南海中央海盆高精度地震勘探揭示的大陆漂移过程  

Continental drift process revealed by high precision seismic survey in the central basin of the South China Sea

作　　者：梁光河[1,2,3] LIANG Guanghe(CAS Key Laboratory of Mineral Resources Research,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;School of Earth and Planetary,University of Chinese Academy of Sciences,Beijing 100029,China;University of Chinese Academy of Sciences,Beijing 100029,China)

机构地区：[1]中国科学院地质与地球物理研究所中国科学院矿产资源研究重点实验室,北京100029 [2]中国科学院大学地球与行星科学学院,北京100029 [3]中国科学院大学,北京100029

出　　处：《地学前缘》2022年第4期293-306,共14页Earth Science Frontiers

基　　金：科学技术部第二次青藏高原综合科学考察研究项目(2019QZKK0805)。

摘　　要：南海的形成和演化得到了广泛研究,前人提出了超过5种成因模式,当前流行是海底扩张模式,但它难以合理解释南海洋壳上的洋中脊跳跃和南海中央海盆上的大陆残片。本文首先基于南海中央海盆中的两条高精度地震勘探剖面,在深入剖析洋壳的分层结构基础上,对这两条地震勘探剖面进行了新的构造地质解释。然后通过伸展构造的形成过程,发展了地幔上涌和陆壳重力滑移双驱动大陆漂移模型,最后深入研究了南海的形成和演化过程。结果说明,南海的形成是一种“构造挤出+主动漂移”模式。构造挤出是印度-欧亚大陆碰撞造成的欧亚东南缘微陆块大规模被动挤出,而主动漂移是微陆块在被挤出后发生了主动裂解漂移。南海中央海盆上残留的地震反射特征,是微陆块主动漂移后造成的海底被扩张现象。并进一步恢复了南海演化过程中周边陆块的运动演化历史。所提出的新模式能够合理解释南海的洋中脊跳跃现象及大陆残片的成因机制。新大陆漂移模型为板块运动提供了一个新的动力模式。The formation and evolution of the South China Sea have been widely studied.More than five genetic models have been proposed.The current popular model is seafloor spreading,but the model could not reasonably explain the mid-ocean ridge jumping in the South China Sea and the continental fragments found in the central basin of the South China Sea.In this study,based on two high precision seismic exploration sections in the central basin of the South China Sea,a new tectonic geological interpretation of the two seismic exploration sections was given on the basis of an in-depth analysis of the layered structure of the oceanic crust.Then,through examination of the formation process of extensional tectonics,a model of continental drift driven by mantle upwelling and continental crust gravity slip was developed.Finally,the formation mechanism and evolutionary process of the South China Sea was studied in detail.The formation of the South China Sea can be described by a“tectonic extrusion+active drift”model,where“tectonic extrusion”refers to large-scale passive extrusion of the microcontinents in the southeastern margin of the Eurasia plate caused by the India-Eurasia collision,while“active drift”refers to active drift of the microcontinents after extrusion.The residual seismic reflection in the central basin of the South China Sea is a phenomenon of seafloor spreading caused by active drift of microcontinents.Furthermore,the geotectonic evolution of the microcontinents surrounding the South China Sea was restored.The proposed new model can reasonably explain the phenomenon of mid-ocean ridge jumping in the South China Sea and the genetic mechanism of continental debris.The proposed new continent drift model provides a new dynamic model for plate movement.

关 键 词：南海中央海盆 南海成因 高精度地震勘探 动力机制 大陆漂移 

分 类 号：P541[天文地球—构造地质学] P631.4[天文地球—地质学] P313