南海南部造山运动及其与古南海俯冲的成因联系  

Orogenic events in Southern South China Sea and their relationship with the subduction of the Proto South China Sea

作　　者：赵帅 李学杰[2] 姚永坚[2] 解习农 肖苏芸 何西 邓雨恬 石梦临 周末 ZHAO Shuai;LI Xuejie;YAO Yongjian;XIE Xinong;XIAO Suyun;HE Xi;DENG Yutian;SHI Menglin;ZHOU Mo(College of Marine Science and Technology,China University of Geosciences(Wuhan),Wuhan 430074,China;Guangzhou Marine Geological Survey,Guangzhou 510075,China;South China Sea Marine Engineering surveying Center,State Oceanic Administration,Guangzhou 510399,China;Technology Center,Fuling Shale Gas Company,Jianghan Oilfield,China Petrochemical Corporation,Chongqing 408000,China)

机构地区：[1]中国地质大学(武汉)海洋学院,武汉430074 [2]广州海洋地质调查局,广州510075 [3]中国国家海洋局南海调查技术中心,广州510399 [4]中国石化重庆涪陵页岩气勘探开发有限公司,重庆408000

出　　处：《海洋地质与第四纪地质》2019年第5期147-162,共16页Marine Geology & Quaternary Geology

基　　金：南海南部海域1:100万海洋区域地质调查成果集成与应用研究(DD20160138);国家自然科学基金面上基金“南沙海域盆地的地层系统与深部结构研究:从南部海域解读南海的演化历史”(D0603);国家自然科学基金青年基金“中—晚始新世东亚季风气候对渤海湾盆地济阳坳陷富有机质页岩发育的控制作用”(41802175);国家重大科技专项课题(2017Z05026-005)

摘　　要：古南海的展布范围以及俯冲消亡过程等一直是地质学家们争论的焦点问题。这不仅与南海扩张诱因密切相关,而且对南海地球动力学研究有重大的指导意义。在研究前人文献的基础上,对南海南部造山运动以及古南海俯冲过程之间的关系进行详细的论述。结果表明,南海南部构造活动主要分为两期:第一期运动从早白垩纪到晚白垩纪,古太平洋的洋壳俯冲到婆罗洲岛下方,俯冲带位于现今卢帕尔线一带,引起了曾母-南沙地块不断向西南婆罗洲靠近,并于晚白垩纪引发了碰撞造山运动。由于婆罗洲自身是由众多地块拼合而成,所以在始新世期间发生了多期碰撞之后的地块变形重组事件。最终在晚始新世(37Ma)完成最后一期变形(沙捞越运动)。第二阶段是晚始新世(35Ma)到中中新世(15.5Ma),位于西巴拉姆线以东至菲律宾卡加延一带的古南海从西巴拉姆线以东,向婆罗洲岛下方俯冲,随后扩散到沙巴以及巴拉望岛以南的地区,直至菲律宾的民都洛岛一带停止俯冲。由此产生的拖曳力是南海扩张的主要诱因。与古太平洋板块俯冲产生的效果相似,古南海的俯冲使得婆罗洲岛与南沙地块不断靠近。在中中新世(15.5Ma),引起南沙地块与婆罗洲岛在沙巴地区的碰撞(沙巴造山)以及巴拉望北部陆壳与菲律宾岛弧的碰撞而停止。由此带来的不整合面在南海南部普遍可见,甚至到达了巴拉望岛一带。而现今南沙海槽与巴拉望海槽并非是俯冲带的前渊,前者是对沙巴新近纪增生楔重力驱动变形的响应,后者是巴拉望岛北侧伸展背景下产生的半地堑盆地,在后期增生楔的作用下发生强烈沉降所形成。真正的俯冲带则分别位于南沙海槽东南部以及巴拉望海槽东南部。据现有证据推测,最少在10Ma之前古南海就在菲律宾民都洛一带停止俯冲,从而完成了整个古南海的封闭。The original location of the Proto South China Sea and the processes related to its subduction and termination have remained under debates,and no consensus has been reached up to date.It is not only closely related to the expansion of the South China Sea,but also significant to the study of the geodynamics of the region.After a thorough review of previous literatures,this paper is devoted to the orogenic processes and their bearing on the subduction of the Proto South China Sea.The results show that the tectonic activities in the Southern South China Sea could be divided into two phases.The first phase of the activities happened from Early Cretaceous to Late Cretaceous,while the oceanic crust of the Paleao-Pacific subducted below the island of Borneo.The subduction zone was located along the current Lupal line,which caused the Zengmu- Nansha block to move towards the southwestern Borneo.It was closed in Late Cretaceous by a collision orogeny.Since Borneo itself is composed of many blocks and suffered multiple collisions during the period of Eocene,there were the deformation and reorganization of blocks after collision.Eventually,the final phase of the deformation (i.e.the Sarawak Movement) was completed in Late Eocene (37 Ma).The second phase of movement was from Late Eocene (35 Ma) to Middle Miocene (15.5 Ma).The Proto South China Sea from east of the West Baram Line to Cagayan of Philippines,was subducting eastward from the West Baram Line towards the island of Borneo.It swooped and then spread to Sabah and the area to the south of Palawan and stopped at the Mindoro Island,the Philippines.The resulting drag force was driving the expansion of the South China Sea.Similar to the effect of the subduction of the Paleo-Pacific plate,the subduction of the Proto South China Sea triggered the closure of the sea between the Borneo Island and the Nansha block in Middle Miocene (15.5 Ma),causing the collision between the Nansha block and the Borneo island in Sabah (i.e.the Saba orogen) and the collision between the Palawan

关 键 词：古南海俯冲 造山运动 南沙地块 婆罗洲 巴拉望 南海南部 

分 类 号：P736.1[天文地球—海洋地质]