Development of depositional systems in the southeastern Yellow Sea during the postglacial transgression

摘要

This study focuses on the development of depositional systems in the southeastern Yellow Sea during the postglacial transgression, based on the analysis of closely spaced high-resolution seismic profiles (Chirp) and piston cores. Transgressive deposits comprise the paralic component of estuarine channel fills, seaward prograding wedge, and along-shore prograding mound, and the marine component of sand veneer, mud blanket, and offshore ridge. These transgressive deposits were developed through three distinctive stages in terms of possible sea-level position. During the early stage, tidal sand ridges and sand veneer formed south of Jeju Island, resulting from shoreface erosion associated with a relatively slow transgression. The following transgression, in the middle stage, inundated subaerially formed interfluves along the central part of the sea, and affected development of estuarine environments with increasing tidal regime in the eastern part of the sea. Combined with the strong tidal reworking, insufficient sand supply enhanced the formation of erosional ridges. Short-period increase in fluvial discharge affected the deposition of coastal wedge in the western part. Fine-grained sediments from either fluvial discharge or tidal reworking were dispersed seaward to form mud blanket. The late stage was characterized by the deposition of veneered sands off the Jiangsu coast, which was due to relatively slow rise in sea level. Further offshore, along-shore prograding mound was constructed by Huanghe-derived sediment influx, and subsequently eroded and redeposited by wave and tide activities, thus detached from the proximal source. The depositional processes and variability of the transgressive deposits in the southeastern Yellow Sea were largely controlled by changes in rate of sea-level rise during the transgression, most likely related to the global flooding events triggered by melt water pulses. The changes in shoreline configuration and oceanographic regime have also influenced the distribution and morphology of the transgressive deposits. A short-period increase in riverine discharge caused the temporal sediment progradation off the Jiangsu coast.