| 北喜马拉雅扎西康铅锌锑银矿床成因的多元同位素制约 |
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| 引用本文： | 张建芳,郑有业,张刚阳,高顺宝,叶先仁,张众,刘敏院,李及秋.北喜马拉雅扎西康铅锌锑银矿床成因的多元同位素制约[J].地球科学,2010,35(6):1000-1010. |
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| 作者姓名： | 张建芳 郑有业 张刚阳 高顺宝 叶先仁 张众 刘敏院 李及秋 |
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| 作者单位： | 1.中国地质大学资源学院, 湖北武汉 430074 |
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| 基金项目： | 教育部重大项目(No.308018); 国家科技支撑计划项目(No.2006BAB01A04) |
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| 摘 要： | 扎西康矿床是北喜马拉雅金锑多金属成矿带中发现的唯一一个大型Pb-Zn-Sb-Ag共生矿床.矿体赋存于SN向的高角度张扭性断裂带中, 该矿床的黄铁矿、闪锌矿、方铅矿、硫锑铅矿和辉锑矿等硫化物的δ34S值为4.5‰~12.0‰, 多数集中在8‰~11‰, 富集重硫且变化较小, 表明其硫源是一致的, 主要来源于围岩中的海相地层还原硫.206Pb/204Pb、207Pb/204Pb、208Pb/204Pb比值分别在18.474~19.637, 15.649~15.774和39.660~40.010范围内, 并成一条直线, 具有放射性异常铅的特征, 投图落在上地壳铅演化线附近.流体包裹体的δDV-SMOW为-127‰~-135‰, δ18OH2O为-13.7‰~12.4‰, 偏向于西藏地热水的分布范围; He-Ar同位素组成表明成矿流体主要为地壳流体和饱和大气水的混合, 没有明显的地幔流体成分混入.其多元同位素组成与北喜马拉雅成矿带的金或金锑等其他矿床具有明显的差异, 表明其成矿作用具有特殊性, 在中新世随着印度与欧亚板块后碰撞挤压向伸展走滑阶段转换, 在北喜马拉雅构造带内形成一系列的SN向高角度断裂, 并促使地壳发生部分熔融形成熔融层, 引起局部热流值剧增, 地温异常梯度增大, 驱动地下水对流循环, 萃取晚三叠世-早侏罗世的一套浊流或喷流灰黑色碳硅泥岩系地层中的成矿物质, 沿着SN向断裂带充填交代成矿, 属于沉积-构造-热泉水改造的多阶段充填交代热液脉状矿床.
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| 关 键 词： | 同位素 铅锌锑银矿 矿床地质 矿床成因 地球化学 北喜马拉雅 |
| 收稿时间： | 2010-05-27 |
Genesis of Zhaxikang Pb-Zn-Sb-Ag Deposit in Northern Himalaya:Constraints from Multi-Isotope Geochemistry |
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| ZHANG Jian-fang,ZHENG You-ye,ZHANG Gang-yang,GAO Shun-bao,YE Xian-ren,ZHANG Zhong,LIU Min-yuan,LI Ji-qiu .Faculty of Earth Resources,China University of Geosciences,Wuhan ,China .School of the Earth Sciences , Resources,Beijing ,China.State Key Laboratory of Geological Processes , Mineral Resources,China .Lanzhou Institute of Geology,Chinese Academy of Sciences,Lanzhou ,China .Tibet Huayu Minin....Genesis of Zhaxikang Pb-Zn-Sb-Ag Deposit in Northern Himalaya:Constraints from Multi-Isotope Geochemistry[J].Earth Science-Journal of China University of Geosciences,2010,35(6):1000-1010. |
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| Authors: | ZHANG Jian-fang ZHENG You-ye ZHANG Gang-yang GAO Shun-bao YE Xian-ren ZHANG Zhong LIU Min-yuan LI Ji-qiu Faculty of Earth Resources China University of Geosciences Wuhan China School of the Earth Sciences Resources Beijing ChinaState Key Laboratory of Geological Processes Mineral Resources China Lanzhou Institute of Geology Chinese Academy of Sciences Lanzhou China Tibet Huayu Minin |
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| Institution: | ZHANG Jian-fang1,ZHENG You-ye2,3*,ZHANG Gang-yang1,GAO Shun-bao1,YE Xian-ren4,ZHANG Zhong1,LIU Min-yuan5,LI Ji-qiu5 1.Faculty of Earth Resources,China University of Geosciences,Wuhan 430074,China 2.School of the Earth Sciences and Resources,Beijing 100083,China3.State Key Laboratory of Geological Processes and Mineral Resources,China 4.Lanzhou Institute of Geology,Chinese Academy of Sciences,Lanzhou 730000,China 5.Tibet Huayu Minin... |
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| Abstract: | Zhaxikang deposit is the only large Pb-Zn-Sb-Ag symbiotic deposit in the northern Himalayas gold-antimony polymetallic belt, with its ore body located in the high-angle twisting fault zone striking SN direction. The δ34S of pyrite, sphalerite, galena, jamesonite, stibnite ranges from 4.5‰ to 12.0‰, with the majority ranging from 8‰ to 11‰, and it is enriched in sulfur with a narrow range, indicating that the same sulfur source, mainly from the rock formation in the marine sulfur reduction. The ratio of 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb is at 18.474-19.637, 15.649-15.774 and 39.660-40.010 respectively, falling near the upper crust of lead evolution line within the investment plan, and into a straight line. δDV-SMOW values of water in fluid inclusions of quartz varies from -127‰ to -135‰, δ18OH2O to -13.7‰ to 12.4‰, in the distribution of geothermal water in Tibet. He-Ar isotopes shows that the ore-forming fluid was mainly derived from rustal fluids and saturated meteoric water, and apparently there is no mixing mantle fluid composition. The multi-isotope composition of the deposit has significant difference with gold or gold-antimony deposit in North Himalayan metallogenic belt, which indicates its unique mineralization of Zhaxikang deposits. As the Indian plate colliding to Eurasian plate in Miocene post-collisional transition environment from intra-continental orogeny to extension slip in North Himalayan belt, there formed a series of high-angle fault zones of SN direction, causing partial melting of crust which increased local heat flux sharply and geothermal gradient anomalies driving groundwater convection cycle, extracting metallogenic elements from Late Triassic-Early Cretaceous turbidite or black carbon and silicon gray mudstone strata The deposit formed by replacement and filling along the SN fault zone, which belongs to sedimentary-structural-geothermal water multi-stage replacement and hydrothermal vein deposits. |
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| Keywords: | isotope lead-zinc-antimony and silver ore deposit deposit geology deposit genesis geochemistry North Himalayan |
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