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| 新疆喀什凹陷巴什布拉克铀矿流体包裹体及有机地球化学特征 | |
| 引用本文： | 韩凤彬,陈正乐 陈柏林 李细根 刘增仁.新疆喀什凹陷巴什布拉克铀矿流体包裹体及有机地球化学特征[J].中国地质,2012,39(4):985-998. |
| 作者姓名： | 韩凤彬 陈正乐 陈柏林 李细根 刘增仁 |
| 作者单位： | 1. 中国地质科学院地质力学研究所,北京,100081 2. 核工业216大队,新疆乌鲁木齐,830011 3. 有色金属矿产地质调查中心新疆地质调查所,新疆乌鲁木齐,830011 |
| 基金项目： | 国家重点基础研究发展计划(973)项目，国家自然科学基金，国家305项，全国危机矿山接替资源找矿项目 |
| 摘 要： | 巴什布拉克铀矿床位于新疆喀什凹陷北西部一套陆相碎屑沉积岩中。野外调查发现,伴随铀矿化发育大量地沥青、油气残留物。本文对采自巴什布拉克铀矿床的地沥青含矿砂岩矿石进行了流体包裹体测试和有机地球化学分析,以确定成矿流体的温度和盐度以及成矿物理化学背景,追索有机质的来源,进而探讨矿床成因。镜下观测发现,含矿砂岩中含有大量的油气包裹体,其中以液烃包裹体为主,含有少量气液烃包裹体和含烃盐水包裹体。流体包裹体测温结果表明,成矿流体均一温度为71~193℃,盐度为0.71~23.05(wt%NaCl),整体上属于低温低盐度的成矿流体。同时求得巴什布拉克铀矿成矿压力为77.90~211.75(105Pa),成矿深度在0.26~0.71 km。有机地球化学分析表明,矿区有机质的氯仿沥青"A"变化不大,为0.0019%~0.0026%,有机质来源以海相藻类为主。样品的OEP(奇偶优势指数)为0.72~0.84,平均为0.78,显示了有机质高成熟的特征;CPI(碳优势指数)为1.16~1.35,平均为1.25,指示热演化程度较高;Pr/Ph(姥鲛烷/植烷)为0.77~1.01,平均为0.89,说明有机质处在还原环境中。结合野外地质特征,认为巴什布拉克铀矿床为油气还原成因,沿断裂和岩石孔隙上升的油气的还原作用是铀成矿的主要因素。 |
| 关 键 词： | 流体包裹体 有机地球化学 铀矿 巴什布拉克 喀什凹陷 |
Fluid inclusion and organic geochemistry characteristics of the Bashibulake uranium deposit in Kashi Sag, Xinjiang |
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| HAN Feng-bin,CHEN Zheng-le,CHEN Bai-lin,LI Xi-gen,LIU Zeng-ren.Fluid inclusion and organic geochemistry characteristics of the Bashibulake uranium deposit in Kashi Sag, Xinjiang[J].Chinese Geology,2012,39(4):985-998. | |
| Authors: | HAN Feng-bin CHEN Zheng-le CHEN Bai-lin LI Xi-gen LIU Zeng-ren |
| Institution: | 1.Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China;2.No.216 Geological Party,CNNC,Urumqi 830011,Xinjiang,China;3.Xinjiang Geological Survey,China Non-ferrous Metals Resources Geological Survey,Urumqi 830011,Xinjiang,China) |
| Abstract: | Located in Kashi Sag on the northwestern margin of Tarim basin,Xinjiang,the Bashibulake uranium deposit is hosted in clastic sedimentary rocks of continental facies,where lots of organic matters are widely spread,such as residues of oil,gas and asphalt.This paper mainly presents analytical data of fluid inclusions and organic geochemistry of asphalt sandstone ore bodies,with the purpose of constraining the ore-forming fluid temperature,salinity and ore-forming physical-chemical background,tracing the organic matter source and discussing uranium mineralization.Fluid inclusions in the ore-hosting sandstone under microscope are predominantly petroleum inclusions,composed mostly of liquid hydrocarbon inclusions with minor hydrocarbon-bearing brine inclusions.The homogenization temperature of the ore-forming fluid changes from 71 to 193℃,and the salinity varies from 0.71 to 23.05(wt% NaCl),indicating a kind of low temperature and low salinity ore-forming fluid.The mineralization pressure varies from 77.90 to 211.75 ×10 5 Pa,and the mineralization depth varies from 0.26 to 0.71 km.The content of chloroform bitumen "A" in organic matter changes insignificantly from 0.0019 to 0.0026 wt%,suggesting that the organic matter should be derived from the marine algae.The ratio of pristine to phytane(Pr/Ph) from samples changes from 0.77 to 1.01,0.89 on average,indicating a deoxidization environment for the organic matter.Odd-even predominance index(OEP) varies from 0.72 to 0.84,0.78 on average,implying that the maturity of the organic matter is relatively high.Carbon preference index(CPI) is from 1.16 to 1.35,1.25 on average,indicating a higher degree in thermal evolution.Combined with field geological characteristics,the authors hold that the uranium mineralization of this ore deposit was intimately related to the reduction of oil and gas which migrated upward along fractures and rock pores. |
| Keywords: | fluid inclusion organic geochemistry uranium deposit Bashibulake Kashi Sag |
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