Three-dimensional analysis of a stratigraphic surface model by the borehole data interpolation in consideration of the formation process of buried geomorhic surfaces : a case of the basal surface model of the latest Pleistocene to Holocene incised-valley fills in the northern Tokyo lowland and the southern Nakagawa lowland, central Japan

Abstract

Three-dimensional analysis of a stratigraphic surface model by the borehole data interpolation in consideration of the formation process of buried geomorhic surfaces : a case of the basal surface model of the latest Pleistocene to Holocene incised-valley fills in the northern Tokyo lowland and the southern Nakagawa lowland, central Japan AbstractThe article presents a D analysis method by interpolating borehole data to improve the precision of the surface model of the base of the latest Pleistocene to Holocene incised-valley fill, called the Chuseki-so in Japan. The study area is located in the northeastern part of the metropolis, where the northern Tokyo and the southern Nakagawa lowlands meet and are surrounded by adjacent uplands. A borehole database for this area was used for analysis.The procedure to construct the surface model involves the following steps : ( ) generate primary point data of (a) the basal horizon of the Chuseki-so using borehole data, (b) a D boundary line between the alluvial lowland and the adjacent Pleistocene upland areas, and (c) the adjacent upland area using a digital elevation model at a -m grid resolution; ( ) add secondary point data to adjust the geomorphic form of both the valley branches and boundary lines between terraces and cliffs buried by the Chuseki-so; ( ) generate point data of each buried river terrace and abrasion platform, and finally; ( ) construct the surface model by spatially interpolating the point data generated in steps -.It is necessary to consider the geologic and geomorphic formation process and evolution of this area so as to improve the form of the surface model of the base of the Chuseki-so and to better understand the geomorphic features of the incised-valley.