SEISMOLOGY AND GEOLOGY ›› 2014, Vol. 36 ›› Issue (3): 574-585.DOI: 10.3969/j.issn.0253-4967.2014.03.003

• CONTENTS • Previous Articles     Next Articles

CENOZOIC TECTONIC EVOLUTION OF CONTINENTAL EASTERN ASIA

ZHANG Pei-zhen, ZHANG Hui-ping, ZHENG Wen-jun, ZHENG De-wen, WANG Wei-tao, ZHANG Zhu-qi   

  1. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China
  • Received:2014-08-03 Revised:2014-08-20 Online:2014-09-30 Published:2014-09-30

东亚大陆新生代构造演化

张培震, 张会平, 郑文俊, 郑德文, 王伟涛, 张竹琪   

  1. 中国地震局地质研究所, 地震动力学国家重点实验室, 北京 100029
  • 作者简介:张培震|男|1955年生|1987年在美国麻省理工学院获得地球物理学博士学位|研究员|中国科学院院士|主要研究方向为地震地质、新生代构造地质研究|电话:010-62009520|E-mail:peizhen@ ies.ac.cn。
  • 基金资助:

    中国科学院先导项目(XDB03020200)资助

Abstract:

Interactions of two global-scale geodynamic systems control Cenozoic tectonic evolution of continental eastern Asia: the collisional and convergent system between Indian and Eurasian plates, the subduction and back-arc extensional system along the western Pacific and Indonesian oceanic margins. The warm and broad Tethys Ocean separates the Indian plate in the south from the Eurasian plate in the north, while the former subducts beneath the latter. In the meanwhile, the Pacific plate continuously subducts westward beneath the Eurasian plate. As the rate of subduction decreases with the time, back-arc extensional basins began to form due to trench rollback along the subduction zone. Though it is still under debate on the timing of initiation of collision between India and Eurasia, the main stage or significant collision probably took place between 55 and 45Ma. The collision and subsequent penetration of India into Eurasia cause retreat of the Tethys Ocean, crustal thickening of the southern and central Tibet, uplifting of Proto-Tibetan plateau, and southeastward extrusion of crustal material of Tibetan plateau. The timing and direction of extrusion of Tibet's crustal material coincide with acceleration of trench rollback of back-arc extensional system along the western Pacific and Indonesian oceanic margins. The collision caused shortening and trench rollback induced extension appear to form a causal "source-sink relationship". In the period of 30 to 20Ma, the northeastward convergence of the Tibetan plateau increased as the southeastward extrusion slowed down that in turn caused northeastward and eastward growth of the plateau. The Main Boundary Thrust became southern collisional boundary between the Indian and Eurasian plates. The northern deformational boundary migrated to the Kunlun Fault zone, forming compressional foreland basins such as the Qaidam, Hexi Corridor, and Longxi Basins. The rapid trench rollback has decreased along the subduction and back-arc extensional system along the western Pacific and Indonesian oceanic margins. As a result, the Japan Sea has ceased extension and the North China Plain Basin has changed from rifting to thermal subsidence. The east-west direction extension initiates in the interior of Tibetan plateau since approximate 10Ma ago, forming a series of north-trending grabens and half-grabens in the high altitudes above 5 000m. In the same time, the Tibetan plateau grows outward so that the Qilian Shan uplifted to form a major mountain range along the northern boundary and the Longmen Shan uplifted again to form an about 4000 relief with respect to Sichuan Basin. Along the eastern coast of Eastern Asia, subduction of Pacific plate beneath the Eurasian plate has accelerated to terminate back-arc extension.

Key words: trench rollback, source-sink relationship, outward growth of the Tibetan plateau, back-arc extension, continental eastern Asia

摘要:

东亚大陆的新生代构造演化受两大地球动力系统所控制:印度-欧亚板块的碰撞及陆内汇聚体系、西太平洋-印度尼西亚板块俯冲消减体系。从晚白垩纪到古新世期间,温暖宽阔的新特提斯洋分割着欧亚大陆和印度次大陆,并且向北俯冲消减于欧亚板块之下。与此同时,太平洋板块继续向西俯冲消减于欧亚板块之下,随着俯冲速率的大幅度降低,俯冲边界发生海沟后撤(trench rollback),使得欧亚大陆东边界开始形成一系列NNE走向的弧后拉张盆地。尽管印度与欧亚大陆碰撞的起始时间仍有争议,但至少强烈碰撞发生在距今45~55Ma期间。陆-陆碰撞及印度板块持续的楔入作用导致了新特提斯海的退出,青藏高原南部和中部的地壳增厚,并隆起形成 “原青藏高原”。碰撞及其强烈的楔入作用还导致了青藏高原南部岩石圈块体向SE方向的大规模挤出。青藏高原南部块体的挤出时间与西太平洋-印度尼西亚海洋俯冲消减带的加速后撤是一致的,表现为沿消减带上盘弧后盆地的快速拉张和裂陷,构成具有成因联系的 “源-汇关系”。距今20~30Ma期间,随着青藏高原大规模南东挤出的减弱,碰撞和楔入引起了向NE方向挤压的增强,导致了青藏高原本身向S和向NE方向的扩展。构造变形向南迁移到主边界逆冲推覆带,向北扩展到昆仑山断裂,造成柴达木盆地、河西走廊、陇西盆地开始接受最初的新生代沉积,形成青藏高原东北缘的大规模晚新生代沉积盆地群。西太平洋-印度尼西亚板块的海沟后撤大幅度减速或停止,直接导致了日本海扩张的停止,华北盆地裂陷期终止,进入整体热下沉阶段。大约距今10Ma以来,青藏高原内部的高海拔地区晚中新世以来开始出现近SN向的拉张,形成一系列SN向裂谷以及NW向右旋和NE向左旋的共轭走滑断裂系。与此同时,青藏高原向周边生长扩展,祁连山快速隆起形成高原北边界,龙门山也第2次加速隆升,与四川盆地形成近4 000m的地貌高差。在东部,沿西太平洋-印度尼西亚板块俯冲消减带的运动开始加速,不仅弧后拉张作用停止,一些早新生代的拉张盆地还发生反转而遭受到挤压缩短作用。

关键词: 海沟后撤, 源-汇关系, 青藏高原向外扩展, 弧后拉张, 东亚大陆

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