东非海岸重点盆地渐新世构造事件-沉积体系耦合关系研究  

The relationship between tectonic events and sedimentarysystems in coastal key basins of the East Africa

作　　者：李华[1] 梁建设 邱春光 赵红岩 胡滨 饶溯 王贝贝 孔令武 蔡俊[1] 吴东胜[1] 何幼斌[1] 郭笑 LI Hua;LIANG Jianshe;QIU Chunguang;ZHAO Hongyan;HU Bin;RAO Su;WANG Beibei;KONG Lingwu;CAI Jun;WU Dongsheng;HE Youbin;GUO Xiao(School of Geosciences,Yangtze University,Wuhan,Hubei 4301001,China;CNOOC International Company Limited,Beijing 100028,China;CNPC Qinghai Oil Fields Haixi,Qinghai 817000,China)

机构地区：[1]长江大学地球科学学院,湖北武汉430100 [2]中国海洋石油国际有限公司,北京100028 [3]中国石油青海油田,青海海西817000

出　　处：《地质学报》2022年第5期1855-1867,共13页Acta Geologica Sinica

基　　金：国家科技重大专项(编号2017ZX05032-002-003);湖北省自然科学基金(编号2020CFB745);地质资源与地质工程一流学科开放基金项目(编号2019KFJJ0818010)联合资助的成果。

摘　　要：本文以东非海岸鲁伍马、坦桑尼亚及拉穆盆地为对象,利用钻井、测井及地震资料,揭示了渐新世构造事件-古地貌特征-沉积体系的耦合关系,服务研究区油气勘探选区。结果表明:(1)板块构造事件控制宏观地貌格局及沉积环境变化。随着印度-塞舌尔板块与非洲板块分离,印度洋逐渐扩张,海水南侵,沉积环境由陆相变为海相。由于Afar地幔柱作用及地层抬升等因素,东非海岸整体呈西高东低地貌格局;(2)洋中脊扩展及断层活动控制盆地隆坳格局及沉积体系宏观展布规律。研究区发育西部坳陷带、中部斜坡带及东部深海平原带,东部Davie东及Davie西断层构成Davie构造带。从西向东发育四大河流-三角洲-海底扇沉积体系;西部坳陷带以三角洲沉积为主,中部斜坡带发育海底扇,东部深海平原带以半深海—深海泥最为常见,沉积体系多发育在Davie构造带以西;(3)次级断层活动影响沉积体系的发育规模及分布。沉积体系多发育在西部坳陷带及中部斜坡带的凹陷中。因凹陷及次级断裂影响,鲁伍马盆地北部、坦桑尼亚盆地南部沉积体系呈北偏特征,而拉穆盆地具南偏趋势。Based on drilling, seismic datasets, etc., relationships between tectonic movement, palaeogeomorphology and sedimentary systems have been studied in the Rovuma, the Tanzania, and the Lamu basins, which were helpful for oil and gas exploration in the study area. The palaeogeomorphology, depositional center distribution, sedimentary environment, and sedimentary system can be controlled by tectonic movement. The results show(1) plate tectonics event affected large scale palaeogeomorphology pattern and environment change. Because the India-Seychelles Plates and African Plate, the Indian Ocean extension, seawater southward invasion, the sedimentary environment changed from land to marine facies. The East Africa showed high west-low east topographic features for the Afar mantle plume and strata lift.(2) The Mid-oceanic ridge arch and expansion, fault movement affected uplifts and depressions, sedimentary system distribution. The west depression belt, middle slope belt, and east abyssal plain belt were divided in the study area. Davie ridge consisting of East Davie and West Davie faults developed in east of the study area. There were four large-scale “fluvial-delta-marine fan systems” that developed from west to east in the Oligocene. Delta formed in the west depression belt, submarine fan developed in the middle slope belt, and deep-water deposits in the east abyssal plain belt, which are usually distributed in the west of Davie ridge.(3) Distribution and volume of sedimentary system were influenced by secondary faults, which mostly formed in the sags of west depression and middle slope belts. The sedimentary system shows northward deflection in the north of the Rovuma basin and south Tanzania basin, and southward deflection in the Lamu basin for sags and secondary faults.

关 键 词：构造事件 沉积体系 海底扇 东非 

分 类 号：P618.13[天文地球—矿床学]