Evolution of radiative sand ridge field of the South Yellow Sea and its sedimentary characteristics

A sand ridge field of 22 470 km(2) consists of fine sands and silts origina lly from the old Changjiang River sediment during the late Pleistocene peri od. Late Holocene sand stratum with its well-preserved laminary bedding of more clay particles reflects the influence from the Yellow River. There are three genetic types of morphology of sand ridge field as follows: (i) reformed alluvial sandy bodies and old river valleys, located in the c entral and southern parts, formed from the end of Pleistocene to the presen t, ii) Radiative current ridges and patrimonal valley type, located in the northeastern part, formed during the early or middle Holocene time. (iii) E roded-depositional sandy bodies in the north and outer parts, and erosional trough in the north formed since the middle Holocene transgression. The sand ridge field has a periodic nature of developing processes: the per iod of sediment accumulation by rivers during cold epoch with low sea level and the period of erosional formation by tidal currents during warm epoch of transgression. The river-sea interactive process in the area is closely related to the climate change; the rising and falling of the sea level is t he detonating agent of the coast zone land-sea dynamic interactive processe s. They can be summarized as "transgression-dynamic-sedimentation" processe s.