Analysis of Lithospheric Extension and Post rift Subsidence in Taixinan Basin

Abstract:

The effective elastic thickness, different scales of extension factors and post rift subsidence are important in reflecting characteristics of an extensional basin. 2D structural simulation softwares based on the flexure isostasy model and the flexural cantilever mode were employed to model the interpreted seismic profiles across Taixinan Basin. Results show that the appropriate effective elastic thickness value in Taixinan basin is 1.5 km. The extension is characterized by the lateral heterogeneity and depth dependence of lithospheric extension in Taixinan Basin, the extension factor changing between 1.2 and 4.8 in lithosphere, between 1.2 and 2.9 in the whole crust, and between 1.0 and 1.2 in the upper crust. Being different from subsidence characteristics of a classical extensional basin, the post rift subsidence rate in Taixinan Basin is not of obvious regularity, which is mainly affected by the formation of slope and Dongsha tectonic movement.