鄂西宜昌地区页岩气勘探发现对MVT铅锌矿成矿的指示意义  

Exploration Discovery of Shale Gas and Its Indicative Significance to Mineralization of MVT Lead-Zinc Deposit in Yichang Area,West Hubei

作　　者：高键 李英强[1] 何生 何治亮[1] 李双建[1] 沃玉进[1] 李文[2,3] 翟刚毅 Zhao Jian-xin Gao Jian;Li Yingqiang;He Sheng;He Zhiliang;Li Shuangjian;Wo Yujin;Li Wen;Zhai Gangyi;Zhao Jian-xin(Petroleum Exploration and Production Research Institute,SINOPEC,Beijing 100083,China;Key Laboratory of Tectonics and Petroleum Resources,Ministry of Education,China University of Geosciences,Wuhan 430074,China;Chongqing Research Institute,China Coal Science and Engineering Group,Chongqing 400039,China;Oil&Gas Survey,China Geological Survey,Beijing 100029,China;Radiogenic Isotope Facility,School of Earth and Environment Sciences,The University of Queensland,Brisbane 4072,Australia)

机构地区：[1]中国石化石油勘探开发研究院,北京100083 [2]中国地质大学构造与油气资源教育部重点实验室,湖北武汉430074 [3]中国煤炭科学与工程集团重庆研究院,重庆400039 [4]中国地质调查局油气资源调查中心,北京100029 [5]Radiogenic Isotope Facility,School of Earth and Environment Sciences,The University of Queensland,Brisbane 4072,Australia

出　　处：《地球科学》2021年第6期2230-2245,共16页Earth Science

基　　金：国家自然科学基金项目(Nos.91755211,U19B6003,41672139,41772152,42002137);国家科技重大专项(No.2017ZX05005-001);中国石化集团科技部项目(No.P19021-3).

摘　　要：油气成藏和有机质参与金属成矿的内在联系是近年来国内外地学界关注的热点问题.根据流体包裹体岩相学观察和激光拉曼光谱分析,在鄂西宜昌地区震旦系陡山沱组和下寒武统牛蹄塘组页岩储层及震旦系灯影组MVT(Mississippi Valley type)铅锌矿床中发现了高密度甲烷包裹体,并利用甲烷包裹体的甲烷拉曼散射峰v1计算了甲烷包裹体的密度;同时采用Rb-Sr、Sm-Nd同位素定年确定了MVT铅锌矿成矿年代.鄂阳页1井陡山沱组页岩石英脉和何家坪MVT铅锌矿方解石样品中甲烷包裹体密度分别为0.237~0.278 g/cm^(3)和0.213~0.271 g/cm^(3),属于高密度甲烷包裹体.何家坪铅锌矿共生矿物闪锌矿和方铅矿的Rb-Sr等时线年龄为189.1±1.8 Ma,方解石的Sm-Nd等时线年龄为189.9±2.0 Ma,指示铅锌矿形成于燕山早期的构造挤压运动;共生矿物的初始^(87)Sr/_(86)Sr值(0.71192)和方解石的初始^(87)Sr/^(86)Sr值(0.71203~0.71227)指示何家坪铅锌矿成矿流体的Sr同位素主要来源于页岩层.何家坪铅锌矿中捕获的以流体包裹体形式存在的高密度甲烷流体最有可能来源于陡山沱组页岩和/或牛蹄塘组页岩内高密度超压甲烷流体.页岩气层和MVT铅锌矿中高密度甲烷包裹体的发现及MVT铅锌矿成矿时间的确定为探讨有机质参与MVT铅锌矿成矿提供了新证据.The coupling relationship between hydrocarbon accumulation and the involvement of organic matter in metal mineralization has been a frontier scientific question in recent years.On the basis of the petrography and Raman spectral analysis of fluid inclusions,high-density methane inclusions were discovered in the samples of quartz and calcite veins from Sinian Doushantuo shales,Lower Cambrian Niutitang shales,and MVT(Mississippi Valley type)lead-zinc deposit of Sinian Dengying Formation in Yichang area.The Raman scatter peak v1 of methane inclusions was applied to calculate the density of pure methane inclusions,and the ore-forming ages of MVT lead-zinc deposit were determined by using Rb-Sr and Sm-Nd isochron dating.The density of methane inclusions trapped in the quartz veins within the Doushantuo shales of well EYY 1 mainly ranges from 0.237 to 0.278 g/cm^(3),and the density of methane inclusions trapped in the calcite veins within the Hejiaping MVT lead-zinc deposit mainly ranges from 0.213 to 0.271 g/cm^(3),which signifies methane inclusions of high density.Paragenetic mineral association sphalerite and galena within the Hejiaping lead-zinc deposit have a Rb-Sr isochron age of 189.1±1.8 Ma,and calcite within the Hejiaping lead-zinc deposit yields a Sm-Nd isochron age of 189.9±2.0 Ma,which indicates is the mineralization of Hejiaping lead-zinc deposit was closely related to the Yanshanian tectonic compressions.The ^(87)Sr/^(86)Sr values of the paragenetic mineral association(0.71192)and calcite(0.71203-0.71227)indicate that the ore-forming fluids of the Hejiaping lead-zinc deposit were derived largely from shale sources.The high-density methane trapped in fluid inclusions within the Hejiaping lead-zinc deposit was most likely derived from the high-density overpressure methane generated by the Doushantuo shales and/or Niutitang shales.The discovery of high-density methane inclusion in the shale gas layer and MVT lead-zinc deposit,and the determination of oreforming ages of MVT lead-zinc deposit provide new evid

关 键 词：页岩气 MVT铅锌矿 高密度甲烷包裹体 Rb-Sr等时线定年 Sm-Nd等时线定年 成矿-成藏耦合 石油地质 

分 类 号：P588.22[天文地球—岩石学] P595[天文地球—地质学]