
5
0
2
6
3
1
7
5
5
0
M 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
n .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
O 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3
3
4
3
1
4
2
2
1
1
1
2
2
1
2
2
2
O 3
M 0
0
1
0
0
0
1
0
0
0
0
0
0
0
0
0
g .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
O 7
7
0
4
3
6
1
4
3
3
2
2
1
0
6
4
4
2
6
0
4
2
9
7
4
0
9
5
1
2
4
6
C
2
1
2
1
0
1
1
1
0
0
0
0
0
0
0
1
a
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
O
3
9
2
2
5
5
3
3
4
6
3
1
6
8
5
9
3
8
1
2
3
7
0
2
3
9
3
3
7
7
6
1
N 5
4
5
2
2 4 3 3 2 2 1 1 2 3 2 4
a .
.
.
.
.
9
8
1
9
3 1 2 1 6 3 8 7 8 1 7 0
O 5
3
7
1
9 7 7 2 7 4 2 4 3 3 3 0
2
.
.
.
.
.
.
.
.
K
1 1 2 5 6 3 5 5 5 6 8 8 5 7 6 4
2
.
O
8 9 2 1 9 9 0 7 9 0 5 6 9 2 0 0
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
4 8 1 1 5 0 3 6 3 0 3 0 8 0 0 3
.
.
.
P
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
2
.
O
1 0 1 0 0 1 0 1 0 0 0 0 0 0 0 2
5
4 6 4 8 2 3 8 0 4 1 4 7 2 2 4 2
L
1 1 0 0 0 2 0 0 0 0 0 0 0 0 0 1
O
.
I
0 0 8 8 3 9 9 6 7 6 4 5 4 6 6 1
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
6 6 4 6 8 8 8 2 8 6 4 8 4 6 8 4
T 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 O 7 8 6 6 7 6 7 7 7 8 8 7 7 7 7 6 T .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
A 0 2 3 7 7 7 5 0 4 2 9 5 7 1 9 9 L 4 7 1 6 8 4 8 3 4 4 9 2 5 3 7 2
M
3
3
4
2
3
2
4
2
2
3
4
1
g
1
7
0
1
1
5
6
5
0
4
1
8
8
2
4
2
3
2
# S
6
4
1
4
4
7
4
3
3
3
4 3
4
4
7
4
c
.
.
0
.
.
.
.
.
.
6
0 .
.
.
.
.
9
2
.
3
3
0
2
4
3
.
.
9
2
0
6
1
1
7
5
9
9
3
3
7
2
2
0 7
7
2
9
4
3
5
2
1 5
3
3
1
2
1
7
2
2
1
4
8
9
5
9
7 3
0
1
7
5
7
.
.
7
6
5
.
.
.
.
.
.
.
.
0
8
1
6
.
.
4
8
5
1
0 4
2
7
5
6
3
9
8
C
1
1
3
1
1
1
1
7
1
8
4
1
5
8
1
1
r
7
1
0
7
3
1
8
.
6
1
4
1
.
.
8
0
.
.
.
.
.
8
.
.
.
.
7
3
.
.
3
2
5
5
7
6
9
3
4
7
9
3
8
V
.
C
5
4
1
2
3
7
8
4
1
5
3
1
1
2
2
1
o
.
.
2
.
.
.
.
.
.
6
3
.
.
.
.
4
2
3
4
2
9
0
1
3
.
.
2
1
3
5
.
3
8
4
3
9
1
2
N
6 6 1 6 5 1 1 3 5 9 1 3 1 3 8 6
i
.
.
5 .
0 3 .
.
1 0 .
7 6 .
.
.
0 0 .
1 2 .
.
.
.
.
4
6
6
5
6
3
.
9 8 9 1 3
5 1 9 7 3 7 1 1 9 0 3 5 8 5 7 3
C
4
3
1
4
4
9
1
5
2
5
1
6
1 5
3
4
u
3
.
0
.
.
.
5
.
.
1
6
.
.
.
.
.
7
.
8
9
1
.
9
9
.
.
0
8 4
8
8
1
4
4
6
7
2
3
2
1
8
2
6
0 8
9
0
Z
3
2 5
2
4 6
5
2
1
1
2
1
2
1
2
2
n
6
7 7
6
1 7
1
6
7
7
1
8
4
0
2
8
.
.
.
.
.
.
.
2
9
.
.
.
.
.
6
0 5
1
0 9
4
5
7
9
7
5
8
6
.
.
.
G
2 1 1
1
2
2
1
1
2
2
2
1
1
1
1
2
a
0 7 9
8
3
0
8
6
0
2
2
2
7
4
4
3
.
.
.
0 0 7
.
.
.
.
.
.
.
.
.
.
.
.
7
3
7
7
6
1
6
1
5
4
7
2
R
4 5 9 2 1 1
1 1 1 4 8 2 2 2 1 9
b
0 3 1 4 9 1
4 7 7 7 5 0 0 0 5 5
.
9 2 3 .
.
.
6 5 2
7 2 8
.
5 7 0 6 .
1 9
6
S
2 2 3 7
2 9
2 3 1 5 3 1 8 2 2 6
r
6 3 1 4
3 3
9 3 4 0 8 8 9 6 2 2
5 4 4
3
4 3 7 2 5 9 .
0 3 3
6
Z
3
1
1
2
3
1
1
3
5
1
3
1 3
4
1
8
r
1
6
3
8
8
0
0
6
7
1
0
9 7
5
5
4
5
5
1
0
3
5
9
4
7
5
4
.
.
2
4
0
1
7
N
1
6
7
8
1
5
6
2 2
1
1 2
3
0
3
3
b
2
.
.
.
0
.
.
.
5
7 .
.
.
.
.
.
6
9
9
.
0
2
6 6
.
.
8
1
9
8
0
6
3
6
3
1
3
9
0 8
4
0 3
3
2
6
8
.
C
0 0 0 0 0 0 0 0 0 0 1
0 0 0 1 0
s
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
3 4 5 8 6 7 7 3 5 8 6
4 4 4 1 2
7 2 3 8 3 1 3 5 4 7 8
7 0 1 7 7
B
6 5 8 9 1 1 1 1 1 3 1 2 6 2 1 1
a
6 7 6 5 3 0 1 9 1 8 3 6 2 5 4 6 5 2 2 5 1 2 3 3 4 7 1 3 0 2 4 2 7 4 2 3 7
7 3
6 8 5
L
6 1 3 1 1 1 3 1 1 1 6 5 4 5 1 2
a
2 8 9 2 7 8 6 3 6 4 2 . .
.
.
3 8 .
.
.
3 .
.
2 .
0 .
8 4
3 .
.
6 4 2
.
8 7 5
8 2 8 8 1 1 2
0
C
1 3 6 1 3 3 6 2 3 3 1 8 7 6 3 4
e
0 1 7 8 1 2 0 0 0 0 2 . 7 .
.
6 4 .
1 3
.
.
0 .
1 0 1
1 .
4 2 .
9
5 0
9 .
.
3 4 6 8 4
P
1 3 7 2 3 3 5 2 2 3 1 1 8 0 4 4
r
2 . .
.
1 0 .
6 4 .
.
.
.
7 .
3 8 0 .
5 .
9 .
.
.
.
.
0 6 6 8 4
2 1 2 4 4 2 2 6 5 0 5 6 2 9 3 6
N
4 1 2 6 8 1 1 7 7 1 6 4 3 2 1 1
d
1 2 5 5 7 1 7 . .
.
.
.
.
.
.
4 6 1 .
2 .
.
.
0 .
1 .
9 6
3 .
.
1 6 4 4 5 8 5 2 4 6 9 0 4 3 0 0
S
5 2 4 8 9 1 1 1 6 3 1 0 4 0 3 2
m
.
.
.
.
.
.
.
.
.
.
1 .
9 0 2 2 1 7 9 0 5 8 .
.
.
.
.
6 8 3 3 2
7 8 2 3 8 4 1 5 0 9 4 6 3 7 9 2
E
1 0 1 1 1 0 0 1 0 1 2 0 0 0 0 1
u
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
3 7 0 1 2 7 8 0 7 5 7 5 4 3 8 2 6 4 2 2 1 4 6 1 2 6 8 0 7 3 2 7
G
4 1 3 4 5 1 1 1 3 4 1 0 3 0 2 1
d
.
.
.
.
.
.
.
.
.
.
0 .
2 6 5 8 1 2 1 0 3 0 .
.
.
.
.
4 3 2 4 5
2 4 0 7 9 3 5 3 6 6 2 7 9 9 8 9
T
0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0
b
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
5 2 5 5 6 1 1 1 3 6 4 0 4 0 3 2
6 3 1 1 3 5 2 0 3 3 8 6 5 4 5 0
D
2 1 2 1 2 0 0 0 0 3 8 0 1 0 1 0
y
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
9 2 8 5 3 7 4 4 9 7 6 2 9 2 8 8 0 0 6 0 5 2 7 9 1 8 7 8 8 0 6 6
H
0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0
o
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
5 2 5 2 4 1 0 1 1 7 7 0 3 0 3 1 2 0 8 0 0 3 7 0 4 1 3 5 0 4 3 6
E
1 0 1 0 1 0 0 0 0 2 4 0 0 0 0 0
r
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
4 5 7 5 2 3 2 3 5 0 9 1 7 1 8 4 7 5 5 8 3 5 0 0 5 3 4 4 5 1 9 9
T
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
m
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
1 0 2 0 1 0 0 0 0 2 6 0 0 0 1 0 9 8 4 6 5 4 2 5 6 7 8 2 9 2 2 7
Y
1 0 1 0 0 0 0 0 0 1 4 0 0 0 0 0
b
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
2 5 6 4 9 2 1 3 5 6 3 1 6 1 7 5 7 3 7 4 2 6 7 8 2 4 4 4 2 1 5 8
L
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
u
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
1 0 2 0 1 0 0 0 0 2 6 0 0 0 1 0 9 8 6 7 4 4 3 7 8 5 5 2 9 2 1 9
Y
1
6
1
5
1
3
2
3
4
2
5
1
8
1
1
5
6
.
9
.
2
.
.
.
.
3
7
.
.
.
0
.
.
8
.
7
.
7
4
3
3
.
.
5
5
2
.
4
4
8
9
8
7
4
8
7
7
5
7
6
7
5
1
7
H
8
4
3
6
9
2
2
7
1
2
6
0 8
0 4
1
f
.
.
.
.
.
.
.
.
3
.
.
.
.
7
0
4
3
6
1
5
5
6
.
6
2
5 8
9 1
.
1
1
6
8
1
1
8
7
3
3
9
6 7
8 2
7
2
2
T
0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0
a
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
3 2 2 2 3 1 2 1 1 2 9 1 1 0 1 1 7 4 8 7 4 9 6 0 6 9 0 6 1 7 2 1
P
5
4
7
9
2
4
4
7
5
3
1
5
9
4
9
7
b
.
.
.
.
0
.
.
.
.
.
5
.
.
.
.
.
8
1
0
0
.
1
2
0
7
5
6
0
8
2
2
8
2
1
9
2
9
6
2
8
5
9
5
1
9
9
T
1
5
1
4
8
0 6
0 5
1
5
0 1
0 1 0
h
7
.
0
3
7
.
.
.
.
.
.
.
2
.
.
.
4 3
5 .
1
1
7 .
3 8 8
2
6
6
5
1
0 8
3 9
3
1 8
9 1 1
.
1
2
.
.
4 U
0 0 0 0 1 0 0 0 0 0 1
0 1
0 0 0
.
.
.
.
.
.
.
.
.
.
.
.
.
.
1 2
1 4 4
3 0 2 6 0 3 0 7 3 0 8
1 4
4 0 9
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
/ 7 1 7 5 4 4 6 9 4 1 7 6 3 0 8 9 E 9 8 9 0 9 7 4 4 2 9 7 3 4 3 2 6 u *
(
3 2 1 2 1 5 1 2 2 6 1 2 4 3 1 2
L 5 5 6 0 3 1 5 5 2 . a .
.
.
/ 3 1 8 Y b
.
6 5 8 6 1 2 2 3 7 2 1
E 0 1 0 0 0 1 1 2 0 1 0 2 0 3 0 1 u .
.
2 9 . 1
7 . 4
0 6 9 3 7 9
6 4 .
.
.
.
.
.
9 3 9 4 3 3 9
) N
S
1 3 1 1 1 2 1
9 3 2 6
1 1 2 2 1
r
6 4 5 2 8 4 1
8 3 1 .
2 0 0 2 1
/
.
.
1 .
Y
2 0 8 8 4 9
.
.
.
.
.
9
.
.
7
9 6 4
5
D 2 2 1 3 2 2 2 1 1 2 2 2 3 1 2 1 y .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
/ 2 2 7 4 5 7 7 2 7 3 0 1 1 7 4 4 Y 8 8 1 3 6 1 8 9 5 1 0 1 9 3 8 8 b
R 0 0 0 3 0 1 0 0 1 0 0 1 2 0 0 0 b .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
/ 1 2 2 3 8 2 5 5 1 0 2 0 3 7 7 1 S 5 3 9 1 4 0 1 2 8 9 2 8 1 7 0 5 r
G 3 3 2 1 5 4 6 2 6 2 2 3 5 2 3 2
8 . 1
4
d .
.
.
1 .
/ 3 1 1 .
.
.
.
.
.
.
.
.
.
.
.
6 6 8 7 4 4 3 5 4 5 3 7
Y 2 2 0 1 7 3 2 0 7 7 5 0 5 4 1 3 b
1217
● Three episodic magmatism (2.55–2.49 Ga, 2.33–2.25 Ga
1218
and 1.87–1.80 Ga) were revealed from the Mts. Huashan
1219
granitoids.
1220
● The ~2.5 Ga rocks represent an episodic crustal growth,
1221
while the ~2.3 Ga rocks reflect both crustal growth and
1222
reworking.
1223
● The 1.87–1.80 Ga rocks probably resulted from crustal
1224
reworking during the collision between the Eastern and
1225
Western Blocks.
1226
● Transformation from an Andean-type continental margin
1227
arc setting to continent-arc-continent collision in the
1228
southern TNCO during Late Neoarchean to Paleoproterozoic
1229
is suggested.
1230
58