渝东南地区下志留统石牛栏组混合沉积作用及对生物礁发育的制约  

Mixed sedimentation and constraints on reef of Shiniulan formation in lower Silurian, southeast of Chongqing

作　　者：谭先锋[1,2] 李志军 蒋艳霞[3] 李航[2] 

机构地区：[1]复杂油气田勘探开发重庆市重点实验室,重庆401331 [2]重庆科技学院石油与天然气工程学院,重庆401331 [3]成都理工大学地球科学学院,四川成都610059

出　　处：《油气地质与采收率》2014年第3期6-9,14,共5页Petroleum Geology and Recovery Efficiency

基　　金：重庆市自然科学基金项目"渝东南地区下志留统石牛栏组珊瑚礁及造礁环境研究"(cstc2012jjA90007)

摘　　要：渝东南地区下志留统石牛栏组广泛发育碳酸盐与陆源碎屑的混合沉积。通过野外观察、薄片鉴定、同位素分析等手段,对研究区石牛栏组混合沉积作用及对生物礁的制约进行了研究。结果表明,渝东南地区石牛栏组主要发育泥质灰岩与砂质泥岩、泥晶灰岩与泥岩、生物灰岩与灰质泥岩3种混积层系和泥质灰岩、砂质/粉砂质灰岩、含粉砂生物礁灰岩(生物灰岩)、灰质粉砂岩、灰质泥岩6种混积岩。沉积环境的演化过程表现为早期浅水混积陆棚—中期生物礁滩—晚期礁前斜坡及浅水混积陆棚;陆源碎屑含量从底部到顶部总体为降低的过程,与海平面的演化规律存在一定的耦合。混合沉积主要发生于浅水混积陆棚及生物礁滩/斜坡2种沉积环境。在石牛栏组生物礁发育过程中,陆源碎屑的注入是制约生物礁及生物群落发育的根本原因。Mixed sediments of carbonate and clastic origin are widely developed in Shiniulan formation of lower Silurian, southeast ofChongqing. Taking the typical Shiniulan profile as the study object, through the field observations, thin section analysis, isotope analy-sis and other means, the mixed sediments and the constraints on the reef of Siniulan formation are studied. The results show that, theremainly developed argillaceous limestone and sandy mudstone, micritic limestone and mudstone, biological limestone and lime mud-stone, which have formed three diamictic strata. There develops the argillaceous limestone, sandy limestone, silty clay limestone, siltyreef limestone(biogenic limestone), gray siltstone, lime mudstone, that is, six kinds of gray diamictites. In Siniulan formation, the depo-sitional environments are mainly early shallow mixed continental shelf, that is, interim reef deposits-advanced reef slope sedimentaryevolution, and the terrigeneous content reduces from bottom to top in the overall process, and the mixed deposition occurs mainly inshallow mixed continental shelf and reef and beach/ramp, two depositional environments. It is confirmed that, in the Shiniulan reef de-velopment process, the injected terrigeneous debris is the major cause which has constrained the development of the reef and the biolog-ical communities.

关 键 词：混合沉积 混积岩 生物礁 石牛栏组 渝东南地区 

分 类 号：TE111.3[石油与天然气工程—油气勘探]