Final breakup of continental block and opening of oceanic lithosphere: insights from deep crustal structure and tectonic evolution of the ocean–continent transition zone in the northern South China Sea

Abstract

As an important transition domain between the thinnest continental crust and the initial oceanic crust, the ocean–continent transition zone (OCT) preserves a wealth of information on the processes of lithospheric extension and breakup. The northern margin of the South China Sea (SCS) is a non‐typical, magma‐poor passive continental margin with a particular structural pattern and sedimentary formation. The OCT in the northern margin of the SCS was developed by a series of continental rifting and seafloor spreading. Based on several multi‐channel seismic reflection profiles, crustal‐scale structural profiles extracted from gravity data and ocean‐bottom seismometers (OBS) data, this paper studies the deep crustal structures, deformation and geodynamics of the OCT to further understand the structural patterns and tectonic process from the lithospheric extension to its breakup. The OCT of the northern margin of the SCS is characterized by a crustal thinning and high‐velocity layer (HVL) in the lower crust. The OCT has three structural units: rift depression, volcanic zone and tilted fault blocks. The HVL is mainly limited in the eastern portion of the northern SCS. The HVL is distributed essentially within the OCT but does not clearly develop everywhere in the OCT. We propose a hybrid model of rifting to fit characteristics of the northern margin of the SCS. A crustal‐scale largely symmetric process predominated at the initial rifting stage. The basin‐controlling faults subsequently penetrated the entire crust, resulting in asymmetric tectonic evolution. Then, the OCT occupied this asymmetric location. Copyright © 2016 John Wiley & Sons, Ltd.

The basement and volcanic activities of the Xisha Islands: Evidence from the kilometre‐scale drilling in the northwestern South China Sea

“…The South China Sea (SCS) is located in the junction of the Eurasian Plate, the Pacific Plate, and the Indian–Australian Plate (Figure ). It is a typical representative of western Pacific marginal seas (Li, Li, Yu, Wang, & Jourdan, ; Lei et al, ; Liu et al, ; Lü, Hao, Yao, Xing, & Qiu, ; Guo et al, ; Zhu, Li, Sun, & Li, ; Zhang, Li, Guo et al, ; Zheng et al, ). Despite its relatively short tectonic evolution history, the SCS has roughly experienced a complete Wilson cycle, including continental break‐up, seafloor spreading, and subduction (Fang, Ding, Fang, Zhao, & Feng, ; Li, Yan, Chen, & Shi, ; Wang et al, ; Yang & Fang, ).…”

Cenozoic evolution of the Yangjiang-Yitong’ansha fault zone in the northern South China Sea: Evidence from 3D seismic data

“…Less attention has been devoted to understanding the NW-trending ones, for example, the Yangjiang-Yitong'ansha Fault Zone (YYFZ). Previous studies indicate that the YYFZ is an important NWtrending strike-slip fault zone influencing crustal structure, continent-ocean transition zone, basement lithology, sedimentary facies, Mesozoic tectonic environment, Cenozoic fault strike, and basin structure in the northern SCS (Figure 2; Hu et al, 2009;Wang et al, 2006;Guo et al, 2016;Wei et al, 2011;Sun et al, 2008;Zhong et al, 2014;Liu et al, 2013;Cai et al, 2021;Sun et al, 2014;Zhu et al, 2017;Lu et al, 2011;Li et al, 2019). Owing to its specific geographical location, the YYFZ is an ideal site for investigating the NWtrending strike-slip fault zones.…”

Mechanisms of submarine canyon formation on the northern continental slope of the South China Sea

“…(a) Simplified structural map of Southeast Asia and location of the study area within the South China Sea (Modified from Li et al, ; Pubellier & Morley, ). (b) Shaded bathymetric map for the northern margin of the South China Sea obtained from previous studies (Guo et al, ), showing features of scarps annotated in red dotted lines and the location of the three canyon zones depicted in the black boxes and the extent of the studied region: (1) Xisha Canyon‐Xs C; (2) Shenhu Canyon‐ Sh C; (3) Taiwan Canyon‐ Tw C; (c) the depth of water in the canyon zones and three locations of seismic profiles in Figure . Abbreviations: PRMB: Pearl River Mouth Basin, QDNB: Qiongdongnan Basin, TXNB: Taixinan Basin, BBWB: Beibuwan Basin, YGHB: Yinggehai Basin, RRF: Red River Fault, MT: Manila Trench.…”