琼东南盆地莺歌海组陆架边缘轨迹演化及主控因素  

Evolution and Main Controlling Factors of Continental Shelf-edge Trajectory in Yinggehai Formation,Qiongdongnan Basin

作　　者：岳翀 赵晓明[1,2] 葛家旺 马畅 廖晋 宋鹏 方小宇 范廷恩 YUE Chong;ZHAO XiaoMing;GE JiaWang;MA Chang;LIAO Jin;SONG Peng;FANG XiaoYu;FAN TingEn(School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,China;Natural Gas Geology Key Laboratory of Sichuan Province,Chengdu 610500,China;Research Institute of Hainan Branch,CNOOC,Haikou 570100,China;Guangdong Laboratory of Southern Marine Science and Engineering-Zhanjiang,Zhanjiang,Guangdong 524000,China;CNOOC Research Center Co.Ltd.,Beijing 100028,China)

机构地区：[1]西南石油大学地球科学与技术学院,成都610500 [2]天然气地质四川省重点实验室,成都610500 [3]中海石油(中国)有限公司海南分公司,海口570100 [4]南方海洋科学与工程广东省实验室(湛江),广东湛江524000 [5]中海油研究总院有限责任公司,北京100028

出　　处：《沉积学报》2023年第1期110-125,共16页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(42072183,41902124,41872142);南方海洋科学与工程广东省实验室(湛江)基金项目(ZJW-2019-03)。

摘　　要：陆架边缘连接浅水陆架及深水区,其迁移轨迹动态演化可记录和反馈浅水—深水物质输送过程及样式,开展陆架边缘轨迹量化分析,对预测深水沉积体系及油气勘探意义重大。基于井—震资料并选取过研究区LS33a钻井的地震剖面,利用典型的地震同相轴接触关系在琼东南盆地上新统莺歌海组顶底及内部共计识别出5个层序界面,将莺歌海组自下而上划分为4套三级层序。依据地震反射特征量化统计琼东南盆地莺歌海组陆架边缘轨迹,识别并划分出超高角度滑塌型(50°<α<180°)、高角度上升型(5°<α<50°)和低角度上升型(0°<α<5°)等三种陆架边缘轨迹类型。琼东南盆地上新世陆架边缘迁移轨迹经历了4个演化阶段:阶段一(5.5~4.2 Ma)构造稳定且盆地北部陆架物源供给充足,该阶段陆架边缘轨迹迁移角度大多低于5°;阶段二(4.2~3.2 Ma)由于海平面迅速下降、物源供给减弱,陆架边缘滑塌致使陆架边缘轨迹迁移角度增大;阶段三(3.2~2.7 Ma)由于青藏高原隆升、气候转变(3 Ma开始南海及周边地区冬季风增强),指示物源供给增强,陆架边缘轨迹迁移角度再次减小;阶段四(2.7~1.8 Ma)联合受控于东亚冬季风气候及伴随的物源供给增强,陆架坡折带迅速向盆地方向推进且迁移角度迅速减小,陆架边缘整体为低角度上升型迁移轨迹。由于琼东南盆地西部整体物源供给速率高于东部地区,西部陆架边缘轨迹以低角度上升型为主,东部则以发育高角度上升型及高角度滑塌型为特征。莺歌海组时期大规模滑塌体系与陆架边缘轨迹迁移角度存在一定的相关性:即当陆架边缘轨迹迁移角度大于50°时,陆架边缘体系往往失稳并向下陆坡及深水平原区输送大规模块体搬运沉积体系。研究结果对深化南海北部陆架边缘体系理论认知及深海矿产资源评价具有积极意义。Shelf-edge connects the shallow shelf and deep water area,and the dynamic evolution of its migration trajectory can well record and feedback the process and style of shallow-deep water material transport.The quantitative analysis of shelf edge trajectory is of great significance for predicting deep water sedimentary system and oil and gas exploration.Based on well seismic data and selected seismic sections from the LS33a well in the study area,five sequence interfaces were identified at the top and bottom of the Upper Miocene Yinggehai Formation in Qiongdongnan Basin by using typical seismic termmationt relationship.The Yinggehai Formation was divided into four sets of thirdorder sequences from bottom to top.According to the quantitative statistics of the continental shelf edge trajectory of Yinggehai Formation in Qiongdongnan Basin based on the seismic reflection characteristics,three types of shelf edge trajectories—ultra-high-angle slip(50°-180°),high-angle rise(5°-50°)and low-angle rise(0°-5°)—were identified and classified.The migration trajectory of the Pliocene continental shelf edge in the Qiongdongnan Basin has experienced four stages.In stage 1(5.5-4.2 Ma),it has stable structure and sufficient supply of continental shelf provenance,and the migration angle of continental shelf edge trajectory in this stage is mostly lower than 5°.In stage 2(4.2-3.2 Ma),due to the rapid drop of sea level and the weakening of sediment supply,the shelf edge collapse leads to the increase of the shelf edge trajectory migration angle.In stage 3(3.2-2.7 Ma),due to the uplift of the Qinghai-Tibet Plateau and the climate change(the winter monsoon began to strengthen around 3 Ma in the South China Sea and surrounding areas),the supply of sediment sources increased,and the migration angle of the shelf edge trajectory decreased again.In stage 4(2.7-1.8 Ma),it is jointly controlled by the East Asian winter monsoon climate and the accompanying rapidly increased material source supply.The continental shelf slope break belt

关 键 词：琼东南盆地 上新统莺歌海组 地层格架 陆架边缘轨迹 主控因素 

分 类 号：P618.13[天文地球—矿床学]