Sequence aggradation and systems tracts partitioning in the mid-eastern Yellow Sea: roles of glacio-eustasy, subsidence and tidal dynamics

In the mid-eastern Yellow Sea, late Pleistocene–Holocene glacio-eustatic sea-level fluctuations and a local subsidence regime have formed an aggradational set of high-resolution sequences (sequences I–V in descending order). Extensive tidal scour-and-fill processes during transgressions played a significant role in marked partitioning of non-marine to paralic clast-rich lowstand systems tract (LST) and tidal fine-grained transgressive–highstand systems tract (TST–HST) within each sequence. The lateral extent and thickness of sequences and component systems tracts reflect differences in magnitude and duration between eustatic sea-level cycles. Sequence V is characterized by extensive LST, indicating sea-level fall to the shelf-margin area. Sequences IV and III display a limited extent of LST, reflecting small-scale sea-level falls during the late Pleistocene. Sequence II displays seaward restriction of TST–HST owing to a small-scale sea-level rise prior to the last glacial maximum (LGM). Sequence I has formed since the LGM and is characterized by discontinuous TST–HST over the entire shelf area, reflecting rapid retreat of sediment sources during the post-glacial sea-level rise. Along with the predominant controls of local subsidence, glacio-eustasy and transgressive tidal dynamics on the overall stratal architecture, minor variations in architectural characteristics were added by other local factors such as changing sediment flux, antecedent topography and basin physiography.