Progradational sediment: succession and paleo-channel system in the central South Yellow Sea since the Late Pleistocene

High-resolution seismic profiles and depositional stratigraphy of cores in the central South Yellow Sea (SYS) since the Late Pleistocene were analyzed. The sequence stratigraphy succession and its response to sea-level changes were studied. Results indicate that high-resolution seismic stratigraphy could be divided into six seismic units (U5, U4, U3, U2, U1-2, and U1-1 from early to late times), and they were closely related to depositional units of cores. Based on the two sequence boundaries R4 and R2, corresponding to sea-level lowstands of MIS4 and the Last Glacial Maximum (LGM) respectively, three distinct sequences (SQ3, SQ2, SQ1 from bottom to top) were identified. There are three stages of progradational sedimentation and two stages of paleo-channel systems. Two eastward progradational successions match the sea-level highstands after sea-level falls of MIS5 and MIS3, with thickness maxima 24 m and 40 m in the western part of the study area respectively; and they mainly consist of highstand systems tract (HST) and falling stage systems tract (FFST) (neritic and littoral facies), and obviously become thinner eastward. The seaward progradational succession since the sea-level highstand of the Holocene, with a maximum thickness of 24 m, is related to HST (mud sediment of neritic facies from the Yangtze River). The two stages of paleo-channel systems were dated to MIS4 and LGM, with the maxima thickness of 36 m and 24 m respectively, and they correspond to the lowstand systems tract that were closely associated with the Yellow River and Yangtze River in the past. The paleo-channel systems extended to the Yellow Sea trough and its eastern area could reach the Jeju Island (Korean Peninsula) coast in the past especially in the LGM.