Shallow anatomy of a continent–ocean transition zone in the northern South China Sea from multichannel seismic data

• Published in: Tectonophysics
• Main Authors: Zhu, Junjiang, Qiu, Xuelin, Kopp, Heidrun, Xu, Huilong, Sun, Zongxun, Ruan, Aiguo, Sun, Jinlong, Wei, Xiaodong
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2012
• Subjects: Greenland
• Online Access: https://oceanrep.geomar.de/id/eprint/15301/; https://oceanrep.geomar.de/id/eprint/15301/1/Kopp.pdf; https://doi.org/10.1016/j.tecto.2012.05.027

The Cenozoic tectonic evolution of the South China Sea is reflected in diverse tectonic processes including continental rifting, seafloor spreading, subduction, terrane collision and strike-slip fault movement. A continent-ocean transition zone in the northern South China Sea caused by the lithospheric extension when the continent underwent break-up, rifting and later seafloor spreading, is clearly imaged in the multi-channel seismic data presented in this study. The morphological units of the continent-ocean transition zone are the rift-depression, the volcanic zone and tilted fault blocks. The volcanic zone represents a highest extension zone within the continent-ocean transition zone and is mainly distributed in the southern slope uplift zone along the northern passive margin of the South China Sea. The large listric-normal faults bounding the Dongsha Rise and Baiyun Sag are evidenced in the seismic image. The passive margin in the northern South China Sea underwent the wide-rift to narrow-rift process in the transition zone as inferred from the relation between the surface heat flow and initial rifted crustal thickness. The continent-ocean transition zone in the continental margin of the South China Sea is consistent with high heat flow zone (average 90 mW.m(-2)) observed in the previous heat flow measurements and at ODP Site 1148, and is manifested in a sharp change of the P-wave velocity. The rifted margin of the South China Sea is a non-typical magma poor passive margin or an intermediary form between the Iberian-type non-volcanic and the Greenland-type volcanic margin compared to the world's typical passive margins