Approximately 70% of sediment trans

Approximately 70% of sediment transported to coastal areas is deposited in the subaqueous delta region that is no more than 15 km away from the mouth of the river (Qin and Li, 1983). The Pinghu Formation of Xihu Depression is mainly developed in bay, delta influenced by tide,braided river delta and tidal flat, the main sedimentary facies of Block A and B are tidal delta front sub-facies and tidal flat facies. The tidal-delta facies always with relatively strong hydrodynamics, and the cores mainly exhibit medium sandstone with double clay layer or irregular mudstone conglomerate, tidal bedding, and tidal channel sandbodies with single clay layer and cross-bedding (Fig. 5). The tidal flat facies always with relatively weak hydrodynamics, and the cores mainly exhibit lenticular bedding and wave bedding, bioturbation, and carbonized plant stems, leaves and nautiloid fossil (Fig. 4). All the sequences display nearly the similar sediments dispersal pattern and inherited depositional systems, with different characteristics of lithology and facies distribution (Fig. 10).