Neoproterozoic peraluminous granitoids in the Jiangnan Fold Belt: Implications for lithospheric differentiation and crustal growth

Accepted Manuscript Neoproterozoic peraluminous granitoids in Jiangnan Fold Belt: Implications for lithospheric differentiation and crustal growth Hang Liu, Jun-Hong Zhao PII: DOI: Reference:

S0301-9268(16)30353-9 http://dx.doi.org/10.1016/j.precamres.2017.05.001 PRECAM 4761

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Precambrian Research

Received Date: Revised Date: Accepted Date:

2 September 2016 26 March 2017 2 May 2017

Please cite this article as: H. Liu, J-H. Zhao, Neoproterozoic peraluminous granitoids in Jiangnan Fold Belt: Implications for lithospheric differentiation and crustal growth, Precambrian Research (2017), doi: http:// dx.doi.org/10.1016/j.precamres.2017.05.001

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Neoproterozoic peraluminous granitoids in Jiangnan Fold Belt: Implications for lithospheric differentiation and crustal growth

Hang Liu 1, 2

Jun-Hong Zhao 1, 2*

1 State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China 2. School of Earth Sciences, China University of Geosciences, Wuhan 430074, China

Corresponding author: [email protected]

Abstract Neoproterozoic magmatism in the Jiangnan Fold Belt of South China is characterized by voluminous ca. 820 Ma peraluminous granitoids which show a large range of chemical compositions. The Meixian dioritic and the Lantian granitic intrusions from the central Jiangnan Fold Belt were emplaced at 821± 6 Ma and 823 ± 7 Ma, respectively. The Meixian diorites are mainly composed of amphibole (10-40 %), biotite (5-30 %), plagioclase (30-60 %) and quartz (5-10 %). They have low SiO2 (59.42-63.15 wt.%), moderate MgO (2.96-3.56 wt.%) and Na2O (3.51-4.39 wt.%), and relatively high V (102-137 ppm) and Cr (47.1-58.7 ppm). They show nearly zero εNd (-0.6 to -0.1) and high εHf values (+2.3 to +10.6). These mineralogical and geochemical features suggest that mantle-derived melts were

involved

in their

petrogenesis.

Modeling

calculations reveal that the Meixian diorites were formed by fractional crystallization of mantle-derived melts associated with 10-30% contamination by the country rocks. However, the Lantian granites are fractionated I-type granites that are composed of plagioclase (10-25 %), quartz (30-40 %), K-feldspar (15-20%), biotite (5-15 %) and amphibole (5%). They have high SiO2 (72.3-80.2 wt.%), moderate K2O (1.58-4.11wt.%) and Na2O (2.78-3.94 wt.%), and low MgO (0.50-0.80 wt.%) and CaO (0.16-0.50 wt.%). Their negative εNd (-2.3 to -1.4) and positive εHf values (+0.4 to +9.9) are similar to those of the Neoproterozoic arc-affinity mafic rocks in the region, suggesting that the Lantian granites were derived from the mafic juvenile crust. The

Neoproterozoic igneous rocks in the Jiangnan Fold Belt are mainly composed of peraluminous granites with minor diorites. The large volume of peraluminous granitoids are generally partial melts of the continental crust, whereas the limited diorites are differentiation products of the basaltic magmas. The petrogenesis of the granitoids in the Jiangnan Fold Belt suggests that basaltic magma underplating triggered crustal anatexis during or after collision between the Yangtze and Cathaysia Block. Key words: Peraluminous granitoids; Neoproterozoic; Jiangnan Fold Belt; South China.

1. Introduction Peraluminous granitoids, comprising S- and some I-type granitoids, are widespread in various tectonic settings, but generally formed within tectonically thickened crust during or after continental collision (Barbarin, 1996; Simons et al., 2016). S-type granites are considered to be produced by melting of weathered supracrustal rocks (Chappell and White, 1992, 2001; Clemens, 2003). Experimental and geochemical evidences suggest that metaigneous rocks are also involved in their petrogenesis (Patiño Douce and Beard, 1995; Martínez et al., 2014; Simons et al., 2016). I-type granites are traditionally supposed to be products of infracrustal anatexis (White and Chappell, 1977; Chappell and White, 1992, 2001; Clemens, 2003); their geochemical variations probably depend on crust heterogeneity (Clemens and Stevens, 2012; Kemp

and Hawkesworth, 2014), melting condition (Patiño Douce, 1999), fractional crystallization (Wyborn et al., 2001), crystal entrainment and unmixing (Chappell et al., 1987; Clemens, 2003; Stevens et al., 2007). Nevertheless, mantle-derived melts are also suggested to be necessary components for some I-type granitoids (Collins, 1996; Soesoo, 2000; Kemp et al., 2007; Clemens et al., 2016); their geochemical variations are alternatively considered to have resulted from magma mixing of crustal- and mantlederived materials (Depaolo et al., 1992; Dias et al., 2002; Weidendorfer et al., 2014). Thus, both I- and S-type granites are good carriers to investigate the crustal growth and reworking process during their formation. The Yangtze Block underwent strong crustal growth and reworking during the Neoproterozoic (Zheng et al., 2007, 2008a, b, 2013; Zhao and Cawood, 2012; Zhang and Zheng, 2013). Neoproterozoic igneous rocks are widespread along the margins of the Yangtze Block and their formation was closely related to the assemblage and breakup of the supercontinent Rodinia (Li et al., 1999; Cawood et al., 2013). The magmatism in the southeastern margin of the Yangtze Block is characterized by voluminous peraluminous S- and I-type granitoids associated with minor mafic and ultramafic rocks (Li, 1999; Li et al, 1999, 2003; Wang et al., 2004, 2013; Zheng et al., 2007, 2008a; Zhao et al., 2011; Zhang et al., 2013; Zhao and Aismow, 2014). The peraluminous granitoids are suggested to have been formed by partial melting of supracrustal and infracrustal rocks in syn-collisional or rift settings during

orogenic collapse at ca. 820 Ma (Li et al., 2003; Wu et al., 2006; Zheng et al., 2007, 2008a; Wang et al., 2013, 2014; Yao et al., 2014). However, it is still unclear whether mantle-derived materials were involved in the petrogenesis of those peraluminous I-type granitoids (Chen et al., 2014) and whether the metaigneous rocks were participated in formation of the S-type granites. In this paper, we present new zircon U-Pb ages, major and trace elements, and Sr-Nd-Hf isotopes of the two typical intermediate and felsic intrusions (Meixian and Lantian plutons) from the central Jiangnan Fold Belt to discuss their petrogenesis. Combined with the other 820 Ma intermediate to felsic rocks in the region (Li et al., 2003; Chen et al., 2014), a revised model is proposed for their formation. 2. Geological background South China comprises the Yangtze Block and the Cathaysia Block which were joined together along the Jiangnan Fold Belt during the Neoproterozoic (Fig.1a; Zheng et al., 2013; Zhao, 2015). The Jiangnan Fold Belt mainly consists of the Early Neoproterozoic strata that are unconformably overlain by the Middle Neoproterozoic strata (Wang and Li, 2003). The Early Neoproterozoic Lengjiaxi Group and its equivalents (e.g. Sibao Group in Guangxi province) underwent greenschist-facies metamorphism, and consists of tholeiitic and boninitic lavas in the lower part (Zhang et al., 2013; Zhao and Asimow, 2014) and flysch turbidite sequences in the upper section. The tholeiitic and boninitic lavas are proposed to have been formed in an arc

setting during the Early Neoproterozoic (Wang et al., 2008; Zhang et al., 2013; Li et al., 2016). The sedimentary rocks from the Lengjiaxi Group comprise sandstone, siltstone, tuff, schist, phyllite and slate that were considered to have been deposited in a back-arc basin during 870 - 830 Ma based on studies of their geochemistry and zircon U-Pb ages (Wang et al., 2010a, 2012a, 2014; Wang and Zhou, 2012). The overlying Middle Neoproterozoic Banxi Group and contemporary sequences are made up of pelite, sandstone, conglomerate and minor carbonate that were deposited in the intra-continental Nanhua rift basin from 820 Ma to 715 Ma (Wang and Li, 2003; Wang et al., 2010b, 2012b). There are numerous felsic and mafic intrusions emplaced into the Early Neoproterozoic strata and are unconformably overlain by the Middle Neoproterozoic sequences. The Guibei and Jiuling peraluminous granitic complexes in the Jiangnan Fold Belt cover areas of ca. 1500 km2 and 2500 km2, respectively (Fig. 1a). The Guibei complex comprises the Sanfang, Yuanbaoshan and Bendong leucogranite intrusions and the Dongma dioritic intrusion that emplace into the Sibao Group. The Jiuling intrusion in the Jiangxi Province emplaces into the Lengjiaxi Group and consists of biotite-rich, cordierite-bearing granodiorite associated with minor two-mica leucogranite. The Meixian and Lantian intrusions in this study intrude into the Lengjiaxi Group and are unconformably overlain by the Banxi Group in the central part of the Jiangnan Fold Belt (Figs.1a and b; Hunan BGMR, 1988). They are small

plutons covering an area of 1-4 km2. Rocks from the Meixian intrusion are medium grained diorites to tonalites which are composed of amphibole (10-40 %), biotite (5-30 %), plagioclase (30-60 %), K-feldspar (5-10 %) and quartz (5-10 %). Plagioclase generally includes acicular apatite and anhedral amphibole. Amphioble are partially altered into chlorite (Fig. 2a). Rocks from the Lantian intrusion are fine-grained granites and consist of plagioclase (10-25 %), quartz (30-40 %), biotite (5-15 %), K-feldspar (15-20%) and amphibole (5%) with minor muscovite, Fe-Ti oxides and zircons. Feldspars are partially altered into sericite (Fig. 2b).

3. Analytical methods 3.1. Major and trace elements analyses Major element abundances were obtained using X-ray fluorescence (XRF) on fused glass beads at the State Key Laboratory of Geological Processes and Mineral Resources (GPMR), China University of Geosciences (CUG), Wuhan. Trace elements were analyzed on an ELAN DRC-e ICP-MS at the Institute of Geochemistry,

Chinese

Academy

of

Sciences.

Closed

beakers

in

high-pressure bombs were used to ensure complete digestion (Qi et al., 2000). Pure elemental standards were used for external calibration and BHVO-1 and SY-4 were used as reference materials. Accuracies for major elemental oxides are better than 2%, and those for trace elements by ICP-MS are constrained between 5-10%.

3.2. Rb-Sr and Sm-Nd isotopic analyses Whole-rock Sr and Nd isotopic ratios were measured by a Triton thermal ionisation mass spectrometer at the GPMR, CUG, Wuhan. Sr and Nd isotopic analytical procedures are available in Gao et al. (2004). 147Sm/144Nd

87Rb/86Sr

and

ratios were calculated from Rb, Sr, Sm and Nd concentrations

measured by ICP-MS. The measured Sr and Nd isotopic ratios were normalized to

86Sr/88Sr

= 0.1194 and

146Nd/144Nd

Analyses of NBS987 standard yield an average (2δ) and BCR-2 standard has an average

= 0.7219, respectively.

87Sr/86Sr

ratio of 0.710239±10

143Nd/144Nd

ratio of 0.512620±2

(2δ). 3.3. Zircon U-Pb dating and Lu-Hf isotope analyses Zircon grains were separated by heavy liquid and magnetic techniques, handpicked under a binocular microscope, mounted in epoxy discs and polished to expose their centers. U-Pb ages and Lu-Hf isotope analyses were conducted at the GPMR, CUG, Wuhan. Zircon U-Pb ages were analyzed using LA-ICP-MS. The 193 nm ArF excimer laser was used to ablate zircon surface with ablation diameter of 32 µm and energy of 50 mJ/pulse at a repetition ratio of 6 Hz. Carrier gas Helium efficiently transport the aerosols to the ICP-MS. Zircon 91500 was used as an external standard to correct elemental fractionation, and NIST 610 was used for quality control. Data reduction was performed off-line with ICPMSDataCal (Liu et al., 2010). The data were processed using the ISOPLOT program (Ludwig, 2003).

Zircon Hf isotopic analyses were carried out using a Resonetics Resolution M-50 193 nm excimer laser ablation system, attached to a Nu Plasma HR multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS). Zircons were ablated with a beam diameter of 44 µm and a repetition rate of 8 Hz for 30 s of each spot. Zircon 91500 was used as external calibration to evaluate the reliability of the analytical data. Detailed operating conditions and analytical methods are described by Hu et al. (2012). Interference of

176Yb

on

176Hf

was corrected against the

0.7876 (McCulloch et al., 1977). Interference of

176Lu

by measuring the intensity of the interference-free

on

175Lu

176Yb/173Yb 176Hf

ratio of

was corrected

isotope and using a

recommended 176Lu/175Lu ratio of 0.02656 (Blichert-Toft and Albarède, 1997).

4. Analytical results 4.1. Major and trace elements The Meixian diorites have high MgO (2.96-3.56 wt.%), Fe2O3 (5.22-6.27 wt.%), CaO (4.51-5.79 wt.%) and Na2O contents (3.51-4.39 wt.%) (Table 1). They are geochemically classified as diorite in the TAS diagram (Fig. 4a). The rocks are slightly peraluminous with moderate A/CNK (1.03-1.12) and high A/NK ratios (2.26-2.69) (Fig. 4b). They belong to the calcic and magnesian series (Figs. 4c-d). The Meixian diorites show LREE-enriched REE patterns with slightly positive Eu anomalies (Eu/Eu* = 1.13-1.23; Fig. 5a). Their spider diagrams show enrichment of Rb, Ba, Th and U and depletion of Nb and Ta

with positive Pb and Sr anomalies (Fig. 5b). The Lantian granites have low MgO (0.42-0.80 wt.%) and CaO (0.16-0.50 wt.%), high K2O (1.58-4.11 wt.%), Na2O (2.78-3.94 wt.%) and Al2O3 (11.5-15.1 wt.%) (Table 1). These rocks show strong peraluminous affinities with high A/CNK (1.24-1.75) and A/NK ratios (1.34-1.83) due to high alkali contents (Figs. 4a-b). They are calc-alkalic in composition (Fig. 4c) and also belong to the magnesian series (Frost et al., 2001). The Lantian granites show LREE enriched REE patterns (LaN/YbN = 9.26-18.87) with variable negative Eu anomalies (Eu/Eu* = 0.51-0.70) (Fig. 5a). Their primitive mantle normalized trace-element patterns are characterized by enrichment of LILE and depletion of Nb and Ta with positive Zr-Hf and negative Sr and Ti anomalies (Fig. 5b). 4.2. Whole rock Sr-Nd isotopic compositions Initial

87Sr/86Sr

ratios and εNd values are calculated back to the

emplacement ages of 820 Ma (Table 2). The Meixian diorites have low initial 87Sr/86Sr

ratios (0.698911 to 0.705695) and nearly zero εNd values (-0.6 to

-0.1). However, the Lantian granites show a wide range of initial

87Sr/86Sr

ratios (0.665728 to 0.698997) and negative εNd values (-2.3 to -1.4). Three samples (MX60, LT04 and LT08) in this study have very low initial ratios that were probably caused by high

87Rb/86Sr

87Sr/86Sr

ratios due to the early

disturbance of the Rb-Sr system by hydrothermal alteration (Table 2). 4.3. Zircon U-Pb ages Zircon grains from the Meixian diorites (sample MX52) are subhedral to

euhedral, transparent and colorless. The crystal length ranges from 80 to 150 µm with length/width ratios of 1:1 to 3:1. Most grains contain unzoned or weakly zoned interior rimed by clear oscillatory zoning belts; few grains contain inherited cores (Fig. 6a). Two grains display old ages (MX52-08 and MX52-09), probably inherited from source region or introduced from wall rocks (Table 3; Fig. 7a). The remaining analyses yield concordant or nearly concordant 206Pb/238U

ages ranging from 802 ± 8.0 Ma to 852 ± 8.0 Ma and produce a

weighted mean age of 821 ± 6 Ma (n=22, MSWD=2.2; Fig. 7a). Subhedral to euhedral zircons from the Lantian granites (sample LT01) are also transparent and colorless. The grains are 80-150 µm in length with aspect ratios of 1:2 to 1:3. Zircon microstructures are characterized by unzoned interior surrounded by oscillatory-zoned rims (Fig. 6b). Three analysis deviate from the concordia line (LT01-01, LT01-05, LT01-06; Fig. 7b) and probably resulted from Pb loss. Two inherited cores (LT01-07, LT01-08) show old U-Pb ages (938 ± 9.7 Ma and 874 ± 11.5 Ma). The remaining magmatic zircons display

206Pb/238U

ages from 808 ± 7.0 Ma to 843 ± 8.9 Ma, yielding a

weighted mean age of 823 ± 7 Ma (n=10, MSWD=1.6; Fig. 7b). 4.4. Zircon Lu-Hf isotopes Magmatic zircons from the Meixian diorites display positive εHf values ranging from +2.3 ± 0.7 to +10.6 ± 0.9 with an average value of +8.2 ± 0.6 (1σ) (Table 4). Their single-stage model ages are from 0.96 Ga to 1.28 Ga and two-stage model ages from 1.05 Ga to 1.58 Ga. The two inherited grains

(MX52-08 and MX52-09) display εHf values of +9.3 and -1.6, respectively. Magmatic zircons from the Lantian granites show larger variable εHf values (+0.4 ± 0.6 to +9.9 ± 0.7) with an average value (+6.5 ± 0.6) (Table 4, Fig. 8). Their single- and two-stage Hf model ages vary from 1.01 to 1.38 Ga and from 1.11 to 1.71 Ga, respectively. Two inherited grains (LT01-07 and LT01-08) show high εHf values (+10.1 and +12.4).

5. Discussion 5.1 Meixian diorites formed by differentiation of mafic magmas Partial melting of the lower mafic crust (Chappell and White, 1992, 2001; Clemens, 2003) and differentiation of mafic magmas (Soesoo, 2000; Kemp et al., 2007) are general models for diorite formations. Early Neoproterozoic (850-830 Ma) arc-affinity mafic and ultramafic igneous rocks are widespread in the Jiangnan Fold Belt, recording progressive enrichment of the lithospheric mantle and crustal growth during the subduction (Zhang et al., 2013; Zhao and Asimow, 2014). The Meixian diorites show initial Nd isotopes similar to those of the ca. 830 Ma arc-affinity basalts, implying that the diorites were probably generated by partial melts of the juvenile mafic crust that was chemically similar to the arc-affinity basalts. Sisson et al. (2005) suggests that partial melting of K-depleted basaltic materials generally produces low-K intermediate to felsic melts. The Meixian diorites have low K2O contents, whereas the arc-affinity basalts have moderate K2O content (Fig. 9a). The Meixian diorites

also have higher MgO (2.99-3.56 wt. %), Cr (47.1-58.7 ppm) and Ni (50.3-63.5 ppm) than the partial melts of the lower mafic crust (Fig. 9b). In addition, their high and variable amounts of biotite (5-30 %) and amphibole (10-40 %), indicating high H2O contents in the melts (Naney, 1983; Bogaerts et al., 2006; Lu et al., 2015). High amphibole contents did not result from mineral accumulation because of constant Dy/Yb ratios (1.62-1.81; Fig. 9c). These lines of evidence suggest that the Meixian diorites were not partial melts of mafic crust, but more likely differentiation products of the mantle-derived melts. Fractionalization of basaltic magmas with or without crustal contamination is an alternative way to generate intermediate rocks. It was possible that the parental magmas of the Meixian diorites were chemically similar to the mafic and ultramafic rocks. The Meixian diorites have εNd values (-0.6 to -0.1) that are significantly lower than those of the 850-Ma MORB-like tholeiites (+9.4 to +4.7, Zhang et al., 2013), but similar to those of the 830-Ma crustal contaminated arc-affinity rocks (-4.0 to -1.9; Figs. 10a-c). Their high Th/Sc (0.12 - 0.23) and La/Sm ratios (4.2 - 5.2) form a positive correlation that is inconsistent with the fractional crystallization trend of the basaltic magma (Fig. 9d). Inherited zircons have also been found in the diorites (Fig. 6a). Thus, an open magmatic system was required for the formation of the Meixian diorites. Crustal materials were involved in the Meixian diorites either by magma mixing or AFC processes. Magma mixing between the mantle- and crust-derived melts, represented by the MORB-like tholeiites or arc-affinity

basalts and the Lantian granites, respectively, cannot explain the geochemical variations of the Meixian diorites (Figs. 10a-b). Therefore, AFC probably was the key process in the petrogenesis of the Meixian diorites. Two main potential crustal contaminants include the Archean basement rocks and the Neoproterozoic metasedimentary country rocks. The Kongling metamorphic complex is the only Archean unit cropped out in South China (Gao et al., 1999; Zhang et al., 2006), and is suggested to be widespread beneath the Yangtze Block (Zheng et al., 2006). The country rocks, such as the Early Neoproterozoic sediments, are also widely distributed along the southeastern Yangtze Block (Fig. 1). Inherited zircons identified in the Meixian diorites show Neoproterozoic ages and Hf isotopic compositions within the range of the Lengjiaxi Group (Fig. 8), implying that the sedimentary rocks from the Lengjiaxi Group are appropriate contaminants. AFC calculations reveal that most samples fit well with the crustal assimilation curves defined by the rocks from the Lengjiaxi Group (Figs. 10a-c). 10%-20% assimilation of sediments for the tholeiitic basalts or 20%-30% for the boninitic basalts can explain the elemental and isotopic compositions of the Meixian diorites (Figs. 10a-c).

5.2. Lantian I-type granites derived from the juvenile crust 5.2.1 Classification of the Lantian granites Granites are broadly subdivided into I- and S- types which have different lithology and geochemistry according to the studies of the Paleozoic granites

from the Lachlan Fold Belt in SE Australia (White and Chappell, 1977; Collins, 1996; Chappell and White, 2001). Both minerals and chemical compositions of the Lantian granites are akin to those of the I-type suites. The Lantian granites contain amounts of mafic minerals, such as biotite (5-15 %) and amphibole (5%), which are rare in S-type granites (Chappell and White, 1992). The Lantian granites are strongly peraluminous and show a positive correlation between A/CNK (1.29-1.79) and A/NK (1.34-1.83) that probably resulted from feldspar alteration rather than inherited from the source region (Figs. 2d and 4b). The Lantian granites display negative εNd (-2.3 to -1.4) and positive εHf values (+2.9 to +10.1). In addition, their δ18O values (+5.9 to +8.4‰) are slightly higher than δ18O values of mantle-like zircons (5.3 ± 0.6 ‰; Valley et al., 1998), but significantly lower than those of the supracrustal-derived Guibei granites (δ18O = 8.8-11.6 ‰; Li, 1999; Wang et al., 2013; Zhao et al., 2013). Thus, the Lantian granitoids are considered to be typical I-type granites. 5.2.2. Partial melting of the juvenile crust It has long been a matter of debate whether I-type granites are differentiation products of mantle-derived melts (Depaolo et al, 1992; Soesoo, 2000; Beard et al., 2005; Jacob et al., 2015; Keller et al., 2015) or partial melts of pre-existing igneous rocks (Petford and Atherton, 1996; Chappell and White, 2001; Whalen et al., 2002). The Lantian granites are highly fractionated I-type granites which are synchronous with the Meixian diorites (Fig. 7). The two types of rocks show similar whole-rock εNd and zircon εHf values (Figs. 8 and

10a-b), suggesting that the Lantian granites were probably comagmatic with the Meixian diorites. If that was the case, the Lantian granites should have higher incompatible trace element concentrations than the Meixian diorites. However, rocks from the two intrusions show similar LILE and LREE concentrations (Fig. 5, Table 1). In the plot of La/Sm vs. Th/Sc and La, the Lantian granites follow a positive trend, different from the fractional crystallization trend (Fig. 9d, e). These chemical evidences rule out the possibility that the Lantian granites were fractionated from the Meixian diorites. Although the granites and diorites form a linear correlation between Rb and Ba (Fig. 9f), they show similar Rb and Ba concentrations (such as MX60 and LT01) that may have resulted from feldspar alteration. Melting of metaigneous rocks is probably the only process to explain the generation of the Lantian I-type granites (e.g. Rapp and Watson, 1995; Petford and Atherton, 1996; Sisson et al., 2005). Previous studies revealed that some ca. 820 Ma felsic rocks in the Jiangnan Fold Belt show high εHf, moderate εNd and mantle-like zircon δ18O values, and thus were proposed to have been derived from the mafic juvenile crust (Wu et al., 2006; Zheng et al., 2007; Zhao et al., 2013). The Lantian granites show relatively low δ18O values (+5.9 to +8.4‰; Zhao et al., 2013). Their negative εNd values (-2.3 to -1.4) are within the range of the 830 Ma arc-affinity basalts (-4.0 to -1.9) (Figs. 10a-c; Zhao and Asimow, 2014), suggesting that they were more likely to have been derived from the newly formed mafic crust. The older zircon grains (LT01-07,

08) probably inherited from their source regions. The Lantian granites show high silica (72.30-80.24 wt.%) and low CaO content (0.16-0.5 wt.%), which are rarely observed in the partial melts of basaltic rocks (Patiño Douce, 1999), indicating fractional crystallization of Ca-bearing minerals during emplacement. Their Al2O3 and K2O are negatively correlated with SiO2, implying K-feldspar fractionation. Fe2O3 and TiO2 decreasing with SiO2 increasing probably resulted from Fe-Ti oxides separation (Fig. 3). The fractional crystallization processes are also supported their positive correlations in the plots of Th/Sc and La against La/Sm (Fig. 9d, e). Thus, the Lantian granites were produced by partial melting of mafic crust and underwent significant fractionation.

5.3. Interaction between the mantle and crust in the Jiangnan Fold Belt Neoproterozoic diorites and granitoids in the Jiangnan Fold Belt show large variable geochemical compositions, and contain important information of crustal growth and differentiation. The diorites, such as rocks from the 830 Ma Dongma intrusion in Guangxi Province, contain high contents of amphibole and biotite (Li et al., 2003; Chen et al., 2014). They have low SiO2 (59.21-66.55 wt.%)and high MgO contents (3.37-8.29 wt.%), as well as high Ni (47.2-194 ppm), V (24.3-113 ppm) and Sc (5.56-16.8 ppm) concentrations (Li et al., 2003). The decoupling of Cr# and Mg# and the occurrence of quartz + apatite minerals in chromites suggest that the Dongma diorites were formed by mixing between the basaltic magmas and

the crust-derived melts (Chen et al., 2014). AFC modeling suggests that the Dongma diorites may also have been formed by fractional crystallization of basaltic magmas associated with assimilation by the country rocks from the Sibao Group (Figs. 10a-c). The Meixian diorites in this study further demonstrate that basaltic melts contributed to the petrogenesis of the Neoproterozoic diorites in the Jiangnan Fold Belt. The S-type granitoids in the Jiangnan Fold Belt are typically represented by the Guibei granites and the Jiuling granodiorites (Fig. 1a). Both experiments (Patiño Douce and Harris, 1998; Koester et al., 2002) and theoretical calculations (Harris and Inger, 1992; Guo and Wilson, 2012) revealed that peraluminous S-type leucogranites could be formed by incongruent melting of metasediments in equilibrium with plagioclase, K-feldspar and biotite and some accessory minerals (such as allanite and zircon). The Guibei granites contain tourmaline, muscovite and biotite, and have high SiO 2 (74.95-77.72 wt.%) and low MgO contents (0.13-0.41 wt.%), as well as low Na2O/K2O (0.46-0.87) and Sr/Rb (0.02-0.29) ratios (Fig. 3), similar to the melts produced by fluid absent melting of muscovite-rich schist under low pressures (Figs. 11a-b; Patiño Douce and Harris, 1998). They also show low εHf (-24.9 to +5.6), εNd (-9.0 to -4.5) and high δ18O values (8.8 to 11.6 ‰), consistent with their supracrustal origin (Wang et al., 2013). However, the Jiuling granitoids comprise mainly of biotite-rich, cordierite-bearing granodiorites that generally contain dioritic enclaves. They display large variable compositions that are in

the range between the diorites and the granites (Fig. 3) and vary from the melts of amphibolites to those of supracrustal rocks (Figs. 11a-b). They show nearly zero εNd (-2.06 to +0.02) and positive εHf values (+3.4 to +5.4) (Fig. 8; Li et al., 2003; Wu et al., 2006; Wang et al., 2013; Zhao et al., 2013). These features rule out the possibility that the Jiuling granodiorites were produced by assimilation or mixing of basaltic magmas due to their isotopic compositions matching more than 80% crustal contaminants (Figs. 10a-c), but suggest that they were formed by magma mixing (Zhao et al., 2013) or derived from a heterogeneous source (Wu et al., 2006; Wang et al., 2013). Thus, both infraand supracrustal rocks were involved in the petrogenesis of S-type granites (Fig. 11a-b). Combined with the I-type Lantian granites in this study, melts derived from the supracrust, juvenile lower mafic crust and the mantle source were more or less involved in the petrogenesis of the peraluminous granitoids in the Jiangnan Fold Belt (Figs. 10a-c). Underplating of the basaltic magmas triggered crustal anatexis at different levels and then mixed among them with variable proportions. The limited outcrop of diorites suggests that less mantle-derived magmas were involved in the formation of the peraluminous granitoids, similar to that of Lachlan Fold Belt (Clemens et al., 2016). The lithosphere differentiation and crustal growth process is very similar to the magmatism at deep crustal hot zones in continental arc settings (Annen et al., 2006). The ca. 820 Ma granites are dominated by S-type granites with minor

I-type granites, suggesting that they were formed syn- or after the collision of the Yangtze and Cathaysia Block.

6. Conclusion (1) The Meixian diorites and the Lantian granites were emplaced at ca. 820 Ma. The Meixian diorites were produced by fractional crystallization of basaltic magmas associated with crustal assimilation, whereas the Lantian granites were formed by dehydration melting of the juvenile crust. (2) The Neoproterozoic felsic-intermediate igneous rocks in the Jiangnan Fold Belt comprise S- and I-type granites, and minor diorites. Melts derived from the lithospheric mantle initiated partial melting of the lower mafic juvenile crust and the supralcrustal rocks, mixing among them generated various types of granitoids in the Jiangnan Fold belt. The Neoproterozoic peraluminous granitoids were formed during or after collision between the Yangtze and Cathaysia Blocks.

Acknowledgement This work was substantially supported by the National Nature Science Foundation of China (41373016, 41573020) and the research program of the State Key Laboratory of Geological Processes and Mineral Resources (MSF GPMR06). Reviews by three anonymous referees are gratefully acknowledged.

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Figure captions Figure. 1. (a) Simplified geological map of the Neoproterozoic granitoids in the Jiangnan Fold Belt (modified from Zhao et al., 2013); (b) Geological map of the Meixian and Lantian intrusions.

Figure. 2. Photomicrographs of the Meixian diorite and the Lantian granite. (a) The Meixian diorites consist of plagioclase, quartz, K-feldspars, amphibole and biotite; (b) The Lantian granites consist of amphibole, quartz and feldspars. Am: Amphibole; Bi: Biotite; Pl: Plagioclase; Kf: K-feldspar; Ms: Muscovite; Q: Quartz; Ap: Apiatite.

Figure. 3. Harker diagrams of the Meixian diorites and Lantian granites. The Neoproterozoic diorites and granitoids in the Jiangnan Fold Belt are shown for comparison (Li et al., 2003; Chen et al., 2014).

Figure. 4. Plots of total alkalis vs. SiO2 (Middlemost, 1994), molar Al/(Na + K) vs. Al/(Ca + Na + K) (Maniar and Piccoli, 1989), Na 2O + K2O - CaO vs. SiO2 and FeOt/(FeOt +MgO) vs. SiO2 (Frost et al., 2001) for the Meixian diorites and Lantian granites. The greyish fields are the same as in Fig.3.

Figure. 5. (a) Chondrite-normalized REE patterns and (b) primitive mantle-normalized trace-element diagrams for the Meixian diorites and

Lantian granites. Normalizing values are from Sun and McDonough (1989).

Figure. 6. Cathodoluminescence (CL) images of representative zircons from the Meixian diorites and Lantian granites.

Figure. 7. Zircon U-Pb Concordia diagrams for the Meixian diorites and the Lantian granites.

Figure. 8. Plot of εHf vs. U-Pb ages (Ma) for zircons with concordant ages from the Meixian diorites and the Lantian granites. εHf values are calculated to individual crystallization age. The Jiuling granodiorites, the Guibei granites and the Lengjiaxi sediments are shown for comparison (Zhao et al., 2013; Wang et al., 2014). Reference lines of chondrite and depleted mantle are from Blichert-Toft and Albarède (1997) and Griffin et al. (2000), respectively.

Figure. 9. Whole-rock chemical variations for the Meixian diorite and Lantian granite. The ca. 850-Ma tholeiitic and 830-Ma boninitic basalts (Zhang et al., 2013; Zhao and Aismow, 2014) and the sedimentary rocks from the Lengjiaxi Group (Gu et al., 2002) are also shown for comparison.

Figure. 10. Plots of Th/Zr, Th/Nb and Th/Ni ratios against εNd for the Meixian diorites and Lantian granites. The tholeiitic and boninitic basalts represent the

mantle-derived melts (Zhang et al., 2013; Zhao and Aismow, 2014). Calculations reveal that the Meixian diorites were produced by fractional crystallization of the mantle-derived melts associated with assimilation by the country rocks from the Lengjiaxi Group (solid lines), rather than by mixing between the tholeiitic or boninitic basalts and the Lantian granites (dotted lines). Similarly, the Dongma diorites could be explained by AFC processes of the mantle-derived melts by the sedimentary rocks from the Sibao Group (bold line). Numbers along the lines are percentages of crustal contamination. Fields of the Dongma diorite, Jiuling granodiorite and Guibei granite are the same as in Fig. 3.

Figure. 11. Plots of CaO+MgO+FeOt+TiO2 vs. CaO/(MgO+FeOt+TiO2) (a) and Al2O3+MgO+FeOt+TiO2 vs. Al2O3/(MgO+FeOt+TiO2) (b) for the peraluminous granitiods in the Jiangnan Fold Belt. Fields of experimental melts derived from pelites, greywackes and amphibolites/metabasalts are from Patiño Douce (1999).

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6

20

Meixian diorite Lantian granite granodiorite

CaO (wt.%)

Al2O3 (wt.%)

18

16

14

4

granodiorite

2

diorite

diorite

12

granite

granite

0

10 55

65

75

55

85

65

SiO2 (wt.%)

85

SiO2 (wt.%)

8

6

granite

granodiorite

6 granodiorite

K2O (wt.%)

Fe2O3 (wt.%)

75

diorite

4

granite

4 diorite

2 2

0

0 55

65

75

85

55

65

SiO2 (wt.%) 10

85

5

8

granodiorite

6

Na2O (wt.%)

MgO (wt.%)

75

SiO2 (wt.%)

diorite

4

3

granite

2

diorite

granite

granodiorite

0

1 55

65

75

85

55

65

75

85

SiO2 (wt.%)

SiO2 (wt.%) 0.3

1.0 granodiorite

0.2

TiO2 (wt.%)

P2O5 (wt.%)

0.8 granite

granodiorite

0.6

0.4

diorite

0.1 0.2 diorite

granite

0.0

0.0 55

65

75

85

55

SiO2 (wt.%)

Fig.3 Liu and Zhao

65

75

SiO2 (wt.%)

85

9

3.0

7

(b)

Quartz Monzonite

Peraluminous

Diorite

2.5

Metalum inous

Monzonite

A/NK

Na2O+K2O (wt.%)

(a)

1.5

Granite

5

2.0

Granodiorite

Granite Diorite

1.0

Granodiorite

3 55

65

Meixian diorite

Peralkaine

75

Lantian granite

0.5

85

0.5

1.0

1.5

SiO2 (wt.%)

2.5

3.0

A/CNK 1.0

12

(c)

(d)

Granite

Granodiorite

8

Granite

FeOt/(FeOt+MgO)

Na2O+K2O-CaO (wt.%)

2.0

Alkalic

4

ic alc c li ka lic Al lka a lc Ca

0

0.8

Ferroan

Granodiorite 0.6

Magnesian Diorite

Diorite

Calcic -4 55

65

75

85

0.4 55

SiO2 (wt.%)

Fig.4 Liu and Zhao

65

75

SiO2 (wt.%)

85

100

Sample/Chondrite

(a)

10

Meixian diorite Lantian granite 1 La Ce Pr Nd

Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

1000

Sample/Primitive mantle

(b) 100

10

1

0.1 Rb Th Ta La Pb Sr Zr Sm Ti Tb Y Er Yb Ba U Nb Ce Pr Nd Hf Eu Gd Dy Ho Tm Lu

Fig.5 Liu and Zhao

(a)

MX52-07 813±8.1 9.0±0.6 MX52-03 810±8.1 8.1±0.6

MX52-01 815±11.3 8.1±0.5

MX52-04 833±10.0 8.8±0.8 MX52-21 814±7.5 8.8±0.6

MX52-09 894±10.2 -1.6±0.6

MX52-13 820±9.9 7. 9±0.7

MX52-17 819±9.2 8.5±0.5

(b) LT01-04 820±6.9 4.9±0.6

LT01-02 830±11.9 2.7±0.8

LT01-03 826±7.6 4.5±0.6

LT01-07 933±10.3 10.1±0.6

LT01-14 808±7.0 8.8±0.4 LT01-10 843±8.9 9.9±0.7

U-Pb pit

LT01-12 826±7.4 0. 4±0.6

Hf pit

Fig.6 Liu and Zhao

LT01-15 817±7.9 4.5±0.6

0.16

(a) MX52 from the Meixian pluton

940

900

206

Pb/238 U

0.15 206

09

238

Mean Pb/ U weight

age of 22 spots=821±6Ma MSWD=2.2

08

860

0.14

820

0.13

780

0.9

1.1

1.3 207

Pb/

0.17

235

1.5

U

1000

(b) LT01 from the Lantian pluton 0.16

07

900 08 01

0.14

206

Pb/238 U

0.15

800

206

238

Mean Pb/ U weight

0.13

05

age of 10 spots=823±7Ma MSWD=1.6

06

0.12

0.9

1.1

1.3

1.5 207

Pb/

1.7 235

1.9

U

Fig.7 Liu and Zhao

2.1

2.3

20

10

Dep

1 .1 G a

lete

dm

ant

εHf(t)

1.4Ga

0

-10

le

Chondrite 1 .8 G a

Jiuling granodiorite

Lengjiaxi Group Guibei granite Meixian diorite Lantian granite

-20 700

800

900

1000

2000

Age(Ma)

Fig.8 Liu and Zhao

magmatic inherited magmatic inherited

3000

4000

6

(a) S N

(b)

Lantian granite

Nakajima and Arima.1998

3

4 Boninitic basalt

3

experiment melts composition

2 1

Meixian diorite

Sisson et al., 2005

MgO (wt.%)

K 2 O (wt.%)

5

4 Starting material

S

Wang et al., 2006

experimental melts

2

1

S N

0

0 45

50

55

60

65

70

75

50

80

60

SiO 2 (wt.%) 2.0

70

80

90

SiO 2 (wt.%) 10

(c)

(d)

1

2

3

g in ix

4 AF

C

or

Boninitic basalt

2 Tholeiitic basalt

0 0.0

1.0 0

Lengjiaxi Group

6

m

La/Sm

1.5 ac Am cu ph m ibo ul le at io n

Dy/Yb

8

4

MgO (wt.%)

0.5

Fractional crystallization

1.0

1.5

2.0

Th/Sc

10

10000 (e)

(f)

1000

Ba

La/Sm

8

LT01

100

P m arti el al tin g

6

MX60

Fractional crystallization

10

4 0

10

20

30

10

La

100

Rb

Fig.9 Liu and Zhao

500

10

(a)

Tholeiitic basalt

Meixian diorite Lantian granite Ave. Sibao Group Ave. Lengjiaxi Group

10

5

Magma mixing

20 5

εNd

40

Granodiorite

10

0

60

20

5

Lengjiaxi Group

40 80

10 20

-5

Sibao Group

60

80

40

Boninitic basalt Dongma diorite

-10 0.00

Granite

0.05

0.10

0.15

0.20

Th/Zr 10 Tholeiitic basalt 10

(b)

Magma mixing

5 20

εNd

5 40

0 5

10 20 40

Lengjiaxi Group 60

80

10

Granodiorite

Boninitic basalt

-5

20

60 40

Dongma diorite

80

Sibao Group

Granite

-10 0

1

2

3

Th/Nb 10

Tholeiitic basalt

( c)

5

εNd

5

granodiorite

5 10

0

20

5

20

60

Lengjiaxi Group 80

40

Sibao Group

10

-5

Boninitic basalt

20 40

60

Dongma diorite

-10 0.001

0.01

80

granite

0.1

1

10

Th/Ni

Fig.10 Liu and Zhao

50

1.0 (a)

CaO/(MgO+FeOt+TiO2)

Pelite Greywacke

0.8

Amphibolite

0.6 0.4 0.2 0.0

granodiorite

granite

0

3

diorite

6 9 12 15 CaO+MgO+FeOt+TiO2 (wt.%)

18

Al 2 O 3 /(Al 2 O 3 +MgO+FeOt+TiO 2 )

15 (b)

Pelite

10 Greywacke

Amphibolite

5 granite granodiorite

diorite

0 10

15

20

25

Al 2 O 3 +MgO+FeOt+TiO 2 (wt.%)

Fig.11 Liu and Zhao

30

Table 1. Major and trace elements for the Meixian diorite and Lantian granite in South China Meixian diorite (28°49'37.2"N, 113°35'56.4"E) Sample MX45 MX47 MX48 MX50 MX51 MX52 MX53 MX55 MX56 MX57 MX59 MX60 Major element (wt.%) SiO2 60.74 59.42 59.57 61.13 60.98 59.28 60.43 61.17 61.25 63.15 61.38 59.78 Al2O3 18.28 18.08 18.31 17.95 18.61 18.31 17.81 17.72 18.13 17.47 17.60 17.62 Fe2O3 6.10 6.22 6.18 6.02 5.43 5.95 6.27 6.25 5.99 5.22 5.86 5.90 MgO 3.41 3.40 3.37 3.37 2.99 3.33 3.56 3.55 3.27 2.96 3.45 3.44 CaO 5.73 5.68 5.69 5.69 5.79 5.77 5.60 5.56 5.76 4.51 5.26 5.04 Na2O 3.91 3.77 4.39 3.70 4.01 3.77 3.88 3.56 3.89 3.51 3.59 3.74 K2O 0.78 0.84 0.40 0.86 0.59 0.56 0.58 0.95 0.78 1.56 1.05 1.51 MnO 0.09 0.10 0.11 0.10 0.09 0.10 0.10 0.10 0.10 0.09 0.09 0.09 P2O5 0.16 0.16 0.16 0.15 0.15 0.16 0.16 0.16 0.16 0.13 0.14 0.15 TiO2 0.74 0.80 0.77 0.73 0.67 0.76 0.80 0.77 0.72 0.62 0.68 0.75 LOI 1.32 1.66 1.27 1.10 1.27 1.38 1.26 1.40 1.07 1.43 1.24 1.24 Total 101.26 100.14 100.22 100.80 100.57 99.36 100.45 101.19 101.11 100.64 100.34 99.25 Trace element (ppm) Li 47.3 59.6 19.2 54.9 29.7 46.6 44.2 51.9 54.8 43.3 63.5 87.9 Be 1.48 2.02 24.3 1.40 1.59 1.59 1.43 1.12 1.43 1.43 1.36 6.17 Sc 17.9 17.3 17.0 17.0 16.2 17.3 17.5 17.9 17.3 15.0 16.1 17.7 V 125 125 137 124 104 122 124 127 125 102 129 118 Cr 54.4 58.7 53.9 54.2 47.1 56.3 58.7 56.8 54.3 53.5 56.8 58.0 Co 19.4 20.2 18.2 19.5 17.1 20.5 20.6 20.7 19.5 17.6 20.5 21.4 Ni 58.6 62.5 50.3 58.2 52.2 60.7 63.5 60.5 58.6 51.8 60.4 61.1 Rb 30.9 42.0 17.8 44.0 28.9 25.2 21.9 36.4 31.4 63.6 55.7 89.6 Sr 282 276 267 282 305 297 281 274 295 235 286 272 Y 13.3 11.9 12.7 12.0 10.9 11.8 12.2 12.4 12.0 10.8 10.9 11.8 Zr 80.9 80.2 66.5 90.9 76.7 73.3 76.7 104 84.7 122 87.9 93.4 Nb 5.12 5.51 4.81 4.87 4.50 5.25 5.32 4.93 5.00 5.36 4.50 6.17 Cs 33.6 41.5 8.98 56.1 19.3 27.3 11.9 16.5 15.5 14.8 52.8 221 Ba 130 144 60 134 82 88 102 149 130 166 170 226 La 10.3 9.98 9.51 11.00 9.88 9.37 12.2 12.2 11.1 12.4 9.28 13.3 Ce 21.1 19.3 19.7 22.3 19.5 18.6 24.9 24.6 22.5 25.0 19.0 26.9 Pr 2.49 2.36 2.32 2.61 2.28 2.18 2.91 2.86 2.69 2.91 2.29 3.15 Nd 9.96 9.53 9.10 10.3 9.13 9.00 11.3 11.2 10.4 11.1 9.01 12.2 Sm 2.35 2.37 2.18 2.31 2.12 2.10 2.48 2.48 2.38 2.41 2.01 2.57 Eu 0.88 0.84 0.88 0.85 0.84 0.86 0.83 0.82 0.86 0.74 0.78 0.81 Gd 2.22 2.16 2.08 2.11 1.97 2.13 2.17 2.15 2.17 2.07 1.85 2.29 Tb 0.41 0.38 0.38 0.40 0.35 0.38 0.39 0.41 0.38 0.36 0.34 0.39 Dy 2.27 2.11 2.24 2.17 1.91 2.14 2.14 2.12 2.09 1.96 1.96 2.06 Ho 0.54 0.49 0.51 0.47 0.43 0.49 0.49 0.47 0.47 0.42 0.44 0.46 Er 1.42 1.27 1.43 1.27 1.14 1.33 1.30 1.30 1.28 1.13 1.15 1.22 Tm 0.21 0.20 0.20 0.19 0.17 0.19 0.18 0.20 0.19 0.16 0.17 0.18 Yb 1.40 1.16 1.38 1.22 1.12 1.25 1.24 1.25 1.21 1.14 1.11 1.19 Lu 0.20 0.19 0.19 0.18 0.16 0.17 0.17 0.18 0.18 0.16 0.16 0.17 Hf 2.04 2.02 1.64 2.30 1.85 1.88 1.84 2.36 2.01 3.01 2.17 2.27 Ta 0.36 0.40 0.39 0.37 0.35 0.39 0.40 0.36 0.36 0.46 0.33 0.45 Pb 10.8 10.7 9.82 10.1 10.7 10.6 9.76 9.26 10.2 13.6 9.91 10.3 Th 2.46 2.17 2.11 2.91 1.99 2.19 3.31 3.61 3.16 3.69 2.46 4.01 U 0.58 0.55 0.54 0.53 0.60 0.63 0.63 0.56 0.67 0.64 0.58 0.69

Table 1 (Continued) Lantian granite (29°04'41.0"N, 113°26'24.8"E) Sample LT01 LT04 LT05 LT06 LT08 LT10 LT11 LT12 Major element (wt.%) SiO2 77.80 80.24 74.13 75.40 76.68 73.79 73.93 72.30 Al2O3 12.78 11.50 14.88 15.11 14.30 14.37 14.50 14.97 Fe2O3 0.90 1.19 1.91 1.42 1.10 1.01 2.14 1.96 MgO 0.50 0.80 0.70 0.58 0.42 0.49 0.79 0.74 CaO 0.16 0.16 0.23 0.26 0.19 0.50 0.30 0.36 Na2O 3.86 2.78 2.92 3.29 3.70 3.81 3.94 3.51 K2O 2.01 1.58 3.17 3.30 3.05 4.11 2.66 2.74 MnO 0.01 0.01 0.01 0.01 0.01 0.01 0.04 0.04 P2O5 0.05 0.05 0.06 0.06 0.07 0.06 0.05 0.05 TiO2 0.20 0.18 0.28 0.25 0.26 0.27 0.26 0.25 LOI 1.22 1.24 2.11 1.83 1.51 2.02 2.02 2.14 Total 99.47 99.73 100.41 101.50 101.29 100.45 100.63 99.06 Trace element (ppm) Li 24.7 22.2 42.2 43.9 34.2 38.2 38.7 40.4 Be 3.03 3.38 3.69 3.79 4.49 8.16 4.41 5.65 Sc 6.71 5.67 8.41 7.44 7.41 7.43 8.97 8.60 V 19.9 24.0 27.9 25.9 21.9 27.8 28.3 25.7 Cr 6.29 3.72 26.60 6.11 6.83 7.48 6.84 8.76 Co 2.13 1.82 1.98 1.61 3.48 3.01 4.09 5.11 Ni 3.19 3.69 12.30 3.00 3.19 3.37 7.18 10.6 Rb 102 101 184 180 169 243 145 158 Sr 72.1 74.3 64.0 80.8 65.1 115 90.6 99.7 Y 6.58 8.97 13.2 9.11 13.2 8.22 12.5 13.4 Zr 115 95.6 139 132 160 142 134 145 Nb 6.32 4.30 7.62 6.67 8.89 6.64 7.94 7.13 Cs 6.16 9.47 19.8 14.6 14.6 23.5 14.2 16.1 Ba 246 223 435 457 394 5100 422 420 La 19.1 18.0 21.4 12.3 18.2 16.6 19.7 18.9 Ce 29.9 28.0 32.2 21.2 32.4 29.7 35.0 35.1 Pr 3.25 3.18 3.73 2.27 3.25 3.10 3.64 3.58 Nd 11.4 11.2 12.7 8.1 11.4 10.2 13.0 12.3 Sm 2.17 2.11 2.44 1.60 2.29 1.94 2.59 2.40 Eu 0.47 0.44 0.51 0.33 0.45 0.30 0.54 0.52 Gd 1.83 1.74 2.09 1.43 2.07 1.61 2.29 2.29 Tb 0.28 0.31 0.37 0.25 0.38 0.28 0.37 0.37 Dy 1.29 1.58 2.11 1.40 2.05 1.42 2.01 2.11 Ho 0.26 0.33 0.46 0.31 0.46 0.31 0.44 0.46 Er 0.68 0.88 1.33 0.92 1.32 0.92 1.32 1.27 Tm 0.10 0.14 0.19 0.15 0.19 0.13 0.19 0.20 Yb 0.73 0.95 1.36 0.95 1.19 0.95 1.26 1.32 Lu 0.11 0.15 0.19 0.15 0.17 0.15 0.18 0.20 Hf 3.01 2.36 3.40 3.15 3.72 3.34 3.19 3.28 Ta 0.98 0.75 1.14 1.00 1.33 0.80 1.14 0.91 Pb 10.3 19.9 24.0 10.5 27.2 11.9 22.3 21.6 Th 11.4 9.59 13.3 11.7 12.5 13.4 12.7 12.6 U 1.89 1.47 2.72 2.05 2.03 1.97 1.49 1.54

Table 2. Whole rock Sr - Nd isotopes for the Meixian diorite and Lantian granite in South China.

Sample

87

Rb/86Sr

87

Sr/86Sr

2σ

(87Sr/86Sr)

147

Sm/144Nd 143Nd/144Nd ±2σ εNd(t)

TDM1(Ga)

TDM2(Ga)

Meixian diorite MX45 MX52 MX60

0.3173 0.2457 0.9539

0.708606 5 0.708573 4 0.710083 7

0.704890 0.1431 0.705695 0.1416 0.698911 0.1278

0.512317 0.512318 0.512263

8 4 7

-0.6 -0.5 -0.1

1.79 1.75 1.57

1.54 1.52 1.49

0.745098 4 0.753770 3

0.698997 0.1143 0.665728 0.1219

0.512122 0.512120

7 9

-1.4 -2.3

1.57 1.71

1.60 1.67

Lantian granite LT04 LT08

3.9362 7.5172

Table 3. Zircon U-Pb ages for the Meixian diorite and Lantian granite in South China 207 Spot Th U Th/U Pb/206 Pb Sample MX52 from the Meixian intrusion MX52-01 35 84 0.42 0.0686 MX52-02 32 76 0.43 0.0653 MX52-03 54 124 0.43 0.0724 MX52-04 45 85 0.53 0.0678 MX52-05 61 117 0.52 0.0719 MX52-06 94 146 0.64 0.0680 MX52-07 91 156 0.58 0.0680 MX52-08 67 134 0.50 0.0699 MX52-09 251 393 0.64 0.0690 MX52-10 122 191 0.64 0.0684 MX52-11 39 78 0.50 0.0696 MX52-12 182 316 0.58 0.0704 MX52-13 74 118 0.63 0.0666 MX52-14 98 192 0.51 0.0667 MX52-15 85 200 0.43 0.0719 MX52-16 55 130 0.43 0.0682 MX52-17 62 123 0.50 0.0680 MX52-18 40 98 0.40 0.0669 MX52-19 84 152 0.55 0.0675 MX52-20 82 162 0.51 0.0679 MX52-21 91 172 0.53 0.0670 MX52-22 260 356 0.73 0.0656 MX52-23 46 111 0.42 0.0701 MX52-24 95 196 0.48 0.0625 Sample LT01 from the Lantian intrusion LT01-01* 79 148 0.53 0.0966 LT01-02 109 271 0.40 0.0666 LT01-03 103 196 0.53 0.0653 LT01-04 155 306 0.51 0.0698 LT01-05* 253 261 0.97 0.0723 LT01-06* 146 956 0.15 0.0813 LT01-07 124 133 0.93 0.0704 LT01-08 267 471 0.57 0.0704 LT01-09 315 142 2.22 0.0653 LT01-10 77 131 0.59 0.0674 LT01-11 66 112 0.59 0.0714 LT01-12 186 253 0.73 0.0744 LT01-13 130 266 0.49 0.0695 LT01-14 212 370 0.57 0.0685 LT01-15 105 197 0.53 0.0662

Discordant zircons are labeled by *

1σ

207

Pb/235 U

1σ

206

Pb/238 U

1σ

208

Pb/232 Th

1σ

207

Pb/206 Pb 1σ

207

Pb/235 U

1σ

206

Pb/238 U

1σ

208

Pb/232 Th 1σ

0.0032 0.0031 0.0026 0.0031 0.0027 0.0025 0.0025 0.0026 0.0019 0.0023 0.0029 0.0020 0.0028 0.0021 0.0021 0.0024 0.0026 0.0027 0.0023 0.0023 0.0022 0.0016 0.0026 0.0023

1.2508 1.2077 1.3405 1.2816 1.3470 1.2744 1.2623 1.3934 1.4231 1.2978 1.3426 1.3109 1.2434 1.2628 1.3486 1.2792 1.2687 1.3008 1.2674 1.2587 1.2427 1.2856 1.3306 1.1402

0.0531 0.0560 0.0485 0.0563 0.0511 0.0450 0.0457 0.0548 0.0417 0.0439 0.0542 0.0363 0.0494 0.0411 0.0384 0.0429 0.0471 0.0516 0.0443 0.0413 0.0376 0.0317 0.0497 0.0391

0.1347 0.1339 0.1339 0.1379 0.1353 0.1361 0.1344 0.1445 0.1488 0.1375 0.1404 0.1345 0.1356 0.1361 0.1355 0.1364 0.1356 0.1406 0.1353 0.1339 0.1346 0.1413 0.1382 0.1324

0.0020 0.0017 0.0014 0.0018 0.0016 0.0016 0.0014 0.0023 0.0018 0.0017 0.0018 0.0017 0.0017 0.0015 0.0015 0.0017 0.0016 0.0019 0.0015 0.0014 0.0013 0.0014 0.0017 0.0014

0.0429 0.0432 0.0418 0.0448 0.0432 0.0417 0.0423 0.0462 0.0459 0.0437 0.0454 0.0410 0.0394 0.0424 0.0442 0.0431 0.0439 0.0452 0.0424 0.0416 0.0403 0.0454 0.0437 0.0377

0.0015 0.0015 0.0013 0.0014 0.0014 0.0012 0.0012 0.0016 0.0011 0.0012 0.0015 0.0011 0.0010 0.0012 0.0011 0.0014 0.0015 0.0017 0.0012 0.0011 0.0011 0.0011 0.0015 0.0011

887 785 998 865 984 878 878 926 898 880 917 939 833 831 983 872 878 835 854 866 839 794 931 700

96.3 98.1 106.0 94.9 75.2 75.2 75.9 77.8 55.6 70.4 91.7 58.2 82.4 64.8 59.3 73.0 79.6 83.8 71.4 102.8 68.5 58.3 77.0 77.8

824 804 863 838 866 834 829 886 899 845 864 851 820 829 867 837 832 846 831 827 820 839 859 773

24.0 25.8 21.0 25.1 22.1 20.1 20.5 23.3 17.5 19.4 23.5 16.0 22.4 18.5 16.6 19.1 21.1 22.8 19.8 18.6 17.0 14.1 21.7 18.6

815 810 810 833 818 823 813 870 894 830 847 813 820 822 819 824 819 848 818 810 814 852 834 802

11.3 9.5 8.1 10.0 9.3 9.0 8.1 13.0 10.2 9.5 10.4 9.4 9.9 8.6 8.5 9.7 9.2 11.0 8.3 7.9 7.5 8.0 9.8 8.0

849 854 829 886 855 826 837 913 907 865 898 813 782 839 874 853 869 893 840 825 798 898 865 748

29.2 29.6 25.2 26.4 27.3 24.2 22.4 31.0 22.0 22.5 29.4 20.7 20.4 23.4 21.3 26.3 28.6 32.8 24.1 22.3 20.6 20.4 28.3 20.8

0.0039 0.0018 0.0021 0.0017 0.0021 0.0019 0.0024 0.0019 0.0021 0.0024 0.0026 0.0020 0.0020 0.0018 0.0022

1.8899 1.2680 1.2336 1.3142 1.2841 1.4392 1.5203 1.4316 1.2216 1.3009 1.3670 1.4105 1.3184 1.2705 1.2427

0.0704 0.0380 0.0387 0.0316 0.0356 0.0329 0.0524 0.0435 0.0396 0.0471 0.0490 0.0373 0.0382 0.0332 0.0412

0.1422 0.1374 0.1366 0.1357 0.1281 0.1274 0.1556 0.1460 0.1353 0.1396 0.1384 0.1367 0.1367 0.1335 0.1352

0.0015 0.0021 0.0013 0.0012 0.0011 0.0010 0.0019 0.0019 0.0014 0.0016 0.0016 0.0013 0.0013 0.0012 0.0014

0.0601 0.0427 0.0417 0.0413 0.0404 0.0685 0.0484 0.0442 0.0401 0.0423 0.0471 0.0434 0.0440 0.0413 0.0427

0.0017 0.0011 0.0010 0.0009 0.0009 0.0019 0.0013 0.0010 0.0008 0.0012 0.0013 0.0009 0.0011 0.0009 0.0012

1561 833 783 924 994 1228 940 940 783 850 969 1054 922 883 813

75.9 57.4 66.7 50.0 25.5 45.2 69.6 56.3 63.9 74.5 74.1 53.7 59.3 86.1 68.5

1078 832 816 852 839 905 939 902 811 846 875 893 854 833 820

24.7 17.0 17.6 13.9 15.8 13.7 21.1 18.2 18.1 20.8 21.0 15.7 16.8 14.8 18.7

857 830 826 820 777 773 933 879 818 843 835 826 826 808 817

8.4 11.9 7.6 6.9 6.4 5.6 10.3 10.8 8.2 8.9 8.9 7.4 7.4 7.0 7.9

1180 844 826 817 801 1339 955 874 795 837 929 858 870 818 844

33.2 21.0 19.1 17.5 16.7 35.8 25.1 19.2 16.1 22.9 24.9 18.4 21.7 18.0 23.8

Table 4. Zircon Hf isotopes for the Meixian diorite and Lantian granite in South China 1σ

TDM(Ga) TDMC(Ga)

8.1

0.5

1.05

1.21

7.3

0.7

1.08

1.25

0.000018 0.282495

8.1

0.6

1.06

1.20

0.282513

0.000022 0.282500

8.8

0.8

1.04

1.17

0.000363 0.000850 0.000015

0.282498

0.000019 0.282485

7.9

0.7

1.06

1.22

0.031986

0.000755 0.001422 0.000033

0.282551

0.000018 0.282529

9.6

0.6

1.00

1.12

MX52-07

0.023239

0.000108 0.001063 0.000007

0.282535

0.000018 0.282519

9.0

0.6

1.02

1.15

MX52-08

0.017726

0.000550 0.000784 0.000021

0.282504

0.000016 0.282491

9.3

0.6

1.05

1.17

MX52-09

0.020573

0.000703 0.000873 0.000027

0.282184

0.000018 0.282169

-1.6

0.6

1.50

1.88

MX52-10

0.035914

0.001561 0.001547 0.000060

0.282506

0.000017 0.282482

8.1

0.6

1.07

1.22

MX52-11

0.022770

0.000463 0.001015 0.000018

0.282504

0.000018 0.282488

8.7

0.6

1.06

1.19

MX52-12

0.027177

0.000397 0.001195 0.000017

0.282524

0.000018 0.282505

8.5

0.6

1.04

1.18

MX52-13

0.022125

0.000211 0.000995 0.000010

0.282500

0.000019 0.282484

7.9

0.7

1.07

1.22

MX52-14

0.028280

0.000388 0.001245 0.000017

0.282493

0.000014 0.282474

7.6

0.5

1.08

1.24

MX52-15

0.020678

0.000652 0.000878 0.000026

0.282341

0.000019 0.282327

2.3

0.7

1.28

1.58

MX52-16

0.025350

0.000324 0.001115 0.000014

0.282442

0.000019 0.282425

5.9

0.7

1.15

1.35

MX52-17

0.020664

0.000296 0.000918 0.000012

0.282516

0.000015 0.282501

8.5

0.5

1.04

1.18

MX52-18

0.018271

0.000491 0.000768 0.000021

0.282493

0.000019 0.282481

8.4

0.7

1.07

1.21

MX52-19

0.025523

0.000178 0.001169 0.000007

0.282533

0.000022 0.282515

9.0

0.8

1.02

1.15

MX52-20

0.027923

0.000524 0.001265 0.000024

0.282580

0.000017 0.282560

10.4

0.6

0.96

1.05

MX52-21

0.035469

0.000961 0.001505 0.000038

0.282535

0.000018 0.282512

8.8

0.6

1.03

1.16

MX52-22

0.040890

0.003045 0.001835 0.000122

0.282545

0.000014 0.282516

9.8

0.5

1.02

1.13

MX52-23

0.031326

0.000875 0.001390 0.000039

0.282572

0.000025 0.282550

10.6

0.9

0.97

1.06

MX52-24

0.025603

0.000459 0.001122 0.000019

0.282488

0.000014 0.282471

7.0

0.5

1.09

1.26

Spot

176

176 Yb/177Hf 1σ Lu/177Hf 1σ Sample MX52 from the Meixian intrusion

176

Hf/177Hf 1σ

176

Hf/177Hf(t) εHf(t)

MX52-01

0.016338

0.000173 0.000751 0.000009

0.282504

0.000014 0.282492

MX52-02

0.016252

0.000272 0.000739 0.000013

0.282484

0.000020 0.282473

MX52-03

0.039864

0.000329 0.001756 0.000015

0.282521

MX52-04

0.017361

0.000189 0.000776 0.000007

MX52-05

0.018941

MX52-06

Sample LT01 from the Lantian intrusion LT01-01*

0.031769

0.000757 0.001446 0.000033

0.282490

0.000015 0.282466

8.1

0.5

1.09

1.24

LT01-02

0.031488

0.000807 0.001288 0.000032

0.282350

0.000022 0.282330

2.7

0.8

1.29

1.56

LT01-03

0.030832

0.001004 0.001332 0.000040

0.282404

0.000017 0.282383

4.5

0.6

1.21

1.45

LT01-04

0.039785

0.000571 0.001701 0.000023

0.282424

0.000018 0.282398

4.9

0.6

1.19

1.42

LT01-05*

0.045222

0.001692 0.001938 0.000065

0.282520

0.000016 0.282492

7.2

0.6

1.06

1.23

LT01-06*

0.057319

0.000586 0.002393 0.000021

0.282424

0.000023 0.282389

3.5

0.8

1.22

1.47

LT01-07

0.030800

0.001023 0.001312 0.000040

0.282497

0.000018 0.282474

10.1

0.6

1.08

1.17

LT01-08

0.048125

0.001077 0.002014 0.000043

0.282607

0.000018 0.282573

12.4

0.6

0.94

0.98

LT01-09

0.020092

0.001278 0.000813 0.000049

0.282353

0.000015 0.282341

2.8

0.5

1.26

1.55

LT01-10

0.038727

0.000428 0.001721 0.000012

0.282554

0.000019 0.282526

9.9

0.7

1.01

1.11

LT01-11

0.040396

0.000167 0.001865 0.000006

0.282537

0.000021 0.282508

9.1

0.7

1.04

1.16

LT01-12

0.035641

0.000635 0.001459 0.000024

0.282290

0.000018 0.282267

0.4

0.6

1.38

1.71

LT01-13

0.034744

0.000491 0.001591 0.000023

0.282526

0.000019 0.282501

8.7

0.7

1.04

1.18

LT01-14

0.035630

0.000396 0.001610 0.000018

0.282540

0.000012 0.282515

8.8

0.4

1.03

1.16

LT01-15

0.035226

0.000412 0.001507 0.000017

0.282411

0.000018 0.282388

4.5

0.6

1.21

1.44

Discordant zircons are labeled by *

1. The 820-Ma Meixian diorite and Lantian granite were derived from the mantle and crust, respectively. 2. The Neoproterozoic peraluminous granitoids were generally partial melts of the continental crust, whereas the limited diorites are differentiation products of the basaltic magmas. 3. The granitoids were formed during or after collision between the Yangtze and Cathaysia Block.