http://www.sciencedirect.com/science/article/pii/S1674987111000491 |
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Authors: | Weiwei Ding Mingbi Li Lihong Zhao Aiguo Ruan Zhenli Wu |
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Institution: | 1. Key Laboratory of the Submarine Geoscience, State Oceanic Administration, 32# North Baochu Road, Hangzhou 310012, China 2. Shandong University of Science and Technology, Qingdao 266510, China |
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Abstract: | 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. |
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Keywords: | Continental rifting Cenozoic Tectono-sedimentarycharacteristics Extension model Northwest Sub-basin Marginal sea |
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