Analysis of tectonic evolution characteristics of Wan'an Basin in the southwest of the South China Sea

doi:10.7523/j.issn.2095-6134.2020.06.009

Abstract

Abstract: The South China Sea Basin is located at the junction of Tethys, Pacific margin, and paleo-Asia tectonic domains. The representative Wan'an Basin in the southwest of the South China Sea Basin has the well-developed Cenozoic strata, but the underappreciated expansion and evolution remains because of a limited understanding of tectonic subsidence and extension mechanism of the basins. Based on the regional geological data, including structural style and stratigraphic sequence, the tectonic evolution history of Wan'an Basin is simulated by utilizing the backstripping method, and the extension factor and extension velocity of Wan'an Basin are obtained after fitting the structural subsidence history through an iterative adjustment of the tensile factor in the McKenzie pure shear tensile model. Furthermore, the heat transfer equation of the lithosphere is used to determine the heat flow of the substrate. The results are given as follows. 1) It is the combined action of the South China Sea expansion, the ridge jump, and the southwest sub-basin expansion that control the sedimentation, extension, and thermal anomalies in Wan'an Basin. 2) Wan'an Basin has unique characteristics of space-time evolution that the left and right rotations of the fracture zone affect the sedimentation which presents a V-shaped transition and that “early east and west, then north and south” is the mainly feature of the extension. 3) Due to the tectonic activity, the extension and thermal anomalies in the basin gradually decline in the directions from the fault to the both sides at different rates.

Key words: Wan'an Basin, sedimentation rate, stretch rate, basement heat flow

CLC Number:

P736

WANG Beiyu, ZHANG Jian, AI Yifei. Analysis of tectonic evolution characteristics of Wan'an Basin in the southwest of the South China Sea[J]. , 2020, 37(6): 784-792.

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