Late Pleistocene sea-level changes and the formation and fill of bent valleys incised into the shelf of the western South China Sea

During times of lowered sea level, Mekong River and Red incised valleys into the ancient coastal plains exposed shelves western South China Sea. The deglacial fill history valley was investigated by seismic surveys sediment cores. channels mainly exhibit a low-sinuosity course, but some channel segments are bent. oldest part channel-bend exhibits shingled reflectors in Parasound records documenting lateral migration typical meandering rivers. Above, vertically stacked reflectors, which extend from inner-bend side onto cut-bank document that river-mouth turned to depositional mode. Vertical aggradation started when level ~ 1–2 m below river water-level. this phase, about two-third depth filled “fluvial-to-estuarine” mud having negative log(Ti/Ca) values as evidenced XRF core scan data. Typically estuarine conditions developed water-level approximate level. Today bends form estuaries within zone bedload convergence. Therefore, it is suggested studied represent antecedent, inherited features formed during phases prolonged lowered, relatively stable allow morphologically develop. In fact, occur not only Sea also other areas world range corresponds retarded sea-level fall MIS 5b, 5d, 4, 3.