He-Ar-H-O isotopic signatures in AuAg bearing ore fluids of the Sunshin epithermal gold-silver ore deposits, South Korea

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• 作者：Kyu Han Kim ; Seungyeol Lee ; Keisuke Nagao ; Hirochika Sumino ; Kyounghee Yang ; Jong Ik Lee
• 关键词：Mantle helium ; Fluid inclusions ; Oxygen isotopes ; Epithermal gold-silver ore deposits ; Sunshin gold-silver deposits
• 刊名：Chemical Geology
• 出版年：2012
• 出版时间：6 August, 2012
• 年：2012
• 卷：320-321
• 期：Complete
• 页码：128-139
• 全文大小：1866 K

文摘

Helium (³He/⁴He), argon (⁴⁰Ar/³⁶Ar) and oxygen (¹⁸O/¹⁶O) isotopic ratios in fluid inclusions trapped in quartz and pyrite from the Sunshin epithermal gold-silver ore deposits in South Korea were analyzed to investigate the magmatic contribution to ore forming fluids. Mantle helium with high ³He/⁴He ratios (up to ³He/⁴He ~ 9R_A, where R_A = 1.4 ¡Á 10^? 6 for air) were identified from fluid inclusions in auriferous quartz veins, which are characterized as low sulfidation (adularia-sericite) type. The ratios provide direct evidence of links between low sulfidation ore fluids in epithermal gold deposits and magma from a mantle source. Interestingly, the oxygen and hydrogen isotopic compositions of the ore fluids (¦Ä¹⁸O = ? 1.9 to ? 6.6¡ë, ¦ÄD = ? 82 to ? 100¡ë), calculated from ore quartz, indicate that meteoric waters were predominant during precipitation of the AuAg ore. Microthermometric measurements for fluid inclusions indicate relatively low temperatures (¡Ü 300 ¡ãC) for the formation of the low sulfidation epithermal ore deposits.