| 南海后扩张期大陆边缘闭合过程及成因机制 |
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| 引用本文： | 解习农,赵帅,任建业,杨允柳,姚永坚.南海后扩张期大陆边缘闭合过程及成因机制[J].地球科学,2022,47(10):3524-3542. |
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| 作者姓名： | 解习农 赵帅 任建业 杨允柳 姚永坚 |
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| 作者单位： | 1.中国地质大学海洋地质资源湖北省重点实验室, 湖北武汉 430074 |
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| 基金项目： | 国家自然科学重点基金项目42130408 |
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| 摘 要： | 南海是西太平洋海域最大的边缘海，然而南海扩张终结后动力学过程研究仍较为薄弱.通过构造变革界面识别、褶皱冲断带沉积记录等方面的系统研究，揭示南海南部和东部陆缘在南海后扩张期的演化历程.研究表明南海南部和东部边缘经历了多个微板块从俯冲到碰撞的演变历程，形成了陆-陆碰撞、弧-陆碰撞、洋-弧俯冲等多个特征迥异的板块边界.南海南部陆缘属于古南海俯冲拖曳构造区，婆罗洲西北沙捞越-曾母地块率先碰撞，随后经历了婆罗洲东北沙巴-南沙地块碰撞、西南巴拉望-卡加延岛弧碰撞.南部多个微板块碰撞导致古南海呈剪刀式从西向东逐渐关闭和消亡，总体形成了以微地块碰撞、深海槽发育和造山带前缘巨厚沉积充填为特色的碰撞陆缘.东部陆缘属于菲律宾海俯冲-碰撞构造区，南海东部洋壳自中新世开始向菲律宾海板块俯冲，弧-陆碰撞仅局限于东部陆缘南北两端.澳洲-印度板块、菲律宾海板块与欧亚板块相互作用控制了南海边缘海闭合过程，南海正在进行的关闭过程主要集中在东缘和南缘，东缘呈现了以南海洋壳消亡为特征的闭合过程，而南缘则呈现以微陆块碰撞为特征的古南海闭合过程.显然，南部后扩张期陆缘演变可为边缘海闭合过程研究提供极佳的范例，同时对我国海洋权益保护和南海大陆边缘动力学研究具有重要意义.
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| 关 键 词： | 南海南部和东部边缘 南海后扩张期 板块俯冲与碰撞 大陆边缘动力过程 微板块多幕碰撞 海洋地质 |
| 收稿时间： | 2022-04-19 |
Marginal Sea Closure Process and Genetic Mechanism of South China Sea during Post-Spreading Period |
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| Abstract: | The South China Sea (SCS) is the largest marginal sea in the West Pacific, but the study of dynamic processes after the termination of the SCS seafloor spreading is not so clear. In this paper it reveals the evolution of the southern and eastern margins of the SCS during the post-SCS spreading period through systematic studies on the identification of tectonically unconformities, contemporaneous sedimentary records of fold-and-thrust belt. The results show that the southern and eastern margins of the SCS have undergone the evolution of multiple microplates from subduction to collision since the Miocene. Several collision boundaries with different characteristics were developed, including continent-continent collision, arc-continent collision and ocean-arc subduction. The southern margin of the SCS belongs to the proto-SCS slab pull tectonic zone, the Sarawak-Zengmu block in northwest Borneo took the lead in the collision, followed by the Sabah-Nansha block collision in northeast Borneo and the Palawan-Cagayan arc collision in the southwest Palawan island. Since the Middle Miocene, these tectonic events have led to the gradual extinction of the proto-SCS from west to east in a scissor-like pattern, and in the formation of a southern collisional margin characterized by microplate collisions, deep-sea trough development and thick sediments filling in the orogenic foreland. The eastern margin of the SCS is part of the Philippine subduction-collision tectonic zone. Subduction of the SCS oceanic crust to the Philippine Sea plate began in the Miocene, but the arc-continent collisions confined to the northern and southern ends of the eastern margin with further oblique subduction of the Philippine Sea plate. The interaction among the Australia-India plate, the Philippine Sea plate and the Eurasian plate controls the marginal sea closure process in the SCS. The ongoing closure process in the SCS is mainly concentrated on the southern and eastern margins, the eastern margin shows a closure process characterized by the extinction of oceanic crust, while the southern margin is a closure process characterized by the collision of microplates. Therefore, the continental margin evolution during the post-SCS spreading period can provide an excellent example for the study of marginal sea closure process, and is also important for the protection of national maritime rights and interests and the study of the dynamics of continental margins in the SCS. |
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