Numerical modeling of extensional sedimentary basin formation with MATLAB: Application to the northern margin of the South China Sea

The coupled simple-shear/pure-shear model (CSSPSM) with broad application for studying the evolution of continental extensional sedimentary basins was proposed by Kusznir and co-workers. It can be used to determine the geometry of sedimentary basins and their crustal structure by integration of the rheological, thermal and isostatic response of lithosphere to various loads caused by lithosphere extension. We developed a MATLAB code, MODBAS, to model extensional sedimentary basin formation based on the CSSPSM. The validity of the code was tested with a single listric fault model and a multiple-fault model. The application of the code in the Pearl River Mouth Basin (PRMB) on the northern margin of the South China Sea demonstrates (1) the effective elastic thickness of the lithosphere beneath the PRMB is very low (<5 km), which may support the idea of a very weak continental crust beneath the northern margin of the South China Sea; and (2) there are significant misfits between predicted and observed basements beneath the two high-standing areas on the profile, which was interpreted as an indication of substantial dynamic support from small-scale mantle convection.