Source and nature of ore-forming fluids of the Edmond hydrothermal field,Central Indian Ridge:evidence from He-Ar isotope composition and fluid inclusion study

作     者：WANG Yejian HAN Xiqiu QIU Zhongyan 

作者机构：Key Laboratory of Submarine GeosciencesSecond Institute of OceanographyState Oceanic AdministrationHangzhou 310012China 

出 版 物：《Acta Oceanologica Sinica》 (海洋学报（英文版）)

年 卷 期：2017年第36卷第1期

页      面：101-108页

核心收录：

学科分类：08[工学] 0824[工学-船舶与海洋工程] 

基　　金：The National Natural Science Foundation of China under contract No.41306056 the China Ocean Mineral Resources R&D Association Project under contract No.DY125-12-R-03 the Scientific Research Fund of the Second Institute of Oceanography,SOA under contract No.JG1308 

主　　题：fluid inclusion helium and argon isotopes phase separation massive sulfides Central Indian Ridge 

摘      要：To understand the source and nature of the ore-forming fluids of the Edmond hydrothermal field on the Central Indian Ridge, we studied the He-Ar isotope composition and fluid inclusions of the hydrothermal *** results show that the sulfide samples contain noble gases He, Ne, Kr, and Xe with their abundances in between those of air-saturated water（ASW） and mid-ocean ridge basalt（MORB）. The ^3He/^4He ratio varies from1.3 to 8.7 Ra（n=10, average： 5.1 Ra）, whereas the ^40Ar/^36Ar ratio is from 285.3 to 314.7（n=10, average： 294.8）. These results suggest that the He was derived from a mixture of MORB with variable amounts of seawater, but the Ar in the ore-forming fluids trapped in the sulfides is predominantly derived from seawater. The fluid inclusions of barite have a wide range of homogenization temperatures and salinities varying from 163℃ to 260℃ and 2.6 wt%to 8.5 wt% Na Cl equiv., respectively. It is suggested that the ore-forming fluids were produced by phase separation, which agreed with the present-day vent fluid study.