Where is the Suture between Indochina and South China: Insights from U-Pb Ages and Hf isotopes of detrital zircons from the Nanpanjiang Basin in South China

Description

Table S1 is La-ICP-MS zircons U-Pb isotope measurements and ages from the Middle Triassic samples in Nanpanjiang basin. Table S2 is detrital zircon Hf-isotope data measured by MC-LA-ICPMS from the Middle Triassic in the Nanpanjiang basin. Table S3 is La-ICP-MS zircons U-Pb isotope measurements and ages from Upper Middle Triassic in the Nanpanjiang basin, which data from Ye,2012. Table S4 is La-ICP-MS zircons Nb, Yb, Hf, Th, U elements measurements from the Middle Triassic samples.

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Zircon U-Pb dating, and trace element analyses were conducted using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) at the State Key Laboratory of Geological Processes and Mineral Resources (GPMR) at China University of Geosciences in Wuhan. The laser ablation system and ICP-MS instrument were operated according to the same conditions as described by Liu et al., [2010]. ICPMS-Data-Cal software was used for off-line selection and integration of background and analyte signals, time-drift correction, and quantitative calibration for both trace element analyses and U-Pb dating. For U-Pb dating, the zircon 91500 was used as an external standard and was analyzed every five analyses, with two measurements taken each time. To correct for time-dependent drifts of U-Pb isotopic ratios, linear interpolation with time was used based on the variations of 91500. The preferred U-Th-Pb isotopic ratios for 91500 were taken from Wiedenbeck et al., [1995]. Isoplot/Ex_ver3 software was used to create Concordia diagrams and perform weighted mean calculations. Zircon standard GJ-1 was measured as an unknown during the study and yielded a weighted average 206Pb/238U age of 604.9 ± 3.1 Ma (n = 31; MSWD = 1.5), which agrees with recommended values within analytical uncertainties as reported by Jackson et al., [2004]. We conducted in situ zircon Lu-Hf isotopic analyses at the Institute of Geology and Geophysics, Chinese Academy of Sciences in Beijing using a Neptune multi-collector ICP-MS with a Geolas-193 laser-ablation system after performing zircon U-Pb dating. Our instrumental conditions and data acquisition methods were similar to those described in a previous study by Wu et al., [2006]. We also analyzed standard zircon (GJ-1), which was treated as an unknown sample, and obtained a 176Hf/177Hf ratio of 0.2820131 ± 0.0000062 (2σ; MSWD=0.59; n=62), which agrees well with the reported value by Elhlou et al., [2006], indicating the reliability of our results. To calculate the εHf(t) values, we used the constant decay 1.867×10-11 for 176Lu (Soderlund et al., 2004) and a Chondrite with (176Hf/177Hf) CHUR=0.282772 and (176Lu/177Hf) CHUR=0.0332 [Blichert-Toft and Albarède, 1997]. For the crustal model age, we used an average crustal 176Lu/177Hf of 0.015 and a depleted mantle model with (176Hf/177Hf) DM=0.28325 and (176Lu/177Hf) DM=0.0384 [Griffin et al., 2000].

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