Control Effect of the Paleomarine Environment on Gas Hydrate Reservoir Since the Pleistocene in the Dongsha Area, Northern South China Sea

Abstract The Dongsha area, a key target for gas hydrate exploration, is influenced by multiple factors, including sedimentary processes and the paleoenvironment, which play critical roles in gas hydrate formation. To elucidate the coupling among sedimentary processes, paleoenvironment, and gas hydrate accumulation, this study investigates the Site DS‐W16 using particle size analysis, biological component content, and geochemistry data. Oxygen isotope data from foraminifera and biostratigraphic evidence indicate that sedimentation at the bottom of core interval from Site DS‐W16 began during MIS 11 (Marine isotope stage). The sedimentation dynamics of the studied layers are complex, involving gravity flows, traction currents, and suspended deposition. Organic matter shows a significant correlation with transgressive–regressive cycle. The site DS‐W16 contains two distinct gas hydrate reservoirs: a shallow reservoir (10–24 mbsf) and a deep reservoir (below 182 mbsf). The paleomarine environment influences gas hydrate accumulation by altering sedimentary processes and sediment characteristics, especially the distribution of biological components. Both shallow and deep gas hydrate reservoirs formed under dynamic conditions dominated by traction currents and are characterized by a higher abundance of foraminifera. Sedimentary layers rich in foraminifera and modified by traction currents represent key intervals for preferential gas hydrate accumulation.