塔里木盆地苏盖特布拉克剖面寒武系第二统第三阶微生物岩结构类型  

Fabric types of microbialites from the Stage 3 of Cambrian Series 2 in Sugaitebulake section,Tarim Basin

作　　者：李莹 潘文庆[4] 吴亚生[1,2,3] 杨果[4] 孙崇浩 姜红霞[5] Li Ying;Pan Wen-Qing;Wu Ya-Sheng;Yang Guo;Sun Chong-Hao;Jiang Hong-Xia(Key Laboratory of Petroleum Resources Research,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Innovation Academy for Earth Science,Chinese Academy of Sciences,Beijing 100029,China;University of Chinese Academy of Sciences,Beijing 100049,China;Research Institute of Petroleum Exploration and Development,Tarim Oilfield Company,PetroChina,Xinjiang Korla 841000,China;Institute of Paleontology,Hebei GEO University,Shijiazhuang 050031,China)

机构地区：[1]中国科学院油气资源研究重点实验室,中国科学院地质与地球物理研究所,北京100029 [2]中国科学院地球科学研究院,北京100029 [3]中国科学院大学,北京100049 [4]中国石油塔里木油田公司,新疆库尔勒841000 [5]河北地质大学古生物研究院,河北石家庄050031

出　　处：《古地理学报》2020年第4期663-679,共17页Journal of Palaeogeography：Chinese Edition

基　　金：国家科技重大专项(编号:2016ZX05004-004);中国科学院战略性先导专项(B)(编号:XDB26000000);国家自然科学基金项目(编号:41972320)共同资助。

摘　　要：塔里木盆地阿克苏地区寒武系第二统第三阶肖尔布拉克组主要由微生物白云岩组成,代表性的剖面在阿克苏市西南90 km处的苏盖特布拉克。由于成岩作用改造严重,对这套微生物碳酸盐岩的特征和形成环境的认识还存在很多分歧,制约了勘探工作。通过详细野外勘察和室内研究,将肖尔布拉克组微生物岩分为4种结构类型:凝块结构、纹层结构、砂屑结构和骨架结构。首次对凝块结构和纹层结构进行了亚类型的划分,其中凝块结构可划分为蠕虫状、网状和斑点状3种亚类型,纹层结构可划分为致密纹层、短薄纹层、颗粒纹层以及单纹层、纹层组、复合纹层。肖Ⅰ段-肖Ⅲ段发育凝块石白云岩、凝块-层纹石白云岩和层纹石白云岩,肖Ⅳ段发育凝块石微生物丘,肖V段下部发育网状结构凝块石白云岩,肖V段上部发育砂屑白云岩和肾形菌骨架岩。白云石化作用、溶蚀作用、重结晶作用是改变肖尔布拉克组微生物岩结构最重要的成岩作用,且该组下部比上部遭受了更强的成岩作用改造;微生物岩结构对成岩作用改造的抵抗能力为:砂屑结构>纹层结构>凝块结构。根据微生物岩结构,推测肖Ⅰ段-肖Ⅲ段形成于潮坪环境,肖Ⅳ段和肖V段下部形成于深水潮下环境,肖V段上部形成于浅水潮下环境。以上成果为认识塔里木盆地肖尔布拉克组微生物岩的平面分布规律和今后开展被成岩作用强烈改造的白云岩型微生物岩的研究提供了一个重要参考。The Xiaoerbulake Formation(Stage 3,Cambrian Series 2)in the Aksu area of the Tarim Basin is mainly composed of microbial dolostone with its reprehensive section at Sugaitebulake,90 km southwest of Aksu city.This formation can be ideal petroleum reservoirs for its good pores which has been extensively studied.Due to serious diagenesis alteration,however,their features have not been fully identified,which causes difficulty in understanding their formative processes and hampers the petroleum exploration.Here,based on detailed observation on outcrops and thin sections,we identified four types of microbialite fabrics,including thrombolitic fabric,laminated fabric,intraclastic fabric and framestone fabric,and established high-precision vertical evolutionary sequence of microbialites.The thrombolitic and the laminated fabrics can be further subdivided.The MembersⅠtoⅢare mainly composed of thrombolitic dolostone,thrombolitic-laminated dolostone and laminated dolostone.The Member IV consists of microbial thrombolite mounds,whereas the lower Member V is net-thrombolitic dolostone and the upper Member V intraclastic dolostone and Renalcis framestone.This study reveals that the original fabrics have been affected by dolomitization,recrystallization and dissolution,and the alteration degree of the microbialite fabric is more severe in the lower parts of this formation.The intraclastic fabric has the strongest resistance to diagenesis,followed by the laminated fabric,and then the thrombolitic fabric.The MembersⅠtoⅢrepresent tidal flat environments;the MemberⅣand the lower MemberⅤrepresent deep subtidal environments;the upper MemberⅤrepresents shallower subtidal environments.

关 键 词：寒武系 微生物岩 凝块石 结构 层纹石 

分 类 号：P588.245[天文地球—岩石学]