鄂尔多斯盆地富县地区马家沟组热液改造特征与研究意义  

Mechanism and significance of hydrothermal activity in the Majiagou Formation,Fuxian area,Ordos Basin

作　　者：齐荣[1] 李国蓉[2] 张军涛[3] 王付斌[1] 李宇翔[1] 杨飞[1] 刘璐[1] 何赛[2,4] 田家奇 李肖肖 QI Rong;LI Guorong;ZHANG Juntao;WANG Fubin;LI Yuxiang;YANG Fei;LIU Lu;HE Sai;TIAN Jiaqi;LI Xiaoxiao(North China Company,Sinopec,Zhengzhou 450006,China;College of Energy,Chengdu University of Technology,Chengdu 610059,China;Research Institute of Petroleum Exploration and Development,Sinopec,Beijing 102206,China;Sichuan Zhongcheng Institute of Coalfield Geophysical Engineering,Chengdu 610072,China)

机构地区：[1]中国石化华北油气分公司,河南郑州450006 [2]成都理工大学能源学院,四川成都610059 [3]中国石油化工股份有限公司石油勘探开发研究院,北京102206 [4]四川中成煤田物探工程院有限公司,四川成都610072

出　　处：《古地理学报》2024年第3期632-643,共12页Journal of Palaeogeography：Chinese Edition

基　　金：中国石化科技部项目(编号:P22179)资助。

摘　　要：构造—热事件对油气生成、储集层演化和成藏有重要的控制作用,但是鄂尔多斯盆地构造—热事件对碳酸盐岩的影响研究较少。以富县地区奥陶系马家沟组储集层为例,通过岩心及薄片观察,利用阴极发光、包裹体测温、碳氧稳定同位素、锶同位素、电子探针微区元素分析、稀土元素分析,岩石学与地球化学研究充分结合,识别出区内存在2期与燕山期热事件相关的胶结作用:第Ⅰ期以缝洞内鞍形白云石发育为特征,其δ^(13)C值和δ^(18)O值均较偏负,锶同位素值较正常海相灰岩高,稀土元素Eu和La负异常,元素分析显示FeO含量异常高、MnO含量较高、SrO含量较高、K_(2)O及Na_(2)O含量低,胶结物包裹体均一温度高;第Ⅱ期以缝孔洞内石英充填及交代和切割鞍形白云石的裂缝方解石发育为特征,其δ^(13)C值与奥陶系碳酸盐岩背景值接近、δ^(18)O值总体偏低,锶同位素值更高,稀土元素展现出特别的La负异常和Eu正异常,元素分析MnO及FeO含量较高,部分K_(2)O及Na_(2)O含量较高,石英包裹体均一温度高。第Ⅰ期流体为早白垩世拉张断裂作用下上覆石炭—二叠系地层有机流体、奥陶系地层内部流体、少量深部流体三者联合作用形成;第Ⅱ期流体为早白垩世拉张断裂作用下深部流体与少量奥陶系地层内部流体两者联合作用形成,深部流体穿越了下伏马家沟组内蒸发盐岩地层。早白垩世热事件对奥陶系碳酸盐岩储集层的影响具有双向性:第Ⅰ期热流体活动多为建设性,与大规模油气生成的时间一致,裂缝和溶蚀孔洞可构成油气有效输导和储集空间;第Ⅱ期热流体活动以孔隙和裂缝充填为主,多为破坏性,但规模较小。It is of great significance to study the mechanism of hydrothermal activity,related to the Yanshanian thermal events in Majiagou Formation,Fuxian area of the Ordos Basin,to reveal the origin of reservoirs.The two stages of hydrothermal activity related to the Yanshanian thermal events in Majiagou Formation,Fuxian area are identified,based on a comprehensive analysis of petrology and geochemistry,including core and thin section observation and cathode luminescence,homogenization temperature of fluid inclusions,carbon and oxygen stable isotopes,strontium isotope,electron probe microanalysis and rare earth element analyses.The results show that the stage-Ⅰhydrothermal activity is characterized by the development of saddle dolomite in the fissure-cavern systems,with low and negativeδ^(13)C andδ^(18)O values,higher strontium isotope value than normal marine limestone,negative abnormal Eu and La in rare earth elements,rich content of MnO,FeO,SrO and poor content of K_(2)O and Na_(2)O in trace elements,and high homogenization temperature of fluid inclusions.The geochemical characteristics reveal that the saddle dolomite was formed by the combined action of internal fluids in the Ordovician strata,shallow fluids in the Carboniferous-Permian strata,and deep hydrothermal fluid under Early Cretaceous extensional fault activity,in which the deep hydrothermal fluid is post-magmatic hydrothermal fluid related to basalt eruption.The stage-Ⅱhydrothermal activity is characterized by quartz precipitation in fracture-vug systems,and the development of fractures calcite that cut saddle dolomite,withδ^(13)C values close to the background value of Ordovician carbonate rocks,lowδ^(18)O value,higher strontium isotope value than saddle dolomite,negative abnormal La and positive abnormal Eu in rare earth elements,rich content of MnO,FeO,K_(2)O,Na_(2)O in trace elements,and high homogenization temperature of fluid inclusions in quartz.The geochemical characteristics reveal that the calcite and quartz were formed by the combined act

关 键 词：鄂尔多斯盆地 富县地区 马家沟组 碳酸盐岩 热液作用 

分 类 号：P618.13[天文地球—矿床学]