金湖凹陷西斜坡陆相湖盆灰砂混积岩成因分析  

SEDIMENTOLOGY OF MIXED LIMESTONE AND SANDSTONE IN THE NONMARINE FUNING FORMATION(EOCENE)OF THE WESTERN JINHU SAG

作　　者：林波[1] 刘金华[1] 孙东升[1] 闵路[1] 葛政俊[1] 

机构地区：[1]中石化江苏油田勘探开发研究院,江苏扬州225012

出　　处：《地层学杂志》2017年第1期110-116,共7页Journal of Stratigraphy

基　　金：中石化科技攻关项目"小断块油藏油水过渡带提高采收率技术研究"(编号:P13125)资助

摘　　要：金湖凹陷西斜坡阜宁组第二亚段(E1f22)发育一套生物碎屑灰岩为主的灰砂岩混积地层,该地层属于层系混积地层。在前人研究基础上,通过对古气候、古盐度、沉积环境的分析,认为研究区阜宁组第二亚段沉积时期为亚热带气候,存在海侵事件,水体盐度较大,整体为一套碳酸盐岩坪沉积体系。沉积相垂向序列研究等发现阜宁组第二亚段发育两类沉积旋回,以下部为泥页岩、上部为生物碎屑灰岩或泥灰岩的沉积旋回及下部为粉砂岩、上部为生物滩坝灰岩的旋回,仅在局部发育少量全部为砂岩的小层,并且砂岩多数与断层的发育存在密切关系,从而提出了"Y"型同生断层输送碎屑沉积物模式。研究区灰砂混积岩沉积是在湖盆湖平面上升期,湖盆为咸化湖泊,存在形成沉积范围较广生物碎屑灰岩条件的大环境下,由于陆源碎屑不断堆积,断层断距不断减小直至消失,在碎屑岩顶部形成灰岩层,从而形成了灰砂混积岩。The Second Member of the Eocene Funing Formation （E1f2^2） consists of a mixture of limestone and sandstone, the former of which is mainly composed of bioclastic limestone. The Second Member of the Funing Formation was deposited in subtropical environments with high paleosalinity and transgression events. Facies and sequence stratigraphic analysis revealed two main kinds of sequences in this unit： some sequences consist of mudstone overlain by bioclastic limestone or muddy limestone, whereas others consist of sandstone overlain by limestone. In addition, a small number of sequences consisting of sandstone occur locally; these sandstone beds were controlled by small syndepositional faults. The mixed sandstone and limestone in the Second Member of the Funing Formation were deposited in a lacustrine environment with changing lake levels： when lake-level rose, bioclastic limestone was deposited in brackish waters, and as sediments were accumulated, syndepositional faults were buried and the supplies of siliciclastic sediments diminished. As a result, siliciclastic rocks were succeeded by limestone, leading to the formation of sequences with mixed sandstone and limestone.

关 键 词：岩石地层 混积岩 混积层系 陆相湖盆 成因机理 阜宁组 古近系 金湖凹陷 江苏 

分 类 号：P534.61[天文地球—古生物学与地层学]