新疆东天山照壁山金铅锌多金属矿床地质特征及矿床成因  

Geological characteristics and ore genesis of Zhaobishan Au-Pb-Zn polymetallic deposit in eastern Tianshan,Xinjiang

作　　者：张雪琴 徐登峰[3] 赵云 薛春纪[1,4] 刘一浩[1] 李旭广[1] 陈波 游延祥 ZHANG XueQin;XU DengFeng;ZHAO Yun;XUE ChunJi;LIU YiHao;LI XuGuang;CHEN Bo;YOU YanXiang(School of Earth Sciences and Resources,State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Beijing 100083,China;Key Laboratory of Western China’s Mineral Resources and Geological Engineering,Ministry of Education Chang’an University,Xi’an 710054,Shaanxi,China;Second Regional Geological Survey Brigade of Xinjiang Bureau of Geology and Mineral Resources,Changji 831100,Xinjiang,China;The National 305 Project Office of Xinjiang,Urumqi 830000,Xinjiang,China;Xinjiang Tianchi Energy Co.Ltd.,Changji 831100,Xinjiang,China)

机构地区：[1]中国地质大学(北京),地质过程与矿产资源国家重点实验室,地球科学与资源学院,北京100083 [2]西部矿产资源与地质工程教育部重点实验室长安大学,陕西西安710054 [3]新疆维吾尔自治区地质矿产勘查开发局第二区域地质调查大队,新疆昌吉831100 [4]新疆维吾尔自治区人民政府国家305项目办公室,新疆乌鲁木齐830000 [5]新疆天池能源有限责任公司,新疆昌吉831100

出　　处：《矿床地质》2023年第6期1121-1138,共18页Mineral Deposits

基　　金：新疆维吾尔自治区人力资源和社会保障厅“天池英才”项目;地质过程与矿产资源国家重点实验室开放课题编号(编号:GPMR202307);长安大学中央高校基本科研业务费专项资金(编号:300102263505);企事业单位委托科技项目(编号:3-4-2021-266)联合资助。

摘　　要：照壁山金铅锌多金属矿床位于东天山博格达岛弧带中部,是近年来新发现的矿床。矿体赋存于柳树沟组第三岩性段火山岩-火山碎屑岩中,以脉状、浸染状矿化为主,发育硅化、明矾石化蚀变,其成矿过程可分为3个阶段:①石英-黄铁矿-毒砂阶段(Ⅰ);②石英-金-黄铁矿-闪锌矿-方铅矿阶段(Ⅱ);③石英-黄铁矿-黄铜矿阶段(Ⅲ)。赋矿围岩为双峰式火山岩组合,玄武岩高Mg(Mg^(#)=36.25%~58.77%)、富钠贫钾(w(Na_(2)O/K_(2)O)=1.95~27.35),铝饱和指数(A/CNK)在1.25~1.69之间,属过铝质拉斑玄武岩系列,较高的La/Nb(2.49~3.83)、Ba/Nb(41.00~315.38)、Ba/La(14.50~92.45)比值,反映了玄武质岩浆受到了一定的地壳物质混染,Rb、Ba、K等元素相对富集,Th、Nb、Ta等元素相对亏损,具有板内玄武岩的特征;流纹岩具有较高的全碱含量(w(Na_(2)O+K_(2)O)=9.50~12.45),属钾玄岩系列,轻微富集轻稀土,富集Rb、U、K等元素,亏损Nb、Ta、Sr、Ti等元素,反映了流纹岩来源于地壳物质的部分熔融;石英脉中的流体包裹体主要为气液两相,均一温度为194.2~253.5℃(Ⅱ)、156.7~201.6℃(Ⅲ),盐度为7.9%~13.2%(Ⅱ)、7.3%~12.4%(Ⅲ),成矿流体表现为中温、中低盐度、低氧逸度、低pH值特征;δD_(v-SMOW)变化范围为-115.7‰~-95.4‰,δO_(v-SMOW)变化范围为-0.51‰~7.19‰,表明成矿流体为岩浆热液与大气降水的混合热液。结合系统的地质、地球化学对比,文章推测照壁山金铅锌多金属矿床为中硫型浅成低温热液矿床。The Zhaobishan Au-Pb-Zn polymetallic deposit is a new discovery in the middle segment of the Bogda is land arc in Eastern Tianshan.The deposit is hosted by the volcanic-pyroclastic rocks of the third lithologic member of the Liushugou Formation,with the major type as veinlet and disseminated mineralization,silicification and alum alteration.The ore-forming process can be divided into three stages:①quartz-pyrite-arsenopyrite stage(Ⅰ);②quartz-gold-pyrite-sphalerite-galena stage(Ⅱ);③quartz-pyrite-chalcopyrite stage(Ⅲ).The host rock is bimodal volcanic rock.The basalts have high values of Mg(Mg^(#)=36.25%~58.77%),Na_(2)O/K_(2)O(1.95~27.35),A/CNK(1.25~1.69),belonging to the peraluminous tholite series.The high La/Nb(2.49~3.83),Ba/Nb(41.00~315.38),Ba/La(14.50~92.45)ratios indicate that the basalts have experienced a certain degree of crustal contamination.These rocks are enriched in Rb,Ba,K and depleted in Th,Nb,Ta,which are comparable with the geochemical features of intraplate basalts.The rhyolites of bimodal volcanic rocks exhibit high ALK(w(Na_(2)O+K_(2)O)=9.50~12.45),belonging to the potassium basalt series.They are slightly enriched in rare LERR,Rb,U,K and depleted in Nb,Ta,Sr,Ti,which indicate that the rhyolites have been derived from partial melting of crustal materials.The primary fluid inclusions trapped in quartz are mainly composed of gas and liquid.Homogenization temperatures is 194.2~253.5℃(Ⅱ),and 156.7~201.6℃(Ⅲ).Salinity is 7.9%~13.2%(Ⅱ),7.3%~12.4%(Ⅲ),respectively.TheδD_(v-SMOW) values of fluid inclusion hosted by quartz vary from-115.7‰to-95.4‰,andδO_(v-SMOW) values of oreforming fluid using homogenization temperature method vary from-0.51‰to 7.19‰,indicating that the oreforming fluid is a mixture of magmatic water and meteoric water.Combined with systematic geological and geochemical comparison,it is concluded that the Zhaobihsan Au-Pb-Zn polymetallic deposit may belong to intermediate-sulfidation epithermal deposit.

关 键 词：地质特征 矿床成因 浅成低温热液 博格达岛弧带 东天山 

分 类 号：P618.42[天文地球—矿床学] P618.51[天文地球—地质学]