Cenozoic tectono-sedimentary characteristics and extension model of the Northwest Sub-basin, South China Sea

Geoscience Frontiers

Mingbi Li¹  Weiwei Ding¹  Aiguo Ruan¹  Zhenli Wu¹  Lihong Zhao² 

[1] Key Laboratory of the Submarine Geoscience, State Oceanic Administration, 32 North Baochu Road, Hangzhou 310012, China;Shandong University of Science and Technology, Qingdao 266510, China;

关键词: Continental rifting;    Cenozoic;    Tectono-sedimentary characteristics;    Extension model;    Northwest Sub-basin;    Marginal sea;   

DOI  :  10.1016/j.gsf.2011.05.010

来源: DOAJ

【 摘 要 】

Based on the interpretations of three seismic profiles and one wide-angle seismic profile across the Northwest Sub-basin, South China Sea, stratigraphic sequences, deformation characteristics and an extension model for this sub-basin have been worked out. Three tectonic-stratigraphic units are determined. Detailed analyses of extension show that the event occurred mainly during the Paleogene and resulted in the formation of half-grabens or grabens distributed symmetrically around the spreading center. Sediments are characterized by chaotic and discontinuous reflectors, indicating clastic sediments. Farther to the southwest, the sub-basin features mainly continental rifting instead of sea-floor spreading. The rifting would have been controlled by the shape of the massif and developed just along the northern edge of the Zhongsha-Xisha Block, rather than joined the Xisha Trough. After 25 Ma, a southward ridge jump triggered the opening of the Southwest Sub-basin. The NW-directed stress caused by the sea-floor spreading of the Northwest Sub-basin may have prevented the continuous opening of the sub-basin. After that the Northwest Sub-basin experienced thermal cooling and exhibited broad subsidence. The deep crustal structure shown by the velocity model from a wide-angle seismic profile is also symmetrical around the spreading center, which indicates that the Northwest Sub-basin might have opened in a pure shear model.

【 授权许可】

Unknown