Journal article

Early Paleozoic Orogenic Gold Deposit in the Cathaysia Block, China: A first example from the Shuangqishan Deposit


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Publication Details

Author list: Ma Y, Jiang S-Y, Frimmel HE, Xiong S-F, Zhu L-Y, Chen R-S

Publisher: Elsevier

Publication year: 2021

Journal: Gondwana Research

Volume number: 91

Start page: 231

End page: 253

Total number of pages: 23

ISSN: 1342-937X

URL: http://dx.doi.org/10.1016/j.gr.2020.11.014


Abstract

The Shuangqishan gold deposit (>20t gold) is located in a hitherto poorly-documented gold province in the southeastern Cathaysia Block, South China. It is hosted by Neoproterozoic amphibolite-facies metamorphic rocks and consists of quartz-sulfide veins with distinct alteration haloes. Three stages of hydrothermal activity have been identified, and gold is mainly associated with veins of Stage II (quartz-pyrite±chalcopyrite). Gold occurs both as refractory gold hosted by pyrite and free gold enclosed in, or filling, microfractures of pyrite and quartz. U-Pb isotope dating of hydrothermal apatite from the Substage IIa veins yielded an age of 436.8 ± 7.6 Ma. The ore fluid was of carbonic-aqueous composition and low oxygen fugacity. Total homogenization temperatures in Substage IIa and IIb range from 270° to 310°C and 250° to 295°C, respectively. Variable CO2/H2O ratios indicate fluid unmixing under fluctuating pressures. Stage I quartz veins show evidence of ductile deformation and have δ18Ofluid and δD values of 10.3 to 11.2‰ and −67to −66‰, respectively, consistent with a metamorphic fluid. Stage II veins have slightly higher δ18O values of 10.9 to 13.7‰, with calculated δ18Ofluid values of 4.8 to 8.0‰. The 3He/4He ratios of pyrite are elevated (0.06–0.23 Ra) relative to crustal He reservoirs (<0.01 Ra). Fluid inclusions in quartz yielded δ13CCO2values of −23.0to −11.4‰ (V-PDB), reflecting variable contributions of organic carbon. The sulfide δ34SV-CDT values range from −4.7to −1.0‰, consistent with a deep-seated sulfur source. The Pb isotope compositions of pyrite (206Pb/204Pb=17.141–17.871, 207Pb/204Pb=15.484–15.570) are more radiogenic than those of unaltered host rocks. All available data demonstrate that the Shuangqishan deposit is the first report orogenic gold deposit formed during the late Wuyi-Yunkai intracontinental orogeny in the Cathaysia Block.


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Last updated on 2021-11-02 at 19:26