Study on the Physical and Chemical Conditions of Ore Formation of Hetai Ductile Shear Zone—Hosted Gold Deposit and Discovery of Melt Inclusions

• Published in: Acta geochimica Vol. 21; no. 1; pp. 40 - 51
• Main Author: 李兆麟 翟伟 等
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 2002; State Laboratory of Metallogenesis, Nanjing University, Nanjing 210093, China; Department of Earth Sciences, Zhongshan University, Guangzhou 510275, China%Department of Earth Sciences, Zhongshan University, Guangzhou 510275, China
• Subjects: Calcium ions; Carbon dioxide; Fluid inclusions; Gases; Geochemistry; Geology; Gold; Isotopes; Magnesium; Metamorphic rocks; Metamorphism; Mineral assemblages; Mineral deposits; Minerals; Ores; Orthoclase; Quartz; Shear zone; Silicate minerals; Silicates; Silurian; Silver; Temperature; Trace gases; Veins (geology); Wollastonite; 成矿作用; 成矿带; 热液交互作用; 物理化学条件; 金矿床; physical-chemical condition; melt and fluid metallogenesis; melt inclusion; gold deposit; Hetai; ductile shear zone; fluid-melt inclusion
• ISSN: 1000-9426; 2096-0956; 1993-0364; 2365-7499
• DOI: 10.1007/BF02838051

The Hetai ductile shear zone-hosted gold deposit occurs in the deep-seated falut mylonite zone of the Sinian-Silurian metamorphic rock series.In this study there have been discovered melt inclusions,fluid-melt inclusions and organic inclusions in ore-bearing ruartz veins of the ore deposit and mylonite for the first time.The homogenization temperatures of the various types of inclusions are 160℃,180-350℃，530℃and 870℃ for organic inclusions,liquid inclsions two-phase immiscible liquid inclusions and melt inclusion,respectively,Ore fluid is categoriezed as the neutral to basic K^+-Ca^2+-Mg^2+-Na^+-SO4^2--HCO3^-Cl^- system.The contents of trace gases follow a descending order of H2O>CO2>CH4>(or<)H2>CO>C2H2>C2H6>O2>N2.The concentrations of K^+,Ca^2+,SO4^2-,HCO3^-,Cl^-,H2O and C2H2 in fluid inclusions are related to the contents of gold and the Au/Ag ratios in from different levels of the gold deposit.This is significant for deep ore prospecting in the region.Daughter minerals in melt inclusions were analyzed using SEM.Quartz,orthoclase,wollastonite and other silicate minerals were identified.They were formed in different mineral assemblages.This analysis further proves the existence of melt inclusions in ore veins.Sedimentary metamophic rocks could form silicate melts during metamorphic anatexis and dynamic metamorphism,which possess melt-soulution characteristics.Ore formation is related to the multi-stage forming process of silicate melt and fluid.