湖相细粒沉积岩沉积动力学机制与沉积模式——以鄂尔多斯盆地铜川地区延长组长7油层组露头为例  

Sedimentary Dynamics and Deposition model of Lacustrine Finegrained Sedimentary Rocks:A case study of the Chang 7 oil member from the Yanchang Formation in the Ordos Basin,Tongchuan area

作　　者：黄军平[1] 杨田 张艳 李相博[1] 董岐石 杨占龙[1] Guilherme Bozetti 郑泽宇 HUANG JunPing;YANG Tian;ZHANG Yan;LI XiangBo;DONG QiShi;YANG ZhanLong;Guilherme Bozetti;ZHENG ZeYu(PetroChina Research Institute of Petroleum Exploration&Development-Northwest,Lanzhou 730020,China;Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu 610059,China;School of Earth Sciences,China University of Petroleum(Beijing),Beijing 102249,China;Universitéde Strasbourg,Strasbourg 67084,France)

机构地区：[1]中国石油勘探开发研究院西北分院,兰州730020 [2]成都理工大学沉积地质研究院,成都610059 [3]中国石油大学(北京)地球科学学院,北京102249 [4]Universitéde Strasbourg,Strasbourg 67084,France

出　　处：《沉积学报》2023年第4期1227-1239,共13页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(42072126,41772099);2019年中国石油科技创新基金研究项目(2019D-5007-0106);中国石油天然气股份有限公司前瞻性基础性战略性技术攻关项目(2021DJ0401)。

摘　　要：为了明确鄂尔多斯盆地南部三叠系延长组长7油层组细粒沉积特征及沉积模式,以衣食村、瑶曲等典型野外剖面为研究对象,在野外踏勘和测量的基础上,分析其岩相及岩相组合特征,探讨沉积相类型及特征,并建立了细粒沉积中不同岩相的演化模式。结果表明:铜川地区延长组中下部野外露头主要发育叠覆冲刷正粒序粉砂—细砂岩相、块状层理粉砂—细砂岩相、软沉积变形砂泥混杂岩相、块状泥岩相、水平纹层泥页岩相、凝灰岩相共6种岩相类型。铜川地区长7油层组发育背景泥质沉积、凝灰岩与重力流沉积的垂向组合、滑动滑塌与背景泥岩互层叠置、重力流沉积砂岩、泥岩垂向叠置。衣食村剖面下部长73亚油层组以块状层理碎屑流沉积和滑塌沉积为主;长72亚油层组以深水原地沉积为主,岩性从粉砂岩—粉砂质泥岩过渡到水平纹层泥岩再到页理极其发育的黑色页岩;瑶曲剖面长71亚油层组发育丰富的软沉积变形构造,如液化砂岩脉、块状砂岩内具有泥质条带以及火焰状构造等。研究区延长组长73亚油层组沉积期,主要为三角洲前缘沉积物垮塌再搬运形成的相对厚层滑动滑塌沉积;长72亚油层组沉积期以深水页岩沉积为主,夹杂火山灰和少量的低密度浊流薄层粉砂岩沉积;至长71亚油层组沉积期,部分三角洲垮塌再搬运形成砂质碎屑流沉积和低密度浊流沉积;整体指示了长7油层组沉积时期湖平面先升高后降低的周期性变化特征。湖平面的升降变化控制了细粒沉积物的搬运方式与沉积模式,该研究对于明确细粒沉积物的搬运机制与分布规律具有重要的指导意义。To clarify the fine-grained sedimentary characteristics and depositional models of the Chang 7 oil member of the Triassic Yanchang Formation in the southern Ordos Basin,we take Yishi Village,Yaoqu,and other typical field sections as research objects.Based on field reconnaissance and survey,we analyze the lithofacies and lithofacies assemblage characteristics,discuss sedimentary facies characteristics,and establish different fine-grained sedimentary lithofacies evolution models.The results show that the outcrops in the middle and lower sections of the Yanchang Formation in the Tongchuan area primarily developed overlying and scouring positive-order silt-fine sandstone,massive bedding silt-fine sandstone,soft sedimentary deformed sand-shale mixed,and massive mudstone facies.There are 6 lithofacies types in the horizontal laminar shale facies and tuff facies.The typical characteristics of the lower 73 sub-oil member of the Yishicun section are sandy clastic flows and slump deposits with massive bedding.The deepwater in-situ deposits from different outcrop sections of the Chang 72 sub-oil member,whose lithology transitions from siltstone-silty mudstone to horizontal laminar mudstone to black shale with extremely developed shales,were examined.The Chang 71 sub-oil member of the Yaoqu section is rich in soft sedimentary deformation structures,such as liquefied sandstone veins,argillaceous bands,and flame-like structures in massive sandstones.The lithofacies assemblage types of the fine-grained sediments in the Chang 7 oil member from the Yanchang Formation in the Tongchuan area include background argillaceous deposits,vertical assemblages of tuff and gravity flow deposits,superposition of sliding landslides and background mudstones,gravity flow deposits of sandstones,and mudstones.The sedimentary period of the Chang 73 sub-oil member in Yishi Village was a relatively thick sliding slumping deposit formed by the re-transportation of the delta front sediment.The depositional period of the Chang 72 sub-oil member was comp

关 键 词：细粒沉积岩相 沉积模式 长7油层组 铜川地区 鄂尔多斯盆地 

分 类 号：P512.2[天文地球—地质学]