南沙海域礼乐盆地沉积过程和演化  

Depositional Process and Evolution of Liyue Basin in Southern South China Sea

作　　者：李鹏春[1] 赵中贤[1,2] 张翠梅[1] 谢辉[1,2] 陈广浩[1] 

机构地区：[1]中国科学院南海海洋研究所边缘海地质重点实验室,广东广州510301 [2]中国科学院研究生院,北京100049

出　　处：《地球科学（中国地质大学学报）》2011年第5期837-844,共8页Earth Science-Journal of China University of Geosciences

基　　金：中国科学院知识创新工程重要方向项目群项目(No.KZCX2-YW-Q05-04)

摘　　要：礼乐盆地所经历的张裂-漂移-碰撞沉降构造历史,在沉积物沉积样式、沉降历史及断裂构造样式中均有反映,因此,分析盆地沉积过程及其与构造的耦合关系可揭示其演化过程.通过对礼乐盆地沉积充填过程、沉降方式及构造特征的分析,认为礼乐盆地具双层结构模式特征,以T60(23.8Ma)不整合面为界,下部为不对称楔状半地堑.早期沉积受控于边界铲式断层,以构造沉降为主;自23.8Ma以来转变为以热沉降为主.礼乐盆地表现为3个幕式沉降特点,每个沉降幕都为由慢至快的沉降过程.其经历了3个沉积充填旋回,对应于古新世-早渐新世的张裂、晚渐新世-中中新世的张裂-漂移,以及晚中新世-第四纪裂后沉降这3个演化阶段,应力场相应由早期拉张环境转变为中期拉张-走滑以及晚期的挤压-走滑环境.The evolution of rift-drift-subsidence can usually be illuminated by sedimental style,subsidence history and structural style,so it＇s possible to understand basin evolution through analysis of depositional process and coupling tectonic-sedimentary.In this paper,infill stratigraphy,subsidence history and structural characteristics are analyzed.The results show that Liyue basin is characterized by typical ＂tow-layer＂ structural pattern,which is separated by a regional breakup unconformity（T60）.The horsts and grabens are in low basin overlain by upper depressions of the Neogene.And the half-grabens characterized by asymmetric wedge-shape are bounded by both normal faults and large-scale listric faults,which controlled the sedimentary cycles.The subsidence method is mainly tectonic subsidence before 23.8 Ma but is thermal subsidence after Late Oligocene.There were three regional subsidence episodes,and each subsidence rate was from slow to fast.Liyue basin is primarily composed of three regressive cycles of rift infilling influenced by regional tectonic,which correspond to three stages of basin development.The first stage,characterized by extensional stress,is related to early rift development from approximately 45 Ma until Early Oligocene.Featured by both extension and strike-slip stress,the second is associated with rift-drift development from initiation of sea floor spreading in South China Sea at 30 Ma until the end of sea floor spreading at Middle Miocene.And the third is late post-rift subsidence from approximately 16 Ma until 5.5 Ma,which is controlled by transpressive stress field.

关 键 词：海洋地质 沉积 盆地演化 礼乐盆地. 

分 类 号：P736.21[天文地球—海洋地质]