川中地区灯影组四段微生物岩沉积模式及主控因素  

Deposition Model and Main Factors Controlling Depositional Processes for Microbialites in the Fourth Member,Dengying Formation,Central Sichuan Basin

作　　者：李安鹏 高达[1,2] 胡明毅 赵玉茹[1,2] 朱传勇 戴逸晨 LI AnPeng;GAO Da;HU MingYi;ZHAO YuRu;ZHU ChuanYong;DAI YiChen(School of Geosciences,Yangtze University,Wuhan 430100,China;Key Laboratory of Exploration Technologies for Oil and Gas Resources,Ministry of Education,Wuhan 430100,China)

机构地区：[1]长江大学地球科学学院,武汉430100 [2]油气资源与勘探技术教育部重点实验室,武汉430100

出　　处：《沉积学报》2023年第4期1080-1096,共17页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(41502104);湖北省自然科学基金项目(2017CFB533);油气资源与勘探技术教育部重点实验室开放基金(K2018-06)。

摘　　要：为建立川中地区灯影组四段微生物岩的沉积模式,明确微生物岩沉积的主控因素,利用钻井、岩心、薄片等资料,从中观和微观尺度开展了精细的沉积微相分析。在研究区识别出8种岩相,其中微生物岩包括凝块石和叠层石,并将叠层石划分为波状凝集叠层石、波状骨架叠层石和层状细粒叠层石。这些岩相在垂向上有序组合,发育了潮下—局限潟湖沉积、潮下带凝块石、浅潮下—潮间带叠层石—颗粒滩复合体、潮间带叠层石等4种岩相组合。连井层序地层格架内微相对比显示,微生物丘和颗粒滩主要发育在层序的上部,且在灯四段由下至上发育规模变大。平面上,丘滩体在台地边缘发育规模大,向局限台地内规模减小且分布连续性变差。综合以上认识,提出了灯影组四段微生物岩的沉积模式。凝块石主要发育在浪基面之下的潮下带,水动力弱,局部微生物捕获黏结颗粒形成凝块。波状凝集叠层石主要发育在潮间带下部,各种菌类等微生物繁盛,受强烈的波浪和潮汐作用的影响,微生物捕获黏结大量鲕粒、似球粒等颗粒。波状骨架叠层石主要发育在能量中等的潮间带上部,主要受潮汐作用的影响,微生物通过诱导沉淀和原地钙化作用形成泡沫绵层,并捕获黏结少量球粒。层状细粒叠层石主要发育在潮间带上部,微生物沉积作用以诱导沉淀为主。In order to establish the deposition model of microbialites in the Fourth member of Dengying Formation in central Sichuan Basin,and to clarify the main controlling deposition factors,a detailed deposition microfacies analysis was carried out on macrostructures and microfabrics using data from drill cores and thin sections.Eight lithofacies were identified in the study area,among which the microbialites include thrombolites and stromatolites.The stromatolites are further divided into wavy-laminated agglutinated stromatolites,wavy-laminated skeletal stromatolite and flatlaminated fine-grained stromatolites.The stacking patterns indicate four types of lithofacies associations:subtidalrestricted lagoon deposition;subtidal thrombolites;shallow-subtidal to intertidal stromatolites to shoal complex;and intertidal stromatolites.The microfacies distribution in the sequence stratigraphic framework shows that microbial mounds and shoals were located mainly in the upper part of the sequences,which became better-developed from bottom to top in this member of the Dengying Formation.The mound-shoals were more developed at the platform margin,decreasing in scale and continuity at the restricted platform.A microbialite deposition model was established based on the macrostructures,microfabrics and vertical sequence of the microbialites for the Fourth member of Dengying Formation.The thrombolites were mainly deposited in the subtidal environment below the wave base,with low hydrodynamics.Clots were locally formed by microbial trapping and binding small grains.The wavy-laminated agglutinated stromatolites were mainly deposited in the lower part of intertidal zone,in which various types of microbes flourished,and were formed by microbial trapping and binding of ooids and peloids in conditions of strong waves and tides.The wavy-laminated skeletal stromatolites were mainly deposited in the upper part of intertidal zone with moderate hydrodynamics dominated by the tide.The sponge structures were formed by microbially induced precipitati

关 键 词：微生物岩 叠层石 凝块石 层序地层 沉积模式 灯影组 四川盆地 

分 类 号：P588.245[天文地球—岩石学]