摘要
A sand ridge field of 22 470 km2 consists of fine sands and silts originally from the old Changjiang River sediment during the late Pleistocene period. Late Holocene sand stratum with its well-preserved larmnary 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 central and southern parts, formed from the end of Pleistocene to the present. (ii) Radiative current ridges and patrimonal valley type, located in the northeastern part, formed during the early or middle Holocene time. (iii) Eroded-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 period 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 the detonating agent of the coast zone land-sea dynamic interactive processes. They can be summarized as “transgression-dynamic-sedimentation” processes.
A sand ridge field of 22 470 km^2 consists of fine sands and silts originally from the old Changjiang River sediment during the late Pleistocene period. 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 central and southern parts, formed from the end of Pleistocene to the present. (ⅱ) Radiative current ridges and patrimonal valley type, located in the northeastern part, formed during the early or middle Holocene time. (ⅲ) Eroded-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 period of sediment accumulation by rivers during cold epoch with low sea level and the period of erosional formation by tidal currents
基金
Project supported by the National Natural Science Foundation of China (Grant No. 49236120). Project coding: SCIEL 21198103.
