Along-strike segmentation of the South China Sea margin imposed by inherited pre-rift basement structures

Multibeam bathymetric, seismic and borehole data are used to investigate a large-scale strike-slip structure, the Baiyun-Liwan Fault Zone, in the northern South China Sea. This fault zone comprises NW- to NE-striking faults and negative flower structures that were generated by oblique extensional displacement. Notably, the interpreted data reveals that the Baiyun-Liwan Fault Zone was active during the Cenozoic, recording intense magmatism, and accommodating significant intraplate deformation during progressive continental rifting and ocean spreading. It bounds two distinct crustal segments and played a significant role in segmenting the northern margin of the South China Sea. The geometry of faults and strata within the Baiyun-Liwan Fault Zone also controlled local sediment routing and depocentre evolution during the Cenozoic. As basement and syn-rift structures change markedly across the Baiyun-Liwan Fault Zone, we propose this structure to be inherited from a lithospheric-scale fault zone separating the Mesozoic arc from forearc-related terrains. We therefore stress the importance of pre-existing structures in the development of rifted margins, with the example provided by the Baiyun-Liwan Fault Zone having profound implications for palaeogeographic reconstructions in the South China Sea. At present, the Baiyun-Liwan Fault Zone is incised by the Pearl River Canyon and eroded by recurrent submarine landslides, forming a major area of sediment bypass towards the abyssal plain.