Constraints of detrital zircon U–Pb ages and Hf isotopes on the provenance of the Triassic Yidun Group and tectonic evolution of the Yidun Terrane, Eastern Tibet

Sedimentary Geology 289 (2013) 74–98

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Constraints of detrital zircon U–Pb ages and Hf isotopes on the provenance of the Triassic Yidun Group and tectonic evolution of the Yidun Terrane, Eastern Tibet Bai-Qiu Wang a, Wei Wang a, Wei Terry Chen a, Jian-Feng Gao a, Xin-Fu Zhao a, Dan-Ping Yan b, Mei-Fu Zhou a,⁎ a b

Department of Earth Sciences, The University of Hong Kong, Hong Kong, China Faculty of Geology, China University of Geosciences, Beijing, PR China

a r t i c l e

i n f o

Article history: Received 1 July 2012 Received in revised form 10 December 2012 Accepted 12 February 2013 Available online 21 February 2013 Editor: B. Jones Keywords: Yidun Terrane Detrital zircon U–Pb ages Hf isotopes Yidun Group Eastern Tibet

a b s t r a c t Eastern Tibet to the west of the Yangtze Block consists of the Yidun and Songpan–Ganzi Terranes, separated by the Ganzi–Litang suture zone. The Yidun Terrane includes the Zhongza Massif to the west, but the eastern part of the Yidun terrane is covered by the Yidun Group extending from the south (Shangri-La region) to the north (Changtai region). The Yidun Group, from the base upward, includes the Lieyi, Qugasi, Tumugou and Lanashan formations, which are mainly composed of volcanic-flysch successions. Based on the ages of volcanic interlayers and plutonic intrusions, depositional ages of the Qugasi and Tumugou formations are considered to be slightly older than 230 Ma and ca. 220–230 Ma respectively, which are prominently older than the previous estimates. The Yidun Group in the Changtai region has two prominent detrital zircon age peaks at 400–480 and 880–980 Ma and a minor peak at 2.45–2.50 Ga. This pattern suggests a detritus source from the Zhongza Massif, which was a micro-continent separated from the western Yangtze Block. In contrast, the Yidun Group in the Shangri-La region has various zircon age spectra among different formations. The Qugasi Formation in this region has detrital zircon age patterns similar to the Yidun Group in the Changtai region. However, the overlying Tumugou Formation shows distinct age peaks at Triassic (220–240 Ma), Neoproterozoic (~720–880 Ma), and Paleoproterozoic (~1.75–1.90 Ga). This age pattern is similar to that of the Xikang Group of the Songpan– Ganzi Terrane to the east. The detrital zircon age difference between the Qugasi and Tumugou formations in this region indicates a transition of sedimentary sources from the Zhongza Massif to locally distributed Triassic magmatic rocks at ~230 Ma. It is thus suggested that the Songpan–Ganzi Terrane may have been connected to or collided with the southern part of the Yidun Terrane during the Late Triassic, whereas the Songpan–Ganzi Terrane and the northern part of the Yidun Terrane were still separated by the Ganzi–Litang Ocean. © 2013 Elsevier B.V. All rights reserved.

1. Introduction Triassic evolution of the Paleo-Tethys in central Asia involved numerous subduction systems and collisional events among (micro-) continents and island arcs, whose final amalgamation occurred in the Early Jurassic (Şengör, 1979; Hsü et al., 1995; Metcalfe, 1996; Metcalfe, 2006; Pullen et al., 2008; Roger et al., 2008; Roger et al., 2010). The Yidun Terrane, a Triassic arc terrane, juxtaposed with the Songpan–Ganzi Terrane and Qiangtang Block along two major Paleo-Tethyan suture zones, the Jinsha and Ganzi−Litang suture zones, is important in deciphering the regional tectonic processes. However, tectonic history of the Yidun Terrane, including its derivation, spatial–temporal evolution of related Triassic subduction systems along the suture zones, remains ambiguous or controversial (Chen et al., 1987; Hou, 1993; Wang et al., 2000; Song et al., 2004; Reid et al., 2005b, 2007; Pullen et al., 2008; Roger et al., 2010). ⁎ Corresponding author. Tel.: +852 28578251; fax: +852 25176912. E-mail address: [email protected] (M.-F. Zhou). 0037-0738/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.sedgeo.2013.02.005

The Yidun Terrane has widespread Triassic flysch deposits that comprise the Yidun Group, in addition to extensive arc igneous rocks (BGMRSP, 1991; Hu et al., 1992; Hou, 1993; Hou et al., 2001b). This flysch sequence was thought to be similar to the Xikang Group of the adjacent Songpan–Ganzi Terrane (BGMRSP, 1991). The provenance of Triassic sedimentary rocks in the Yidun Terrane is thus key to the understanding of the Triassic tectonic evolution of the Yidun Terrane and its relationship with the neighboring Songpan–Ganzi Terrane and Qiangtang Block. Previous studies mainly concerned with igneous rocks of the Yidun Terrane (Hou et al., 2001b, 2004; Reid et al., 2005a,c, 2007; Weislogel, 2008; Wang et al., 2011). Studies of Triassic sedimentary rocks and related basin evolution are not available in the literature. Provenance and timing of deposition of siliciclastic rocks may provide important constraints on tectonic setting of sedimentary basins and paleogeographic reconstructions (Dickinson et al., 1983; Bhatia and Crook, 1986; Roser and Korsch, 1986; Dickinson, 1988; Haughton et al., 1991; Murphy et al., 1996; Thomas et al., 2004; Weislogel et al., 2006; Sun et al., 2008; Gehrels et al., 2011; Wang and Zhou, 2012; Wang W. et al., 2012a). Sedimentary strata may have undergone

B.-Q. Wang et al. / Sedimentary Geology 289 (2013) 74–98

2. Geological background

intense deformation, but detrital zircons can survive such deformation and can be used for examining the timing and tectonic evolution of sedimentary basins (c.f. Cawood and Nemchin, 2001). Particularly, detrital zircon age spectra may contain information about various sources linked to eustatic, depositional and tectonic change (e.g. Wang W. et al., 2010, 2012b), and thus can provide insight into the basin–orogen coupling (Cawood and Nemchin, 2001; Wang and Zhou, 2012). In addition, Hf isotopes of zircons can be used to differentiate juvenile or reworked source magmas (Griffin et al., 2004; Wang W. et al., 2012b). In this paper, we report for the first time U–Pb ages and Lu–Hf isotopic analyses of detrital zircons from sandstones of the Triassic Yidun Group in the Yidun Terrane. We use this new dataset to determine the provenance and tectonic setting of the Yidun Group. Combining available data from nearby tectonic entities, we further develop a more comprehensive scenario for the Triassic tectonic evolution of the Yidun Terrane.

Ganzi

0

The Yidun Terrane is bounded by the Jinsha suture zone to the west and Ganzi–Litang suture zone to the east. These two suture zones merge to the north as a single zone known as the Jinsha suture zone (Fig. 1). Both the Jinsha and Ganzi–Litang suture zones are marked by ophiolites, remnants of the Paleo-Tethys branch oceans that were consumed by the Permian–Triassic subductions (Dewey et al., 1988; Mo et al., 1994; Chang, 1997; Wang et al., 2000; Reid et al., 2005b). The Ganzi–Litang suture zone was almost obliterated by later faulting system to the south where the Songpan–Ganzi Terrane wedges out, and the suture appears to be in contact with the Yangtze Block (Fig. 1; Yin and Harrison, 2000). Closures of the Jinsha and Ganzi–Litang Oceans subsequently led to the collisions of the Yidun Terrane with the eastern Qiangtang Block during the Early-Middle Triassic (Mo et al., 1993; Wang et al., 2000; Hou et al., 2003; Reid et al., 2005b; Zhu et al., 2011) and with the Songpan–Ganzi

Post-Triassic granitoid pluton

500 1000km

Tarim block

XG

Changtai Changtai

F

Triassic granitoid pluton

Tib eta n pla tea u

31°N

Yangtze block

Fig. 2a

0

Yi d u n Yidun

50

Triassic strata

100 km

nz

SGT

i-L ng Su

Zhongza Z hongza

Speculative suture zone

ita

Fault

tu

u t u rree Sutu ha S i n s ha JJins

Ga

YDT YDT

Paleozoic strata Suture zone

Litang

30°N

75

re

29°N

XG

QTB Q TB

F

Fig. 2b JS 28°N Shangri-La Shangri-La

99°E

100°E

101°E

Fig. 1. Geological map of the Yidun Terrane modified from Pan et al. (2004). SGT: Songpan–Ganzi Terrane; YDT: Yidun Terrane; QTB: Qiangtang Block; XGF: Xiangcheng–Geza fault.

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Terrane at the end of the Triassic (Chen et al., 1987; Hou, 1993; Hou et al., 2004; Wang et al., 2011). 2.1. Eastern Qiangtang Block The eastern Qiangtang Block is composed mainly of Late Paleozoic shallow marine metamorphosed sedimentary rocks overlain by widespread Triassic and Jurassic shallow marine carbonates and terrestrial clastic rocks (Chen et al., 1987; Chang, 1997). A Triassic magmatic arc belt, the Jiangda–Weixi arc belt, is to the west of the Jinsha suture zone (Mo et al., 1993, 1994; Wang et al., 1999; Hou et al., 2003), and contains large volume of late Triassic, post-collisional volcanic rocks which hosts numerous VMS deposits (Hou et al., 2003, 2007). The Jiangda–Weixi arc was considered as a result of westward subduction of the Jinsha Ocean (Mo et al., 1993; Wang et al., 2000; Xiao et al., 2008), although an eastward subduction was also proposed (Chang, 1997; Reid et al., 2005b). 2.2. Yidun Terrane From west to east, the Yidun Terrane includes the Zhongza Massif and the Eastern Yidun Terrane (Fig. 1), separated by the north–south trending Xiangcheng–Geza fault zone (Fig. 1) (BGMRSP, 1991; Hou, 1993). The Zhongza Massif has a basement complex of the Neoproterozoic granitic gneisses and metavolcanic rocks (BGMRSP, 1991). The cover sequence includes Paleozoic greenschist facies shallow- to deep-marine carbonates and clastic rocks intercalated with sporadic mafic volcanic rocks (BGMRSP, 1991; Chang, 2000), comparable to the Paleozoic passive continental margin sedimentary sequence of the western Yangtze Block (BGMRSP, 1991; Reid et al., 2005b). It was commonly thought that the Zhongza Massif has been broken up from the western Yangtze Block with the opening of the Ganzi–Litang Ocean, triggered by the Late Permian Emeishan mantle plume (Chen et al., 1987; Tan, 1987; Song et al., 2004). The Paleozoic strata in the Zhongza Massif was intruded by Middle Triassic granitic plutons (Reid et al., 2007) and are overlain by Triassic clastic and volcanic rocks on the eastern margin. Post-Triassic depositional records are absent in the Zhongza Massif. A metamorphic belt, which is considered to be correlated with the amalgamation between the Yidun Terrane and the Qiangtang Block during the Early Triassic (Reid et al., 2005b, 2007), can be recognized on the western part of the Zhongza Massif (Chen et al., 1987; Wang et al., 2000). The Eastern Yidun Terrane is covered by the Triassic Yidun Group and arc-related igneous rocks. The Triassic Yidun Group is composed mainly of a flysch-volcanic succession (BGMRSP, 1991; Hou, 1993; Hou et al., 1994), unconformably overlain by Cenozoic red beds, the Relu Formation (Fig. 2; BGMRSP, 1991). Numerous dioritic–granitic plutons, forming a north–south trending belt along the eastern margin of the Yidun Terrane, range in ages from late Triassic to Cenozoic but with predominant ages at Late Triassic (~230 to 202 Ma) (Fig. 1; Hou et al., 2001b; Liu et al., 2006; Reid et al., 2007; Weislogel, 2008; Wang et al., 2011). These plutons have resulted from westward subduction of the Ganzi–Litang Ocean (Hou, 1993; Hou et al., 2001a, 2001b; Reid et al., 2007; Weislogel, 2008), associated with extensive deformation, a single generation of upright folds and north–south striking faults, of the Yidun Group (Reid et al., 2005b). 2.3. Songpan–Ganzi Terrane The Songpan–Ganzi Terrane has a triangular shape with area of more than 2 × 10 5 km2, consisting predominantly of the Middle-Late Triassic flysch deposits of the Xikang Group (Fig. 1; Huang and Chen, 1987; Nie et al., 1994; Zhou and Graham, 1996). The ~10 km thick Xikang Group is composed dominantly of slates and quartz–feldspathic sandstones (Nie et al., 1994). The strata underwent low-grade metamorphism and extensive deformation during the Late Triassic probably due to the convergence between the Songpan–Ganzi Terrane and the

Yidun Terrane or Qiangtang Block (Harrowfield and Wilson, 2005; Reid et al., 2005b; Weislogel, 2008). In addition, the Songpan–Ganzi Terrane contains numerous Late Triassic granitic plutons which have resulted from lithospheric delamination (Cai et al., 2010; Yuan et al., 2010). 3. Stratigraphy of the Yidun Group The Yidun Group includes, from the base upward, the Lieyi, Qugasi, Tumugou and Lanashan Formations (Figs. 2 and 3; BGMRSP, 1991), of which the Lieyi Formation is least exposed. Lithostratigraphical descriptions are based on two cross sections in the Changtai and Shangri-La regions, i.e. the northern and southern parts of the Yidun Terrane, respectively (Figs. 2 and 3). The Lieyi Formation is sporadically distributed in parts of the Yidun Terrane (e.g. BGMRSP, 1991; Hou, 1993). This formation is about 600 m thick, and comprises black carbonaceous slates and fine- to coarsegrained grey sandstones with interlayered pelitic siltstone. Graded bedding and scour marks are locally present in sandstones. These rocks are also locally folded, associated with sandstone boudins and thrust faults (Fig. 4a). The Lieyi Formation is unconformably overlain by the Qugasi Formation. This formation is composed of dark grey slates, fine-grained quartz sandstones, limestones and mafic volcanic rocks with a basal conglomerate unit (BGMRSP, 1991). Sandstone layers are generally 0.5 to 1 m thick and are interbedded with thin limestone and slate layers. The mafic volcanic rocks are mainly massive basalts with local amygdaloidal and vesicular textures. In the Shangri-La region, the Qugasi Formation was intruded by ~230 Ma quartz diorite (Wang et al., 2011), which constrained the minimum depositional age. The Tumugou Formation, conformably underlain by the Qugasi Formation, is about 5000 m thick and consists of grey slates, sandstones, intermediate-felsic volcanic rocks and tuffs with minor mafic volcanic rock interlayers (Fig. 4b). A dacitic interlayer of upper Tumugou Formation has zircon U–Pb age of ~221 Ma in the Shangri-La region (Wang et al., 2011), indicative of depositional age. A thick conglomerate layer with poorly sorted pebbles and abundant deformed quartz grains marks the base of the Tumugou Formation (Fig. 4c). Local VMS and porphyry Cu deposits are thought to be related to volcanic activities in the Tumugou Formation (e.g. Hou et al., 2001a, 2007; Li et al., 2011). Conformably overlying the Tumugou Formation, the Lanashan Formation is dominated by dark grey slates and feldpathic quartz sandstones with minor coal beds and pelitic limestone lenses (Fig. 4d). Both slates and sandstones are constantly intercalated with each other from the lower to upper parts of the formation. 4. Analytical techniques Totally seven samples were selected for detrital zircon U–Pb analyses and six of them were also used for zircon Lu–Hf isotopic analyses. Zircon grains were extracted using conventional heavy liquid and magnetic techniques, handpicked randomly, mounted in epoxy and polished. 4.1. Zircon U–Pb dating Zircon U–Pb geochronological analyses were carried out at the State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, using an Agilent 7700× ICP-MS equipped with a GeoLasPro laser-ablation system. The 193 nm ArF excimer laser was homogenized by a set of beam delivery systems and focused on the zircon surface with the fluency of 15 J/cm 2. A spot diameter of 32 μm at 5 Hz repetition rate for 45 s (equating to 225 pulses) was applied for single analysis. Helium was employed as the carrier to efficiently transport aerosol to ICP-MS. Zircon 91500 was used as a external standard to correct elemental fractionation while

B.-Q. Wang et al. / Sedimentary Geology 289 (2013) 74–98

98°45'E

99°00'E

99°15'E

77

99°30'E

99°45'E

0

31°30'N

5 10 km

31°20'N

GB185

31°10'N

GB77 GB77 GB133

Changtai

GB101

31°00'N

a 0

b

5

10 km

Cenozoic strata

221 Ma

Lanashan Formation

BQ156

28°10'N

Tumugou Formation

BQ23

Yidun Group Qugasi Formation

BQ156

Lieyi Formation 230 Ma

Unclassified LowerMiddle Triassic strata

28°00'N

Paleozoic strata Triassic granitoid pluton Mafic dike

27°50'N

Shangri-La

Fault Zircon sample location

99°50'E

100°00'E

100°10'E

100°20'E

Fig. 2. a) Geological map of the Changtai region; b) Geological map of the Shangri-La region modified from Sun et al. (1977) and Wang et al. (1982). 221 Ma and 230 Ma in b) represent zircon U–Pb ages of a dacitic interlayer and a small adakitic intrusion, respectively (Wang et al., 2011).

zircon GJ-1 and Plešovice were tested as quality controls. U, Th and Pb contents of zircon grains were externally calibrated against NIST SRM 610 with Zr as a internal standard. Data reduction was performed off-line by ICPMSDataCal (Liu et al., 2010).

4.2. Zircon Lu–Hf isotopic analyses Zircon Hf isotope analyses were conducted using a Nu Plasma HR MC-ICPMS in connection with a Resonetics RESOlution M50 Excimer

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Formations Relu (Eocene)

Sedimentary structure

Purple conglomeritic sandstone with siltstone and sandstone interbeds

1762~2429 m

Lanashan Formation

Lithological description

Lithological log

Dark grey slates with feldpathic quartz sandstone interbeds in the upper part

Parallel bedding; ferruginous nodules

Medium-thick layered sandstones with dark grey slate interbeds in the lower part; locally limestone lenses present

Parallel bedding; lenticular bedding; scour marks

>5000 m

Tumugou Formation

Grey slate with sandstone interbedds

Intermediate-felsic volcanic rock, tuff, limestone slate and sandstone with minor mafic volcanic rock

Parallel bedding

Grey slate and limestone with sandstone interbeds; conglomeritic sanstone and conglomerite at the base

c

2000~5000 m

Qugasi Formation

c

c c

c

c

>600 m

c c

c

c

c

Dark grey carbonaceous slate and grey slate with quartz sandstone and limestone interbeds mafic volcanic rock on the top

Grey medium-thick layered sandstone and slate with local mafic volcanic rock; coarse sandstone and conglomerate at the base c

Lieyi Formation

c c

c

c

c

c

c

c

c

c

c

c

c

c

c

c c

c c

c c

Parallel bedding; vesicular and amygdaloidal lava

Black carbonaceous slate, grey sandstone with interlayered pelitic siltstone

Parallel bedding; graded bedding; scour marks

c c

c

Fig. 3. Stratigraphy of the Yidun Group based on measured cross-sections of BGMRSP (1991) and our field mapping. The sedimentary beds in the column are not strictly to scale.

Laser Ablation System at the Department of Earth Sciences, the University of Hong Kong. Laser ablation was performed with a beam diameter of 55 μm and repetition rate of 6 Hz. Typical ablation time was 40 s for each measurement. Atomic masses 172–179 were simultaneously measured in static-collection mode. Isobaric interference of 176Yb on 176 Hf was corrected against the 176Yb/172Yb ratio of 0.5886 (Chu et al., 2002). Interference of 176Lu on 176Hf was corrected by measuring the intensity of the interference-free 175Lu isotope and using a recommended 176Lu/175Lu ratio of 0.02655 (Machado and Simonetti, 2001). Zircon standard 91500 was used as an external calibration to evaluate the reliability of the analytical data. 5. Analytical results Most of zircon grains from sandstones are stumpy to elongate. They have variable lengths but mostly less than 100 μm, and have Th/U ratios generally higher than 0.4, indicative of a magmatic origin

(Table 1). Only those grains with U–Pb age of discordance less than 10% are used for statistical consideration. 5.1. Yidun Group in the Changtai region Sample GB133, a fine-grained quartz–lithic sandstone, was collected from the Lieyi Formation. Among 104 analyses, 95 analyses yield concordant ages. The U–Pb ages exhibit a wide spectrum from ca. 400 Ma to 3.5 Ga. A large cluster of ages spans from ~870 Ma to ~1.1 Ga with a prominent peak at ~950 Ma (Fig. 5a). Subordinate ages are scattered from ~400 to ~850 Ma. There is also a minor peak at ~2.45 Ga. The oldest zircon grains have an Archean age of 3.48 Ga. Sample GB101, collected from a medium-grained sandstone layer of the Qugasi Formation, has numerous zircon grains. Among 115 analyses, 112 yield concordant ages. These ages comprise two major peaks at ~450 and ~1000 Ma and a sort of ages ranging from ~600 to ~900 Ma (Fig. 5b). A subordinate portion of analyses (36%) yield ages older than

B.-Q. Wang et al. / Sedimentary Geology 289 (2013) 74–98

79

b

a

Andesite interlayer

Slate

Slate

1m 1m

d

c

Diabase

Slate 2cm 1m

Fig. 4. Field photos of a) intensive deformation of sandstone bedding within the Lieyi Formation; b) slate and dacites within the Tumugou Formation; c) basal conglomerate within the Tumugou Formation; d) a diabase sill intruding slate of the Lanashan Formation.

1.2 Ga with two minor peaks at ~1.75 and ~2.45 Ga. A few zircon grains have Archean ages as old as 3.46 Ga. Sample GB77, a medium-grained quartz–lithic sandstone from the Tumugou Formation, has zircon grains with 100 concordant ages. Among them, 31 distribute between 400 and 500 Ma with a peak at ~ 450 Ma, similar to those of the sample GB 101 (Fig. 5c). There are 20 analyses between 880 and 1000 Ma, and form two small bimodal peaks at ~ 950 and ~ 1000 Ma, respectively. The third cluster of ages defines a small peak at ~ 2.47 Ga. There are also two Archean grains with ages of 2.75 and 3.04 Ga. Sample GB185 is a fine-grained quartz sandstone from the Lanashan Formation. Among 101 zircon grains analyzed, 96 analyses yield concordant ages. This sample contains three major populations of zircon ages with peaks at ~470 Ma, 900–1000 Ma and ~2.47 Ga, comparable to those of the sample GB77 (Fig. 5d). A single grain with an age of 2.67 Ga is the oldest. In summary, samples from different formations of the Yidun Group in the Changtai region have similar age spectra (Fig. 6a and b; Table 2). Zircon grains from each spectrum also have comparable Hf isotopic compositions for different formations. Paleozoic zircon grains have variable Hf isotopic compositions with εHf(t) values ranging from − 19.7 to 11.3 and TDM from 2.67 to 0.70 Ga. Most of the Neoproterozoic zircons have a relative narrow range of εHf(t) values from 0.281972 to 0.282439 with TDM from 2.44 to 1.20 Ga, except for five zircon grains having extremely low εHf(t) values from −22.9 to −18.9. Minor Late Paleoproterozoic to Early Neoarchean zircons have negative εHf(t) values from −12.7 to 2.4. 5.2. Yidun Group in the Shangri-La region Sample BQ156A, a medium-grained quartz-lithic sandstone, was collected from the Qugasi Formation. Among 102 analyses, 87 analyses yield concordant ages with multiple populations (Fig. 5e). The first group (17%) ranges from 385 to 466 Ma with a major peak at ~ 440 Ma. The second group (44%) has ages varying from 900 to 1000 Ma with bimodal age peaks at ~ 910 and ~ 970 Ma. The remaining two groups define flat peaks at ~ 1.85 and ~ 2.50 Ga. In

addition, two grains have much older ages of 2.76 and 3.50 Ga. Paleozoic zircon grains have εHf(t) values varying from − 12.3 to 6.5 and TDM from 2.16 to 1.03 Ga, whereas the Neoproterozoic zircon grains have εHf(t) values varying from − 13.7 to 5.4 and TDM from 2.53 to 1.43 Ga (Fig. 6c and d). Samples BQ23 and BQ114, medium- to coarse-grained sandstones, were collected from lower and upper sections of the Tumugou Formation, respectively. In sample BQ23, 83 out of 94 analyses yield concordant ages with two prominent peaks at ~ 220–240 and ~ 450 Ma (Fig. 5f). Neoproterozoic grains (23%) have ages from ~ 750 to ~ 1000 Ma but without obvious peaks, while some Paleoproterozoic ages (20%) form a flat peak at ~ 1.80 Ga. Sample BQ114 has 98 zircon grains with concordant ages forming four major peaks at ~ 235 Ma, at ~ 430 Ma, at ~ 800 Ma and ~ 1.80 Ga, and a minor peak at ~ 2.45 Ga. Permian–Triassic zircon grains of the sample BQ23 have variable εHf(t) values from −22.5 to 5.7, whereas Ordovician to Devonian zircon grains have negative εHf(t) values mostly as low as −18.1 (Fig. 6c and d). Early Paleoproterozoic zircon grains have εHf(t) values ranging from − 11.3 to 2.2. 6. Discussion 6.1. Depositional age of the Yidun Group Accurate depositional ages of the individual formations of the Yidun Group have remained unknown, although it was previously thought that this group has a Triassic age according to the limited fossil records (BGMRSP, 1991; Lin et al., 2007). Previously, the Lieyi Formation was thought to be Middle Triassic, whereas the Qugasi, Tumugou and Lanashan Formations were all considered to be Upper Triassic (e.g. BGMRSP, 1991). Dacitic interlayers of the lower Tumugou Formation contain zircon grains with U–Pb ages of ~230 Ma (Wang B.Q. et al., 2012), consistent with 206Pb/238U age of 228 ±3 Ma (Disc. =1.7%) for the youngest detrital zircon from the lower Tumugou Formation (Table 1), suggesting that the deposition of the Tumugou Formation initiated at ca. 230 Ma. The upper Tumugou Formation has zircon grains with 206Pb/238U ages as young as 223 ±2 Ma (Disc. =−6.3%; Table 1),

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Table 1 LA-ICPMS zircon U–Pb data for the sandstones of the Yidun Group. Spot no.

Th (ppm)

U Th/U (ppm)

Isotopic ratios 207 206

Pb/ Pb

1σ

Isotopic age (Ma) 207 235

Pb/ U

1σ

206 238

Pb/ U

GB133: Lieyi formation in Changtai region, Lower-Middle Triassic (N 31°04.196′,E 99° 09.261′), GB133-01 262 687 0.38 0.0757 0.0009 1.9811 0.0232 0.1886 GB0133-03 312 419 0.74 0.0564 0.0007 0.6675 0.0086 0.0853 GB133-04 273 407 0.67 0.0608 0.0009 0.7905 0.0110 0.0938 GB133-06 204 348 0.59 0.0591 0.0008 0.8773 0.0108 0.1072 GB133-07 311 420 0.74 0.1612 0.0015 10.2276 0.0935 0.4568 GB133-08 234 262 0.89 0.0748 0.0010 2.0105 0.0253 0.1940 GB133-09 282 565 0.50 0.0691 0.0007 1.4774 0.0159 0.1540 GB133-10 857 1012 0.85 0.0614 0.0007 0.5359 0.0060 0.0630 GB133-11 245 531 0.46 0.0672 0.0007 1.2719 0.0131 0.1364 GB133-12 199 163 1.22 0.0722 0.0010 1.5840 0.0199 0.1587 GB133-13 54 91 0.60 0.3021 0.0025 29.7920 0.2667 0.7111 GB133-14 318 223 1.43 0.0761 0.0009 1.9055 0.0218 0.1808 GB133-16 261 310 0.84 0.0779 0.0009 2.0834 0.0234 0.1932 GB133-17 172 480 036 0.0727 0.0008 1.6298 0.0179 0.1618 GB133-18 121 344 0.35 0.0713 0.0008 1.4843 0.0182 0.1502 GB133-20 129 365 0.35 0.0597 0.0009 0.7787 0.0117 0.0942 GB133-21 145 147 0.99 0.0745 0.0009 1.9044 0.0230 0.1847 GB133-22 641 1305 0.49 0.0689 0.0006 1.4186 0.0128 0.1484 GB133-23 718 623 1.15 0.0714 0.0007 1.5550 0.0155 0.1571 GB133-24 479 854 0.56 0.0679 0.0008 1.3499 0.0161 0.1435 GB133-25 341 894 0.38 0.0724 0.0007 1.6895 0.0201 0.1681 GB133-26 90 106 0.85 0.0664 0.0014 1.1012 0.0237 0.1201 GB133-27 43 383 0.11 0.0754 0.0008 1.9180 0.0200 0.1836 GB133-28 123 352 0.35 0.0751 0.0008 1.7339 0.0207 0.1666 GB133-29 377 208 1.81 0.0602 0.0014 0.8019 0.0183 0.0960 GB133-30 183 365 0.50 0.0692 0.0008 1.5396 0.0169 0.1606 GB133-31 3 59 0.05 0.0731 0.0017 1.6081 0.0326 0.1613 GB133-32 444 810 0.55 0.0725 0.0008 1.6909 0.0181 0.1679 GB133-33 94 128 0.73 0.0740 0.0011 1.6906 0.0261 0.1656 GB133-34 64 86 0.74 0.0583 0.0015 0.7204 0.0188 0.0899 GB133-35 180 345 0.52 0.1005 0.0010 4.1603 0.0409 0.2980 GB133-37 13 138 0.09 0.0598 0.0013 0.8010 0.0171 0.0968 GB133-38 123 244 0.50 0.0711 0.0009 1.6956 0.0201 0.1723 GB133-39 39 107 0.36 0.1660 0.0019 11.3474 0.1283 0.4925 GB133-40 67 264 0.25 0.0722 0.0010 1.6765 0.0220 0.1675 GB133-41 90 249 0.36 0.0609 0.0009 0.8718 0.0126 0.1034 GB133-42 139 163 0.86 0.0720 0.0010 1.6684 0.0222 0.1672 GB133-43 585 1267 0.46 0.0757 0.0007 1.8572 0.0181 0.1764 GB133-44 63 101 0.63 0.0664 0.0012 1.2182 0.0217 0.1332 GB133-46 61 149 0.41 0.0767 0.0011 1.8139 0.0248 0.1707 GB133-47 153 439 0.35 0.1616 0.0014 10.5572 0.0945 0.4703 GB133-48 147 346 0.43 0.0604 0.0008 0.8800 0.0119 0.1052 GB133-49 79 143 0.55 0.1864 0.0020 13.6533 0.1485 0.5275 GB133-50 53 94 0.56 0.0712 0.0014 1.5588 0.0292 0.1588 GB133-51 272 496 0.55 0.0710 0.0008 1.5201 0.0155 0.1545 GB133-52 71 177 0.40 0.2084 0.0018 16.4543 0.1503 0.5688 GB133-53 128 123 1.04 0.0721 0.0013 1.4334 0.0266 0.1440 GB133-54 704 1489 0.47 0.0617 0.0006 0.6703 0.0066 0.0783 GB133-55 172 282 0.61 0.0716 0.0012 1.4554 0.0249 0.1467 GB133-56 45 193 0.24 0.0760 0.0010 1.9430 0.0262 0.1850 GB133-57 156 72 2.18 0.1062 0.0014 4.5761 0.0612 0.3125 GB133-58 368 666 0.55 0.0771 0.0014 1.6908 0.0278 0.1583 GB133-59 105 232 0.45 0.1583 0.0014 9.9798 0.0907 0.4546 GB133-60 433 1124 0.39 0.0694 0.0006 1.3887 0.0128 0.1442 GB133-62 55 148 0.37 0.0750 0.0010 1.8836 0.0259 0.1815 GB133-63 189 368 0.51 0.0691 0.0008 1.4744 0.0186 0.1539 GB133-65 93 164 0.56 0.0733 0.0011 1.7643 0.0271 0.1737 GB133-66 71 82 0.86 0.0785 0.0013 1.9261 0.0306 0.1775 GB133-68 155 717 0.22 0.1248 0.0011 3.5068 0.0509 0.2008 GB133-69 165 505 0.33 0.0713 0.0007 1.5441 0.0152 0.1560 GB133-70 93 222 0.42 0.0712 0.0009 1.5498 0.0200 0.1572 GB133-71 873 1052 0.83 0.0592 0.0006 0.7008 0.0075 0.0854 GB133-72 163 222 0.73 0.2356 0.0026 11.2428 0.2736 0.3428 GB133-73 414 394 1.05 0.1457 0.0016 5.5277 0.0574 0.2736 GB133-74 280 613 0.46 0.0736 0.0007 1.6797 0.0175 0.1644 GB133-75 85 171 0.50 0.0723 0.0011 1.6288 0.0266 0.1625 GB133-76 67 502 0.13 0.0733 0.0007 1.8287 0.0192 0.1799 GB133-77 96 159 0.60 0.0718 0.0009 1.6844 0.0218 0.1694 GB133-78 335 561 0.60 0.1159 0.0010 5.8159 0.0508 0.3613 GB133-79 119 205 0.58 0.0851 0.0010 2.7794 0.0320 0.2354

1σ

207 206

Pb/ Pb

N = 95/104 0.0010 1087 0.0004 478 0.0005 632 0.0005 572 0.0022 2469 0.0013 1065 0.0008 902 0.0003 654 0.0007 856 0.0009 994 0.0038 3481 0.0009 1098 0.0010 1146 0.0008 1006 0.0011 966 0.0006 591 0.0010 1057 0.0007 898 0.0007 969 0.0008 865 0.0012 998 0.0009 818 0.0009 1080 0.0012 1072 0.0006 609 0.0009 906 0.0013 1017 0.0008 1011 0.0012 1043 0.0009 543 0.0015 1635 0.0007 594 0.0010 961 0.0029 2518 0.0010 991 0.0007 635 0.0010 987 0.0009 1088 0.0010 820 0.0010 1122 0.0023 2473 0.0006 617 0.0031 2711 0.0012 965 0.0007 967 0.0030 2894 0.0013 991 0.0004 665 0.0012 976 0.0011 1094 0.0021 1800 0.0012 1124 0.0022 2439 0.0006 909 0.0011 1069 0.0011 902 0.0012 1033 0.0012 1161 0.0019 2028 0.0007 969 0.0009 961 0.0004 572 0.0074 3091 0.0014 2296 0.0008 1031 0.0012 994 0.0009 1033 0.0009 989 0.0017 1894 0.0012 1320

1σ

Best age estimate 207 235

24 30 25 28 15 25 22 26 22 28 13 23 23 22 24 33 24 17 20 31 22 45 21 22 48 22 46 22 31 57 19 44 8 19 27 61 27 13 34 27 15 34 17 40 −6 14 38 22 34 6 26 36 10 14 28 25 32 32 16 20 −6 22 18 19 20 35 16 27 15 23

Pb/ U

1109 519 591 640 2456 1119 921 436 833 964 3480 1083 1143 982 924 585 1083 897 952 868 1005 754 1087 1021 598 946 973 1005 1005 551 1666 597 1007 2552 1000 637 997 1066 809 1050 2485 641 2726 954 939 2904 903 521 912 1096 1745 1005 2433 884 1075 920 1032 1090 1529 948 950 539 2543 1905 1001 981 1056 1003 1949 1350

1σ

206 238

8 5 6 6 8 9 7 4 6 8 9 8 8 7 7 7 8 5 6 7 8 11 7 8 10 7 13 7 10 11 8 10 8 11 8 7 8 6 10 9 8 6 10 12 6 9 11 4 10 9 11 11 8 5 9 8 10 11 11 6 8 4 23 9 7 10 7 8 8 9

Pb/ U

1114 528 578 656 2426 1143 924 394 825 949 3463 1071 1139 967 902 581 1092 892 941 885 1002 731 1087 993 591 960 964 1000 988 555 1682 595 1025 2581 998 635 997 1047 806 1016 2485 645 2731 950 926 2903 867 486 883 1094 1753 947 2416 869 1075 923 1032 1053 1180 935 941 528 1900 1559 981 970 1067 1009 1988 1363

1σ Age

5 3 3 3 10 7 5 2 4 5 15 5 6 4 6 3 5 4 4 5 7 5 5 7 4 5 7 5 7 5 8 4 5 13 6 4 6 5 6 6 10 4 13 6 4 12 7 2 7 6 10 7 10 4 6 6 6 7 10 4 5 2 35 7 5 7 5 5 8 6

1087 528 578 656 2469 1065 924 394 825 949 3481 1098 1146 967 902 581 1057 892 941 865 998 731 1080 993 591 960 964 1011 988 555 1635 595 961 2518 998 635 997 1088 806 1122 2473 645 2711 950 926 2894 867 486 883 1094 1800 947 2439 869 1069 923 1033 1161 2028 935 941 528 3091 2296 981 970 1033 989 1894 1320

Disc (%)

1σ

24 3 3 3 15 25 5 2 4 5 13 23 23 4 6 3 24 4 4 5 22 5 21 7 4 5 7 22 7 5 19 4 8 19 6 4 6 13 6 27 15 4 17 6 4 14 7 2 7 6 26 7 10 4 28 6 32 32 16 4 5 2 18 19 5 7 16 27 15 23

2.4 1.6 −23 2.5 −1.8 6.8 0.3 −10.5 −1.1 −1.5 −0.5 −2.5 −0.7 −1.5 −2.4 −0.7 3.2 −0.6 −1.2 −03 0.3 −3.1 0.6 −2.8 −1.2 1.4 −1.0 −1.1 −1.7 0.7 2.8 −0.3 6.2 2.5 −0.2 −0.3 0.0 −3.9 −0.3 −10.4 0.5 0.6 0.7 −0.4 −1.3 0.3 −4.1 −7.2 −3.3 0.0 −2.7 −6.1 −1.0 −1.8 0.5 0.3 −0.1 −10.2 −71.9 −1.4 −1.0 −2.1 −62.7 −47.3 −2.0 −1.1 3.1 2.0 4.7 3.1

B.-Q. Wang et al. / Sedimentary Geology 289 (2013) 74–98

81

Table 1 (continued) Spot no.

Th (ppm)

U Th/U (ppm)

Isotopic ratios 207 206

GB133-80 GB133-81 GB133-82 GB133-83 GB133-84 GB133-85 GB133-86 GB133-88 GB133-89 GB133-90 GB133-91 GB 133-92 GB133-95 GB133-96 GB133-97 GB133-98 GB133-99 GB133-100 GB133-101 GB133-102 GB133-103 GB133-104 GB133-105 GB133-107 GB133-108 GB133-109 GB133-110 GB133-112 GB133-113 GB133-114 GB133-115 GB133-116 GB133-117 GB133-118

318 258 73 203 306 445 273 391 219 108 72 76 85 501 157 96 134 119 127 35 439 238 195 480 130 113 137 108 8 88 195 306 429 690

995 587 604 624 128 689 340 684 699 117 480 389 277 1008 460 298 250 103 306 349 470 352 283 417 173 202 131 171 230 212 428 1031 329 870

0.32 0.44 0.12 0.33 2.40 0.65 0.80 0.57 0.31 0.92 0.15 0.20 0.31 0.50 0.34 0.32 0.54 1.16 0.41 0.10 0.93 0.68 0.69 1.15 0.75 056 1.04 0.63 0.04 0.42 0.46 0.30 1.30 0.79

Pb/ Pb

0.1591 0.0682 0.0628 0.0705 0.0588 0.0551 0.0706 0.0740 0.0712 0.0638 0.0580 0.0620 0.0716 0.0573 0.0718 0.0653 0.0687 0.0704 0.0620 0.0714 0.0681 0.1578 0.0722 0.0636 0.0720 0.0682 0.1760 0.0711 0.0621 0.1927 0.1690 0.0595 0.0696 0.0550

1σ

Isotopic age (Ma) 207 235

Pb/ U

0.0015 8.6982 0.0009 1.2573 0.0007 1.0687 0.0007 1.5201 0.0013 0.7232 0.0007 0.5044 0.0008 1.5115 0.0009 1.7938 0.0008 1.5542 0.0013 0.9019 0.0008 0.6411 0.0010 0.7590 0.0009 1.4681 0.0007 0.6268 0.0009 1.5939 0.0011 1.0789 0.0011 1.1417 0.0014 1.4126 0.0008 0.8683 0.0008 1.5508 0.0008 1.3740 0.0016 8.9768 0.0010 1.6802 0.0008 1.0596 0.0010 1.5610 0.0011 1.1420 0.0018 11.8445 0.0011 1.5684 0.0011 0.9240 0.0020 12.6917 0.0017 9.7930 0.0006 0.7350 0.0008 1.3290 0.0007 0.5049

1σ

206 238

0.0860 0.0165 0.0122 0.0155 0.0153 0.0064 0.0183 0.0213 0.0180 0.0177 0.0088 0.0120 0.0179 0.0072 0.0199 0.0218 0.0190 0.0261 0.0113 0.0190 0.0171 0.0954 0.0242 0.0129 0.0213 0.0214 0.1265 0.0243 0.0153 0.1372 0.1027 0.0077 0.0150 0.0064

Pb/ U

0.3933 0.1333 0.1230 0.1560 0.0893 0.0663 0.1548 0.1749 0.1576 0.1034 0.0798 0.0886 0.1482 0.0789 0.1598 0.1186 0.1197 0.1462 0.1011 0.1563 0.1452 0.4097 0.1677 0.1203 0.1565 0.1207 0.4849 0.1592 0.1078 0.4747 0.4167 0.0891 0.1377 0.0662

1σ

207 206

Pb/ Pb

1σ

Best age estimate 207 235

Pb/ U

1σ

206 238

Pb/ U

1σ Age

Disc (%)

1σ 16 −14.4 6 −2.5 4 1.3 5 −0.4 4 −0.2 2 −0.3 5 −0.8 23 −0.3 6 -0.9 5 −2.9 3 −1.6 4 −4.8 5 −2.9 3 −1.0 6 −1.3 8 −2.8 5 −6.1 7 −1.7 4 −2.2 6 −1.6 5 −0.4 17 −9.9 6 −0.2 4 −0.2 6 −1.9 7 −5.3 17 −2.6 6 −0.6 4 −0.7 17 −10.4 17 −13.5 3 −1.7 4 −3.2 2 −0.5

0.0018 0.0010 0.0007 0.0009 0.0007 0.0004 0.0010 0.0012 0.0010 0.0009 0.0005 0.0007 0.0009 0.0005 0.0010 0.0014 0.0009 0.0013 0.0006 0.0011 0.0009 0.0028 0.0012 0.0007 0.0010 0.0012 0.0030 0.0011 0.0007 0.0029 0.0022 0.0005 0.0008 0.0004

2446 876 702 943 567 417 946 1043 965 744 532 672 974 502 989 783 900 939 672 969 872 2432 992 728 987 876 2616 961 680 2766 2548 587 917 413

16 27 24 21 48 28 24 23 22 38 30 33 24 26 26 35 33 45 23 22 19 17 28 26 29 33 17 31 36 17 17 24 23 30

2307 827 738 939 553 415 935 1043 952 653 503 573 917 494 968 743 773 894 635 951 878 2336 1001 734 955 173 2592 958 664 2657 2415 559 858 415

9 7 6 6 9 4 7 8 7 9 5 7 7 5 8 11 9 11 6 8 7 10 9 6 8 10 10 10 8 10 10 5 7 4

2138 807 748 935 552 414 928 1039 943 634 495 547 891 489 956 723 729 879 621 936 874 2213 999 732 937 735 2549 952 660 2504 2245 550 832 413

8 6 4 5 4 2 5 6 6 5 3 4 5 3 6 8 5 7 4 6 5 13 6 4 6 7 13 6 4 13 10 3 4 2

2446 807 748 935 552 414 928 1043 943 634 495 547 891 489 956 723 729 89 621 936 874 2432 999 732 937 735 2616 952 660 2766 2548 550 832 413

GB101: Qugasi Formation in Changtai region, Upper Triassic (N 31° 03.069′, E 99° 15.600′) N = 112/115 GB101-01 137 454 0.30 0.0555 0.0078 0.5636 0.0767 0.0732 0.0051 GB101-02 209 281 0.74 0.0988 0.0123 3.9959 0.4796 0.2906 0.0178 GB101-03 316 597 0.53 0.0551 0.0060 0.5280 0.0552 0.0689 0.0037 GB101-04 194 285 0.68 0.0553 0.0051 0.5479 0.0487 0.0715 0.0032 GB101-07 342 636 0.54 0.1753 0.0074 12.8784 0.5269 0.5278 0.0112 GB101-08 222 300 0.74 0.0749 0.0020 1.8649 0.0492 0.1794 0.0025 GB101-09 136 303 0.45 0.0552 0.0009 0.5222 0.0081 0.0682 0.0005 GB101-10 138 677 0.20 0.1700 0.0016 11.4844 0.1160 0.4846 0.0029 GB101-11 222 387 0.57 0.0596 0.0008 0.8334 0.0104 0.1010 0.0008 GB101-12 404 520 0.78 0.1567 0.0014 9.9501 0.0948 0.4563 0.0029 GB101-13 104 173 0.60 0.0902 0.0011 3.3649 0.0568 0.2662 0.0030 GB101-14 538 550 0.98 0.0683 0.0007 1.3947 0.0134 0.1467 0.0007 GB101-15 83 87 0.95 0.1537 0.0021 9.2104 0.1223 0.4325 0.0037 GB101-16 292 590 0.49 0.1573 0.0016 9.4688 0.0931 0.4326 0.0022 GB101-17 23 51 0.45 0.2972 0.0034 23.5935 0.2707 0.5713 0.0038 GB101-18 186 117 1.58 0.0714 0.0011 1.6495 0.0255 0.1669 0.0012 GB101-19 13 44 0.30 0.0734 0.0015 1.8046 0.0339 0.1788 0.0014 GB101-20 155 169 0.92 0.0549 0.0011 0.5560 0.0104 0.0734 0.0006 GB101-21 210 261 0.80 0.0645 0.0008 1.1758 0.0141 0.1313 0.0008 GB101-22 155 227 0.69 0.0734 0.0008 1.6512 0.0179 0.1623 0.0009 GB101-23 202 241 0.84 0.1508 0.0014 8.3283 0.0743 0.3972 0.0022 GB101-24 308 408 0.76 0.0558 0.0008 0.5447 0.0075 0.0704 0.0005 GB101-25 91 144 0.64 0.0651 0.0010 1.1996 0.0186 0.1327 0.0010 GB101-26 158 774 0.20 0.0702 0.0007 1.5887 0.0163 0.1625 0.0013 GB101-27 261 579 045 0.2951 0.0023 26.5214 0.2327 0.6435 0.0051 GB101-28 34 160 0.21 0.1262 0.0012 6.0055 0.0577 0.3410 0.0029 GB101-29 103 644 0.16 0.0726 0.0007 1.6683 0.0181 0.1644 0.0018 GB101-30 198 1001 0.20 0.1602 0.0013 10.2365 0.0864 0.4565 0.0047 GB101-31 83 84 0.99 0.1541 0.0017 9.5298 0.0995 0.4442 0.0055 GB101-32 175 271 0.65 0.0538 0.0009 0.5125 0.0083 0.0683 0.0009 GB101-33 126 335 0.38 0.1555 0.0016 9.9056 0.1066 0.4543 0.0065 GB101-34 304 696 0.44 0.0738 0.0008 1.7658 0.0197 0.1708 0.0022 GB101-35 267 715 0.37 0.0703 0.0007 1.6224 0.0152 0.1650 0.0018 GB101-36 161 178 0.91 0.0679 0.0009 1.3863 0.0176 0.1464 0.0014 GB101-37 79 181 0.44 0.0614 0.0011 0.8389 0.0144 0.0984 0.0009 GB101-38 292 295 0.99 0.1287 0.0011 6.6541 0.0599 0.3706 0.0027

432 2000 417 433 2609 1066 420 2558 587 2420 1431 880 2387 2428 3457 970 1026 409 767 1033 2355 443 789 933 3456 2046 1006 2458 2392 361 2409 1035 939 865 652 2081

318 234 244 207 70 56 37 16 28 15 23 21 22 18 18 37 40 44 26 22 16 30 33 16 12 17 24 14 18 37 17 21 23 31 44 15

454 1633 430 444 2671 1069 427 2563 616 2430 1496 887 2359 2385 3252 989 1047 449 789 990 2267 442 800 966 3366 1977 997 2456 2390 420 2426 1033 979 883 619 2067

50 98 37 32 39 17 5 9 6 9 13 6 12 9 11 10 12 7 7 7 8 5 9 6 9 8 7 8 10 6 10 7 6 7 8 8

455 1644 430 445 2732 1064 425 2547 620 2423 1521 882 2317 2317 2913 995 1061 456 795 969 2156 438 803 971 3203 1891 981 2424 2369 426 2414 1016 985 881 605 2032

31 89 22 19 47 14 3 13 4 13 16 4 17 10 15 7 8 3 4 5 10 3 6 7 20 14 10 21 25 6 29 12 10 8 5 13

455 31 0.3 2000 234 −21.6 430 22 −0.2 445 19 0.3 2609 70 4.5 1066 56 −0.2 425 3 −0.3 2558 16 −0.4 620 4 0.7 2420 15 0.1 1431 23 5.9 882 4 −0.5 2387 22 −3.0 2428 18 −4.8 3457 18 −18.7 995 7 0.6 1026 40 3.3 456 3 1.6 795 4 0.8 969 5 −2.1 2355 16 −9.2 438 3 −0.7 803 6 0.3 971 7 0.5 3456 12 −7.9 2046 17 −8.2 981 10 −1.5 2458 14 −1.4 2392 18 −0.9 426 6 1.3 2409 17 0.2 1035 21 −1.8 985 10 0.6 881 8 −0.3 605 5 −2.2 2081 15 −2.4

(continued on next page)

82

B.-Q. Wang et al. / Sedimentary Geology 289 (2013) 74–98

Table 1 (continued) Spot no.

Th (ppm)

U Th/U (ppm)

Isotopic ratios 207 206

Pb/ Pb

GB101: Qugasi Formation in Changtai region, Upper GB101-39 331 177 1.87 0.0943 GB101-40 183 148 1.24 0.1602 GB101-41 208 234 0.89 0.1627 GB101-42 364 1188 0.31 0.0713 GB101-43 263 779 0.34 0.0789 GB101-44 72 358 0.20 0.0717 GB101-45 147 233 0.63 0.0551 GB101-46 734 1011 0.73 0.0644 GB101-47 175 506 0.34 0.0708 GB101-48 208 236 0.88 0.0699 GB101-49 133 484 0.28 0.0658 GB101-50 2933 1076 2.73 0.0547 GB101-51 142 793 0.18 0.0664 GB101-52 146 470 0.31 0.0717 GB101-53 142 161 0.88 0.0591 GB101-54 162 474 0.34 0.0701 GB101-56 133 201 0.67 0.0712 GB101-57 504 523 0.96 0.0946 GB101-58 186 218 0.85 0.1592 GB101-59 59 132 0.45 0.0763 GB101-60 207 228 0.91 0.0762 GB101-61 174 352 0.49 0.1637 GB101-62 796 284 2.81 0.0576 GB101-63 191 672 0.28 0.0826 GB101-65 115 352 0.33 0.0922 GB101-66 124 457 0.27 0.0708 GB101-67 198 357 0.55 0.0701 GB101-68 167 399 0.42 0.1826 GB10-1-69 162 297 0.55 0.0569 GB101-70 100 174 0.58 0.0639 GB101-71 42 76 0.56 0.0999 GB101-72 107 882 0.12 0.2009 GB101-73 44.6 964 0.46 0.1218 GE101-74 76 201 0.38 0.0600 GB101-75 558 845 0.66 0.0546 GB101-76 149 267 0.56 0.0950 GB101-77 227 240 0.94 0.0721 GB101-78 33 44 0.74 0.2151 GB101-79 73 434 0.17 0.0604 GB101-80 43 424 0.10 0.0871 GB101-81 111 237 0.47 0.0558 GB101-82 122 154 0.79 0.0563 GB101-83 46 205 0.23 0.0551 GB101-84 201 290 0.69 0.0770 GB101-85 139 235 0.59 0.0917 GB101-86 155 588 0.26 0.1498 GB101-88 137 340 0.40 0.0558 GB101-89 211 449 0.47 0.0705 GB101-90 207 339 0.61 0.0558 GB101-91 44 293 0.15 0.0814 GB101-92 42 279 0.15 0.0704 GB101-93 141 315 0.45 0.0716 GB101-94 38 239 0.16 0.0606 GB101-95 120 147 0.81 0.0577 GB101-96 49 361 0.13 0.0580 GB101-97 117 289 0.40 0.0735 GB101-98 205 268 0.76 0.1575 GB101-99 658 746 0.88 0.0567 GB101-100 323 170 1.90 0.0599 GB101-101 19 609 0.03 0.0701 GB101-102 355 1101 0.32 0.1065 GB101-103 152 299 0.51 0.0659 GB101-104 139 210 0.66 0.1052 GB101-105 176 490 0.36 0.0560 GB101-106 80 142 0.56 0.1909 GB101-107 308 674 0.46 0.1050 GB101-108 87 195 0.45 0.1048 GB101-109 128 515 0.25 0.0720 GB101-110 263 924 0.29 0.0644 GB101-111 37 356 0.10 0.0586 GB101-112 119 388 0.31 0.0742

1σ

Isotopic age (Ma) 207 235

Pb/ U

1σ

206 238

Pb/ U

1σ

207 206

Pb/ Pb

Triassic (N 31° 03.069′', E 99° 15.600'′) N = 112/115 0.0011 3.5343 0.0488 0.2684 0.0023 1513 0.0017 9.8450 0.1038 0.4422 0.0030 2458 0.0016 9.8270 0.0967 0.4338 0.0025 2484 0.0008 1.4197 0.0154 0.1432 0.0008 965 0.0008 2.1658 0.0228 0.1974 0.0010 1169 0.0009 1.6984 0.0211 0.1705 0.0010 976 0.0012 0.5330 0.0105 0.0701 0.0005 417 0.0009 1.0102 0.0139 0.1128 0.0007 767 0.0011 1.6012 0.0245 0.1626 0.0010 954 0.0013 1.5520 0.0285 0.1600 0.0011 925 0.0012 1.1493 0.0206 0.1257 0.0009 1200 0.0009 0.5344 0.0085 0.0703 0.0004 398 0.0009 1.2771 0.0177 0.1382 0.0007 820 0.0010 1.6248 0.0210 0.1633 0.0008 976 0.0011 0.8089 0.0149 0.0988 0.0007 572 0.0008 1.5413 0.0176 0.1586 0.0009 931 0.0011 1.6557 0.0242 0.1677 0.0011 961 0.0010 3.4699 0.0351 0.2639 0.0013 1520 0.0015 10.2239 0.0980 0.4624 0.0026 2447 0.0010 1.8691 0.0249 0.1766 0.0011 1102 0.0009 1.9314 0.0241 0.1825 0.0009 1102 0.0014 8.9585 0.0765 0.3935 0.0017 2495 0.0008 0.6376 0.0087 0.0798 0.0004 522 0.0010 2.5408 0.0559 0.2161 0.0032 1259 0.0011 3.2704 0.0367 0.2552 0.0013 1472 0.0008 1.5935 0.0176 0.1620 0.0008 952 0.0008 1.6030 0.0175 0.1646 0.0008 931 0.0016 13.2020 0.1121 0.5201 0.0023 2676 0.0009 0.5604 0.0084 0.0712 0.0004 487 0.0014 1.0777 0.0249 0.1225 0.0014 737 0.0013 4.0147 0.0509 0.2903 0.0018 1621 0.0022 15.2573 0.2230 0.5423 0.0043 2835 0.0012 6.0969 0.0711 0.3600 0.0025 1983 0.0009 0.8304 0.0129 0.1000 0.0007 606 0.0007 0.5488 0.0075 0.0725 0.0004 394 0.0012 3.6871 0.0562 0.2790 0.0021 1528 0.0011 1.6747 0.0269 0.1680 0.0009 987 0.0034 16.9175 0.2842 0.5689 0.0034 2944 0.0011 0.9286 0.0177 0.1111 0.0006 618 0.0016 2.9066 0.0580 0.2408 0.0012 1365 0.0010 0.5564 0.0096 0.0722 0.0005 443 0.0013 0.5501 0.0117 0.0711 0.0006 461 0.0011 0.5489 0.0111 0.0721 0.0006 417 0.0009 2.1161 0.0246 0.1978 0.0012 1121 0.0010 3.2516 0.0352 0.2557 0.0016 1461 0.0013 8.9058 0.0818 0.4281 0.0024 2344 0.0012 0.5352 0.0108 0.0695 0.0007 443 0.0008 1.5944 0.0187 0.1631 0.0010 944 0.0010 0.5119 0.0086 0.0664 0.0004 443 0.0010 2.2131 0.0269 0.1963 0.0012 1231 0.0010 1.2773 0.0199 0.1308 0.0011 939 0.0009 1.5562 0.0192 0.1568 0.0009 976 0.0010 0.7606 0.0119 0.0908 0.0006 633 0.0012 0.5510 0.0112 0.0695 0.0005 517 0.0011 0.5756 0.0113 0.0715 0.0005 532 0.0010 1.5948 0.0210 0.1562 0.0010 1028 0.0018 9.3433 0.1092 0.4270 0.0027 2429 0.0008 0.5379 0.0070 0.0683 0.0004 483 0.0013 0.6560 0.0137 0.0795 0.0006 598 0.0010 1.4561 0.0200 0.1494 0.0010 931 0.0010 4.4612 0.0456 0.3005 0.0018 1740 0.0009 1.0869 0.0137 0.1188 0.0007 1200 0.0011 4.2623 0.0454 0.2913 0.0016 1718 0.0009 0.5506 0.0087 0.0709 0.0005 454 0.0021 14.2360 0.1618 0.5361 0.0036 2750 0.0012 4.4270 0.0506 0.3029 0.0020 1714 0.0012 4.2298 0.0476 0.2903 0.0018 1711 0.0008 1.6434 0.0184 0.1642 0.0010 987 0.0007 1.0967 0.0113 0.1224 0.0006 754 0.0008 0.7216 0.0102 0.0886 0.0006 554 0.0008 1.7658 0.0193 0.1712 0.0010 1056

1σ

Best age estimate 207 235

22 18 12 22 21 31 46 29 32 39 39 37 30 27 41 31 30 20 16 26 24 15 30 24 22 24 22 14 35 41 29 17 51 33 34 25 33 26 34 36 8 55 46 23 20 15 46 24 37 24 29 31 33 46 43 21 20 36 53 30 17 28 21 42 19 53 16 22 16 30 50

Pb/ U

1535 2420 2419 897 1170 1008 434 709 971 951 777 435 836 980 602 947 992 1520 2455 1070 1092 2334 501 1284 1474 968 971 2694 452 742 1637 2831 1990 614 444 1569 999 2930 667 1384 449 445 444 1154 1470 2328 435 968 420 1185 836 953 574 446 462 968 2372 437 512 912 1724 747 1686 445 2766 1717 1680 987 752 552 1033

1σ

206 238

11 10 9 6 7 8 7 7 10 11 10 6 8 8 8 7 9 8 9 9 8 8 5 16 9 7 7 8 5 12 10 14 10 7 5 12 10 16 9 15 6 8 7 8 8 8 7 7 6 9 9 8 7 7 7 8 11 5 8 8 8 7 9 6 11 9 9 7 5 6 7

Pb/ U

1533 2360 2323 863 1161 1015 437 689 971 957 763 438 834 975 607 949 999 1510 2450 1048 1080 2139 495 1261 1465 968 982 2699 444 745 1643 2793 1982 615 451 1586 1001 2903 679 1391 449 443 449 1163 1468 2297 433 974 415 1155 793 939 560 433 445 936 2292 426 493 898 1694 723 1648 442 2767 1706 1643 980 744 547 1019

1σ Age

12 13 11 5 6 5 3 4 5 6 5 2 4 4 4 5 6 7 11 6 5 8 3 17 7 4 5 10 2 8 9 18 12 4 2 10 5 14 3 6 3 4 3 6 8 11 4 6 3 6 6 5 3 3 3 5 12 2 4 5 9 4 8 3 15 10 9 5 4 4 5

1513 2458 2484 863 1169 976 437 689 971 957 763 438 834 975 607 949 999 1520 2447 1102 1102 2495 495 1259 1472 968 982 2676 444 745 1621 2835 1983 615 451 1528 987 2944 679 1365 449 443 449 1121 1461 2344 433 974 415 1231 793 939 560 433 445 936 2429 426 493 898 1740 723 1718 442 2750 1714 1711 980 744 547 1056

Disc (%)

1σ

22 1.3 18 −4.1 12 −7.0 5 −4.0 21 −0.7 31 3.9 3 0.6 4 −2.9 5 0.1 6 0.6 5 −1.8 2 0.8 4 −0.1 4 −0.5 4 0.9 5 0.2 6 0.8 20 −0.7 16 0.2 26 −5.1 24 −2.0 15 −16.6 3 −1.2 24 0.2 22 −0.5 4 0.0 5 1.1 14 0.9 2 −1.8 8 0.3 29 1.3 17 −1.5 51 −0.1 4 0.1 2 1.6 25 3.7 33 1.4 26 −1.4 3 1.8 36 1.9 3 0.0 4 −0.5 3 1.0 23 3.6 20 0.5 15 −2.0 4 −0.5 6 0.6 3 −1.3 24 −6.6 6 −5.4 5 −1.5 3 −2.5 3 −2.9 3 −3.6 5 −3.5 20 −6.0 2 −2.6 4 −3.8 5 −1.6 17 −2.7 4 −3.3 21 −4.3 3 −0.9 19 0.6 53 −0.5 16 −4.1 5 −0.7 4 −1.0 4 −0.8 50 −3.6

B.-Q. Wang et al. / Sedimentary Geology 289 (2013) 74–98

83

Table 1 (continued) Spot no.

Th (ppm)

U Th/U (ppm)

Isotopic ratios 207 206

GB101-113 GB101-114 GB101-115 GB101-116 GB101-117 GB101-118 GB101-119 GB101-120

160 166 96 257 222 54 900 79

408 328 67 570 484 205 1425 167

0.39 0.50 1.43 0.45 0.46 0.26 0.63 0.47

Pb/ Pb

0.0818 0.1050 0.0728 0.0796 0.0550 0.0992 0.0569 0.1055

1σ

Isotopic age (Ma) 207 235

0.0010 0.0012 0.0015 0.0008 0.0008 0.0013 0.0006 0.0012

GB77: Tumugou Formation in Changtai region, Upper Triassic GB77-01 141 577 0.25 0.0709 0.0006 GB77-02 240 411 0.58 0.0713 0.0007 GB77-03 425 383 1.11 0.1074 0.0008 GB77-04 102 144 0.71 0.0878 0.0009 GB77-05 261 366 0.71 0.0565 0.0008 GB77-06 68 106 0.64 0.0700 0.0011 GB77-07 352 912 0.39 0.1617 0.0014 GB77-08 109 179 0.61 0.1619 0.0015 GB77-09 746 1387 0.54 0.1116 0.0010 GB77-10 146 370 0.39 0.0786 0.0007 GB77-11 58 78 0.74 0.0988 0.0012 GB77-12 360 999 0.36 0.1909 0.0014 GB77-13 463 539 0.86 0.0892 0.0007 GB77-14 200 326 0.61 0.1499 0.0013 GB77-15 305 429 0.71 0.1628 0.0014 GB77-16 123 108 1.14 0.0578 0.0015 GB77-17 115 663 0.17 0.0819 0.0008 GB77-18 114 152 0.75 0.0742 0.0010 GB77-19 216 824 0.26 0.0708 0.0007 GB77-20 281 987 0.28 0.0714 0.0008 GB77-21 162 448 0.36 0.0870 0.0008 GB77-24 142 172 0.83 0.1605 0.0016 GB77-25 252 630 0.40 0.0579 0.0008 GB77-26 208 163 1.27 0.1603 0.0015 GB77-27 248 378 0.66 0.0550 0.0008 GB77-28 229 384 0.59 0.0554 0.0008 GB77-29 320 678 0.47 0.0543 0.0006 GB77-30 49 252 0.20 0.1645 0.0014 GB77-31 294 313 0.94 0.0556 0.0009 GB77-32 128 208 0.62 0.0821 0.0011 GB77-33 121 254 0.48 0.0546 0.0009 GB77-34 426 239 1.79 0.0604 0.0009 GB77-36 211 415 0.51 0.0756 0.0008 GB77-37 39 73 0.53 0.0623 0.0015 GB77-38 112 232 0.48 0.0554 0.0009 GB77-39 88 55 1.58 0.0762 0.0013 GB77-40 138 306 0.45 0.1197 0.0013 GB77-41 219 233 0.94 0.0905 0.0010 GB77-42 466 502 0.93 0.0550 0.0007 GB77-43 232 250 0.93 0.1579 0.0014 GB77-44 119 162 0.73 0.0563 0.0011 GB77-45 203 289 0.70 0.0599 0.0007 GB77-46 84 204 0.41 0.0812 0.0008 GB77-47 130 147 0.88 0.0909 0.0010 GB77-48 158 151 1.05 0.0717 0.0011 GB77-49 162 258 0.63 0.0554 0.0009 GB77-50 150 949 0.16 0.0721 0.0007 GB77-51 84 243 0.34 0.1042 0.0009 GB77-52 91 107 0.84 0.1602 0.0012 GB77-53 141 132 1.07 0.0774 0.0011 GB77-54 134 642 0.21 0.1507 0.0007 GB77-55 98 741 0.13 0.0700 0.0004 GB77-56 322 384 0.84 0.0719 0.0006 GB77-57 221 169 1.31 0.0679 0.0009 GB77-58 129 675 0.19 0.2285 0.0011 GB77-59 313 376 0.83 0.0575 0.0008 GB77-60 274 493 0.56 0.0558 0.0007 GB77-61 264 480 0.55 0.0701 0.0007 GB77-62 313 365 0.86 0.0546 0.0007 GB77-63 338 549 0.62 0.0578 0.0007 GB77-64 214 378 0.56 0.0546 0.0008 GB77-65 327 352 0.93 0.0549 0.0008

Pb/ U

2.1854 4.3545 1.6073 1.8337 0.5025 3.6258 0.4942 4.2708

1σ

206 238

0.0253 0.0499 0.0312 0.0224 0.0071 0.0476 0.0057 0.0468

(N 31° 08.173′, E 99° 1.6903 0.0156 1.6543 0.0151 4.7368 0.0370 2.9843 0.0310 0.5685 0.0084 1.5102 0.0218 9.3911 0.0780 10.3536 0.0971 5.0459 0.0428 2.1945 0.0216 3.7740 0.0443 14.6894 0.1479 3.1382 0.0257 8.4957 0.0688 10.9068 0.0926 0.5773 0.0140 2.5336 0.0263 1.9786 0.0247 1.3204 0.0140 1.5081 0.0170 3.3089 0.0349 10.9665 0.1108 0.6324 0.0090 10.6008 0.0987 0.5439 0.0072 0.5456 0.0074 0.5495 0.0059 10.7290 0.0972 0.5575 0.0092 2.3466 0.0300 0.5702 0.0096 0.7848 0.0112 2.0319 0.0226 0.7100 0.0166 0.5541 0.0087 2.0095 0.0336 5.8173 0.0601 3.2910 0.0355 0.5553 0.0067 9.6071 0.0901 0.5470 0.0101 0.8019 0.0099 2.4877 0.0250 3.1925 0.0362 1.2868 0.0202 0.5479 0.0083 1.6238 0.0150 4.7976 0.0469 10.8164 0.0888 1.4863 0.0232 7.4460 0.0360 1.6760 0.0114 1.5674 0.0139 1.2481 0.0155 18.2140 0.1519 0.5907 0.0081 0.5560 0.0065 1.1726 0.0114 0.5453 0.0071 0.5751 0.0071 0.5555 0.0080 0.5531 0.0083

Pb/ U

0.1926 0.2983 0.1608 0.1657 0.0660 0.2635 0.0625 0.2921

1σ

207 206

0.0011 0.0017 0.0013 0.0013 0.0004 0.0019 0.0004 0.0017

Pb/ Pb

1σ

Best age estimate 207 235

Pb/ U

1σ

206 238

Pb/ U

1σ Age

Disc (%)

1σ −9.2 −2.0 −1.2 −7.0 −0.3 −6.8 −4.3 −4.4

1240 1717 1009 1187 413 1610 500 1724

24 21 41 21 27 25 29 21

1176 1704 973 1058 413 1555 408 1688

8 9 12 8 5 10 4 9

1135 1683 961 988 412 1508 391 1652

6 9 7 7 2 10 2 8

1240 1717 961 988 412 1610 391 1724

24 21 7 7 2 25 2 21

23.964′), N = 100/105 0.1716 0.0008 954 0.1672 0.0008 966 0.3174 0.0013 1755 0.2448 0.0014 1389 0.0726 0.0004 472 0.1563 0.0009 928 0.4178 0.0018 2474 0.4602 0.0022 2476 0.3253 0.0014 1826 0.2008 0.0010 1165 0.2755 0.0015 2000 0.5519 0.0039 2750 0.2532 0.0011 1409 0.4079 0.0018 2346 0.4821 0.0025 2484 0.0732 0.0007 524 0.2224 0.0013 1243 0.1928 0.0012 1056 0.1342 0.0008 951 0.1518 0.0008 969 0.2737 0.0023 1361 0.4912 0.0029 2461 0.0786 0.0005 524 0.4752 0.0021 2459 0.0712 0.0004 413 0.0710 0.0004 428 0.0727 0.0004 387 0.4684 0.0025 2502 0.0724 0.0006 439 0.2056 0.0012 1247 0.0753 0.0005 394 0.0937 0.0005 620 0.1932 0.0013 1084 0.0829 0.0007 687 0.0721 0.0004 432 0.1910 0.0014 1099 0.3496 0.0017 1952 0.2617 0.0013 1437 0.0728 0.0004 413 0.4374 0.0024 2435 0.0704 0.0004 465 0.0964 0.0005 598 0.2210 0.0011 1226 0.2533 0.0014 1456 0.1298 0.0009 989 0.0718 0.0004 428 0.1622 0.0008 991 0.3317 0.0022 1700 0.4868 0.0027 2458 0.1383 0.0009 1131 0.3556 0.0011 2353 0.1724 0.0010 929 0.1571 0.0007 983 0.1334 0.0009 865 0.5717 0.0033 3042 0.0741 0.0004 522 0.0721 0.0004 456 0.1206 0.0005 931 0.0723 0.0004 394 0.0718 0.0004 524 0.0735 0.0004 394 0.0729 0.0005 409

14 19 14 20 33 36 13 15 16 20 22 12 21 14 13 62 14 26 21 22 23 17 36 17 30 31 24 15 39 26 34 31 20 55 35 34 19 20 28 14 43 31 25 16 31 35 19 15 8 29 8 11 21 31 7 31 26 20 34 28 33 33

1005 991 1774 1404 457 935 2377 2467 1827 1179 1587 2795 1442 2285 2515 463 1282 1108 855 934 1483 2520 498 2489 441 442 445 2500 450 1227 458 588 1126 545 448 1119 1949 1479 448 2398 443 598 1268 1455 840 444 979 1784 2507 925 2167 999 957 823 3001 471 449 788 442 461 449 447

6 6 7 8 5 9 8 9 7 7 9 10 6 7 8 9 8 8 6 7 8 9 6 9 5 5 4 8 6 9 6 6 8 10 6 11 9 8 4 9 7 6 7 9 9 5 6 8 8 9 4 4 5 7 8 5 4 5 5 5 5 5

1021 996 1777 1412 452 936 2251 2441 1816 1180 1569 2833 1455 2206 2536 455 1295 1137 812 911 1560 2576 488 2506 443 442 452 2476 451 1205 468 578 1139 513 449 1127 1932 1499 453 2339 439 593 1287 1456 787 447 969 1847 2557 835 1961 1025 941 807 2915 461 449 734 450 447 457 454

4 4 6 7 2 5 8 10 7 6 8 16 6 8 11 4 7 7 5 4 12 12 3 9 2 2 2 11 3 6 3 3 7 4 3 7 8 7 2 11 3 3 6 7 5 3 4 11 12 5 5 5 4 5 13 2 3 3 2 2 2 3

1021 996 1755 1389 452 936 2474 2476 1826 1165 2000 2750 1409 2346 2484 455 1243 1056 812 911 1361 2461 488 2459 443 442 452 2502 451 1247 468 578 1084 513 449 1099 1952 1437 453 2435 439 593 1226 1456 787 447 969 1700 2458 835 2353 929 941 807 3042 461 449 734 450 447 457 454

4 1.6 4 0.5 14 1.2 20 1.6 2 −1.1 5 0.2 13 −9.9 15 −1.4 16 −0.5 20 1.3 22 −27.5 12 2.9 21 3.1 14 −6.4 13 2.1 4 −1.6 14 4.0 26 7.1 5 −5.3 4 −2.5 23 12.7 17 4.5 3 −2.0 17 1.9 2 0.5 2 0.0 2 1.7 15 −1.0 3 0.2 26 −3.5 3 2.1 3 −1.8 20 4.8 4 −6.1 3 0.3 34 2.4 19 −1.0 20 4.1 2 1.1 14 −4.1 3 −1.0 3 −0.8 25 4.8 16 0.0 5 −6.8 3 0.8 4 −1.1 15 8.0 8 3.9 5 −10.8 8 −20.0 11 9.4 4 −1.8 5 −1.9 7 −4.3 2 −2.3 3 0.0 3 −7.3 2 1.8 2 −3.2 2 1.9 3 1.5

(continued on next page)

84

B.-Q. Wang et al. / Sedimentary Geology 289 (2013) 74–98

Table 1 (continued) Spot no.

Th (ppm)

U Th/U (ppm)

Isotopic ratios 207 206

Pb/ Pb

GB77: Tumugou Formation in Changtai region, Upper GB77-66 285 386 0.74 0.0553 GB77-67 393 781 0.50 0.0725 GB77-69 503 478 1.05 0.1598 GB77-70 200 363 0.55 0.0569 GB77-71 207 211 0.98 0.0588 GB77-72 498 572 0.87 0.0744 GB77-73 100 76 1.30 0.0729 GB77-74 188 576 0.33 0.0708 GB77-75 317 407 0.78 0.0558 GB77-76 129 316 0.41 0.0563 GB77-77 157 110 1.43 0.0776 GB77-78 231 264 0.88 0.0569 GB77-79 143 299 0.48 0.0689 GB77-80 218 255 0.85 0.0914 GB77-81 107 263 0.41 0.0706 GB77-82 199 475 0.42 0.0570 GB77-83 318 566 0.56 0.0795 GB77-84 391 210 1.86 0.0589 GB77-85 79 192 0.41 0.0760 GB77-86 49 97 0.51 0.0694 GB77-87 306 720 0.42 0.0558 GB77-89 66 159 0.42 0.0682 GB77-90 88 184 0.48 0.0727 GB77-91 381 537 0.71 0.0989 GB77-92 536 451 1.19 0.0678 GB77-93 59 453 0.13 0.0730 GB77-94 97 156 0.63 0.0710 GB77-95 143 285 0.50 0.0827 GB77-96 32 95 0.34 0.0630 GB77-97 570 422 1.35 0.0765 GB77-98 367 437 0.84 0.1007 GB77-100 79 360 0.22 0.0718 GB77-101 44 134 0.33 0.1065 GB77-103 416 1183 0.35 0.0630 GB77-104 108 668 0.16 0.0706 GB77-105 178 347 0.51 0.0563 GB77-106 110 148 0.74 0.0573 GB77-107 127 184 0.69 0.0552 GB77-109 61 568 0.11 0.0687 GB77-110 161 243 0.66 0.0555 GB77-111 94 655 0.14 0.0783 GB77-113 127 221 0.58 0.0555 GB77-114 580 758 0.77 0.0833

1σ

Isotopic age (Ma) 207 235

Pb/ U

1σ

Triassic (N 31° 08.173'′, E 99° 0.0008 0.5485 0.0081 0.0007 1.4914 0.0148 0.0013 10.5184 0.0862 0.0008 0.5976 0.0085 0.0018 0.6052 0.0177 0.0008 1.6530 0.0182 0.0013 1.8207 0.0305 0.0007 1.6328 0.0156 0.0007 0.5577 0.0069 0.0008 0.5796 0.0077 0.0010 2.1805 0.0269 0.0008 0.5688 0.0084 0.0007 1.5067 0.0166 0.0010 3.3006 0.0355 0.0010 1.6513 0.0302 0.0009 0.5392 0.0079 0.0010 1.9095 0.0230 0.0010 0.7625 0.0127 0.0010 1.8888 0.0250 0.0012 1.4717 0.0248 0.0007 0.5143 0.0063 0.0010 1.4206 0.0199 0.0010 1.6637 0.0236 0.0010 4.0142 0.0417 0.0009 1.2276 0.0175 0.0008 1.5691 0.0191 0.0010 1.6250 0.0235 0.0009 2.2746 0.0257 0.0012 1.0265 0.0194 0.0009 2.0114 0.0268 0.0011 3.8611 0.0419 0.0009 1.7110 0.0209 0.0012 4.5083 0.0537 0.0007 0.8213 0.0090 0.0008 1.5518 0.0169 0.0009 0.5373 0.0086 0.0013 0.5267 0.0118 0.0012 0.5081 0.0102 0.0007 1.4072 0.0152 0.0013 0.5158 0.0125 0.0008 2.0657 0.0218 0.0011 0.5494 0.0111 0.0009 2.3727 0.0260

206 238

Pb/ U

23.964'′), N 0.0718 0.1483 0.4732 0.0758 0.0742 0.1596 0.1803 0.1658 0.0723 0.0745 0.2033 0.0724 0.1577 0.2612 0.1676 0.0683 0.1733 0.0933 0.1795 0.1538 0.0664 0.1505 0.1648 0.2922 0.1303 0.1543 0.1654 0.1979 0.1178 0.1888 0.2759 0.1717 0.3044 0.0939 0.1582 0.0688 0.0667 0.0669 0.1476 0.0671 0.1900 0.0720 0.2053

1σ

207 206

Pb/ Pb

1σ

Best age estimate 207 235

Pb/ U

1σ

206 238

Pb/ U

1σ Age

Disc (%)

1σ

= 100/105 0.0004 433 0.0007 999 0.0021 2454 0.0005 487 0.0007 561 0.0010 1052 0.0013 1013 0.0009 952 0.0004 456 0.0004 461 0.0012 1136 0.0004 487 0.0008 894 0.0015 1455 0.0015 946 0.0004 500 0.0011 1183 0.0007 561 0.0012 1094 0.0012 922 0.0004 443 0.0010 876 0.0012 1006 0.0017 1603 0.0010 861 0.0009 1015 0.0011 967 0.0012 1263 0.0009 709 0.0016 1109 0.0017 1639 0.0012 989 0.0019 1743 0.0006 709 0.0009 946 0.0005 465 0.0006 502 0.0005 420 0.0008 900 0.0006 432 0.0010 1154 0.0007 432 0.0012 1276

33 16 14 31 69 23 40 20 30 31 25 33 22 20 31 33 23 35 −6 35 31 25 23 19 32 24 30 22 8 23 20 25 21 24 22 35 52 46 22 56 16 44 22

444 927 2482 476 481 991 1053 983 450 464 1175 457 933 1481 990 438 1084 575 1077 919 421 898 995 1637 813 958 980 1204 717 1119 1606 1013 1733 609 951 437 430 417 892 422 1138 445 1234

5 6 8 5 11 7 11 6 5 5 9 5 7 8 12 5 8 7 9 10 4 8 9 8 8 8 9 8 10 9 9 8 10 5 7 6 8 7 6 8 7 7 8

447 891 2497 471 461 954 1068 989 450 463 1193 450 944 1496 999 426 1030 575 1065 922 415 904 983 1652 790 925 987 1164 718 1115 1571 1022 1713 578 947 429 416 418 887 419 1122 448 1204

3 4 9 3 4 5 7 5 2 3 7 3 5 8 8 3 6 4 6 7 2 6 7 9 6 5 6 6 5 9 9 7 9 3 5 3 3 3 5 3 6 4 6

447 891 2454 471 461 954 1013 989 450 463 1136 450 944 1455 999 426 1183 575 1094 922 415 904 983 1603 790 925 987 1263 718 1109 1639 989 1743 578 947 429 416 418 887 419 1154 448 1276

3 0.6 4 −4.0 14 1.7 3 −1.0 4 −4.2 5 −3.8 40 5.2 5 0.6 2 0.0 3 −0.2 25 4.8 3 −1.5 5 1.2 20 2.8 8 0.9 3 −2.8 23 −14.9 4 −0.1 −6 -2.8 7 0.4 2 −1.6 6 0.7 7 −1.2 19 3.0 6 −3.0 5 −3.6 6 0.7 22 −8.5 5 0.1 23 0.5 20 −4.3 25 3.2 21 −1.7 3 −5.3 5 −0.5 3 −1.7 3 −3.2 3 0.1 5 −0.5 3 −0.8 16 −2.9 4 0.8 22 −6.0

GB185: Lanashan Formation in Changtai region, Upper Triassic (N 31° 15.069′, E 99° 46.694′), N = 96/101 GB185-01 257 411 0.62 0.0557 0.0007 0.5500 0.0068 0.0714 0.0004 439 GB185-02 285 1172 0.24 0.0707 0.0006 1.4512 0.0125 0.1480 0.0006 948 GB185-03 528 1126 0.47 0.1047 0.0009 3.4990 0.0301 0.2411 0.0013 1709 GB185-04 214 489 0.44 0.0560 0.0007 0.5563 0.0068 0.0718 0.0004 454 GB185-05 54 90 0.60 0.0539 0.0012 0.5417 0.0119 0.0736 0.0006 365 GB185-07 117 295 0.40 0.0795 0.0008 2.3127 0.0303 0.2089 0.0017 1187 GB185-08 60 286 0.21 0.1025 0.0010 4.5879 0.0526 0.3225 0.0025 1669 GB185-09 104 220 0.47 0.0549 0.0009 0.5708 0.0090 0.0753 0.0005 409 GB185-10 219 190 1.15 0.1631 0.0014 10.5707 0.0857 0.4677 0.0022 2488 GB185-11 58 92 0.64 0.1661 0.0023 10.5760 0.1379 0.4611 0.0037 2520 GB185-12 184 220 0.83 0.0748 0.0008 1.8590 0.0188 0.1794 0.0009 1065 GB185-13 55 451 0.12 0.0707 0.0007 1.6399 0.0159 0.1675 0.0010 947 GB185-14 265 145 1.82 0.0704 0.0009 1.5296 0.0190 0.1573 0.0009 939 GB185-16 178 547 0.32 0.0730 0.0007 1.6973 0.0168 0.1673 0.0008 1015 GB185-17 167 413 0.40 0.0566 0.0008 0.5467 0.0076 0.0698 0.0004 476 GB185-18 171 691 0.25 0.0560 0.0007 0.5539 0.0064 0.0715 0.0004 450 GB185-19 104 179 0.58 0.0571 0.0011 0.5811 0.0110 0.0737 0.0005 494 GB185-20 61 420 0.15 0.0760 0.0007 1.9785 0.0173 0.1886 0.0009 1095 GB185-21 126 420 0.30 0.1117 0.0009 5.0133 0.0404 0.3236 0.0017 1828 GB185-22 208 2576 0.08 0.0731 0.0006 1.1127 0.0096 0.1097 0.0005 1017 GB185-23 96 186 0.52 0.0601 0.0009 0.8842 0.0134 0.1065 0.0006 606 GB185-24 753 1369 0.55 0.0969 0.0009 1.9610 0.0191 0.1457 0.0008 1566 GB185-25 121 329 0.37 0.1041 0.0009 4.2955 0.0420 0.2974 0.0017 1698 GB185-26 173 327 0.53 0.0702 0.0007 1.6042 0.0155 0.1648 0.0008 933 GB185-27 162 328 0.49 0.0594 0.0007 0.7956 0.0092 0.0968 0.0005 589 GB185-28 268 1689 0.16 0.0690 0.0005 1.5087 0.0114 0.1575 0.0006 899

32 17 15 23 47 20 18 42 14 24 21 20 22 20 31 21 75 20 15 19 33 17 17 16 26 16

445 910 1527 449 440 1216 1747 459 2486 2487 1067 986 942 1007 443 448 465 1108 1822 759 643 1102 1692 972 594 934

4 5 7 4 8 9 10 6 8 12 7 6 8 6 5 4 7 6 7 5 7 7 8 6 5 5

445 890 1392 447 458 1223 1802 468 2474 2444 1064 998 942 997 435 445 459 1114 1807 671 653 877 1679 984 595 943

2 4 7 2 4 9 12 3 10 16 5 5 5 4 2 2 3 5 8 3 4 4 9 5 3 4

445 890 1709 447 458 1187 1669 468 2488 2520 1065 998 942 997 435 445 459 1095 1828 671 653 877 1698 984 595 943

2 −0.1 4 −2.3 15 −22.7 2 −0.5 4 4.0 20 2.9 18 7.4 3 2.0 14 −0.6 24 −3.1 21 −0.1 5 1.3 5 0.0 4 −1.0 2 −1.8 2 −0.5 3 −1.4 20 1.6 15 −1.1 3 −13.2 4 1.4 4 −25.7 17 −1.2 5 1.2 3 0.2 4 0.9

B.-Q. Wang et al. / Sedimentary Geology 289 (2013) 74–98

85

Table 1 (continued) Spot no.

Th (ppm)

U Th/U (ppm)

Isotopic ratios 207 206

GB185-29 GB185-31 GB185-32 GB185-33 GB185-34 GB185-36 GB185-37 GB185-38 GB185-39 GB185-40 GB185-41 GB185-42 GB185-43 GB185-44 GB185-45 GB185-46 GB185-47 GB185-48 GB185-49 GB185-50 GB185-51 GB185-52 GB185-53 GB185-55 GB185-56 GB185-57 GB185-59 GB185-60 GB185-61 GB185-62 GB185-63 GB185-64 GB185-65 GB185-67 GB185-68 GB185-69 GB185-70 GB185-71 GB185-72 GB185-73 GB185-74 GB185-75 GB185-76 GB185-77 GB185-78 GB185-80 GB185-81 GB185-82 GB185-83 GB185-84 GB185-85 GB185-86 GB185-88 GB185-89 GB185-90 GB185-91 GB185-92 GB185-93 GB185-94 GB185-95 GB185-96 GB185-97 GB185-98 GB185-100 GB185-101 GB185-103 GB185-104 GB185-105 GB185-106 GB185-107 GB185-108

195 54 393 99 132 100 244 499 359 192 408 197 168 141 166 191 132 252 218 238 248 237 203 54 51 448 106 227 388 171 429 68 221 37 684 294 65 53 285 65 179 73 105 165 2 105 319 91 252 29 124 98 224 396 71 169 438 72 252 106 29 572 91 91 693 328 154 257 193 431 122

275 577 569 146 292 1307 244 878 489 646 696 567 311 533 296 253 221 307 367 367 249 301 596 113 720 855 140 347 1867 430 574 141 501 334 376 756 412 78 563 347 1318 1105 120 221 12 378 335 163 364 679 70 366 174 332 774 934 778 163 409 365 941 869 156 235 1117 424 203 353 454 1867 506

0.71 0.09 0.69 0.68 0.45 0.08 1.00 0.57 0.73 0.30 0.59 0.35 0.54 0.26 0.56 0.75 0.60 0.82 0.59 0.65 0.99 0.79 0.34 0.47 0.07 0.52 0.76 0.65 0.21 0.40 0.75 0.48 0.44 0.11 1.82 0.39 0.16 0.68 0.51 0.19 0.14 0.07 0.87 0.75 0.16 0.28 0.95 0.56 0.69 0.04 1.76 0.27 1.29 1.19 0.09 0.18 0.56 0.44 0.62 0.29 0.03 0.66 0.59 0.39 0.62 0.77 0.76 0.73 0.43 0.23 0.24

Pb/ Pb

0.1023 0.0681 0.0555 0.1644 0.0702 0.0581 0.0585 0.1620 0.0709 0.1083 0.0553 0.0678 0.0586 0.0601 0.1677 0.0877 0.0650 0.0557 0.0553 0.1059 0.0686 0.0576 0.1525 0.1613 0.0663 0.0780 0.0745 0.0540 0.0560 0.1002 0.0541 0.0967 0.0756 0.0573 0.0739 0.0634 0.1264 0.1677 0.0698 0.0696 0.0981 0.1079 0.0734 0.0656 0.1620 0.0749 0.0746 0.1602 0.1629 0.1125 0.0784 0.1220 0.0551 0.0637 0.0692 0.1608 0.0541 0.0824 0.0785 0.0689 0.0746 0.0724 0.0724 0.0703 0.0707 0.1582 0.0860 0.0554 0.0710 0.0777 0.1167

1σ

Isotopic age (Ma) 207 235

0.0009 0.0007 0.0007 0.0016 0.0007 0.0005 0.0008 0.0012 0.0007 0.0011 0.0006 0.0006 0.0007 0.0006 0.0013 0.0009 0.0008 0.0009 0.0008 0.0010 0.0008 0.0008 0.0011 0.0015 0.0006 0.0007 0.0009 0.0007 0.0004 0.0009 0.0006 0.0013 0.0008 0.0010 0.0008 0.0007 0.0010 0.0016 0.0006 0.0007 0.0008 0.0009 0.0010 0.0010 0.0035 0.0009 0.0011 0.0020 0.0017 0.0012 0.0015 0.0013 0.0012 0.0009 0.0008 0.0016 0.0008 0.0011 0.0010 0.0010 0.0010 0.0011 0.0014 0.0010 0.0008 0.0019 0.0014 0.0011 0.0009 0.0008 0.0013

Pb/ U

4.2502 1.3782 0.5418 10.7670 1.5523 0.7350 0.7162 10.5523 1.5806 4.4832 0.5623 1.4842 0.5576 0.8403 11.3705 2.8635 1.1592 0.5643 0.5385 4.5754 1.5547 0.6743 7.7941 10.7416 1.3221 1.5852 1.8865 0.5285 0.6749 4.0901 0.5324 4.0179 2.0417 0.5705 1.8921 1.1060 6.6723 10.7590 1.5207 1.5778 3.5948 4.6813 1.6884 1.2013 9.8884 1.8635 1.7825 10.2280 11.1476 5.3568 2.1886 5.8675 0.6213 1.1663 1.6085 10.8964 0.5805 2.5623 2.0564 1.5205 1.6726 1.6795 1.6780 1.6306 1.5924 9.8655 2.8151 0.5493 1.5708 1.8231 5.4910

1σ

206 238

0.0382 0.0130 0.0062 0.1051 0.0159 0.0063 0.0102 0.0757 0.0146 0.0430 0.0063 0.0181 0.0067 0.0087 0.1122 0.0275 0.0138 0.0084 0.0083 0.0446 0.0172 0.0090 0.0589 0.0977 0.0144 0.0166 0.0210 0.0069 0.0057 0.0346 0.0060 0.0532 0.0224 0.0100 0.0202 0.0190 0.0586 0.1120 0.0142 0.0166 0.0290 0.0436 0.0234 0.0177 0.1977 0.0225 0.0258 0.1220 0.1187 0.0613 0.0395 0.0631 0.0131 0.0164 0.0180 0.1084 0.0086 0.0347 0.0251 0.0217 0.0213 0.0236 0.0317 0.0231 0.0175 0.1159 0.0455 0.0100 0.0197 0.0215 0.0572

Pb/ U

0.2993 0.1461 0.0704 0.4724 0.1596 0.0912 0.0887 0.4691 0.1608 0.2983 0.0733 0.1573 0.0687 0.1009 0.4869 0.2350 0.1287 0.0734 0.0702 0.3113 0.1635 0.0846 0.3683 0.4812 0.1440 0.1464 0.1835 0.0709 0.0868 0.2945 0.0709 0.2997 0.1943 0.0720 0.1844 0.1246 0.3802 0.4624 0.1571 0.1634 0.2641 0.3129 0.1668 0.1326 0.4494 0.1797 0.1724 0.4606 0.4916 0.3412 0.2022 0.3452 0.0815 0.1315 0.1668 0.4857 0.0771 0.2238 0.1881 0.1585 0.1609 0.1664 0.1670 0.1667 0.1615 0.4465 0.2343 0.0714 0.1587 0.1679 0.3373

1σ

207 206

0.0016 0.0007 0.0004 0.0025 0.0009 0.0004 0.0006 0.0020 0.0008 0.0021 0.0004 0.0014 0.0004 0.0005 0.0033 0.0012 0.0007 0.0005 0.0004 0.0017 0.0009 0.0004 0.0015 0.0026 0.0009 0.0008 0.0010 0.0004 0.0004 0.0016 0.0004 0.0020 0.0012 0.0005 0.0011 0.0015 0.0021 0.0028 0.0008 0.0008 0.0011 0.0018 0.0010 0.0008 0.0056 0.0011 0.0012 0.0028 0.0029 0.0022 0.0015 0.0020 0.0007 0.0009 0.0009 0.0027 0.0006 0.0015 0.0012 0.0011 0.0010 0.0011 0.0015 0.0011 0.0009 0.0029 0.0020 0.0005 0.0009 0.0012 0.0018

Pb/ Pb

1678 872 435 2502 1000 532 550 2476 954 1772 433 863 550 606 2535 1377 776 439 433 1729 887 522 2376 2469 815 1146 1055 369 454 1629 376 1561 1084 502 1040 724 2050 2535 924 917 1591 1765 1033 794 2477 1065 1057 2458 2487 1840 1167 1987 413 733 906 2465 372 1255 1161 898 1059 998 998 939 950 2437 1339 428 967 1139 1906

1σ

Best age estimate 207 235

16 21 28 17 17 16 36 12 14 18 26 19 32 22 13 19 225 35 35 12 22 30 13 15 20 19 24 64 21 21 58 25 20 41 20 21 15 16 19 21 15 19 29 36 36 23 30 21 19 19 37 19 48 31 22 17 31 28 20 31 28 30 36 31 22 20 31 47 26 22 19

Pb/ U

1684 880 440 2503 951 559 548 2485 963 1728 453 924 450 619 2554 1372 782 454 437 1745 952 523 2208 2501 855 964 1076 431 524 1652 433 1638 1130 458 1078 756 2069 2503 939 962 1548 1764 1004 801 2424 1068 1039 2456 2536 1878 1177 1956 491 785 974 2514 465 1290 1134 939 998 1001 1000 982 967 2422 1360 445 959 1054 1899

1σ

206 238

7 6 4 9 6 4 6 7 6 8 4 7 4 5 9 7 6 5 5 8 7 5 7 8 6 7 7 5 3 7 4 11 7 6 7 9 8 10 6 7 6 8 9 8 18 8 9 11 10 10 13 9 8 8 7 9 6 10 8 9 8 9 12 9 7 11 12 7 8 8 9

Pb/ U

1688 879 439 2494 955 563 548 2480 961 1683 456 942 428 620 2557 1361 780 456 437 1747 976 523 2022 2533 867 881 1086 442 537 1664 441 1690 1145 448 1091 757 2077 2450 941 976 1511 1755 994 802 2393 1066 1025 2442 2578 1892 1187 1912 505 797 994 2552 479 1302 1111 948 962 992 996 994 965 2380 1357 445 949 1001 1874

1σ Age 8 4 2 11 5 3 3 9 4 10 3 8 2 3 15 6 4 3 3 8 5 3 7 11 5 4 5 2 3 8 2 10 6 3 6 9 10 13 5 5 6 9 6 5 25 6 7 13 12 11 8 10 4 5 5 12 3 8 6 6 5 6 8 6 5 13 11 3 5 7 9

1678 879 439 2502 955 563 548 2476 961 1772 456 942 428 620 2535 1377 780 456 437 1729 976 523 2376 2469 867 881 1055 442 537 1629 441 1561 1084 448 1040 757 2050 2535 941 976 1591 1765 994 802 2477 1065 1057 2458 2487 1840 1167 1987 505 797 994 2465 479 1255 1161 948 962 992 996 994 965 2437 1339 445 949 1139 1906

Disc (%)

1σ 16 0.6 4 −0.1 2 −0.2 17 −0.3 5 0.4 3 0.6 3 −0.1 12 0.1 4 −0.1 18 −5.3 3 0.7 8 1.9 2 −5.1 3 0.1 13 0.9 19 −1.2 4 −0.2 3 0.5 3 −0.1 12 1.0 5 2.4 3 0.0 13 −17.5 15 2.5 5 1.3 4 −9.5 24 2.8 2 2.4 3 2.4 21 2.1 2 1.8 25 7.6 20 5.3 3 −2.3 20 4.7 9 0.1 15 1.3 16 −3.5 5 0.2 5 1.5 15 −5.3 19 −0.6 6 −1.0 5 0.2 36 −3.5 23 0.1 30 −3.2 21 −0.6 19 3.5 19 2.7 37 1.7 19 −3.9 4 2.9 5 1.5 5 2.1 17 3.4 3 2.9 28 3.6 20 −4.5 6 1.0 5 −3.8 6 −0.8 8 −0.5 6 1.2 5 −0.2 20 −2.4 31 1.3 3 0.0 5 −1.0 22 −13.8 19 −1.8

(continued on next page)

86

B.-Q. Wang et al. / Sedimentary Geology 289 (2013) 74–98

Table 1 (continued) Spot no.

Th (ppm)

U Th/U (ppm)

Isotopic ratios 207 206

Pb/ Pb

1σ

Isotopic age (Ma) 207 235

Pb/ U

1σ

206 238

Pb/ U

1σ

207 206

Pb/ Pb

GB185: Lanashan Formation in Changtai region, Upper Triassic (2032N 31° 15.069'15, E 99° 46.694′')′, N = 916/101 GB185-109 110 127 0.87 0.0574 0.0015 0.5777 0.0149 0.0735 0.0007 509 GB185-110 412 594 0.69 0.1814 0.0019 12.4481 0.1368 0.4915 0.0030 2666 GB185-111 300 567 0.53 0.0709 0.0009 1.6329 0.0215 0.1653 0.0011 954 GB185-112 321 957 0.34 0.0807 0.0010 2.2852 0.0352 0.2019 0.0017 1215 BQ156: Qugasi Formation in Shangri-La region, Upper Triassic (N 28° 06.839′, E 99° 53.546′), N = 87/102 BQ156-01 210 319 0.66 0.0673 0.0018 1.1752 0.0303 0.1267 0.0011 848 BQ156-02 278 585 0.47 0.1629 0.0011 10.5585 0.0773 0.4690 0.0019 2487 BQ156-03 353 498 0.71 0.0831 0.0011 2.2763 0.0308 0.1983 0.0011 1272 BQ156-04 971 2063 0.47 0.3037 0.0034 27.6277 0.4225 0.6560 0.0050 3500 BQ156-05 891 1153 0.77 0.0673 0.0011 0.5593 0.0095 0.0602 0.0003 856 BQ156-06 186 540 0.34 0.0727 0.0008 1.5378 0.0170 0.1533 0.0008 1006 BQ156-07 291 438 0.66 0.0675 0.0018 0.7063 0.0192 0.0761 0.0007 854 BQ156-08 209 389 0.54 0.0774 0.0012 1.6190 0.0229 0.1522 0.0011 1131 BQ156-09 409 714 0.57 0.0610 0.0015 0.5916 0.0153 0.0701 0.0005 643 BQ156-10 838 1334 0.63 0.0605 0.0009 0.5815 0.0088 0.0695 0.0004 620 BQ156-11 151 169 0.89 0.1510 0.0013 8.4116 0.0833 0.4037 0.0030 2358 BQ156-12 307 225 1.36 0.1175 0.0012 5.4011 0.0592 0.3326 0.0017 1920 BQ156-13 258 496 0.52 0.0629 0.0017 0.6006 0.0161 0.0694 0.0007 706 BQ156-14 192 390 0.49 0.0747 0.0010 1.7271 0.0232 0.1675 0.0010 1061 BQ156-15 263 325 0.81 0.1661 0.0017 10.2536 0.1180 0.4469 0.0032 2520 BQ156-16 1416 2215 0.64 0.0684 0.0005 1.4164 0.0118 0.1498 0.0006 883 BQ156-17 169 464 0.36 0.0690 0.0009 1.3985 0.0192 0.1470 0.0011 898 BQ156-18 215 2020 0.11 0.0701 0.0008 1.1400 0.0153 0.1176 0.0006 931 BQ156-19 682 1097 0.62 0.0570 0.0008 0.5881 0.0079 0.0749 0.0005 500 BQ156-20 102 131 0.78 0.1427 0.0018 7.4524 0.1139 0.3782 0.0039 2261 BQ156-21 357 185 1.93 0.0958 0.0018 3.4716 0.0610 0.2633 0.0028 1544 BQ156-22 379 592 0.64 0.0767 0.0007 1.9576 0.0207 0.1846 0.0009 1122 BQ156-23 561 767 0.73 0.0649 0.0014 0.6656 0.0165 0.0739 0.0006 772 BQ156-24 1608 3180 0.51 0.0554 0.0004 0.5135 0.0045 0.0671 0.0003 428 BQ156-25 464 1486 0.31 0.1724 0.0005 10.7181 0.0440 0.4499 0.0015 2581 BQ156-26 73 88 0.84 0.1817 0.0050 11.3090 0.4194 0.4555 0.0143 2669 BQ156-27 271 466 0.58 0.0609 0.0015 0.5929 0.0146 0.0708 0.0006 635 BQ156-28 260 373 0.70 0.0641 0.0021 0.6777 0.0226 0.0768 0.0011 746 BQ156-29 414 716 0.58 0.0566 0.0011 0.5685 0.0115 0.0728 0.0004 472 BQ156-30 235 391 0.60 0.0862 0.0015 2.0981 0.0420 0.1760 0.0019 1344 BQ156-31 308 286 1.08 0.1683 0.0019 11.1842 0.1506 0.4813 0.0039 2540 BQ156-32 535 1238 0.43 0.0653 0.0009 0.7574 0.0124 0.0839 0.0006 783 BQ156-33 227 345 0.66 0.0724 0.0012 1.5092 0.0248 0.1513 0.0011 998 BQ156-34 545 938 0.58 0.0576 0.0008 0.5958 0.0087 0.0750 0.0005 522 BQ156-35 448 306 1.46 0.0603 0.0014 0.7347 0.0169 0.0886 0.0009 617 BQ156-36 239 263 0.91 0.0837 0.0022 2.2483 0.0684 0.1942 0.0028 1287 BQ156-37 136 117 1.16 0.0736 0.0021 1.6989 0.0506 0.1677 0.0023 1031 BQ156-38 362 476 0.76 0.0597 0.0019 0.6024 0.0143 0.0739 0.0005 594 BQ156-39 442 3494 0.13 0.1553 0.0003 9.2728 0.0284 0.4325 0.0011 2405 BQ156-40 146 102 1.43 0.1556 0.0033 9.5254 0.1908 0.4522 0.0081 2409 BQ156-41 64 85 0.75 0.0684 0.0042 1.2846 0.0814 0.1357 0.0027 881 BQ156-42 483 288 1.68 0.0611 0.0018 0.7496 0.0217 0.0893 0.0008 643 BQ156-43 267 383 0.70 0.0761 0.0012 1.7988 0.0293 0.1717 0.0013 1098 BQ156-44 723 1230 0.59 0.1083 0.0010 4.4126 0.0444 0.2952 0.0019 1772 BQ156-45 391 321 1.22 0.1189 0.0016 4.9496 0.0650 0.3018 0.0021 1940 BQ156-46 598 457 1.31 0.0771 0.0016 1.5505 0.0340 0.1460 0.0017 1124 BQ156-47 87 149 0.59 0.1370 0.0026 6.5347 0.1790 0.3451 0.0068 2190 BQ156-48 126 178 0.71 0.1158 0.0013 5.3759 0.0830 0.3356 0.0025 1892 BQ156-49 393 684 0.58 0.0773 0.0007 2.2607 0.0300 0.2115 0.0010 1128 BQ156-50 125 266 0.47 0.1404 0.0010 8.2390 0.1087 0.4241 0.0021 2232 BQ156-51 191 317 0.60 0.0619 0.0012 0.9602 0.0191 0.1132 0.0010 733 BQ156-52 264 298 0.89 0.1918 0.0009 14.5295 0.1455 0.5475 0.0024 2757 BQ156-53 122 330 0.37 0.0753 0.0016 1.0817 0.0223 0.1047 0.0010 1077 BQ156-54 90 140 0.64 0.1539 0.0014 9.2511 0.1000 0.4358 0.0033 2391 BQ156-55 416 444 0.94 0.0566 0.0014 0.5780 0.0141 0.0741 0.0005 476 BQ156-56 204 130 1.57 0.0747 0.0024 1.4032 0.0468 0.1363 0.0013 1059 BQ156-57 748 471 1.59 0.0677 0.0011 1.2067 0.0215 0.1289 0.0009 861 BQ156-58 447 2200 0.20 0.1480 0.0012 7.5883 0.0740 0.3706 0.0023 2324 BQ156-59 184 382 0.48 0.0748 0.0025 1.2269 0.0425 0.1196 0.0020 1061 BQ156-60 394 606 0.65 0.0839 0.0030 2.0259 0.0803 0.1744 0.0023 1300 BQ156-61 147 199 0.74 0.1116 0.0015 4.7191 0.0633 0.3066 0.0022 1825 BQ156-62 665 707 0.94 0.0607 0.0012 0.7811 0.0159 0.0932 0.0006 628 BQ156-63 451 478 0.94 0.0884 0.0010 2.7743 0.0424 0.2271 0.0023 1391 BQ156-64 506 305 1.66 0.1143 0.0021 4.9295 0.1135 0.3116 0.0037 1869 BQ156-65 298 251 1.19 0.0794 0.0010 2.1752 0.0276 0.1988 0.0011 1183

1σ

Best age estimate 207 235

Pb/ U

55 463 16 2639 31 983 24 1208

56 11 20 17 33 22 57 30 54 33 15 19 53 26 17 17 28 24 30 21 40 19 46 23 5 46 49 70 43 33 19 30 33 30 50 53 64 69 4 36 127 65 31 17 24 43 33 25 19 12 41 8 44 15 54 66 31 15 69 70 19 44 22 34 20

789 2485 1205 3406 451 946 543 978 472 465 2276 1885 478 1019 2458 896 888 773 470 2167 1521 1101 518 421 2499 2549 473 525 457 1148 2539 572 934 475 559 1196 1008 479 2365 2390 839 568 1045 1715 1811 951 2051 1881 1200 2258 683 2785 744 2363 463 890 804 2183 813 1124 1771 586 1349 1807 1173

1σ

206 238

Pb/ U

1σ Age

Disc (%)

1σ

10 10 8 11

457 2577 986 1186

4 13 6 9

457 2666 986 1215

4 16 6 24

−1.3 −3.4 0.3 −2.4

14 7 10 15 6 7 11 9 10 6 9 9 10 9 11 5 8 7 5 14 14 7 10 3 4 35 9 14 7 14 13 7 10 6 10 21 19 9 3 18 36 13 11 8 11 14 24 13 9 12 10 10 11 10 9 20 10 9 19 27 11 9 11 19 9

769 2479 1166 3252 377 920 473 913 436 433 2186 1851 432 998 2381 900 884 717 466 2068 1507 1092 460 419 2395 2420 441 477 453 1045 2533 519 908 466 547 1144 1000 459 2317 2405 820 552 1022 1668 1700 879 1911 1865 1237 2279 691 2815 642 2332 461 824 781 2032 728 1036 1724 575 1319 1749 1169

6 8 6 19 2 4 4 6 3 2 14 8 4 5 14 3 6 3 3 18 14 5 4 2 7 63 4 6 3 10 17 3 6 3 5 15 13 3 5 36 16 5 7 9 10 10 33 12 5 10 6 10 6 15 3 7 5 11 12 13 11 4 12 18 6

769 2487 1272 3500 377 920 473 913 436 433 2358 1920 432 998 2520 900 884 717 466 2261 1544 1122 460 419 2581 2669 441 477 453 1344 2540 519 908 466 547 1287 1000 459 2405 2409 820 552 1098 1772 1940 879 2190 1892 1128 2232 691 2757 642 2391 461 824 781 2324 728 1300 1825 575 1391 1869 1183

6 11 20 17 2 4 4 6 3 2 15 19 4 5 17 3 6 3 3 21 40 19 4 2 5 46 4 6 3 33 19 3 6 3 5 53 13 3 4 36 16 5 31 17 24 10 33 25 19 12 6 8 6 15 3 7 5 15 12 70 19 4 22 34 20

−2.6 −0.3 −9.1 −7.6 −19.7 −2.8 −14.8 −7.1 −8.1 −7.4 −7.8 −3.8 −10.5 −2.0 −5.8 0.4 −0.4 −7.8 −0.9 −9.4 −2.4 −2.8 −12.7 −0.5 −7.8 −10.3 −7.2 −10.1 −1.0 −28.5 −0.3 −10.2 −2.8 −1.8 −2.2 −12.5 −0.8 −4.2 −3.8 −0.2 −2.3 −3.0 −7.5 −6.3 −14.1 −8.2 −14.6 −1.4 8.8 2.0 1.1 2.0 −15.9 −2.5 −0.6 −8.1 −2.9 −14.4 −11.7 −25.5 −5.9 −2.0 −5.4 −6.9 −1.2

B.-Q. Wang et al. / Sedimentary Geology 289 (2013) 74–98

87

Table 1 (continued) Spot no.

Th (ppm)

U Th/U (ppm)

Isotopic ratios 207 206

Pb/ Pb

1σ

Isotopic age (Ma) 207 235

Pb/ U

1σ

206 238

Pb/ U

1σ

207 206

Pb/ Pb

1σ

Best age estimate 207 235

Pb/ U

1σ

206 238

Pb/ U

1σ Age

Disc (%)

1σ

1065 656 576 1237 1432 598 476 972 1011 2587 848 2492 1031 435 2481 1133 928 456 828 831 1288 607 967 1998 976 2489 1159 2072 1017 1850 2258 2294 1856 1106 969 2463 972

31 44 55 20 43 52 47 26 18 10 28 9 23 28 11 18 22 14 31 66 33 23 30 20 21 17 25 18 34 52 17 17 17 22 24 16 40

935 480 483 1230 1358 587 446 980 989 2523 856 2467 938 412 2428 979 874 416 776 708 1254 421 964 1936 977 2465 1144 2023 998 1861 2171 2281 1833 1017 959 2456 936

9 9 8 9 17 10 8 8 6 6 8 5 8 4 7 5 6 7 8 14 12 4 9 10 6 9 8 9 9 9 8 9 8 7 7 9 12

879 445 466 1225 1310 588 442 980 977 2434 858 2424 900 406 2353 933 849 410 753 676 1232 385 958 1864 968 2416 1128 1958 982 1858 2065 2253 1808 969 948 2431 921

5 3 3 8 12 5 4 6 4 8 5 8 5 2 11 4 4 3 4 6 9 3 6 10 5 11 6 9 6 10 9 12 8 5 5 11 6

879 445 466 1237 1432 588 442 980 977 2587 858 2492 900 406 2481 933 849 410 753 676 1288 385 958 1998 968 2489 1159 2072 982 1850 2258 2294 1856 969 948 2463 921

5 3 3 20 43 5 4 6 4 10 5 9 5 2 11 4 4 3 4 6 33 3 6 20 5 17 25 18 6 52 17 17 17 5 5 16 6

−6.3 −7.9 −3.7 −0.9 −9.3 0.2 −1.0 0.0 −1.2 −6.3 0.2 −2.8 −4.3 −1.4 −5.5 −5.0 −3.0 −1.4 −3.1 −4.7 −4.5 −9.6 −0.6 −7.2 −0.9 −3.0 −2.7 −5.9 −1.6 0.4 −9.3 −1.8 −2.6 −4.9 −1.2 −1.3 −1.7

BQ23: Tumugou Formation in Shangri-La region, Upper Triassic (N 28° 08.934′, E 99° 54.246′), N = 82/94 BQ23-01 227 316 0.72 0.1060 0.0015 4.9571 0.0669 0.3395 0.0040 1732 BQ23-02 119 231 0.51 0.0556 0.0022 0.5163 0.0197 0.0674 0.0009 437 BQ23-03 95 380 0.25 0.1102 0.0012 4.8966 0.0508 0.3227 0.0035 1802 BQ23-04 533 942 0.57 0.0522 0.0014 0.3265 0.0086 0.0454 0.0006 294 BQ23-05 184 619 0.30 0.0722 0.0010 1.6313 0.0204 0.1641 0.0018 990 BQ23-06 273 242 1.13 0.0524 0.0038 0.3479 0.0246 0.0482 0.0008 302 BQ23-07 86 148 0.58 0.0863 0.0017 2.7603 0.0517 0.2321 0.0030 1346 BQ23-08 145 230 0.63 0.0739 0.0050 0.4604 0.0294 0.0452 0.0012 1040 BQ23-09 200 437 0.46 0.0524 0.0024 0.3441 0.0152 0.0477 0.0007 302 BQ23-10 102 156 0.65 0.0626 0.0030 0.9806 0.0450 0.1137 0.0022 695 BQ23-11 306 206 1.49 0.0536 0.0021 0.4302 0.0166 0.0582 0.0009 354 BQ23-12 144 166 0.87 0.1253 0.0020 6.4056 0.0990 0.3711 0.0048 2032 BQ23-13 335 632 0.53 0.1122 0.0010 5.0862 0.0444 0.3290 0.0034 1835 BQ23-14 135 128 1.05 0.1481 0.0017 8.8806 0.0947 0.4350 0.0049 2324 BQ23-15 110 126 0.88 0.0831 0.0023 2.4726 0.0654 0.2158 0.0032 1272 BQ23-16 1284 2266 0.57 0.0631 0.0009 0.4719 0.0061 0.0542 0.0006 712 BQ23-17 106 475 0.22 0.1081 0.0012 4.7066 0.0494 0.3158 0.0034 1768 BQ23-18 94 78 1.20 0.0716 0.0046 1.4427 0.0884 0.1463 0.0038 973 BQ23-19 266 412 0.65 0.0558 0.0014 0.5347 0.0130 0.0695 0.0008 444 BQ23-20 198 233 0.85 0.1577 0.0023 8.4356 0.1140 0.3880 0.0049 2431 BQ23-21 267 622 0.43 0.0550 0.0014 0.5088 0.0126 0.0671 0.0008 412 BQ23-22 367 280 1.31 0.0599 0.0053 0.4116 0.0348 0.0498 0.0015 601 BQ23-23 116 51 2.30 0.0802 0.0064 1.3535 0.1031 0.1224 0.0038 1202 BQ23-24 167 172 0.97 0.0676 0.0027 1.3317 0.0506 0.1429 0.0025 856 BQ23-26 499 222 2.25 0.0522 0.0032 0.2929 0.0172 0.0407 0.0008 294 BQ23-27 301 504 0.60 0.0666 0.0016 1.0516 0.0232 0.1146 0.0015 824 BQ23-28 918 1449 0.63 0.0806 0.0011 2.2355 0.0287 0.2012 0.0022 1211 BQ23-29 126 243 0.52 0.0621 0.0018 1.0908 0.0300 0.1274 0.0018 677 BQ23-32 204 258 0.79 0.0653 0.0013 1.1883 0.0227 0.1320 0.0015 783 BQ23-33 357 709 0.50 0.0525 0.0013 0.4770 0.0115 0.0659 0.0008 306 BQ23-34 283 297 0.95 0.1259 0.0018 6.3999 0.0883 0.3687 0.0045 2041 BQ23-35 295 258 1.14 0.0536 0.0028 0.5425 0.0267 0.0734 0.0014 354 BQ23-36 724 342 2.12 0.0652 0.0025 0.9925 0.0360 0.1104 0.0018 780

26 85 20 62 27 156 38 131 100 99 88 29 17 19 53 29 20 126 55 24 56 182 150 81 133 48 26 60 42 56 26 111 78

1812 423 1802 287 982 303 1345 385 300 694 363 2033 1834 2326 1264 393 1768 907 435 2279 418 350 869 860 261 730 1192 749 795 396 2032 440 700

11 13 9 7 8 19 14 20 11 23 12 14 7 10 19 4 9 37 9 12 9 25 44 22 14 11 9 15 11 8 12 18 18

1884 420 1803 286 980 304 1345 285 300 694 365 2035 1834 2328 1260 341 1769 880 433 2114 419 313 745 861 257 699 1182 773 799 412 2024 457 675

19 6 17 4 10 5 15 7 4 13 5 23 16 22 17 3 17 21 5 23 5 9 22 14 5 8 12 10 9 5 21 8 11

1732 420 1802 286 980 304 1346 285 300 694 365 2032 1835 2324 1272 341 1768 880 433 2431 419 313 745 861 257 699 1211 773 799 412 2041 457 675

26 6 20 4 10 5 38 7 4 13 5 29 17 19 53 3 20 21 5 24 5 9 22 14 5 8 26 10 9 5 26 8 11

8.1 −0.5 0.1 −0.2 −0.3 0.1 0.0 −35.0 0.0 0.0 0.4 0.1 −0.1 0.2 −1.0 −15.3 0.1 −3.0 −0.4 −15.0 0.3 −11.7 −16.7 0.2 −1.4 −4.3 −2.5 3.1 0.5 3.8 −0.9 3.6 −3.7

BQ156-66 217 BQ156-67 670 BQ156-68 264 BQ156-69 872 BQ156-70 229 BQ156-71 163 BQ156-72 54 BQ156-73 362 BQ156-74 466 BQ156-75 443 BQ156-76 191 BQ156-77 209 BQ156-78 111 BQ156-79 228 BQ156-80 119 BQ156-81 105 BQ156-82 127 BQ156-83 198 BQ156-84 126 BQ156-85 46 BQ156-86 51 BQ156-87 1543 BQ156-88 157 BQ156-89 45 BQ156-90 91 BQ156-91 148 BQ156-92 277 BQ156-93 669 BQ156-94 142 BQ156-95 300 BQ156-97 238 BQ156-98 174 BQ156-99 147 BQ156-100 215 BQ156-101 179 BQ156-102 527 BQ156-103 25

767 711 464 770 312 107 131 175 575 819 155 336 114 436 117 427 211 179 152 50 78 1822 190 123 615 198 228 1168 300 626 369 162 445 560 355 527 96

0.28 0.94 0.57 1.13 0.74 1.52 0.41 2.07 0.81 0.54 1.23 0.62 0.98 0.52 1.01 0.25 0.60 1.10 0.83 0.92 0.65 0.85 0.83 0.37 0.15 0.75 1.21 0.57 0.47 0.48 0.64 1.07 0.33 0.38 0.50 1.00 0.25

0.0749 0.0612 0.0592 0.0816 0.0903 0.0598 0.0566 0.0715 0.0726 0.1729 0.0673 0.1635 0.0736 0.0556 0.1624 0.0750 0.0700 0.0559 0.0667 0.0668 0.0838 0.0601 0.0710 0.1228 0.0717 0.1632 0.0785 0.1280 0.0731 0.1130 0.1425 0.1455 0.1129 0.0764 0.0714 0.1607 0.0715

0.0010 0.0013 0.0013 0.0009 0.0020 0.0014 0.0014 0.0009 0.0006 0.0010 0.0009 0.0008 0.0010 0.0007 0.0011 0.0006 0.0008 0.0012 0.0010 0.0020 0.0014 0.0007 0.0010 0.0014 0.0007 0.0016 0.0010 0.0013 0.0011 0.0012 0.0014 0.0015 0.0010 0.0008 0.0008 0.0015 0.0014

1.5119 0.6045 0.6096 2.3593 2.8089 0.7828 0.5518 1.6247 1.6481 11.0016 1.3234 10.3575 1.5184 0.4997 9.9297 1.6222 1.3661 0.5058 1.1482 1.0082 2.4389 0.5145 1.5844 5.7306 1.6167 10.3315 2.0856 6.3322 1.6718 5.2535 7.4803 8.4534 5.0819 1.7213 1.5708 10.2284 1.5141

0.0216 0.0137 0.0128 0.0281 0.0622 0.0179 0.0130 0.0213 0.0148 0.0668 0.0172 0.0577 0.0211 0.0061 0.0705 0.0142 0.0151 0.0102 0.0170 0.0279 0.0390 0.0062 0.0229 0.0631 0.0158 0.0985 0.0258 0.0621 0.0235 0.0566 0.0705 0.0853 0.0471 0.0184 0.0186 0.0961 0.0288

0.1462 0.0714 0.0750 0.2093 0.2254 0.0956 0.0709 0.1642 0.1637 0.4588 0.1423 0.4565 0.1498 0.0650 0.4405 0.1557 0.1408 0.0656 0.1239 0.1106 0.2106 0.0615 0.1603 0.3354 0.1621 0.4547 0.1913 0.3548 0.1646 0.3340 0.3776 0.4183 0.3237 0.1623 0.1583 0.4581 0.1535

0.0008 0.0005 0.0005 0.0015 0.0023 0.0008 0.0006 0.0010 0.0008 0.0018 0.0008 0.0018 0.0009 0.0003 0.0024 0.0008 0.0007 0.0005 0.0008 0.0010 0.0017 0.0004 0.0011 0.0021 0.0009 0.0025 0.0012 0.0018 0.0011 0.0021 0.0020 0.0026 0.0017 0.0008 0.0010 0.0024 0.0011

(continued on next page)

88

B.-Q. Wang et al. / Sedimentary Geology 289 (2013) 74–98

Table 1 (continued) Spot no.

Th (ppm)

U Th/U (ppm)

Isotopic ratios 207 206

Pb/ Pb

1σ

Isotopic age (Ma) 207 235

Pb/ U

1σ

206 238

Pb/ U

1σ

207 206

Pb/ Pb

BQ23: Tumugou Formation in Shangri-La region, Upper Triassic (N 28° 08.934'′2032, E 99° 54.246′'), N = 82/94 BQ23-37 324 425 0.76 0.0497 0.0026 0.2560 0.0128 0.0374 0.0007 181 BQ23-38 157 177 0.89 0.0595 0.0025 0.8136 0.0325 0.0991 0.0016 587 BQ23-39 590 372 1.59 0.0530 0.0045 0.2789 0.0227 0.0381 0.0011 330 BQ23-40 228 999 0.23 0.0711 0.0007 1.5368 0.0141 0.1567 0.0015 961 BQ23-41 301 546 0.55 0.1087 0.0015 4.6321 0.0604 0.3089 0.0035 1778 BQ23-42 429 750 0.57 0.0542 0.0032 0.3654 0.0207 0.0488 0.0010 380 BQ23-43 75 360 0.21 0.1101 0.0012 4.8997 0.0509 0.3225 0.0034 1802 BQ23-44 79 1541 0.05 0.1493 0.0009 6.2292 0.0363 0.3026 0.0029 2337 BQ23-45 121 151 0.80 0.0713 0.0019 1.5961 0.0406 0.1623 0.0022 967 BQ23-46 264 394 0.67 0.0530 0.0023 0.3221 0.0133 0.0441 0.0007 327 BQ23-47 198 205 0.97 0.0608 0.0033 0.5239 0.0274 0.0625 0.0013 631 BQ23-48 166 755 0.22 0.1167 0.0008 5.5606 0.0344 0.3455 0.0033 1906 BQ23-49 73 456 0.16 0.0680 0.0011 1.3837 0.0202 0.1476 0.0016 867 BQ23-50 145 171 0.85 0.0995 0.0026 3.9333 0.0969 0.2865 0.0044 1615 BQ23-51 518 337 1.54 0.0668 0.0010 1.2638 0.0176 0.1373 0.0014 830 BQ23-52 139 695 0.20 0.0682 0.0010 1.3795 0.0187 0.1468 0.0015 873 BQ23-53 211 294 0.72 0.1319 0.0012 7.1034 0.0583 0.3905 0.0039 2123 BQ23-54 143 257 0.56 0.0556 0.0029 0.5335 0.0267 0.0695 0.0013 438 BQ23-55 101 151 0.67 0.0986 0.0025 3.7158 0.0889 0.2732 0.0041 1598 BQ23-56 180 197 0.91 0.0524 0.0040 0.3073 0.0228 0.0426 0.0010 301 BQ23-57 56 478 0.12 0.0827 0.0015 1.3025 0.0225 0.1141 0.0013 1263 BQ23-58 417 604 0.69 0.0567 0.0019 0.2776 0.0090 0.0355 0.0005 477 BQ23-59 104 90 1.16 0.1073 0.0023 4.7096 0.0964 0.3182 0.0045 1754 BQ23-60 92 148 0.62 0.0576 0.0035 0.5104 0.0294 0.0643 0.0013 513 BQ23-61 153 295 0.52 0.1898 0.0017 12.2357 0.1047 0.4673 0.0049 2741 BQ23-62 277 359 0.77 0.0667 0.0012 1.2299 0.0206 0.1337 0.0015 828 BQ23-63 103 378 0.27 0.1145 0.0009 5.3551 0.0404 0.3390 0.0033 1873 BQ23-64 123 668 0.18 0.0565 0.0009 0.5613 0.0088 0.0720 0.0008 473 BQ23-65 453 559 0.81 0.0574 0.0023 0.6082 0.0229 0.0769 0.0012 505 BQ23-66 363 483 0.75 0.1582 0.0012 9.4246 0.0695 0.4319 0.0042 2437 BQ23-67 218 262 0.83 0.0655 0.0015 1.0912 0.0237 0.1208 0.0015 790 BQ23-68 447 858 0.52 0.0497 0.0017 0.2464 0.0082 0.0359 0.0005 182 BQ23-69 237 290 0.82 0.1092 0.0014 4.8177 0.0603 0.3200 0.0035 1786 BQ23-70 154 789 0.19 0.0596 0.0018 0.5219 0.0151 0.0635 0.0009 590 BQ23-71 386 1003 0.38 0.0555 0.0007 0.5496 0.0072 0.0714 0.0005 435 BQ23-72 166 475 0.35 0.1126 0.0013 4.9096 0.0560 0.3143 0.0020 1843 BQ23-73 81 284 0.28 0.1142 0.0013 5.0320 0.0550 0.3182 0.0020 1933 BQ23-74 72 511 0.14 0.1514 0.0014 8.1405 0.0771 0.3876 0.0020 2361 BQ23-75 183 594 0.31 0.0580 0.0007 0.5997 0.0087 0.0746 0.0007 532 BQ23-76 182 161 1.13 0.0603 0.0013 0.5699 0.0124 0.0686 0.0005 613 BQ23-77 106 262 0.40 0.0557 0.0010 0.5245 0.0087 0.0682 0.0005 443 BQ23-80 294 499 0.59 0.0534 0.0009 0.3378 0.0066 0.0457 0.0005 346 BQ23-81 196 444 0.44 0.1111 0.0010 4.9013 0.0470 0.3182 0.0016 1817 BQ23-82 211 170 1.24 0.0645 0.0011 1.0526 0.0173 0.1187 0.0009 767 BQ23-83 220 819 0.27 0.1113 0.0010 5.0001 0.0493 0.3240 0.0018 1821 BQ23-84 426 859 0.50 0.0508 0.0008 0.2787 0.0041 0.0397 0.0002 232 BQ23-86 76 172 0.44 0.1066 0.0014 4.5787 0.0627 0.3103 0.0021 1742 BQ23-87 1711 1703 1.00 0.0668 0.0007 0.9339 0.0107 0.1009 0.0006 831 BQ23-88 133 505 0.26 0.0563 0.0008 0.5192 0.0078 0.0667 0.0005 465 BQ23-90 48 86 0.56 0.1081 0.0014 4.1037 0.0523 0.2745 0.0018 1769 BQ23-91 104 124 0.84 0.0589 0.0015 0.5481 0.0136 0.0679 0.0006 561 BQ23-92 563 1146 0.49 0.0531 0.0007 0.2804 0.0036 0.0381 0.0003 332 BQ23-94 112 446 0.25 0.1136 0.0012 5.0819 0.0532 0.3220 0.0019 1858 BQ23-95 58 175 0.33 0.0668 0.0010 1.3007 0.0200 0.1404 0.0010 831 BQ23-96 35 61 0.58 0.1069 0.0015 4.3805 0.0580 0.2968 0.0021 1747 BQ23-97 257 369 0.70 0.0524 0.0010 0.3501 0.0063 0.0484 0.0003 302 BQ23-98 200 503 0.40 0.1224 0.0011 5.7454 0.0508 0.3379 0.0016 1991 BQ23-99 109 1051 0.10 0.0662 0.0006 1.0642 0.0102 0.1158 0.0005 813 BQ23-100 96 379 0.25 0.1399 0.0013 6.9942 0.0686 0.3595 0.0018 2228 BQ23-101 263 779 0.34 0.0548 0.0007 0.5839 0.0072 0.0769 0.0004 406 BQ23-102 237 496 0.48 0.0560 0.0009 0.5216 0.0082 0.0673 0.0005 454 BQ114: Tumugou Formation in Shangri-La region, Upper Triassic (N 28° 09.163′, E 99° 54.214′), BQ114-01 104 674 0.15 0.1121 0.0009 5.0239 0.0443 0.3236 BQ114-02 103 396 0.26 0.1116 0.0008 5.0145 0.0373 0.3246 BQ114-03 158 200 0.79 0.0700 0.0007 1.4348 0.0146 0.1487 BQ114-04 283 731 0.39 0.1111 0.0008 4.1247 0.0335 0.2685 BQ114-05 364 1215 0.30 0.0556 0.0006 0.5090 0.0055 0.0662 BQ114-06 66 154 0.43 0.1178 0.0010 5.6707 0.0528 0.3484 BQ114-07 587 587 1.00 0.0513 0.0006 0.2926 0.0033 0.0413 BQ114-08 562 681 0.83 0.1104 0.0007 4.9734 0.0433 0.3254

N = 98/110 0.0019 1835 0.0015 1825 0.0009 929 0.0018 1817 0.0003 435 0.0022 1924 0.0002 254 0.0022 1806

1σ

Best age estimate 207 235

Pb/ U

1σ

206 238

Pb/ U

1σ Age

Disc (%)

1σ

117 88 182 20 25 128 20 11 54 95 114 12 32 48 30 29 15 113 46 166 36 74 39 127 15 36 14 36 85 13 47 79 24 65 28 21 20 16 32 48 6 37 12 36 17 33 25 23 33 24 56 32 19 33 25 43 16 20 16 28 42

231 605 250 945 1755 316 1802 2009 969 284 428 1910 882 1621 830 880 2125 434 1575 272 847 249 1769 419 2623 814 1878 452 482 2380 749 224 1788 426 445 1804 1825 2247 477 458 428 296 1802 730 1819 250 1745 670 425 1655 444 251 1833 846 1709 305 1938 736 2111 467 426

10 18 18 6 11 15 9 5 16 10 18 5 9 20 8 8 7 18 19 18 10 7 17 20 8 9 6 6 14 7 12 7 11 10 5 10 9 9 6 8 6 5 8 9 8 3 11 6 5 10 9 3 9 9 11 5 8 5 9 5 5

236 609 241 938 1735 307 1802 1704 969 278 391 1913 888 1624 829 883 2125 433 1557 269 697 225 1781 402 2472 809 1882 448 478 2314 735 228 1790 397 444 1762 1781 2112 464 427 425 288 1781 723 1809 251 1742 620 416 1563 424 241 1799 847 1675 305 1877 706 1980 478 420

4 10 7 9 17 6 17 14 12 4 8 16 9 22 8 9 18 8 21 6 8 3 22 8 21 8 16 5 7 19 8 3 17 5 3 10 10 9 4 3 3 3 8 5 9 1 11 3 3 9 4 2 9 5 10 2 8 3 9 3 3

236 609 241 938 1778 307 1802 2337 969 278 391 1906 888 1615 829 883 2123 433 1598 269 697 225 1754 402 2741 809 1873 448 478 2437 735 228 1786 397 444 1843 1933 2361 464 427 425 288 1817 723 1821 251 1742 620 416 1769 424 241 1858 847 1747 305 1991 706 2228 478 420

4 10 7 9 25 6 20 11 12 4 8 12 9 48 8 9 15 8 46 6 8 3 39 8 15 8 14 5 7 13 8 3 24 5 3 21 20 16 4 3 3 3 12 5 17 1 25 3 3 24 4 2 19 5 25 2 16 3 16 3 3

2.1 0.7 −3.6 −0.7 −2.5 −2.9 0.0 −37.2 0.1 −1.9 −9.4 0.4 0.6 0.5 0.0 0.3 0.1 −0.2 −2.6 −1.3 −21.5 −10.5 1.5 −4.3 −10.9 −0.7 0.5 −1.0 −1.0 −5.3 −1.9 1.7 0.2 −7.5 −0.1 −4.6 −8.6 −11.8 −2.8 −7.1 −0.6 −2.6 −2.0 −1.0 −0.7 0.6 0.0 −8.1 −2.1 −13.1 −4.8 −4.0 −3.2 0.1 −4.3 −0.1 −6.1 −4.2 −12.5 2.3 −1.5

14 13 21 12 26 15 24 11

1823 1822 904 1659 418 1927 261 1815

7 6 6 7 4 8 3 7

1807 1812 894 1533 413 1927 261 1816

9 7 5 9 2 11 1 11

1835 1825 894 1817 413 1924 261 1806

14 −1.6 13 −0.7 5 −1.1 12 −18.5 2 −1.1 15 0.2 1 0.0 11 0.6

B.-Q. Wang et al. / Sedimentary Geology 289 (2013) 74–98

89

Table 1 (continued) Spot no.

Th (ppm)

U Th/U (ppm)

Isotopic ratios 207 206

BQ114-09 BQ114-10 BQ114-11 BQ114-12 BQ114-14 BQ114-15 BQ114-16 BQ114-17 BQ114-18 BQ114-19 BQ114-20 BQ114-21 BQ114-22 BQ114-23 BQ114-24 BQ114-25 BQ114-26 BQ114-27 BQ114-28 BQ114-29 BQ114-30 BQ114-31 BQ114-32 BQ114-33 BQ114-34 BQ114-35 BQ114-36 BQ114-37 BQ114-38 BQ114-39 BQ114-41 BQ114-42 BQ114-43 BQ114-44 BQ114-46 BQ114-47 BQ114-48 BQ114-49 BQ114-50 BQ114-51 BQ114-52 BQ114-53 BQ114-54 BQ114-55 BQ114-56 BQ114-57 BQ114-58 BQ114-60 BQ114-61 BQ114-62 BQ114-63 BQ114-64 BQ114-65 BQ114-66 BQ114-67 BQ114-68 BQ114-69 BQ114-70 BQ114-71 BQ114-72 BQ114-73 BQ114-74 BQ114-75 BQ114-76 BQ114-77 BQ114-78 BQ114-79 BQ114-80 BQ114-81 BQ114-82 BQ114-83 BQ114-84

294 159 50 149 384 106 115 400 36 98 864 159 95 76 191 155 199 110 176 80 314 251 155 130 72 1162 834 98 23 70 53 221 163 189 195 99 18 378 312 802 430 448 336 146 562 48 118 379 370 138 272 545 95 67 135 242 119 138 169 71 252 216 578 183 182 51 49 103 218 175 47 216

874 142 65 183 598 804 84 167 265 628 928 272 159 824 776 185 474 425 403 139 479 592 268 424 64 617 2232 215 1099 148 95 470 328 304 358 158 35 520 338 1791 739 745 468 176 1371 111 368 816 1309 436 693 368 474 141 446 641 137 464 1001 738 518 341 648 632 282 84 77 116 127 242 75 306

0.34 1.12 0.76 0.82 0.64 0.13 1.37 2.39 0.14 0.16 0.93 0.58 0.60 0.09 0.25 0.84 0.42 0.26 0.44 0.58 0.65 0.42 0.58 0.31 1.12 1.88 0.37 0.45 0.02 0.47 0.56 0.47 0.50 0.62 0.54 0.63 0.51 0.73 0.92 0.45 0.58 0.60 0.72 0.83 0.41 0.44 0.32 0.46 0.28 0.32 0.39 1.48 0.20 0.48 0.30 0.38 0.87 0.30 0.17 0.10 0.49 0.63 0.89 0.29 0.64 0.61 0.63 0.89 1.71 0.72 0.62 0.71

Pb/ Pb

0.1108 0.0654 0.1073 0.1123 0.0707 0.1134 0.0584 0.0637 0.1100 0.1133 0.1138 0.1189 0.1218 0.1169 0.1125 0.1592 0.0578 0.1112 0.0628 0.0671 0.1630 0.0877 0.1102 0.1097 0.0733 0.1094 0.0588 0.0547 0.0685 0.1111 0.0727 0.1111 0.1570 0.0636 0.1133 0.0629 0.1115 0.1565 0.0650 0.1390 0.0721 0.0597 0.0659 0.1045 0.0540 0.0784 0.1721 0.0515 0.1116 0.1111 0.0941 0.0546 0.1127 0.0666 0.1560 0.1118 0.0665 0.1139 0.0684 0.1211 0.1113 0.0622 0.0544 0.0641 0.0712 0.1061 0.0669 0.0667 0.1563 0.0522 0.0632 0.1519

1σ

Isotopic age (Ma) 207 235

Pb/ U

0.0007 4.6702 0.0008 1.1688 0.0011 4.5902 0.0010 5.1354 0.0007 1.1192 0.0007 5.2981 0.0011 0.6894 0.0008 0.8637 0.0012 4.7484 0.0010 5.2201 0.0009 5.0972 0.0009 5.8185 0.0013 5.2935 0.0008 5.2311 0.0008 5.0340 0.0014 10.1136 0.0007 0.5334 0.0008 4.8284 0.0008 0.6692 0.0010 1.2848 0.0013 10.6002 0.0008 2.8714 0.0012 4.8760 0.0013 4.8182 0.0017 1.2662 0.0017 3.4899 0.0011 0.3991 0.0013 0.4386 0.0010 0.6197 0.0015 5.0467 0.0014 1.4073 0.0013 4.9742 0.0017 9.9077 0.0008 1.0341 0.0011 5.0866 0.0012 0.6910 0.0021 4.5427 0.0012 9.9345 0.0006 1.1667 0.0009 6.9086 0.0006 1.5043 0.0009 0.3116 0.0007 1.2105 0.0012 4.4244 0.0005 0.2631 0.0010 1.7628 0.0012 11.7680 0.0006 0.3217 0.0008 5.0618 0.0008 5.0449 0.0008 3.2379 0.0011 0.3747 0.0010 5.1673 0.0010 1.2310 0.0013 8.4409 0.0010 5.0717 0.0014 1.2189 0.0009 5.3087 0.0006 1.3457 0.0012 5.0362 0.0010 4.4652 0.0008 0.9513 0.0008 0.5094 0.0007 1.1612 0.0008 1.6186 0.0017 4.4015 0.0012 1.2946 0.0011 1.2136 0.0016 9.3113 0.0013 0.3071 0.0016 1.0536 0.0014 8.3054

1σ

206 238

0.0358 0.0157 0.0515 0.0473 0.0110 0.0404 0.0130 0.0107 0.0500 0.0509 0.0428 0.0439 0.0595 0.0476 0.0491 0.1106 0.0062 0.0366 0.0089 0.0193 0.0959 0.0298 0.0544 0.0591 0.0300 0.0561 0.0080 0.0102 0.0091 0.0718 0.0256 0.0614 0.1202 0.0148 0.0482 0.0133 0.0790 0.0788 0.0126 0.0553 0.0165 0.0054 0.0121 0.0489 0.0026 0.0224 0.0889 0.0038 0.0418 0.0435 0.0290 0.0070 0.0499 0.0178 0.0715 0.0728 0.0246 0.0457 0.0153 0.0923 0.0424 0.0125 0.0075 0.0133 0.0198 0.0679 0.0237 0.0204 0.0940 0.0077 0.0275 0.0769

Pb/ U

0.3042 0.1293 0.3100 0.3301 0.1142 0.3373 0.0862 0.0983 0.3116 0.3326 0.3231 0.3534 0.3135 0.3227 0.3223 0.4578 0.0667 0.3133 0.0770 0.1385 0.4693 0.2360 0.3195 0.3167 0.1247 0.2301 0.0489 0.0581 0.0654 0.3281 0.1413 0.3244 0.4570 0.1180 0.3261 0.0796 0.2961 0.4597 0.1299 0.3585 0.1507 0.0376 0.1331 0.3061 0.0352 0.1628 0.4937 0.0452 0.3275 0.3278 0.2483 0.0502 0.3310 0.1347 0.3908 0.3267 0.1332 0.3364 0.1419 0.2955 0.2885 0.1105 0.0674 0.1304 0.1637 0.3002 0.1403 0.1319 0.4295 0.0426 0.1207 0.3938

1σ

207 206

0.0016 0.0009 0.0022 0.0017 0.0006 0.0019 0.0007 0.0006 0.0020 0.0022 0.0018 0.0018 0.0022 0.0023 0.0024 0.0032 0.0004 0.0013 0.0004 0.0010 0.0027 0.0014 0.0020 0.0017 0.0010 0.0015 0.0004 0.0005 0.0004 0.0020 0.0013 0.0019 0.0027 0.0008 0.0019 0.0006 0.0027 0.0022 0.0009 0.0020 0.0013 0.0003 0.0009 0.0023 0.0002 0.0011 0.0025 0.0003 0.0021 0.0019 0.0011 0.0006 0.0019 0.0013 0.0022 0.0036 0.0010 0.0019 0.0011 0.0037 0.0017 0.0008 0.0005 0.0007 0.0010 0.0034 0.0011 0.0010 0.0027 0.0004 0.0011 0.0022

Pb/ Pb

1813 787 1754 1837 950 1854 543 731 1800 1854 1861 1940 1983 1910 1839 2447 520 1820 702 839 2487 1377 1803 1795 1033 1789 561 398 883 1817 1006 1818 2424 728 1854 706 1833 2418 774 2215 991 594 806 1706 372 1167 2589 261 1828 1818 1511 394 1843 826 2413 1829 820 1862 880 1972 1821 680 387 743 965 1800 835 828 2417 295 722 2369

1σ

Best age estimate 207 235

7 26 13 17 19 12 41 32 20 48 15 13 19 13 13 15 26 13 30 30 14 18 19 22 79 28 47 52 34 24 37 22 19 28 19 41 33 13 20 10 17 33 23 22 20 25 12 26 13 13 17 46 16 31 15 15 44 13 19 18 17 30 33 23 25 30 39 35 17 57 56 16

Pb/ U

1762 786 1747 1842 763 1869 532 632 1776 1856 1836 1949 1868 1858 1825 2445 434 1790 520 839 2489 1374 1798 1788 831 1525 341 369 490 1827 892 1815 2426 721 1834 533 1739 2429 785 2100 932 275 805 1717 237 1032 2586 283 1830 1827 1466 323 1847 815 2280 1831 809 1870 866 1825 1725 679 418 783 977 1713 843 807 2369 272 731 2265

1σ

206 238

6 7 9 8 5 7 8 6 9 8 7 7 10 8 8 10 4 6 5 9 8 8 9 10 13 13 6 7 6 12 11 10 11 7 8 8 14 7 6 7 7 4 6 9 2 8 7 3 7 7 7 5 8 8 8 12 11 7 7 16 8 7 5 6 8 13 11 9 9 6 14 8

Pb/ U

1712 784 1741 1839 697 1874 533 605 1748 1851 1805 1951 1758 1803 1801 2430 416 1757 478 836 2481 1366 1787 1774 757 1335 308 364 408 1829 852 1811 2426 719 1820 494 1672 2438 787 1975 905 238 805 1721 223 972 2587 285 1826 1828 1429 316 1843 814 2127 1822 806 1869 856 1669 1634 676 420 790 977 1692 846 799 2303 269 735 2140

1σ Age 8 5 11 8 3 9 4 3 10 11 9 8 11 11 12 14 2 7 3 6 12 7 10 8 6 8 3 3 3 10 7 9 12 4 9 4 13 10 5 9 7 2 5 11 1 6 11 2 10 9 6 4 9 8 10 18 6 9 6 18 8 4 3 4 6 17 6 6 12 2 7 10

1813 784 1754 1837 697 1854 533 605 1800 1854 1861 1940 1983 1910 1839 2447 416 1820 478 836 2487 1377 1803 1795 757 1789 308 364 408 1817 852 1818 2424 719 1854 494 1833 2418 787 2215 905 238 805 1706 223 972 2589 285 1828 1818 1511 316 1843 814 2413 1829 806 1862 856 1972 1821 676 420 790 977 1800 846 799 2417 269 735 2369

Disc (%)

1σ 7 5 13 17 3 12 4 3 20 48 15 13 19 13 13 15 2 13 3 6 14 18 19 22 6 28 3 3 3 24 7 22 19 4 19 4 33 13 5 10 7 2 5 22 1 6 12 2 13 13 17 4 16 8 15 15 6 13 6 18 17 4 3 4 6 30 6 6 17 2 7 16

−5.9 −0.3 −0.8 0.1 −9.4 1.0 0.1 −4.6 −2.9 −0.1 −3.1 0.6 −12.8 −5.9 −2.1 −0.7 −4.3 −3.6 −8.9 −0.3 −0.3 −0.8 −0.9 −1.2 −9.7 −33.9 −10.8 −1.4 −19.9 0.7 −4.7 −0.4 0.1 −0.3 −1.9 −8.0 −9.7 0.8 0.3 −12.1 −3.0 −15.8 0.0 0.9 −6.3 −6.1 −0.1 0.6 −0.1 0.6 −5.7 −2.4 0.0 −0.1 −13.5 −0.4 −0.4 0.4 −1.2 −18.1 −11.5 −0.5 0.6 0.9 0.0 −6.4 0.3 −1.0 −4.9 −1.0 0.6 −10.7

(continued on next page)

90

B.-Q. Wang et al. / Sedimentary Geology 289 (2013) 74–98

Table 1 (continued) Spot no.

Th (ppm)

U Th/U (ppm)

Isotopic ratios 207 206

Pb/ Pb

Isotopic age (Ma)

1σ

207 235

Pb/ U

1σ

206 238

BQ114: Tumugou Formation in Shangri-La region, Upper Triassic (N 28° 09.163′', E BQ114-85 37 42 0.88 0.1013 0.0016 4.1287 0.0628 BQ114-86 59 142 0.42 0.0531 0.0015 0.3250 0.0088 BQ114-87 214 646 0.33 0.1625 0.0014 10.2988 0.0874 BQ114-88 98 231 0.42 0.1120 0.0011 5.2470 0.0547 BQ114-89 28 595 0.05 0.0540 0.0008 0.4811 0.0067 BQ114-90 23 27 0.86 0.0661 0.0023 1.0498 0.0347 BQ114-91 52 113 0.46 0.1823 0.0018 12.7356 0.1245 BQ114-92 139 196 0.71 0.1793 0.0016 12.5636 0.1168 BQ114-93 276 757 0.36 0.1191 0.0010 5.7011 0.0482 BQ114-94 248 525 0.47 0.1106 0.0009 4.7923 0.0405 BQ114-95 157 338 0.47 0.1108 0.0010 4.6320 0.0420 BQ114-96 93 138 0.67 0.0567 0.0012 0.6252 0.0128 BQ114-97 191 208 0.92 0.0647 0.0009 1.1131 0.0151 BQ114-98 233 287 0.81 0.1097 0.0012 4.9038 0.0547 BQ114-99 117 88 1.33 0.0529 0.0019 0.2956 0.0097 BQ114-100 579 1162 0.50 0.0504 0.0006 0.2668 0.0035 BQ114-101 427 310 1.38 0.0828 0.0009 2.5031 0.0251 BQ114-102 103 198 0.52 0.1431 0.0014 8.2705 0.0809 BQ114-103 52 237 0.22 0.0738 0.0009 1.7158 0.0214 BQ114-104 393 603 0.65 0.0631 0.0009 0.6153 0.0086 BQ114-105 131 231 0.57 0.0564 0.0011 0.5045 0.0098 BQ114-106 29 28 1.05 0.0676 0.0021 1.2005 0.0366 BQ114-107 323 1464 0.22 0.0853 0.0008 2.5818 0.0240 BQ114-108 213 403 0.53 0.0790 0.0009 2.0097 0.0215 BQ114-109 285 292 0.98 0.0641 0.0008 1.0806 0.0139 BQ114-110 21 19 1.09 0.0702 0.0028 1.1588 0.0441 BQ114-111 120 258 0.46 0.0532 0.0012 0.2993 0.0067 BQ114-112 122 1101 0.11 0.0509 0.0007 0.2717 0.0034 BQ114-113 161 173 0.93 0.0642 0.0010 1.1323 0.0169 BQ114-114 337 642 0.52 0.1221 0.0012 6.0773 0.0573

Pb/ U

207

1σ

206

Pb/ Pb

99° 54.214′'), N = 98/110 0.2963 0.0025 1648 0.0450 0.0004 332 0.4565 0.0021 2483 0.3375 0.0019 1832 0.0645 0.0004 369 0.1196 0.0015 809 0.5043 0.0030 2674 0.5047 0.0028 2647 0.3445 0.0017 1944 0.3121 0.0015 1809 0.3012 0.0015 1813 0.0801 0.0006 480 0.1241 0.0008 765 0.3217 0.0020 1794 0.0414 0.0005 324 0.0380 0.0002 217 0.2180 0.0011 1266 0.4168 0.0026 2265 0.1674 0.0010 1039 0.0703 0.0005 709 0.0648 0.0005 478 0.1319 0.0015 857 0.2177 0.0010 1324 0.1833 0.0009 1172 0.1217 0.0007 744 0.1240 0.0018 933 0.0408 0.0003 345 0.0385 0.0002 239 0.1277 0.0008 746 0.3581 0.0018 1987

1σ

Best age estimate 207 235

30 65 9 19 61 69 16 15 15 15 17 48 25 21 112 34 16 17 24 30 38 66 19 21 28 83 52 62 33 18

Pb/ U

1σ

206 238

1660 286 2462 1860 399 729 2660 2647 1932 1784 1755 493 760 1803 263 240 1273 2261 1014 487 415 801 1295 1119 744 781 266 244 769 1987

12 7 8 9 5 17 9 9 7 7 8 8 7 9 8 3 7 9 8 5 7 17 7 7 7 21 5 3 8 8

Pb/ U

1673 284 2424 1875 403 728 2632 2634 1908 1751 1697 497 754 1798 262 241 1271 2246 998 438 405 799 1270 1085 740 754 258 243 775 1973

1σ Age

12 3 9 9 2 8 13 12 8 7 7 3 4 10 3 1 6 12 6 3 3 9 5 5 4 10 2 1 5 9

Disc (%)

1σ

1648 284 2483 1832 403 728 2674 2647 1944 1809 1813 497 754 1794 262 241 1266 2265 998 438 405 799 1324 1172 740 754 258 243 775 1987

30 1.5 3 −0.6 9 −2.5 19 2.2 2 1.0 8 −0.1 16 −1.6 15 −0.5 15 −1.8 15 −3.3 17 −6.8 3 0.8 4 −0.7 21 0.2 3 −0.5 1 0.2 16 0.4 17 −0.8 6 −1.7 3 −11.2 3 −2.5 9 −0.3 19 −4.3 21 −8.0 4 −0.5 10 −3.7 2 −3.0 1 −0.3 5 0.8 18 −0.7

1) Analyses with high discordance (absolute value >10%) were not included in Figs. 5 and 7. 2) Disc.% = 100 ∗ (1 − (207Pb/206Pb)age)/(206Pb/238U) age) for age >1000 Ma, or = 100 ∗ (1 − (207Pb/235U)age)/(207Pb/238U) age) for age b1000 Ma.

synchronous to the 221 ±2 Ma dacitic interlayer of the upper Tumugou Formation (Wang et al., 2011), constraining the minimum depositional age of ca. 220 Ma. Therefore, the Tumugou Formation likely deposited

between ca. 230 and 220 Ma. The Qugusi Formation has comparable litho-facies and the conformable contact with the Tumugou Formation. The two formations should represent continuous sedimentation in a

d

GB77 Tumugou Formation

b

15

GB101 Qugasi Formation

10

Number

5 0 35 30 25 20 15 10 5 0

a

GB133 Lieyi Formation

Number

c

Number

GB185 Lanashan Formation

Number

Number

Number

Number

Yidun Group in the Changtai region 25 20 15 10 5 0 30 25 20 15 10 5 0 20

Yidun Group in the Shangri-La region

16 14 12 10 8 6 4 2 0 14 12 10 8 6 4 2 0 16 14 12 10 8 6 4 2 0

g

BQ114 Upper Tumugou Formation

f

BQ23 Lower Tumugou Formation

e

0

BQ156 Qugasi Formation

400

800

1200

1600

2000

Age (Ma) 0

400

800

1200

1600

2000

2400

2800

3200

3600

Age (Ma) Fig. 5. U–Pb age spectra of detrital zircons from the Yidun Group.

2400

2800

3200

3600

B.-Q. Wang et al. / Sedimentary Geology 289 (2013) 74–98

a

c

20

εHf(t)

15

0.0

-10

GB77 GB101 GB133 GB185

-20

b

500

1000 1500 2000 2500 3000 3500 4000

CHUR

15

0.0

= Hf

/

Lu

-20

-30

d

4.5 4.0

GB23 GB156

0

500

1000 1500 2000 2500 3000 3500 4000

0

500

1000 1500 2000 2500 3000 3500 4000

4.0 3.5

3.5

TDM2(Ga)

0

-10

f=

/H Lu

0

DM

10 CHUR

0

-30

20

DM

10

91

3.0

3.0 2.5 2.5 2.0 2.0 1.5

1.5

1.0

1.0 0.5

0

500

1000 1500 2000 2500 3000 3500 4000

Age (Ma)

0.5

Age (Ma)

Fig. 6. Plots of εHf(t) vs. U–Pb ages and TDM2 vs. U–Pb ages: a) and b) Yidun Group in the Changtai region; c) and d) Yidun Group in the Shangri-La region.

unique sedimentary system. Combined with a 230.3±1.7 Ma quartz diorite intruding the Qugasi Formation (Wang et al., 2011), the deposition age of the Qugasi Formation is interpreted to be slightly older than 230 Ma. 6.2. Provenance of the Yidun Group Detrital zircons of the Yidun Group in the Changtai region are characterized by two prominent age peaks at ~400–480 and ~880–980 Ma with a minor peak at ~2.45–2.50 Ga, different from the Yidun Group in the Shangri-La region where five major peaks are identified: ~220– 240 Ma, ~400–480 Ma, ~720–1000 Ma, ~1.75–1.90 Ga and ~2.40– 2.50 Ga (Fig. 7). The different age spectra of detrital zircons suggest that the Yidun Group in the Changtai and Shangri-La regions had different provenances and formed in two depocenters. 6.2.1. Depocenter in the Changtai region The Lieyi, Qugasi, Tumugou and Lanashan Formations of the Yidun Group in the Changtai region show identical detrital zircon age spectra (Fig. 5), indicative of similar sources. The logical candidates of the source include the neighboring Triassic Songpan–Ganzi Terrane, Qiangtang Block, and Zhongza Massif. The Yidun Group is lithologically and temporally similar to the Xikang Group in the adjacent Songpan–Ganzi Terrane (Gu, 1994; Nie et al., 1994; Bruguier et al., 1997; She et al., 2006; Weislogel et al., 2006; Zhang et al., 2008; Wang et al., 2009). Comparison of detrital zircon age spectra between them can thus be used to determine whether the Xikang and Yidun Groups were derived from the same sources. As the Songpan–Ganzi flysch sequence was considered to deposit at several depocenters (sub-basins) which possibly have different material

sources (Enkelmann et al., 2007; Weislogel et al., 2010; Zhang et al., 2012). The “southeastern depocenter” (Weislogel et al., 2010), which is closest to the Yidun Terrane (Fig. 1), is thus selected to compare with the Yidun Group. As indicated in Fig. 7, the Yidun Group in the Changtai region is different from the Xikang Group by lacking significant populations of Carboniferous–Late Triassic (~220–320 Ma) and Paleoproterozoic zircons (~1.75–1.90 Ga). This discrepancy suggests that the Yidun Group in the Changtai region has different sources from those of the Songpan–Ganzi Terrane. The detrital zircon age pattern of the Yidun Group in the Changtai region does not resemble those of the Qiangtang Block. The Early Paleozoic magmatic events in the Qiangtang Block were all older than ~450 Ma, e.g. the 471–476 Ma Duguer Range orthogneisses (Pullen et al., 2011) and 460–540 Ma Amdo orthogneisses (Guynn et al., 2012), and thus are not comparable to the zircon age peak at 400–480 Ma of the Yidun Group in the Changtai region. The Upper Paleozoic strata in the Qiangtang Block have detrital zircon grains with ages predominantly of 500–1000 Ma, but with no zircon grains of 400–480 Ma (Fig. 7; Gehrels et al., 2011; Pullen et al., 2011). In the Triassic strata of the Qiangtang Block, although Ordovician–Silurian zircon grains were sparsely reported (Gehrels et al., 2011; Pullen et al., 2011), these grains were thought to be derived from the distal Qilian Shan Terrane to the north (Gehrels et al., 2011) which was far from the northern part of the Yidun Terrane (Fig. 7). The major Neoproterozoic age population (~880–980 Ma) of the Yidun Group is consistent with the extensive tectonothermal event of the western Yangtze Block (e.g. Zhou et al., 2006; Sun et al., 2009), and the Early Paleozoic age population (~400–480 Ma) mainly reflects distinct signature of the break-up of North Gondwana recorded in the adjacent Qinling Terrane (e.g. Meng and Zhang, 2000; Hacker et al.,

92

B.-Q. Wang et al. / Sedimentary Geology 289 (2013) 74–98

Table 2 LA-MC-ICPMS zircon Lu–Hf isotopic data for the sandstones of the Yidun Group. Spot no.

176

Hf/177Hf

2σ

176

Lu/177Hf

176

Yb/177Hf

Age

(176Hf/177Hf)i

εHf(t)

2σ

TDM(Ga)

TDM2(Ga)

Sample GB133 GB133-03 GB133-07 GB133-08 GB133-12 GB133-13 GB133-14 GB133-16 GB133-17 GB133-18 GB133-20 GB133-21 GB133-24 GB133-25 GB133-27 GB133-32 GB133-35 GB133-40 GB133-41 GB133-42 GB133-43 GB133-48 GB133-50 GB133-51 GB133-52 GB133-53 GB133-54 GB133-55 GB133-60 GB133-63 GB133-65 GB133-69 GB133-70 GB133-76 GB133-77 GB133-78 GB133-79 GB133-83 GB133-90 GB133-96 GB133-97 GB133-98 GB133-103 GB133-116

0.282071 0.281102 0.281897 0.281937 0.280457 0.282052 0.281879 0.282070 0.282404 0.282423 0.281865 0.282245 0.282152 0.282171 0.281898 0.281830 0.281939 0.282444 0.282112 0.281854 0.282433 0.282332 0.282116 0.281011 0.282167 0.282145 0.281624 0.282053 0.282038 0.282237 0.281975 0.282426 0.282101 0.282019 0.281475 0.281979 0.282492 0.282395 0.282133 0.281980 0.282291 0.281955 0.282123

0.000024 0.000028 0.000024 0.000021 0.000038 0.000032 0.000017 0.000021 0.000038 0.000031 0.000027 0.000032 0.000035 0.000028 0.000020 0.000021 0.000023 0.000026 0.000033 0.000015 0.000029 0.000030 0.000036 0.000031 0.000034 0.000027 0.000035 0.000026 0.000017 0.000031 0.000022 0.000038 0.000034 0.000030 0.000034 0.000021 0.000023 0.000031 0.000029 0.000017 0.000035 0.000038 0.000032

0.000264 0.000363 0.000935 0.000682 0.000643 0.001255 0.000723 0.000707 0.001130 0.000678 0.000785 0.000953 0.001760 0.002072 0.000760 0.000747 0.000642 0.000564 0.001128 0.000452 0.000486 0.000578 0.000778 0.001009 0.000516 0.000885 0.000427 0.000887 0.001606 0.000317 0.000700 0.000689 0.000279 0.000645 0.001101 0.000687 0.002020 0.001502 0.000575 0.000684 0.001411 0.000209 0.000671

0.006487 0.008300 0.022540 0.017422 0.015472 0.029349 0.018487 0.017590 0.023913 0.017245 0.019458 0.024383 0.045771 0.051631 0.018627 0.018410 0.016761 0.014081 0.027578 0.011486 0.011425 0.014280 0.020274 0.028005 0.012125 0.024452 0.009630 0.023141 0.040794 0.006668 0.019457 0.018373 0.005868 0.015533 0.027969 0.017457 0.048060 0.037451 0.015929 0.017154 0.035065 0.005909 0.017670

528 2469 1065 949 3481 1098 1146 967 902 581 1057 865 998 1080 1011 1635 998 635 997 1088 645 950 926 2894 867 486 883 869 923 1033 935 941 1033 989 1894 1320 935 634 489 956 723 874 550

0.282069 0.281085 0.281878 0.281925 0.280414 0.282026 0.281864 0.282057 0.282385 0.282416 0.281849 0.282230 0.282119 0.282129 0.281884 0.281807 0.281927 0.282437 0.282091 0.281845 0.282427 0.282321 0.282102 0.280955 0.282158 0.282137 0.281617 0.282039 0.282010 0.282231 0.281962 0.282414 0.282096 0.282007 0.281436 0.281961 0.282457 0.282378 0.282127 0.281968 0.282272 0.281951 0.282116

−13.3 −4.3 −8.0 −9.0 −4.6 −2.1 −6.7 −3.9 6.3 0.2 −9.3 −0.1 −1.0 1.2 −9.0 2.3 −7.8 2.2 −2.0 −8.7 2.0 5.1 −3.2 0.9 −2.5 −11.8 −21.4 −6.8 −6.6 3.7 −8.0 8.2 −1.1 −5.2 −5.0 0.6 9.5 0.0 −12.0 −7.3 −1.7 −9.7 −11.1

0.8 1.0 0.8 0.7 1.3 1.1 0.6 0.7 1.3 1.1 0.9 1.1 1.2 1.0 0.7 0.7 0.8 0.9 1.2 0.5 1.0 1.1 1.3 1.1 1.2 1.0 1.2 0.9 0.6 1.1 0.8 1.3 1.2 1.1 1.2 0.7 0.8 1.1 1.0 0.6 1.2 1.3 1.1

1.63 2.94 1.90 1.83 3.82 1.70 1.91 1.65 1.20 1.16 1.94 1.42 1.58 1.57 1.89 1.98 1.83 1.13 1.61 1.93 1.14 1.28 1.59 3.12 1.51 1.55 2.25 1.68 1.74 1.41 1.78 1.16 1.59 1.72 2.49 1.78 1.10 1.23 1.56 1.77 1.37 1.79 1.58

2.32 3.24 2.40 2.37 4.03 2.05 2.38 2.07 1.38 1.52 2.47 1.75 1.91 1.84 2.42 2.19 2.34 1.43 1.98 2.46 1.45 1.49 2.00 3.25 1.91 2.20 3.09 2.17 2.20 1.64 2.30 1.29 1.94 2.17 2.84 2.05 1.20 1.57 2.22 2.27 1.75 2.36 2.20

Sample GB101 GB101-01 GB101-07 GB101-10 GB101-12 GB101-13 GB101-15 GB101-16 GB101-21 GB101-26 GB101-27 GB101-30 GB101-31 GB101-33 GB101-35 GB101-37 GB101-39 GB101-40 GB101-45 GB101-46 GB101-48 GB101-51 GB101-52 GB101-56 GB101-57 GB101-60 GB101-63 GB101-65 GB101-68

0.282309 0.281167 0.280984 0.280915 0.281491 0.281044 0.280994 0.281954 0.281968 0.280495 0.281235 0.281082 0.281059 0.281900 0.282184 0.281456 0.281214 0.282317 0.282000 0.282132 0.282163 0.282057 0.281961 0.281474 0.282165 0.281517 0.281832 0.280989

0.000033 0.000032 0.000028 0.000036 0.000039 0.000026 0.000037 0.000023 0.000033 0.000028 0.000018 0.000016 0.000023 0.000027 0.000021 0.000021 0.000029 0.000039 0.000034 0.000031 0.000033 0.000037 0.000021 0.000026 0.000029 0.000030 0.000037 0.000035

0.000594 0.001206 0.000506 0.000490 0.000794 0.000538 0.000539 0.000864 0.000475 0.000595 0.002166 0.000467 0.000673 0.000077 0.000440 0.000596 0.000247 0.000803 0.002210 0.000840 0.000409 0.000298 0.000562 0.000632 0.001118 0.000648 0.001011 0.000580

0.014346 0.028088 0.012130 0.012812 0.019899 0.013432 0.012065 0.018845 0.012863 0.015622 0.048514 0.010771 0.016771 0.001850 0.010605 0.014752 0.005648 0.018172 0.062800 0.022796 0.010384 0.008841 0.013979 0.015141 0.028446 0.015640 0.027079 0.014095

455 2609 2558 2420 1431 2387 2428 795 971 3456 2458 2392 2409 985 605 1513 2458 437 689 957 834 975 999 1520 1102 1259 1472 2676

0.282303 0.281107 0.280959 0.280892 0.281470 0.281020 0.280969 0.281942 0.281959 0.280456 0.281134 0.281060 0.281028 0.281899 0.282179 0.281439 0.281203 0.282311 0.281972 0.282117 0.282156 0.282051 0.281950 0.281456 0.282142 0.281502 0.281804 0.280959

−6.6 −0.3 −6.7 −12.3 −14.3 −8.5 −9.4 −11.8 −7.3 −3.7 −2.8 −7.0 −7.7 −9.1 −7.6 −13.5 −0.4 −6.7 −13.1 −2.0 −3.3 −3.9 −7.0 −12.8 2.1 −17.1 −1.5 −4.0

1.2 1.1 1.0 1.3 1.4 0.9 1.3 0.8 1.1 1.0 0.6 0.6 0.8 0.9 0.7 0.7 1.0 1.4 1.2 1.1 1.2 1.3 0.7 0.9 1.0 1.0 1.3 1.2

1.32 2.92 3.11 3.20 2.45 3.03 3.10 1.82 1.78 3.77 2.90 2.98 3.02 1.85 1.48 2.48 2.78 1.31 1.82 1.57 1.51 1.65 1.79 2.46 1.54 2.40 1.99 3.11

1.85 3.10 3.45 3.69 3.07 3.43 3.52 2.43 2.28 3.96 3.14 3.34 3.40 2.41 2.03 3.08 2.99 1.84 2.44 1.94 1.93 2.08 2.29 3.04 1.79 3.11 2.30 3.38

B.-Q. Wang et al. / Sedimentary Geology 289 (2013) 74–98

93

Table 2 (continued) Spot no.

176

GB101-76 GB101-78 GB101-79 GB101-84 GB101-85 GB101-86 GB101-88 GB101-89 GB101-90 GB101-91 GB101-93 GB101-95 GB101-97 GB101-99 GB101-100 GB101-101 GB101-104 GB101-105 GB101-107 GB101-108 GB101-110 GB101-111 GB101-113 GB101-115 GB101-116 GB101-118 GB101-119

Hf/177Hf

2σ

176

Lu/177Hf

0.281961 0.280952 0.282518 0.281932 0.281860 0.281250 0.282217 0.281910 0.282312 0.282051 0.282032 0.282826 0.282104 0.282574 0.282187 0.282266 0.281760 0.282268 0.281687 0.281752 0.282068 0.282334 0.282055 0.281645 0.282035 0.282028 0.282427

0.000031 0.000023 0.000029 0.000019 0.000026 0.000020 0.000027 0.000034 0.000022 0.000035 0.000039 0.000015 0.000017 0.000014 0.000014 0.000029 0.000022 0.000031 0.000033 0.000016 0.000021 0.000026 0.000029 0.000029 0.000024 0.000031 0.000018

0.000921 0.000562 0.000582 0.000496 0.000866 0.001010 0.000676 0.001043 0.000621 0.000042 0.000905 0.000542 0.000294 0.001162 0.000418 0.000444 0.000508 0.001106 0.000494 0.000877 0.000533 0.000651 0.000889 0.000459 0.000569 0.000722 0.000525

Sample GB77 GB77-01 GB77-02 GB77-04 GB77-06 GB77-09 GB77-14 GB77-15 GB77-16 GB77-21 GB77-25 GB77-26 GB77-28 GB77-40 GB77-48 GB77-52 GB77-61 GB77-64 GB77-69 GB77-70 GB77-75 GB77-79 GB77-80 GB77-87 GB77-92 GB77-93 GB77-97 GB77-101 GB77-111 GB77-114

0.281976 0.282119 0.282069 0.282087 0.281644 0.281028 0.281228 0.282603 0.281842 0.282416 0.280952 0.282733 0.281198 0.281746 0.280990 0.282509 0.282772 0.280897 0.282501 0.282673 0.282238 0.281974 0.282208 0.282231 0.281556 0.281808 0.281634 0.281844 0.281612

0.000026 0.000033 0.000030 0.000036 0.000012 0.000018 0.000034 0.000035 0.000025 0.000034 0.000020 0.000039 0.000033 0.000029 0.000032 0.000037 0.000037 0.000021 0.000032 0.000024 0.000029 0.000034 0.000036 0.000035 0.000034 0.000024 0.000031 0.000023 0.000013

Sample GB185 GB185-01 GB185-02 GB185-07 GB185-09 GB185-14 GB185-25 GB185-28 GB185-29 GB185-40 GB185-41 GB185-44 GB185-46 GB185-48 GB185-50 GB185-51 GB185-59

0.282184 0.282213 0.281799 0.282712 0.282217 0.281660 0.282027 0.281724 0.281448 0.282580 0.282405 0.282015 0.282034 0.281866 0.281910 0.281948

0.000029 0.000038 0.000022 0.000024 0.000025 0.000035 0.000038 0.000038 0.000029 0.000016 0.000018 0.000036 0.000033 0.000025 0.000025 0.000018

176

Yb/177Hf

Age

(176Hf/177Hf)i

εHf(t)

2σ

TDM(Ga)

TDM2(Ga)

0.022059 0.013837 0.012189 0.012564 0.019501 0.024748 0.015501 0.027396 0.014947 0.001163 0.023351 0.012052 0.007495 0.026627 0.010556 0.009492 0.011456 0.028156 0.012049 0.019937 0.013828 0.015831 0.023090 0.010913 0.014468 0.017053 0.012070

1528 2944 679 1121 1461 2344 433 974 415 1231 939 433 936 426 493 898 1718 442 1714 1711 744 547 1240 961 988 1610 391

0.281934 0.280921 0.282511 0.281921 0.281836 0.281204 0.282212 0.281891 0.282307 0.282050 0.282016 0.282822 0.282099 0.282565 0.282183 0.282258 0.281743 0.282259 0.281671 0.281724 0.282061 0.282327 0.282034 0.281637 0.282024 0.282006 0.282423

4.4 0.9 5.7 −5.3 −0.6 −2.9 −10.3 −9.6 −7.3 1.8 −6.0 11.3 −3.1 2.1 −10.0 1.7 1.9 −8.4 −0.8 1.0 −8.7 −3.7 1.4 −18.9 −4.6 8.8 −3.7

1.1 0.8 1.0 0.6 0.9 0.7 0.9 1.2 0.8 1.2 1.4 0.5 0.6 0.5 0.5 1.0 0.8 1.1 1.2 0.6 0.7 0.9 1.0 1.0 0.8 1.1 0.6

1.81 3.16 1.03 1.83 1.95 2.79 1.45 1.89 1.31 1.65 1.71 0.60 1.59 0.96 1.48 1.37 2.07 1.39 2.16 2.10 1.65 1.28 1.68 2.22 1.69 1.71 1.15

1.98 3.29 1.24 2.27 2.24 3.06 2.07 2.43 1.87 1.92 2.18 0.70 2.00 1.28 2.09 1.67 2.28 1.96 2.44 2.33 2.20 1.74 1.94 3.00 2.13 1.77 1.62

0.000650 0.000669 0.000872 0.000488 0.002038 0.000188 0.000649 0.001108 0.000338 0.000576 0.000569 0.000770 0.000365 0.000917 0.000607 0.001935 0.000736 0.000835 0.000613 0.000600 0.000576 0.000794 0.000455 0.001000 0.000421 0.000145 0.001066 0.000389 0.000332

0.016867 0.017354 0.022917 0.011805 0.055141 0.004783 0.015350 0.026972 0.007911 0.013867 0.015186 0.017196 0.009503 0.022716 0.015407 0.054816 0.014664 0.020828 0.011998 0.013671 0.014435 0.019466 0.010817 0.026589 0.011415 0.004020 0.025896 0.008478 0.007117

1021 996 1389 936 1826 2346 2484 455 1361 488 2459 442 1952 787 2458 734 457 2454 471 450 944 1455 415 790 925 1109 1743 1154 1276

0.281964 0.282106 0.282046 0.282078 0.281574 0.281020 0.281197 0.282594 0.281833 0.282411 0.280925 0.282726 0.281184 0.281733 0.280961 0.282482 0.282766 0.280858 0.282495 0.282668 0.282228 0.281952 0.282205 0.282216 0.281548 0.281805 0.281599 0.281835 0.281604

−6.0 −1.5 5.2 −3.9 −1.7 −9.4 0.0 3.7 −3.0 −2.0 −10.2 8.1 −12.6 −19.4 −8.9 6.0 9.9 −12.7 0.6 6.2 1.6 3.4 −10.9 −2.2 −22.9 −9.7 −2.7 −7.6 −13.1

0.9 1.1 1.1 1.3 0.4 0.6 1.2 1.2 0.9 1.2 0.7 1.4 1.2 1.0 1.1 1.3 1.3 0.7 1.1 0.8 1.0 1.2 1.3 1.2 1.2 0.9 1.1 0.8 0.4

1.78 1.58 1.66 1.62 2.31 3.03 2.79 0.92 1.95 1.17 3.16 0.73 2.81 2.11 3.11 1.08 0.68 3.25 1.05 0.81 1.41 1.79 1.45 1.44 2.34 1.98 2.27 1.95 2.26

2.24 1.94 1.82 2.04 2.59 3.46 2.99 1.20 2.31 1.59 3.59 0.91 3.35 2.90 3.51 1.27 0.81 3.74 1.41 1.03 1.70 1.99 2.09 1.83 3.22 2.54 2.58 2.44 2.87

0.001621 0.001955 0.000787 0.000767 0.000895 0.001551 0.001115 0.000963 0.001146 0.000916 0.000405 0.001737 0.000109 0.001822 0.000374 0.000533

0.037748 0.041330 0.018052 0.015154 0.022729 0.036960 0.027036 0.022428 0.028653 0.018575 0.009818 0.048602 0.002726 0.046723 0.009337 0.013705

445 890 1187 468 942 1698 943 1678 1772 456 620 1377 456 1729 976 1055

0.282170 0.282181 0.281781 0.282706 0.282202 0.281610 0.282008 0.281693 0.281409 0.282572 0.282400 0.281970 0.282033 0.281806 0.281904 0.281938

−11.5 −1.2 −8.8 8.0 0.7 −3.3 −6.2 −0.8 −8.7 3.0 0.5 2.2 −16.1 4.4 −9.1 −6.2

1.0 1.3 0.8 0.8 0.9 1.2 1.3 1.3 1.0 0.6 0.6 1.2 1.1 0.9 0.9 0.6

1.53 1.50 2.03 0.76 1.45 2.26 1.73 2.14 2.53 0.95 1.18 1.77 1.67 1.99 1.85 1.81

2.15 1.84 2.54 0.94 1.76 2.59 2.19 2.42 2.98 1.25 1.53 2.00 2.45 2.14 2.40 2.28

(continued on next page)

94

B.-Q. Wang et al. / Sedimentary Geology 289 (2013) 74–98

Table 2 (continued) Spot no.

176

Hf/177Hf

2σ

176

Lu/177Hf

176

Yb/177Hf

Age

(176Hf/177Hf)i

εHf(t)

2σ

TDM(Ga)

TDM2(Ga)

Sample GB185 GB185-62 GB185-63 GB185-64 GB185-67 GB185-68 GB185-69 GB185-70 GB185-71 GB185-72 GB185-73 GB185-76 GB185-82 GB185-88 GB185-89 GB185-91 GB185-97 GB185-100 GB185-103 GB185-106 GB185-107 GB185-108 GB185-111 GB185-112

0.281867 0.282482 0.281388 0.281951 0.282155 0.281948 0.281457 0.280982 0.282058 0.282219 0.282322 0.281303 0.281910 0.281713 0.281263 0.282126 0.282480 0.281086 0.281953 0.282058 0.281422 0.281963 0.282138

0.000028 0.000031 0.000024 0.000034 0.000036 0.000021 0.000021 0.000022 0.000029 0.000030 0.000030 0.000020 0.000023 0.000025 0.000031 0.000027 0.000038 0.000036 0.000027 0.000036 0.000035 0.000025 0.000024

0.000847 0.001048 0.000635 0.001759 0.000723 0.000610 0.000490 0.000402 0.000647 0.000327 0.000548 0.000468 0.000580 0.001777 0.000098 0.000955 0.002165 0.000730 0.000964 0.001333 0.000077 0.000765 0.000765

0.019743 0.022691 0.015917 0.037806 0.018294 0.015191 0.011045 0.009468 0.016323 0.007715 0.013176 0.009912 0.014406 0.045493 0.003036 0.023670 0.057890 0.018520 0.023913 0.034061 0.002151 0.019375 0.014860

1629 441 1561 448 1040 757 2050 2535 941 976 994 2458 505 797 2465 992 994 2437 949 1139 1906 986 1215

0.281841 0.282473 0.281369 0.281936 0.282141 0.281940 0.281438 0.280962 0.282046 0.282213 0.282312 0.281281 0.281905 0.281686 0.281258 0.282109 0.282439 0.281052 0.281936 0.282029 0.281419 0.281949 0.282120

3.3 −0.9 −14.9 −19.7 0.7 −12.7 −1.4 −7.1 −4.9 1.8 5.7 2.4 −19.6 −20.8 1.8 −1.5 10.2 −6.2 −8.6 −1.0 −5.3 −7.3 3.9

1.0 1.1 0.8 1.2 1.3 0.7 0.7 0.8 1.0 1.1 1.1 0.7 0.8 0.9 1.1 1.0 1.3 1.3 0.9 1.3 1.2 0.9 0.8

1.94 1.09 2.58 1.87 1.53 1.81 2.48 3.11 1.67 1.43 1.30 2.68 1.86 2.20 2.71 1.58 1.13 2.99 1.82 1.70 2.50 1.80 1.56

2.12 1.48 3.20 2.67 1.84 2.46 2.74 3.46 2.11 1.72 1.48 2.82 2.70 3.00 2.86 1.94 1.20 3.33 2.35 2.02 2.87 2.30 1.77

Sample BQ156 BQ156-01 BQ156-02 BQ156-03 BQ156-04 BQ156-06 BQ156-08 BQ156-09 BQ156-11 BQ156-12 BQ156-14 BQ156-15 BQ156-16 BQ156-18 BQ156-19 BQ156-20 BQ156-21 BQ156-22 BQ156-29 BQ156-34 BQ156-35 BQ156-37 BQ156-38 BQ156-39 BQ156-41 BQ156-42 BQ156-48 BQ156-49 BQ156-50 BQ156-57 BQ156-61 BQ156-62 BQ156-65 BQ156-66 BQ156-68 BQ156-69 BQ156-71 BQ156-75 BQ156-77 BQ156-82 BQ156-83 BQ156-87 BQ156-88 BQ156-94 BQ156-97 BQ156-100

0.281912 0.281113 0.281877 0.280651 0.282242 0.282134 0.282566 0.281381 0.281559 0.281959 0.281207 0.282386 0.282314 0.282658 0.281406 0.281599 0.282035 0.282573 0.282606 0.282172 0.282202 0.282619 0.281420 0.282022 0.282181 0.281362 0.281991 0.281467 0.282167 0.281582 0.282163 0.281829 0.282279 0.282670 0.281821 0.282267 0.280978 0.280934 0.282146 0.282546 0.282193 0.282053 0.282051 0.281374 0.281970

0.000037 0.000038 0.000037 0.000037 0.000033 0.000036 0.000036 0.000037 0.000034 0.000030 0.000037 0.000034 0.000034 0.000039 0.000031 0.000036 0.000032 0.000031 0.000028 0.000031 0.000030 0.000031 0.000025 0.000033 0.000037 0.000040 0.000039 0.000034 0.000028 0.000036 0.000035 0.000032 0.000037 0.000035 0.000036 0.000017 0.000028 0.000034 0.000036 0.000035 0.000031 0.000022 0.000032 0.000028 0.000034

0.000406 0.000773 0.000281 0.000939 0.001227 0.000382 0.000822 0.000606 0.000494 0.000553 0.000489 0.001412 0.001274 0.001976 0.000772 0.000462 0.000497 0.000530 0.000632 0.000326 0.000482 0.000557 0.000978 0.000307 0.000415 0.000363 0.000466 0.000593 0.000468 0.000651 0.000376 0.000361 0.001238 0.000616 0.001377 0.000749 0.000850 0.000397 0.000552 0.000787 0.000912 0.000488 0.000517 0.000673 0.001206

0.011819 0.021143 0.008338 0.025664 0.035654 0.011455 0.021758 0.017871 0.014011 0.015611 0.013368 0.044307 0.034456 0.053079 0.022312 0.014656 0.014871 0.012798 0.015534 0.010229 0.014067 0.015343 0.025665 0.008749 0.013487 0.010235 0.013824 0.018250 0.012562 0.019871 0.011598 0.011053 0.036291 0.015735 0.043353 0.018483 0.020863 0.009593 0.013552 0.018354 0.027922 0.012155 0.012719 0.014848 0.031276

769 2487 1272 3500 920 913 436 2358 1920 998 2520 900 717 466 2261 1544 1122 453 466 547 1000 459 2405 820 552 1892 1128 2232 781 1825 575 1183 879 466 1237 588 2587 2492 849 410 385 958 982 2258 969

0.281906 0.281077 0.281870 0.280588 0.282221 0.282127 0.282559 0.281354 0.281541 0.281949 0.281183 0.282362 0.282297 0.282640 0.281372 0.281586 0.282024 0.282568 0.282600 0.282169 0.282193 0.282614 0.281375 0.282017 0.282177 0.281349 0.281981 0.281442 0.282160 0.281559 0.282159 0.281821 0.282258 0.282665 0.281789 0.282258 0.280936 0.280915 0.282137 0.282540 0.282186 0.282045 0.282041 0.281345 0.281948

−13.7 −4.2 −3.7 2.1 0.9 −2.6 2.1 2.7 −0.7 −7.0 0.4 5.4 −1.0 5.6 1.1 −7.7 −1.6 2.8 4.2 −9.3 1.6 4.5 4.5 −8.6 −8.9 −8.1 −3.0 3.0 −4.4 −2.2 −9.0 −7.4 1.3 6.5 −7.4 −5.2 −6.9 −9.8 −3.7 0.8 −12.3 −4.5 −4.1 0.1 −7.7

1.3 1.3 1.3 1.3 1.2 1.3 1.2 1.3 1.2 1.1 1.3 1.2 1.2 1.4 1.1 1.3 1.1 1.1 1.0 1.1 1.1 1.1 0.9 1.2 1.3 1.4 1.4 1.2 1.0 1.3 1.2 1.1 1.3 1.2 1.3 0.6 1.0 1.2 1.3 1.2 1.1 0.8 1.1 1.0 1.2

1.85 2.96 1.90 3.59 1.43 1.55 0.97 2.59 2.34 1.80 2.81 1.24 1.33 0.86 2.56 2.28 1.69 0.95 0.91 1.50 1.46 0.89 2.56 1.70 1.49 2.59 1.75 2.47 1.51 2.32 1.51 1.96 1.38 0.82 2.03 1.38 3.15 3.17 1.54 0.99 1.49 1.66 1.67 2.60 1.81

2.53 3.24 2.29 3.65 1.73 1.95 1.29 2.72 2.60 2.29 2.99 1.43 1.69 1.09 2.75 2.74 2.04 1.26 1.18 2.09 1.75 1.15 2.65 2.25 2.07 3.03 2.14 2.61 1.96 2.62 2.09 2.45 1.68 1.03 2.49 1.86 3.48 3.59 1.97 1.35 2.16 2.10 2.09 2.81 2.31

Sample BQ23 BQ23-01 BQ23-02 BQ23-03

0.281590 0.282461 0.281580

0.000020 0.000022 0.000021

0.000661 0.000841 0.000966

0.018822 0.023566 0.028848

1732 420 1802

0.281568 0.282454 0.281547

−4.0 −2.0 −3.2

0.7 0.8 0.7

2.31 1.11 2.34

2.66 1.53 2.66

B.-Q. Wang et al. / Sedimentary Geology 289 (2013) 74–98

95

Table 2 (continued) Spot no.

176

Hf/177Hf

BQ23-04 BQ23-05 BQ23-06 BQ23-07 BQ23-09 BQ23-10 BQ23-11 BQ23-12 BQ23-13 BQ23-14 BQ23-15 BQ23-16 BQ23-17 BQ23-18 BQ23-19 BQ23-21 BQ23-24 BQ23-26 BQ23-27 BQ23-28 BQ23-29 BQ23-32 BQ23-33 BQ23-34 BQ23-35 BQ23-36 BQ23-37 BQ23-38 BQ23-39 BQ23-40 BQ23-41 BQ23-42 BQ23-43 BQ23-45 BQ23-46 BQ23-47 BQ23-48 BQ23-49 BQ23-50 BQ23-51 BQ23-52 BQ23-53 BQ23-54 BQ23-55 BQ23-56 BQ23-59 BQ23-60 BQ23-62 BQ23-63 BQ23-64 BQ23-65 BQ23-66 BQ23-67 BQ23-68 BQ23-69 BQ23-70 BQ23-71 BQ23-76 BQ23-80 BQ23-81 BQ23-83 BQ23-84 BQ23-94 BQ23-95 BQ23-98 BQ23-99

0.282728 0.282148 0.282456 0.281938 0.282321 0.282146 0.282158 0.281241 0.281700 0.281147 0.281726 0.282567 0.281529 0.282224 0.282358 0.282482 0.282151 0.282636 0.282301 0.282097 0.282274 0.282417 0.282602 0.281567 0.282739 0.282009 0.281992 0.282550 0.282271 0.282082 0.281453 0.282566 0.281526 0.282481 0.282358 0.282025 0.281634 0.282242 0.281850 0.282205 0.282217 0.281402 0.282187 0.281828 0.282772 0.281423 0.282089 0.282035 0.281521 0.282209 0.282406 0.280992 0.282086 0.282063 0.281344 0.282259 0.282409 0.282299 0.282295 0.281549 0.281526 0.282480 0.281528 0.282460 0.281448 0.282410

2σ

176

Lu/177Hf

0.000019 0.000019 0.000027 0.000027 0.000022 0.000029 0.000023 0.000017 0.000021 0.000022 0.000021 0.000019 0.000020 0.000027 0.000018 0.000017 0.000021 0.000025 0.000015 0.000018 0.000016 0.000015 0.000018 0.000020 0.000020 0.000022 0.000017 0.000029 0.000024 0.000015 0.000021 0.000022 0.000017 0.000019 0.000018 0.000017 0.000014 0.000019 0.000018 0.000021 0.000021 0.000025 0.000021 0.000020 0.000019 0.000018 0.000017 0.000020 0.000014 0.000014 0.000014 0.000015 0.000015 0.000015 0.000016 0.000012 0.000018 0.000030 0.000023 0.000038 0.000025 0.000036 0.000021 0.000026 0.000027 0.000038

0.001681 0.001639 0.002000 0.001046 0.001348 0.000961 0.000948 0.000783 0.001322 0.000598 0.000511 0.001851 0.001806 0.001103 0.000651 0.001045 0.001089 0.001513 0.001450 0.002307 0.000674 0.001365 0.001291 0.001586 0.000795 0.001760 0.000665 0.001792 0.000944 0.000834 0.000770 0.001957 0.001183 0.001241 0.001102 0.000887 0.000685 0.001297 0.001031 0.003472 0.002442 0.001029 0.001254 0.000631 0.001350 0.000854 0.000020 0.001909 0.000927 0.000131 0.000979 0.000663 0.001590 0.001061 0.000471 0.000503 0.001541 0.000625 0.001175 0.000498 0.001079 0.000838 0.001580 0.000539 0.000550 0.000952

176

Yb/177Hf

0.036828 0.045452 0.056051 0.029715 0.035694 0.026691 0.024418 0.021793 0.037365 0.016597 0.013966 0.056273 0.051564 0.032228 0.017938 0.030126 0.025984 0.043238 0.042395 0.067133 0.021038 0.040431 0.037763 0.046852 0.021353 0.049026 0.017413 0.056951 0.025469 0.024037 0.022345 0.055679 0.034092 0.030054 0.029552 0.022860 0.019921 0.038105 0.028749 0.098140 0.072442 0.028929 0.035933 0.016314 0.036637 0.025813 0.000920 0.054439 0.027432 0.004681 0.031316 0.019199 0.044474 0.028863 0.014247 0.014746 0.037341 0.015502 0.028316 0.012567 0.027171 0.020904 0.039814 0.010974 0.012894 0.025240

2004; Li et al., 2004). Hf isotopic compositions of detrital zircon grains from the Yidun Group reveal magmatic reworking at ca. 2.0 Ga and ca. 2.5 Ga but addition of juvenile material at ca. 800–980 Ma (Fig. 6; Table 2), which coincide with the episodic magmatism and crustal growth of the Yangtze Block (Sun et al., 2009; Wang et al., 2010; Wang L.J. et al., 2012; Wang and Zhou, 2012). In conclusion, both zircon age spectrum and Hf isotopes of the Yidun Group in the Changtai region

Age

(176Hf/177Hf)i

εHf(t)

2σ

TDM(Ga)

TDM2(Ga)

286 980 304 1346 300 694 365 2032 1835 2324 1272 341 1768 880 433 419 861 257 699 1211 773 799 412 2041 457 675 236 609 241 938 1778 307 1802 969 278 391 1906 888 1615 829 883 2123 433 1598 269 1754 402 809 1873 448 478 2437 735 228 1786 397 444 427 288 1817 1821 251 1858 847 1991 706

0.282719 0.282118 0.282444 0.281911 0.282313 0.282134 0.282151 0.281211 0.281654 0.281121 0.281714 0.282555 0.281468 0.282206 0.282353 0.282473 0.282134 0.282628 0.282282 0.282044 0.282264 0.282397 0.282592 0.281506 0.282732 0.281987 0.281989 0.282529 0.282266 0.282068 0.281427 0.282555 0.281486 0.282458 0.282352 0.282018 0.281609 0.282221 0.281819 0.282151 0.282176 0.281360 0.282177 0.281809 0.282765 0.281395 0.282089 0.282006 0.281488 0.282208 0.282398 0.280961 0.282064 0.282058 0.281328 0.282256 0.282396 0.282294 0.282288 0.281532 0.281489 0.282476 0.281472 0.282452 0.281427 0.282398

4.4 −1.5 −4.9 −0.6 −9.6 −7.3 −13.9 −9.9 1.4 −6.4 −9.2 −0.2 −6.7 −0.6 −5.3 −1.3 −3.6 0.6 −1.9 1.1 −0.9 4.4 2.7 0.8 8.7 −12.9 −22.5 4.9 −12.6 −4.2 −8.0 −0.9 −5.3 10.4 −8.7 −18.1 1.4 0.1 2.2 −3.7 −1.6 −2.5 −11.5 1.5 5.7 −9.6 −15.3 −9.3 −3.6 −10.1 −2.7 −9.5 −8.8 −20.3 −11.3 −9.5 −3.5 −7.5 −10.8 −3.4 −4.8 −4.9 −4.6 7.4 −3.1 2.4

0.7 0.7 0.9 0.9 0.8 1.0 0.8 0.6 0.7 0.8 0.7 0.7 0.7 0.9 0.6 0.6 0.7 0.9 0.5 0.6 0.5 0.5 0.6 0.7 0.7 0.8 0.6 1.0 0.8 0.5 0.7 0.8 0.6 0.7 0.6 0.6 0.5 0.7 0.6 0.7 0.7 0.9 0.7 0.7 0.7 0.6 0.6 0.7 0.5 0.5 0.5 0.5 0.5 0.5 0.6 0.4 0.6 1.0 0.8 1.3 0.9 1.3 0.7 0.9 0.9 1.3

0.76 1.58 1.16 1.85 1.33 1.56 1.54 2.79 2.19 2.90 2.11 0.99 2.46 1.45 1.25 1.09 1.55 0.88 1.36 1.68 1.37 1.19 0.93 2.39 0.72 1.78 1.76 1.01 1.38 1.64 2.50 1.00 2.42 1.10 1.27 1.72 2.25 1.44 1.97 1.58 1.52 2.59 1.51 1.98 0.69 2.54 1.60 1.75 2.42 1.44 1.19 3.11 1.67 1.68 2.63 1.38 1.21 1.33 1.36 2.35 2.42 1.09 2.45 1.11 2.49 1.19

1.02 1.93 1.63 2.15 1.93 2.07 2.24 3.25 2.40 3.25 2.63 1.36 2.85 1.79 1.75 1.49 1.97 1.25 1.74 1.94 1.73 1.42 1.23 2.60 0.88 2.41 2.69 1.24 2.07 2.06 2.94 1.38 2.79 1.17 1.85 2.52 2.46 1.76 2.18 1.95 1.86 2.86 2.15 2.21 0.93 3.02 2.36 2.28 2.74 2.07 1.62 3.53 2.20 2.54 3.15 1.99 1.65 1.89 1.99 2.68 2.77 1.59 2.79 1.27 2.80 1.48

support the idea that they have a close affinity to the Yangtze Block. However, the Yangtze Block was separated by the Songpan–Ganzi Terrane from the Yidun Terrane during the Triassic, and thus could not directly contribute to the Yidun Group. Therefore, the potential candidate would be the Zhongza Massif that was separated and drifted away from the Yangtze Block, as suggested by the Paleozoic stratigraphic correlation and fossil records (BGMRSP, 1991; Chang, 2000; Song et

B.-Q. Wang et al. / Sedimentary Geology 289 (2013) 74–98

Number

Number

96

100 80 60 40 20 0

Yidun Group (N=403)

Shangri-La region Yidun Group (N=268)

40 30 20

Yidun Group in the Changtai region (Fig. 7). The ~720–880 Ma, ~1.75– 1.90 Ga and ~2.4–2.5 Ga detrital zircons could be provided by the ancient materials of the crystalline basement of the Yangtze Block, which is also one of the sources for the Triassic strata in the “southeastern depocenter” of the Songpan–Ganzi Terrane (Weislogel et al., 2010). The different age spectra of detrital zircon grains from the lower to upper Yidun Group in the Shangri-La region may reflect a transition of sources supplying from the Zhongza Massif to locally distributed Triassic igneous rocks and the Yangtze Block.

Number

Number

Number

10 0 100 80 60 40 20 0

Xikang Group Songpan-Ganzi (N=444)

Paleozoic strata Qiangtang Block (N=1605)

300 250 200 150 100 50 0 250 200 150 100 50 0

Triassic strata Qiangtang Block (N=722)

0

400

800

1200

1600

2000

2400

2800

3200

3600

Age (Ma) Fig. 7. Compilation of detrital zircon ages from the Yidun Group in the Changtai and Shangri-La regions, Xikang Group in the Songpan–Ganzi Terrane, and Paleozoic and Triassic Qiangtang strata. Zircon age data of the Songpan–Ganzi Triassic turbidites are compiled from Weislogel et al. (2010), Paleozoic Qiangtang strata from Pullen et al. (2011) and Gehrels et al. (2011), and the Triassic Qiangtang strata from Gehrels et al. (2011).

al., 2004). Being affinity of the Yangtze Block, the Zhongza Massif could be the primary source of the Yidun Group in the Changtai region. It was previously thought that the separation of the Zhongza Massif from the western Yangtze Block was triggered by the Late Permian Emeishan mantle plume (Song et al., 2004). However, Late Permian detrital zircon ages are absent from the Yidun Group in the Changtai region (Fig. 5), which suggests that the separation of Zhongza Massif from the Yangtze Block might not be related to the Late Permian Emeishan mantle plume and probably occurred earlier than the Late Permian. 6.2.2. Depocenter in the Shangri-La region In the southern part of the Yidun Terrane, zircon age spectrum and Hf isotopic compositions of sandstones from the Qugasi Formation are similar to those of the northern part of the Yidun Terrane, suggesting that the Zhongza Massif is the major source area for the Qugasi Formations in both regions (Figs. 5e and 7). However, distinctive signature of detrital zircon distribution, with prominent Triassic (~220–240 Ma), Neoproterozoic (~720–880 Ma) peaks and Paleoproterozoic (~1.75– 1.90 Ga) peaks (Fig. 5f), are observed in sandstones of the Tumugou Formation of the Yidun Group in the Shangri-La region. The increased population of ~220–240 Ma detritus was likely sourced from the widespread coeval granitoids and volcanic rocks in the Eastern Yidun Terrane, as no Triassic (~220–240 Ma) source rocks were available around the Yidun Terrane to supply detritus during the sedimentation of the Yidun Group. Middle Carnian (220–224 Ma) and younger flysch deposition in the “southeastern depocenter” of the Songpan–Ganzi Terrane also contains prominent ~220–240 Ma detritus, the source of which is interpreted to be the Yidun Terrane (Weislogel et al., 2010). The Zhongza Massif can be a potential source for the Tumugou Formation, with respect to the prominent ~900–1000 Ma peaks similar to those of the

6.3. Implications for the tectonic evolution of the Yidun Terrane The evolution of the Yidun Terrane involving the Jinsha and Ganzi– Litang subduction system during the Triassic has been a matter of hot debate in the past two decades. The new dataset in this study, however, can provide tighter constraints on certain issues of the Yidun Terrane. The Yidun Terrane was a passive margin during the sedimentation of the Lieyi and Qugasi Formations as they do not have Triassic detrital zircons, which dominantly accumulated recycling materials from the Zhongza Massif. During this period, the Songpan–Ganzi Terrane was separated from the Yidun Terrane by the pre-existing Ganzi–Litang Ocean. At ca. 230 Ma, the subduction of the Ganzi–Litang Ocean was first initiated under the southern part of the Yidun Terrane as recorded ca. 230 Ma adakitic plutons emplaced in the southern part of the Yidun Terrane (Wang et al., 2011). Subsequently, two depocenters in the Yidun Terrane, started to accumulate sediments with different sources. The Tumugou Formation from the southern depocenter was adjacent to a magmatic arc and may have received mixed detritus from the Zhongza Massif and magmatic arc rocks. In contrast, the Tumugou Formation from the northern depocenter, located far wary from the southern magmatic arc, accumulated detritus primarily from the Zhongza Massif. In the northern part of the Yidun Terrane, subduction of the Ganzi–Litang Ocean did not start until ~224 Ma as constrained by the oldest arc plutonism (Weislogel, 2008). The closure of the Ganzi–Litang Ocean in the southern part of the Yidun Terrane was supposed to start at ca. 224 Ma, as the Yidun material (ca. 220–240 Ma) is presented in the 220–224 Ma strata but absent in the 224–228 Ma strata from the “southeastern depocenter” of the Songpan–Ganzi Terrane (Weislogel et al., 2010). The southern part of the Yidun Terrane was thus connected with the Yangtze Block at ~ 224 Ma (Fig. 1). Uplifted crystalline basement of the Yangtze Block may provide ancient material with ages of 720–880 Ma, 1.75–1.90 Ga and ca. 2.4–2.5 Ga to the upper Tumugou Formation of the Yidun Group in the Shangri-La region and the 220–224 Ma strata in the southeastern depocenter of the Songpan–Ganzi Terrane (Weislogel et al., 2010). The Yidun Group in the Changtai region, on the other hand, was limitedly affected by the amalgamation between the southern part of the Yidun Terrane and the Yangtze Block. Similar age spectra of detrital zircons from different formations of the Yidun Group in the Changtai region are indicative of uniform sedimentary sources throughout the sedimentation of the Yidun Group in the Changtai region. 7. Conclusion 1. Depositional ages of the Qugasi and Tumugou Formations are slightly older than 230 Ma and ca. 220–230 Ma respectively, both of which are significantly older than previously thought. 2. The Yidun Group in the Changtai region has two prominent detrital zircon age peaks at ~ 400–480 and ~ 880–980 Ma with a minor peak at ~ 2.45–2.50 Ga, whereas the Yidun Group in the Shangri-La region has five major detrital zircon age peaks at ~ 220–240 Ma, ~ 400–480 Ma, ~ 720–1000 Ma, ~ 1.75–1.90 Ga and ~ 2.40–2.50 Ga.

B.-Q. Wang et al. / Sedimentary Geology 289 (2013) 74–98

3. The Yidun Group in the Changtai region received dominantly and uniformly recycled materials from the Zhongza Massif. In contrast, the Yidun Group in the Shangri-La region accumulated detritus mainly sourced from the Zhongza massif in its lower part (Qugasi Formation), and received mixed sediments from the Zhongza Massif and local Triassic magmatic arc rocks as well as materials transported from the Yangtze Block in the upper part (Tumugou Formation), which indicates transition from a passive margin to a magmatic arc setting in the southern Yidun Terrane. 4. In the southern Yidun Terrane, the subduction of the Ganzi-Litang Ocean initiated at ca. 230 Ma, and the amalgamation between the Yidun Terrane and the Songpan-Ganzi Terrane occurred at ca. 220–224 Ma, allowing the Yidun Terrane to supply ca. 220–240 Ma materials to the ca. 220–224 Ma strata in the “southeastern depocenter” of the Songpan-Ganzi Terrane. Acknowledgments We thank Xiao Fu, Liang Qi, Pingping Liu and Liang Li for their assistance in the laboratory. We gratefully acknowledged the constructive reviews by two anonymous referees and editorial handling by Dr. G.J. Weltje. This study was supported by the Natural Science Foundation of China (41172191), National Basic Research Program of China (2009CB421001), a 973 match grant from CRCG of the University of Hong Kong and the 111 Project (B07011). References BGMRSP, Bureau of Geology and Mineral Resources of Sichuan Province, 1991. Regional geology of Sichuan Province. Geological Memoirs of PRC Ministry of Geology and Mineral Resources, Series 1 (in Chinese with English summary), 23. Geological Publishing House, Beijing (730 pp.). Bhatia, M.R., Crook, K.A.W., 1986. Trace element characteristics of graywackes and tectonic setting discrimination of sedimentary basins. Contributions to Mineralogy and Petrology 92, 181–193. Bruguier, O., Lancelot, J.R., Malavieille, J., 1997. U–Pb dating on single detrital zircon grains from the Triassic Songpan–Ganze flysch (Central China): provenance and tectonic correlations. Earth and Planetary Science Letters 152, 217–231. Cai, H.M., Zhang, H.F., Xu, W.C., Shi, Z.L., Yuan, H.L., 2010. Petrogenesis of Indosinian volcanic rocks in Songpan–Garze fold belt of the northeastern Tibetan Plateau: new evidence for lithospheric delamination. Science China-Earth Sciences 53, 1316–1328. Cawood, P., Nemchin, A., 2001. Paleogeographic development of the east Laurentian margin: constraints from U–Pb dating of detrital zircons in the Newfoundland Appalachians. Geological Society of America Bulletin 113, 1234–1246. Chang, C.F., 1997. Geology and Tectonics of Qinghai-Xizang Plateau. Science Press, Beijing (153 pp.). Chang, E.Z., 2000. Geology and tectonics of the Songpan–Ganzi fold belt, southwestern China. International Geology Review 42, 813–831. Chen, B.W., et al., 1987. Geotectonics of the Nujiang–Lancangjiang–Jinshajiang Region. (in Chinese) Geological Publishing House, Beijing (204 pp.). Chu, N.C., et al., 2002. Hf isotope ratio analysis using multi-collector inductively coupled plasma mass spectrometry: an evaluation of isobaric interference corrections. Journal of Analytical Atomic Spectrometry 17, 1567–1574. Dewey, J., Shackleton, R., Chang, C.F., Sun, Y.Y., 1988. The tectonic evolution of the Tibetan plateau. Philosophical Transactions of the Royal Society of London. Series A. Mathematical and Physical Sciences 327, 379–413. Dickinson, W.R., 1988. Provenance and sediment dispersal in relation to paleotectonics and paleogeography of sedimentary basins. In: Kleinspehn, K.L., Paola, C. (Eds.), New Perspectives in Basin Analysis. Springer-Verlag, New York, pp. 3–25. Dickinson, W.R., et al., 1983. Provenance of North American Phanerozoic sandstones in relation to tectonic setting. Geological Society of America Bulletin 94, 222–235. Enkelmann, E., et al., 2007. How was the Triassic Songpan–Ganzi basin filled? A provenance study. Tectonics 26. http://dx.doi.org/10.1029/2006TC002078. Gehrels, G., et al., 2011. Detrital zircon geochronology of pre-Tertiary strata in the Tibetan–Himalayan orogen. Tectonics 30. http://dx.doi.org/10.1029/2011TC002868. Griffin, W.L., Belousova, E.A., Shee, S.R., Pearson, N.J., O'Reilly, S.Y., 2004. Archean crustal evolution in the northern Yilgarn Craton: U–Pb and Hf-isotope evidence from detrital zircons. Precambrian Research 131, 231–282. Gu, X.X., 1994. Geochemical characteristics of the Triassic Tethys-turbidites in northwestern Sichuan, China: implications for provenance and interpretation of the tectonic setting. Geochimica et Cosmochimica Acta 58, 4615–4631. Guynn, J., Kapp, P., Gehrels, G.E., Ding, L., 2012. U–Pb geochronology of basement rocks in central Tibet and paleogeographic implications. Journal of Asian Earth Sciences 43, 23–50. Hacker, B.P., Ratschbacher, L., Liou, J.G., 2004. Subduction, collision and exhumation in the ultrahigh-pressure Qinling–Dabie orogen. In: Malpas, J., Fletcher, C.J.N., Ali, J.R.,

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