Earth Science Frontiers ›› 2022, Vol. 29 ›› Issue (5): 133-146.DOI: 10.13745/j.esf.sf.2021.9.22

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Mesozoic tectonic evolution of the southwestern Bohai Sea and its dynamic mechanism: Implications for the destruction of the North China Craton

YE Tao1,2(), NIU Chengmin1, WANG Deying1, WANG Qingbin1, DAI Liming1, CHEN Anqing2   

  1. 1. Tianjin Branch of China National Offshore Oil Company Ltd., Tianjin 300452, China
    2. Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China
  • Received:2021-05-25 Revised:2021-08-27 Online:2022-09-25 Published:2022-08-24

Abstract:

Mesozoic of the southwestern Bohai Sea experienced multi-stage tectonic activities and records in detail the destruction process of the North China Craton. Here, to clarify the relationship between Mesozoic tectonic evolution in the southwestern Bohai Sea and regional tectonic setting, the structural characteristics of the Mesozoic are determined, its formation and evolutionary processes are restored, and its dynamic mechanism and response to the destruction of the North China Craton are discussed based on the 3D seismic and deep drilling data, combined with regional tectonic background. As results show, (1) differing from the NEE-trending structure of the onshore oil area of the Bohai Bay Basin, the southwestern Bohai Sea develops multi-strike, multi-type structures. The 3D seismic data reveal negative-inversion, strike-slip thrusting, and folding structures that are different from the Cenozoic extensional structures; among them, the NWW-trending negative-inversion structure dominates. (2) Mesozoic of the Bohai Sea undergoes multi-stage deformation, which includes formation of the Indonesian thrust fold, sino-lateral thrust transformation in the Early Yanshan period, negative inversion in the Middle Yanshan period, and fold in the late Yanshan period; among them, thrust fold during the Indosinian movement was the key stage for the buried-hill formation, and the middle Yanshan negative-inversion stage was the key stage for the tectonic transformation. (3) Formation of the NWW-trending structure is related to the South-North China collision during the Indonesian period. The sinistral strike-slip in the early Yanshan period is the result of the NWW-ward subduction of the Pacific plate, which signifies the replacement of the Paleo-Tethys domain by the Pacific domain for controlling the deformation of the North China plate. The negative inversion in the middle Yanshan period corresponds to the large-scale regional magmatic activity, which is the shallow response to the large-scale destruction of the North China Craton. The proposed model of a NWW-trending negative-inversion towards the preexisting structure of the Indosinian in the middle Yanshanian enriches the simple traditional structural model for the destruction of the North China Craton to form the NEE-trending basins.

Key words: structural characteristics, Mesozoic evolution, southwestern Bohai Sea, dynamic mechanism, North China Craton

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