下刚果盆地中新统重力流沉积演化及控制因素  

Sedimentary Evolution and Controlling Factors of Miocene Gravity Flow Deposits in the Lower Congo Basin

作　　者：吴高奎 张忠民[1] 陈华 郭荣涛 孔凡军[1] 宫越 徐海[1] 张德民[1] WU GaoKui;ZHANG ZhongMin;CHEN Hua;GUO RongTao;KONG FanJun;GONG Yue;XU Hai;ZHANG DeMin(Petroleum Exploration and Production Research Institute,SINOPEC,Beijing 100083,China;Research Institute of Petroleum Exploration and Development,PetroChina,Beijing 100083,China)

机构地区：[1]中国石化石油勘探开发研究院,北京100083 [2]中国石油勘探开发研究院,北京100083

出　　处：《沉积学报》2023年第1期73-84,共12页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(41902119);国家科技重大专项(2016ZX05033);中国石化基础前瞻项目(P22214-2)。

摘　　要：针对下刚果盆地中新统重力流沉积演化及其控制因素认识不够明确的问题,利用下刚果盆地X区块丰富的三维地震、测井及岩心资料,在建立中新统层序格架的基础上,精细识别了重力流沉积单元类型,系统揭示了重力流沉积演化特征并探讨了其控制因素。区内中新统可划分为SQ1(下中新统)、SQ2(中中新统下段)、SQ3(中中新统上段)及SQ4(上中新统)等4个三级层序,主要发育块体搬运、重力流水道(包括侵蚀过路水道、受限侵蚀水道、弱受限侵蚀—加积水道)、天然堤及朵叶体等沉积单元。SQ1早期,重力流沉积多在拉张区呈NW—SE向分布,主导沉积单元为朵叶体。SQ2早期,重力流沉积分布较广(呈NW—SE向),主导发育弱受限侵蚀—加积水道。SQ3早期,重力流沉积在研究区北部呈NWW—SEE向发育且以受限侵蚀水道为主。SQ4早期,重力流沉积全区发育(E—W走向),主导发育侵蚀过路水道。SQ1~SQ4,重力流沉积总体北迁、进积。刚果河携带大量物源向深水搬运(气候变冷、构造隆升及海平面下降所致)是重力流沉积大规模进积的第一要素,陆缘结构(掀斜陆架和宽缓陆坡)及陆坡坡度变化(断层及盐构造所致)控制了沉积分散过程和砂体横向分布。该研究有助于深化区内中新统重力流沉积演化认识,并为深水油气勘探提供借鉴。The sedimentary evolution and controlling factors of the Miocene gravity flow deposits in the Lower Congo Basin are not well understood.Based on the integral analysis of seismic,logging,and core samples in block X of the Lower Congo Basin,the Miocene sequence framework is established,and the sedimentary units of the Miocene gravity flow deposits are fully identified.The sedimentary evolution of the gravity flow deposits is systematically revealed,and the controlling factors are discussed.The Miocene strata in the study area can be divided into four 3rd order sequences,referred to as SQ1(Lower Miocene),SQ2(lower part of Middle Miocene),SQ3(upper part of Middle Miocene),and SQ4(Upper Miocene).Four major types of deep-water sedimentary units are identified:gravity flow channel(including erosional bypassing channel,restricted erosional channel,weakly restricted erosional-aggradational channel and unrestricted aggradational channel),lobe,levee,and mass transport deposits.In SQ1,the gravity flow deposits were primarily developed in the stretching zone of block X with NW-SE extension,and the dominant sedimentary unit was either lobes or unrestricted aggradational channels.During SQ2,the gravity flow deposits were widely distributed(NW-SE trending),and weakly restricted erosional-aggradational channels were dominant.In SQ3,the gravity flow deposits developed in the northern section of the study area with NWW-SEE extension,and restricted erosional channels were widely recognized.In SQ4,the gravity flow deposits developed throughout the entire study area(E-W trending)with erosional bypassing channels being dominant.For SQ1-SQ4,the gravity flow deposits were generally characterized by progradation.That the Congo River delivered an abundant source supply to the deep-water caused by tectonic uplift,climate cooling,and sea level fall was the overriding factor for the progradation of the deposits.The continental margin shape(tilting shelf and wide slope)and the gradient change of the slope caused by salt structure and faults co

关 键 词：重力流沉积 沉积演化 控制因素 中新统 下刚果盆地 

分 类 号：P512.2[天文地球—地质学]