Search

The development of the sedimentary basin in the South Yellow Sea that lies between the Chinese mainland and the Korean Peninsula well documents the tectonic evolution of eastern China. However, the Moho morphology and its relationship with the basin in this area remain poorly understood. Here we used high‐resolution 2D seismic lines and well data to map the geometry, structure, and distribution of the sedimentary basin in the South Yellow Sea. Our results suggest that the South Yellow Sea Basin can be divided into two distinct depressions and three uplifts. The depressions consist of eight depositional sags that are largely controlled by ENE‐, EW‐, and WNW‐striking normal faults. The basin depth reaches 9,500 m in the depressions, but is only <2000 m in the uplift zones. Calculated using a gravity stripping method, the Moho depth varies between 27.4 and 31.5 km. The basin is isostatically compensated and the Moho morphology approximately mirrors that of the basin basement. The Moho lows correspond to the uplift zones and Moho highs correspond to the depression zones, with exception of a sag in the Northern Depression. This exception is caused by the presence of a geological body of high velocity and high density beneath the sag. This body is likely to represent high‐pressure metamorphic rock that initially formed during the collision between the Sino‐Korean and Yangtze cratons and are currently overlain by the sedimentary basin. Based on the stretching factors and strain rates of the South Yellow Sea Basin, we propose that development of the basin was primarily driven by the subduction and retreat of the Pacific Plate since the Late Cretaceous, combined by far‐field effects from the convergence between the Indian and Eurasian plates during the Cenozoic. [ABSTRACT FROM AUTHOR]

Early Mesozoic geodynamic and tectonic relations between different blocks in East China remain controversial. The Subei-South Yellow Sea Basin (SB-SYSB) is located at the junction of different blocks and tectonic zones, including the North China Block (NCB), South China Block (SCB), Sulu Orogen and Tan-Lu Fault Zone (TLFZ). Therefore, the basin is a key location for understanding the regional geologic evolution of East China. Here, we present the geometry and kinematics of opposite thrust systems (OTSs) under the SB-SYSB based on seismic profiles, well data, magnetic reversion data and field observations. The OTSs are composed of two sets of thrust systems with opposite senses of motion: the northern top-to-the-southeast thrust system (N-TS) and southern top-to-the-northwest thrust system (S-TS). According to the structural styles, the N-TS and S-TS can be divided into the root, middle and frontal belts. The strikes of thrusts show a shift from NNE to N E - ENE and then to nearly E-W from west to east. The OTSs were suggested to have formed during the end of the middle Triassic to the middle Jurassic, and its deformation intensity decreased from west to east and from the root belt to the frontal belt. Combining these lines of evidence with published geochronological data for the Dabie-Sulu Orogen and other structural elements in East China, we provide a comprehensive synthesis and propose a new tectonic model to explain the early Mesozoic geodynamic and tectonic relations in East China. We emphasize the following points: (1) The Sulu Orogen might extend to the Northern Depression in the offshore SYSB and be bounded by the North Fault of the Central Massif to the south, indicating that the Sulu Orogen is significantly wider than stated in previous studies. (2) The N-TS was driven by the subduction of the YZB and the exhumation of the Sulu HP–UHP metamorphic rocks. In contrast, the S-TS was probably controlled by the orogenic uplift of the Jiangnan Orogen. (3) The dragging of the thrusts in the SB-SYSB and adjacent areas indicates that the sinistral motion of the TLFZ was coeval with the formation of the OTSs and was likely caused by the clockwise rotation of the SCB. (4) Finally, this clockwise rotation probably triggered intense corner compression between the Sulu Orogen, TLFZ and East Marginal Fault of the Yellow Sea, resulting in a genetic relation among the Sulu Orogen, the SCB, the Korean Peninsula and the Xu-Huai Belt. • The OTSs were controlled by subduction of the SCB, the exhumation of the Sulu Orogen and the uplift of the Jiangnan Orogen; • The Sulu Orogen might extend to the Northern Depression in the SYSB and be bounded by the North Fault of the Central Massif; • The TLFZ was coeval with the formation of the OTSs; • We proposed a model to illustrate the relationship among the Sulu Orogen, the SCB, the Korean Peninsula and the Xu-Huai Belt. [ABSTRACT FROM AUTHOR]