Yanqiu Yang

Despite complex geological conditions and limited exploration activity, the South Yellow Sea Basin has not yet yielded a commercial hydrocarbon discovery. Recent studies indicate substantial hydrocarbon potential within the Upper Sinian–Lower Silurian strata; however, the mechanisms controlling hydrocarbon accumulation in these sequences remain poorly understood. In this study, outcrop, drilling, organic geochemical, and seismic data from the Yangtze Plate are integrated using a land–sea comparison approach to evaluate petroleum geological conditions, identify key controlling factors, and predict hydrocarbon accumulation in the Upper Sinian–Lower Silurian sequences of the Laoshan Uplift. The results indicate that the Upper Sinian–Lower Silurian strata possess favorable petroleum geological conditions, including two effective source–reservoir–seal assemblages. Key controls on deep hydrocarbon accumulation include high-quality Lower Cambrian source rocks, early development of the Laoshan paleo-uplift, structural stable zones, and Lower Silurian detachment layers. Three hydrocarbon accumulation evolution models are proposed: (1) early stage lateral hydrocarbon supply from adjacent depressions, (2) early stage lower-source–upper-reservoir charging, and (3) late-stage deep-burial cracking with structural adjustment. These findings provide important guidance for deep hydrocarbon exploration the Upper Sinian–Lower Silurian sequences of the Laoshan Uplift in the South Yellow Sea Basin.

The East China Sea Shelf Basin (ECSSB) and its adjacent areas, as key regions of the ocean–continent transition zone, have been affected by multiple complex plate collisions, subduction, and back-arc tension since the Mesozoic Era. The structural deformation provides a large amount of geological information on the ocean–continent transition zone. There are significant spatiotemporal differences in the structural deformation within the basin. However, the research remains insufficient and understanding is inconsistent, especially regarding the systematic study of the differences and dynamic mechanisms of north–south structural deformation, which is relatively lacking. This study is based on two-dimensional multi-channel deep reflection seismic profiles spanning the southern and northern basin. Through an integrated re-analysis of gravity, magnetic, and OBS data, the deformation characteristics and processes of the Meso-Cenozoic structures in the basin are analyzed. The differences in structural deformation between the southern and northern basin are summarized, and the controlling effects of deep crust–mantle activity and the influencing factors of shallow structural deformation are explored. Based on deep reflection seismic profiles, the structural deformation characteristics of the Yushan–Kume fault are revealed for the first time, and it is proposed that NW faults, represented by the Yushan–Kume fault, have important tuning effects on the north–south structural differential deformation in the ECSSB. The thermal subsidence of the lithosphere is the direct cause of the development of the Mesozoic ECSSB, while the subduction of the Paleo-Pacific plate is one of the important factors contributing to it. The combined effect of the two has led to significant differences between the northern and southern Mesozoic basin. During the Cenozoic Era, the alternating subduction and changes in the direction of subduction of the Pacific Plate led to spatiotemporal differences in structural deformation within the ECSSB. The development of NW faults was a key factor in the differences in structural deformation between the northern and southern basin. The study of structural deformation differences in the ECSSB not only deepens our understanding of the tectonic evolution in the East Asian continental margin region, but also has important significance for the exploration and evaluation of deep hydrocarbon resources in the ECSSB.

The East China Sea Basin (ECSB) is an integral part of the Western Pacific tectonic system. Its development is linked to the Kula–Pacific Plate and the formation and expansion of the Philippine Sea Basin. Recent advancements in exploration technologies and theory have been applied to Mesozoic basins in the East China Sea. Researchers have posited that the southern basin has great oil and gas exploration potential. However, the characteristics and evolution of fault structures and their influence on hydrocarbon accumulation remain unclear. Here, in-depth geometric and kinematic analyses of Mesozoic fault structures in the southern ECSB were conducted using the latest interpretations of 2D seismic data and structural analysis theory. The findings revealed that the fault system was well developed and predominantly exhibited multiphase extensional and extensional-torsional features. Based on their lateral distribution and morphology, faults were categorized into three structural styles and seven combinations. According to their developmental timing, periods of active faulting were attributed to the Yanshan and Himalayan epochs. Multiphase fault activities strongly controlled the formation of traps and thus hydrocarbon accumulation, while earlier NE-trending faults controlled the formation of structural belts and hydrocarbon source areas.