Abstract:

The bottom boundary of the postglacial strata in Qiantangjiang River Mouth region is recognized as the surface of the regional unconformity formed during the lower sea level period of the last glacial age.The postglacial strata can be divided into four sets corresponding to primary,early,mid and late stages.Channel grails deposited in the primary stage,alluvial flat clay rock and sandy clay rock deposited in the early stage,mudstone deposited in the mide stage,silty clay and limnic clay deposited in the late stage.Sedimentary facies include river bed,alluvial flat,neritic,river mouth and limnetic,littoral,weathered continental drift bed and flood deposit facies.It is suggested that the sandy lenticular bodies of alluvial flat and neritic facies are favourable reservoir zones for ultra shallow biogas exploration.