地质学报2018，Vol.92Issue(4)：787-803,17.
新疆东准噶尔绿源金矿床成因研究:流体包裹体及氢、氧同位素制约
Genesis of the Luyuan Gold Deposit, East Junggar, Xinjiang:Constraints from Fluid Inclusions and Isotopic Compositions
摘要
Abstract
The Luyuan gold deposit,a newly discovered gold deposit,is located in the Qiongheba ore-cluster district in the eastern segment of Yemaquan-Qiongheba Paleozoic arc belt,East Junggar.Its orebodies occur in the Upper Carboniferous Batamayineishan Formation as stratoid,banded and lenticular in shape,and are controlled by fracture structures.Hydrothermal mineralization can be divided into four stages:quartz-pyrite stage,quartz-Au-pyrite stage,quartz-Au polymetallic sulfide stage,quartz-calcite stage,with stages 2 and 3 as the main Au mineralization stages and characterized by complicated metallic mineral assemblage of pyrite-arsenopyrite-sphalerite-chalcopyrite ± electrum.Analyses of fluid inclusions and hydrogen and oxygen isotopic geochemistry were carried out to understand the characteristics,origin and evolution of ore-forming fluids.Petrographic observation indicates that fluid inclusions of the deposit can be divided into three types,i.e.,liquid-rich aqueous inclusions (type-V+ L),vapor-rich aqueous inclusions (type-V) and monophase liquid aqueous inclusions (type-L).Type-V+ L fluid inclusions are most abundant in all stages of the hydrothermal minerals,developed within all the hydrothermal minerals.Fluid inclusions of type-V are smallest in number.Microthermometric measurements indicate that these inclusions yielded total homogeneous temperatures of 115～349℃,salinities of 0.7～8.8％ NaCleqv,and densities of 0.66～0.98g/cm3.The homogeneous temperatures of fluid inclusions decrease gradually,from 268～322℃ at stage 2,through 181～300℃ at stage 3,to 115～176℃ at stage 4.All these features suggest that the ore-forming fluid of the Luyuan gold deposit is characteristic of low temperature,low salinity,and low density,which are similar to those of typical epithermal gold deposits.The mineralization pressures estimated are(75～335) × 105 Pa,with an average of 203× 105Pa,and the corresponding ore-forming depths are 0.24 ～ 1.12km,with an average of 0.68km,indicating that the deposit has some characteristics of epithermal deposit.Laser Raman analysis shows that gas compositions and liquid compositions of the ore-forming fluids are mainly H2O.The hydrogen and oxygen isotopic compositions of the ore-forming fluids show that δDH2O =-108.8‰c～-129.0‰,δ18 OH2O =-7.2‰～4.6‰,which indicates that the ore-forming fluids were formed as a result of multiple fluids,and mainly were derived from meteoric water.On the basis of the geological and fluid inclusion features,we conclude that fluid-boiling during the mineralization stage may be the major cause of ore material precipitation,and the Luyuan deposit is a typical epithermal gold deposit.关键词
流体包裹体/氢、氧同位素/浅成低温热液型金矿/绿源金矿/新疆Key words
fluid inclusion/hydrogen and oxygen isotopes/epithermal gold deposit/Luyuan gold deposit/Xinjiang引用本文复制引用
丁辉,葛文胜,董连慧,邓刚,贾红旭,张佳儒,陈疆,元强..新疆东准噶尔绿源金矿床成因研究:流体包裹体及氢、氧同位素制约[J].地质学报,2018,92(4):787-803,17.基金项目
本文为新疆地质矿产勘查开发局项目(编号:DZKC201504-009)资助成果. （编号:DZKC201504-009）
