충남 부여 궁남평야 충적층의 퇴적구조

Abstract

In this study, with the object of the materials of exploratory holes drilled on the alluvial plain (hereinafter referred as Gungnam plain) that is developed in the whole area of Gungnam pond in Buyeo Chungnam we carried out facies analysis, stratigraphic interpretation and radiocarbon dating to investigate the sedimentary structure and sedimentary period of the alluvium of the Gungnam plain (present altitude above sea level about 5.99~8.00m). The result is as follows. ① It was found that the maximum thickness of the alluvium of the Gungnam plain is about 16.20m and the altitude above sea level of the buried valley bottom corresponding to the river bed of Wangpo Stream (a tributary of the Geum River) in the coldest period of the Last glacial was -10.21m. ② The alluvium of the Gungnam plain is largely classified into the Lower layer, the Middle layer and the Upper layer. The Lower layer is the sand gravel layer (or gravel layer) of pleo-alluvial fan that has strong character of basal gravel layer was sedimented in the coldest period of the Last glacial. ③ The Middle layer is the inorganic layer of mainly the silt (or clay) and it is the granular layer was sedimented together with the rise of sea level in the early~middle (about 9,300~7,100yrB.P.) Holocene. ④ the Upper layer is the inorganic layer such as mainly sand, sandy silt (or clay) and it is the present floodplain layer was sedimented after the longitudinal profile of river bed of the Geum River and Wangpo Stream reached the equilibrium state. And it was confirmed that organic materials (or peat) are buried and existing narrowly in the Middle layer and lower layer.