南海西北次海盆构造演化的沉积响应

发布时间：2018-03-14 07:58

本文选题：南海西北次海盆　切入点：层序地层　出处：《大地构造与成矿学》2017年02期 　论文类型：期刊论文

【摘要】：通过对南海西北次海盆新获得的地震资料进行综合解释和层序地层分析,揭示了海盆中的沉积对构造演化阶段的响应。始新世-早渐新世陆缘裂陷期,盆地以对称裂谷形式,发育地堑裂谷层序,沉积以近物源为特征,相变大,发育了冲积扇-扇三角洲-湖相沉积,沉积体系的配置受同沉积断裂控制明显,快速沉降和充分的物源供给决定了沉积体系的构成特征。晚渐新世海底扩张期,岩石圈破裂,陆缘进一步拉开并开始海底扩张,出现海相沉积,来自陆坡的陆架边缘三角洲越过陆坡进入海盆,在海盆内沉积了一套向海盆中部逐渐减薄的楔状地层,并伴有大量的火山碎屑沉积物。早-中新世以来热沉降期,随着构造沉降增大,相对海平面总体不断上升,进入深水盆地,形成陆架陆坡体系,大量的碎屑物质以重力流、深水底流等深水作用方式进入海盆;沉降晚期陆架-陆坡物源供应减弱,琼东南中央峡谷成为其主要的物质供应来源通道,在此期间二次海平面下降、回升的综合作用下,海盆内发育了多期以下切水道为特征的低水位域沉积体系。
[Abstract]:Based on the comprehensive interpretation and sequence stratigraphy analysis of the newly acquired seismic data in the northwest subbasin of the South China Sea, the response of the sediments in the basin to the tectonic evolution stage was revealed. The basin was in the form of symmetric rift valley during the Eocene to early Oligocene continental margin rifting. The graben rift sequence is developed, the deposition is characterized by near material source, large phase change, alluvial fan, fan delta and lacustrine facies, and the configuration of sedimentary system is obviously controlled by synsedimentary faults. Rapid subsidence and sufficient material supply determine the structural characteristics of the sedimentary system. During the late Oligocene seafloor expansion, the lithosphere ruptured, the continental margin further opened and began to spread, resulting in marine deposits. The continental shelf marginal deltas from the continental slope crossed the slope into the basin and deposited a set of gradually thinning wedge formations in the middle of the basin, accompanied by a large amount of pyroclastic sediments. With the increase of tectonic subsidence, relative sea level rises continuously, and enters deep water basin, forming continental shelf slope system. A large amount of clastic material enters the ocean basin by gravity flow, deep water flow and other deep-water processes. In the late stage of subsidence, the material supply of shelf and slope weakened, and the central valley of southeast Hainan became its main material supply channel. During this period, the secondary sea level dropped and recovered. The sedimentary system in the low water level region is characterized by multiple periods of undercut waterways in the basin.
【作者单位】：国土资源部海底矿产资源重点实验室广州海洋地质调查局;中国科学院深海科学与工程研究所;
【基金】：“南海北部陆坡及台湾海峡盆地西部油气地质特征及赋存归律研究”项目(基[2013]GZH002-31)资助
【分类号】：P736.1

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