南海西北与西南次海盆沉积通量及其控制因素  

Sedimentary Budget and Controlling Factors of the Northwest and Southwest Sub-Basins, the South China Sea

作　　者：王菲[1,2] 吴艳梅 丁巍伟 Wang Fei;Wu Yanmei;Ding Weiwei(School of Oceanography,Shanghai Jiao Tong University,Shanghai 200030,China;Key Laboratory of Submarine Geoscience&Second Institute of Oceanography,MNR,Hangzhou 310012,China;School of Earth Sciences,Zhejiang University,Hangzhou 310027,China)

机构地区：[1]上海交通大学海洋学院,上海200030 [2]自然资源部海底科学重点实验室,自然资源部第二海洋研究所,浙江杭州310012 [3]浙江大学地球科学学院,浙江杭州310027

出　　处：《地球科学》2021年第3期986-1007,共22页Earth Science

基　　金：全球变化与海气相互作用专项(Nos.GASI-02-SHB-15,GASI-GEOGE-01);国家自然科学基金项目(Nos.42025601,91858214,41890811)。

摘　　要：作为西太平洋陆源沉积"源-汇"过程的重要场所,南海海盆半封闭的构造环境使得其与开放大洋的物质交换十分有限,沉积物保存基本完整,可以建立起南海沉积过程与区域重大构造事件、气候变化、海平面变化等之间的系统联系.选取南海西南与西北两个次海盆为对比研究区,基于穿越海盆的高分辨率多道地震测线和国际大洋发现计划(International Ocean Discovery Program,简称IODP)在南海获取的钻井数据,井震结合划分沉积单元,计算不同地质历史时期沉积通量,从而对海盆的沉积过程进行半定量化约束,并对控制因素和可能物源进行探讨.结果表明:南海西北次海盆和西南次海盆深海盆区的沉积过程整体上受到大型构造事件(青藏高原隆升-剥蚀作用)、东亚季风演化、陆缘水系(珠江、湄公河等)发展和相对海平面变化的控制,但在不同的区域会由于所处地理位置不同,以及局部构造事件影响而变得复杂化,从而使得西北次海盆与西南次海盆沉积通量在相同的地质时期呈现出不同的特征.西北次海盆沉积物主要源自华南大陆,并有少量来自红河、海南岛、北部陆架区局部隆起(如东沙隆起)的贡献.而西南次海盆的沉积物在晚中新世之前主要来自印支半岛、南沙地区和巴拉望,而在之后主要来自于现代湄公河.South China Sea(SCS) is not only the crucial pathway for transporting terrigenous materials from Eurasia to the western Pacific Ocean since the Early Oligocene, but also the dominant accumulation and preservation place as a result of limited material exchange between the semi-closed oceanic basin and the open ocean since the Middle Miocene. Calculation of the sedimentary budget in different geological times is an important part in quantifying the sedimentary process in the SCS, which will not only construct the relationship between the sedimentary process of the SCS and the regional tectonic events, climate change, eustatic sea level change, etc, but also to improve our understanding on the"source-to-link"process of the West Pacific region. Based on multichannel seismic profiles across the northwest sub-basin(NWSB) and the southwest sub-basin(SWSB), combined with drilling results from IODP Expeditions, the sedimentary budget of the NWSB and SWSB has been calculated, and the controlling factors in different geological times have been discussed to reconstruct the Cenozoic sedimentary history. Efforts have been also made on the sedimentary provenance analysis. The sedimentary budget of the NWSB and the SWSB showed distinct characteristics in different geological times. Sedimentation is generally dominated by regional tectonic events(such as the uplift of the Tibet Plateau), monsoon, continental fluvial systems and sea-level changes, but will be complicated by local tectonic events and geographic position. The main sediment source of the NWSB was the terrestrial sediment transported from the South China,and a small amount from Red River, the Hainan Island, and Dongsha local uplifts. The sediment provenance of the SWSB was mainly from the Indo-China Peninsula, the Nansha area, and the Palawan before the Late Miocene. After that, sediments were mainly transported from the modern Mekong River.

关 键 词：IODP 多道地震数据 沉积通量 南海海盆 控制因素 海洋地质 

分 类 号：P67[天文地球—海洋地质]