Abstract:

Based on a comprehensive analysis of the geological and geophysical data of the East China Sea region, especially the latest geophysical data from the past ten years, the basic geological characteristics of the research area were sorted out, and the extension of the continental tectonic units in the sea area was discussed. The results showed that the Bohai Sea and the northern Yellow Sea are typical North China style basement where North China style sedimentary caprock is developed. The South Yellow Sea is typical Yangtze style oceanic basement and developed Yangtze style sedimentary caprock. The East China Sea shelf is Cathaysia type basement, and the eastern part is likely to have Late-Paleozoic sedimentary caprock overlaid by that of the Late Triassic. The western side of the lower Yangtze Block is wedged into the North China Block through the sinistral strike-slip Tanlu Fault Zone, while the eastern side is wedged through the dextral strike-slip fault zone in the western margin of the Korean Peninsula. The fault zone of the western margin of the Korean Peninsula has the characteristics of both strike-slip and subduction zones. The whole Korean Peninsula is similar to the North China Block in terms of metamorphic basement and sedimentary cover. The lower crust beneath the Yangtze Block is subducted north-eastward under the North China Block, while the upper crust is thrust upward over the North China Block. The Jiangshan-Shaoxing Suture Zone is a 50-70 km wide high magnetic anomaly belt in the NE direction. After entering the Hangzhou Bay, it turns to the EW direction, passing through the Daqushan Island of Zhoushan Islands then over the Hupi Reef Uplift of the East China Sea shelf to enter the Kyushu Island of Japan. The Hupi Reef Uplift is a set of subduction accretion complex, similar to the Daqushan Island.

Key words: geological characteristics, tectonic boundary, basement type, East China Sea