The Relationship Between Isotopic Compositions of Metals,Non-Metal,and Rare Gases in Seafloor Hydrothermal Sulfides and Its Geological Significances
The isotopic composition of seafloor hydrothermal sulfides can not only trace their sources but also record the fluids and their precipitation processes.This article analyzes the isotopic compositions of metals(lead,rhenium,osmium,iron,copper,zinc),non-metal(sulfur),and rare gases in fluid inclusions of global seafloor hydrothermal sulfides,and explores the relationship between the isotopic compositions of metals,non-metal,and rare gases in sulfides.The results indicate that there is a negative correlation between sulfur isotopic composition and osmium,iron isotopic compositions,as well as between iron,lead,and helium isotopic compositions in seafloor hydrothermal sulfides.There is a positive correlation between osmium isotopic composition and iron isotopic composition,and between xenon isotopic composition and lead,osmium isotopic compositions.During the stage of magma degassing and material injecting fluid,sulfides are formed with the characteristics of low δ34SVCDT values(about 0‰)and high 3He/4He(＞8 Ra),40Ar/36Ar(＞300),and 129Xe/132Xe(＞0.99)ratios.In the stage of fluid-rock interaction,as lead-containing minerals in the rock continue to dissolve,i.e.,the degree of fluid-rock interaction increases,the lead content of pyrite,chalcopyrite,and sphalerite precipitated in the fluid increases,accompanied by a slight decrease in the 206 Pb/204 Pb ratios.In the fluid-seawater mixing stage,with the increase of seawater influence degree,the Os content(about 0X10-9)in sulfides can sharply decreased,and the δ Fe value(＜-1.6‰),the 187 Os/188 Os ratio(＞1)significantly increases;With the enhancement of fluid-seawater mixing degree,the δ31 SVCDT values of pyrite in sulfides will increase with a slight decrease in the 3 He/4 He,40 Ar/36 Ar,and 129Xe/132Xe ratios in its fluid inclusions,while their3He/4 He ratios will decrease with a decrease in its 130Xe/132Xe ratios.The above indicates that by comprehensively analyzing the isotopic composition and content of metals,non-metal,and rare gases,and discussing their relationships,the effects of magma degassing,fluid-rock interaction,and fluid-seawater mixing on seafloor hydrothermal circulation can be revealed,and the degree of fluid-rock interaction and fluid-seawater mixing during sulfide precipitation can be understood.
metal,non-metal,and rare gas isotopesthe relationship between isotopic compositionsseafloor hydrothermal sulfide
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