滨里海盆地东南缘石炭系MKT组“反向前积”构型的性质  

Nature of “reverse prograding deposits” at the southeast margin of Pre-Caspian Basin

作　　者：代寒松[1] 陈彬滔[1] 郝晋进[1] 刘雄志[1] 洪亮[1] 赵旭[2] 邓国鑫 Dai Hansong;Chen Bintao;Hao Jinjin;Liu Xiongzhi;Hong Liang;Zhao Xu;Deng Guoxin(Northwest Research Institute of Petroleum Exploration and Development,PetroChina,Lanzhou,Gansu 730020,China;Petroleum Exploration and Production Research Institute,SINOPEC,Beijing 100083,China)

机构地区：[1]中国石油勘探开发研究院西北分院,甘肃兰州730020 [2]中国石化石油勘探开发研究院,北京100083

出　　处：《石油与天然气地质》2018年第6期1246-1254,1279,共10页Oil & Gas Geology

基　　金：中国石油股份公司海外专项(2008E-1606)

摘　　要："前积"是油气勘探中常见的沉积构型,多为沉积物由物源区向卸载区逐步堆积叠加而成,其倾向指向卸载区。滨里海盆地东南缘中区块MKT组泥岩内部由一系列向西(早期隆起物源区)倾斜的"反向前积层"构成,由于其成因存在较大的争议,导致了研究区石炭系沉积演化规律缺乏统一认识,制约了后续勘探工作的开展。文章以区域背景、钻井、地震资料为基础,通过沉积作用、岩性、古地理位置、形态与规模等要素分析比较,对"反向前积"的形成机理进行了探讨,提出MKT组属于深水牵引流沉积而非水进退积楔,"反向前积"是其沉积物在深水牵引流作用下向陆迁移而形成的特殊沉积构型。最终,文章尝试对MKT组沉积演化进行分析总结,并将其划分为:初始形成、强烈作用、晚期衰退和后期调整4个阶段。MKT组深水牵引流沉积的发现不仅完善了宾里海盆地东南缘石炭系沉积演化规律,为后期工作扫清了障碍,丰富了盆地的沉积类型,更为全球古生界深水牵引流研究提供了宝贵实例。Progradating deposits,a result of the progressive accumulation and superimposition of sediments transported from provenance to unloading areas,is a normal sedimentary configuration in petro-exploration,dipping to the unloading areas.The interior MKT Formation mudstone of the middle block at the southeast margin of Pre-Caspian Basin is composed of a series of“reverse prograding deposits”dipping west(i.e.towards the early uplifted provenances).As the origin of the sedimentary configuration has triggered many controversies,there is no consensus as to the sedimentation and evolution of the Carboniferous,which has constrained follow-up exploration.Through the analysis of regional setting,dril-ling and seismic data,we made a comparative analysis of such elements as depositional mode,lithology,paleo-geographic location,geometry and scale,discussed the genetic mechanism of the“reverse prograding deposits”,and proposed that the MKT Formation is deep water tractive current deposits,instead of a retrogradation wedge of transgression origin.Therefore,the“reverse prograding deposits”is a peculiar sedimentary configuration resulted from landward migration of sediments along with the deep water tractive current.In the end,we analyzed the evolution of the MKT Formation and divided it into four stages,namely initiation,peak,recession and late adjustment.The discovery of deep water tractive current deposits not only improves our understanding of the sedimentary evolution rules at the southeast margin of the Carboniferous Pre-Caspian Basin,paves the way for further exploration,and enriches the category of basin sedimentation,but also provides a precious case for global research on the Paleozoic deep water tractive current.

关 键 词：反向前积 深水牵引流沉积 向陆迁移 水进退积楔 沉积演化 石炭系 滨里海盆地 

分 类 号：TE121.3[石油与天然气工程—油气勘探]