Types, distribution patterns, and controls of fluid seep systems in the East China Sea

The East China Sea, as a typical active continental marginal sea in the western Pacific, has developed diverse submarine fluid seepage system units under the influence of complex geological processes such as back-arc spreading of the Okinawa Trough, compression of the Ryukyu subduction zone, and rapid Cenozoic sedimentation. In this paper, we systematically reviewed geological and geophysical research achievements in the continental shelf, slope, and Okinawa Trough regions of the East China Sea, providing a comprehensive synthesis of the types, spatial distribution patterns, formation mechanisms, and coupling relationships of fluid seepage systems. Research indicates that the fluid seepage systems in the East China Sea include mainly shallow gas, pockmarks, mud diapirs, mud volcanoes, cold seeps, and hydrothermal activities, exhibiting distinct spatial differentiation across the shelf-slope-trough regions: shallow gas and pockmarks are found predominantly in the shelf-slope transition zone, mud diapirs and mud volcanoes are concentrated along the fault zones on the western slope of the Okinawa Trough, while hydrothermal activities are distributed along the NE-trending tectonic lines of the trough axis. These fluid seepage systems do not sit in isolation but form an interconnected complex fluid migration-seepage network under the combined control of tectonic factors (e.g., fault activity, earthquakes, magmatism) and sedimentary environments (e.g., rapid sedimentation, sea-level changes, bottom current erosion). We also summarized the latest research advances in the fluid seepage systems of the East China Sea and, based on these findings, presented a spatial distribution map of the fluid seepage systems. This review provided a support for the exploration of marine oil, gas, and gas hydrate resources, the assessment of submarine geological hazards, and studies of the global carbon cycle.