摘要
东准噶尔绿源金矿是近年来新发现的矿床,位于野马泉-琼河坝古生代岛弧带东段的琼河坝矿集区。矿体主要产于上石炭统巴塔玛依内山组中酸性火山岩中,呈似层状、条带状、透镜状,多受断裂构造控制。流体成矿作用可分为4个阶段:石英-黄铁矿阶段、石英(玉髓)-金-黄铁矿阶段、石英-金-多金属硫化物阶段、石英-碳酸盐阶段,其中阶段2和阶段3为金主要成矿阶段。金属硫化物组合主要为黄铁矿-毒砂-闪锌矿-黄铜矿±银金矿组合。文章从流体包裹体和H、O同位素研究入手,对该矿床成矿流体和矿床成因进行探讨。流体包裹体岩相学特征显示,本矿床热液矿物中流体包裹体存在3种类型:富液相气液两相水溶液包裹体(V+L型)、富气相气液两相水溶液包裹体(V型)和纯液相水溶液包裹体(L型)。其中,V+L型包裹体数量最多,各阶段热液矿物中均有发育;V型包裹体数量最少;L型包裹体数量较少。显微测温结果显示:绿源金矿床石英中流体包裹体均一温度介于115~349℃之间,盐度集中于0.7%~8.8%NaCl eqv.之间,密度介于0.66~0.98g/cm^3之间;从阶段2至阶段4,流体均一温度从268~322℃,经181~300℃,降为115~176℃。这些都表明绿源金矿床成矿流体具有低温、低盐度、低密度的特征,与典型浅成低温热液型金矿成矿流体特征相似。对成矿压力和深度的估算表明,其成矿压力为(73~335)×10~5Pa(均值203×10~5Pa),成矿深度为0.24~1.12km(均值0.68km),显示出浅成热液矿床的特征。流体包裹体激光拉曼探针分析显示,各阶段包裹体成分类似,气相成分和液相成分主要为H_2O。成矿流体氢、氧同位素组成分别为δD_(H_2O)=-108.8‰^-129.0‰、δ^(18) O_(H_2O)=-7.2‰~4.6‰,表明成矿流体具有多来源,以大气降水为主的特征。综合矿床地质特征和成矿流体研究,认为流体不混溶作用可能是绿源金矿床的重要成矿机制,该矿床应属浅成低温热液型金矿床。
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 0.66～0.98 g/cm^3.The homogeneous temperatures of fluid inclusions decrease gradually,from268～322℃ 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）×10^5 Pa,with an average of 203×10^5 Pa,and the corresponding ore-forming depths are 0.24～1.12 km,with an average of 0.68 km,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 thatδD（H2O）=-108.8‰ ～-129.0‰,δ^18 O（H2O）=-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.
作者
丁辉
葛文胜
董连慧
邓刚
贾红旭
张佳儒
陈疆
元强
DING Hui;GE Wensheng;DONG Lianhui;DENG Gang;JIA Hongxu;ZHANG Jiaru;CHEN Jiang;YUAN Qiang(School of Earth Sciences and Resources, China University of Geosciences , Beijing , 100083;Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing , 100029;Xinjiang Bureau of Geology and Mineral Resources, Urumqi , 830000;No. 6 Geological Party of Xinjiang Bureau of Geology and Mineral Resources, Xinjiang, Hami, 839000)
出处
《地质学报》
EI
CAS
CSCD
北大核心
2018年第4期787-803,共17页
Acta Geologica Sinica
基金
新疆地质矿产勘查开发局项目(编号：DZKC201504-009)资助成果
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
fluid inclusion
hydrogen and oxygen isotopes
epithermal gold deposit
Luyuan golddeposit
Xinjiang
作者简介
丁辉，男，1990年生。博士研究生，矿产普查与勘探专业。Email：dinghui201309@163．com。;通讯作者：葛文胜，男，1968年生。博士，副教授，主要从事矿床学与地球化学研究。Email：gews@cugb．edu．cn。
