FN Archimer Export Format PT J TI Seismic Imaging Of an Intracrustal Deformation In the Northwestern Margin Of the South China Sea: the Role Of a Ductile Layer In the Crust BT AF Huang, Haibo KLINGELHOEFER, Frauke Qiu, Xuelin Li, Yuhan Wang, Ping AS 1:1,3;2:2;3:1,3,4;4:1,4;5:1,3; FF 1:;2:PDG-REM-GM-LAD;3:;4:;5:; C1 Chinese Academy of Sciences, Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Innovation Academy of South China Sea Ecology and Environmental Engineering, Guangzhou 511458, P.R. China. IFREMER, Department of Marine Geosciences, Plouzané 29280, France South Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, P.R. China University of Chinese Academy of Sciences, Beijing 100049, P.R. China C2 CHINESE ACAD SCI, CHINA IFREMER, FRANCE SOUTH MARINE SCI ENGIN GUANGDONG, CHINA UNIV CHINESE ACAD SCI, CHINA SI BREST SE PDG-REM-GM-LAD IN WOS Ifremer UPR copubli-int-hors-europe copubli-sud IF 5.261 TC 9 UR https://archimer.ifremer.fr/doc/00627/73900/80963.pdf https://archimer.ifremer.fr/doc/00627/73900/81991.docx LA English DT Article DE ;continental margin;crustal deformation;ductile layer;seismic modeling;South China Sea AB The continental margins of the South China Sea (SCS) have undergone episodic rifting since the Cenozoic, and there are ongoing debates surrounding the processes of crustal deformation and seafloor opening. In this work, we present a P‐wave velocity model extending from the north of Xisha Trough to the Zhongshanan Basin in the northwestern SCS margin, using ocean bottom seismometer data of the wide‐angle seismic profile OBS2013‐1. The results show that the crust thins symmetrically across the western Xisha Trough, from more than ∼20 km at the flanks to ∼10 km in the central valley where the sedimentary layers thicken to over 6 km. In the Zhongsha Trough, closer to the deep basin, the upper crust is detached in a ∼20 km wide region and the lower crust has seismic velocities increased by more than ∼0.3 km/s. The top boundary of the lower crust is located at a depth of ∼13 km across the Zhongsha Trough, and a ∼5 km thick midcrustal ductile layer is imaged. A ∼50 km wide ocean‐continent transition region beneath the Zhongshanan Basin characterizes a ∼6 km thick continental crust underlain by serpentinized and magnetized upper mantle. These observations, together with plate reconstructions based on gravity and magnetic analysis, suggest that deformation of the continental margin was controlled by a ductile crustal layer. Magmatism, associated with the early stage oceanic accretion, has mixed with the highly extended continental crust. Developments of the failed rifted basins were controlled by the westward propagation of the continental breakup. PY 2021 PD FEB SO Tectonics SN 0278-7407 PU Wiley VL 40 IS 2 UT 000624423100001 DI 10.1029/2020TC006260 ID 73900 ER EF