A 3D Snapshot of Crustal Breakup Deduced From Seismic Analysis of the Tip of the NW South China Sea

P. Chao (1) , G. Manatschal (1) , P. Chenin (1) , C. Zhang , J. Ren , X. Peng , J. Zheng

1 ITES - Institut Terre Environnement Strasbourg

Based on a high-resolution seismic reflection data set, we describe and map rift domains at the tip of the V-shaped NW-South China Sea (NW-SCS) Basin. We compare our rift domain map with seismic refraction, magnetic and gravity field data, and previously mapped Continent-Ocean Boundaries (COB). We also define and map syn-breakup sedimentary and magmatic sequences across the sediment-rich NW-SCS, which enables us to reconstruct the tectono-stratigraphic evolution of the area. This work enables us to describe and discuss the 3D architecture and nature of the crust at the tip of the NW-SCS, investigate how extensional and magmatic processes interacted during the breakup, and propose a kinematic model for late rifting, breakup, and finally stalling of the seafloor spreading system. This study provides exceptionally well-documented insights into the spatial and temporal evolution at the tip of a so-called "rift propagator," and enables us to show that breakup in the NW-SCS may rather correspond to a "retrogrador," in which the extension zone retreats due to the reorganization of a failing rift system.

Mots clés: NW South China Sea; V-shaped basin; lithosphere breakup; syn-breakup magmatism; oceanic crust; retrogrador

Domaines: Planète et Univers [physics]; Tectonique

P. Chao, G. Manatschal, P. Chenin, C. Zhang, J. Ren, et al.. A 3D Snapshot of Crustal Breakup Deduced From Seismic Analysis of the Tip of the NW South China Sea. Tectonics, 2022, 41, ⟨10.1029/2021TC007127⟩. ⟨insu-03824792⟩