Abstract: The conjugate continental margins of the South China Sea are being studied increasingly not only for their reserves of oil and gas but also for the data that recorded the processes of expansion of the South China Sea. In this study, five long deep-water multi-channel seismic reflection profiles from both northern and southern slopes are selected to calculate the stretching factors along the profiles based on various initial crustal rheological structures. By comparing the results and the related/respective crustal evolution processes of the margins from the numerical simulation, we propose the following. First of all, the crustal extension of the northern slope is stronger than the southern slope, representing provability of different tectonics between the two since the Mesozoic Era, the latter of which could also be related to the post-extrusions and collisions on the southern margin. Secondly, the Pearl River Basin and Liyue Basin on the northern and southern slopes, respectively, crossed by the seismic profiles, had different initial crustal structures and in turn the evolution histories of the two were inconsistent during the formation of the South China Sea conjugate margins. Moreover, the crustal stretching factor of the southern slope becomes greater toward south, showing no compliment with the principle basin expansion theories. This could be indicative to the southward subduction of the paleo-South China Sea plate.

Key words: conjugate continental margin, stretching factor, Liyue Basin, paleo-South China Sea