Three-dimensional models of lithofacies and N-values of alluvial deposits obtained using borehole logs : An example of the latest Pleistocene to Holocene incised-valley fills in the northern part of the Tokyo Lowland, central Japan

Abstract

Three-dimensional models of lithofacies and N-values of incised-valley fills deposited since after the last glacial maximum were constructed using 2,175 borehole logs under the northern part of the Tokyo Lowland. The procedure for the construction is as follows : (1) the descriptions of lithofacies and N-values were extracted from the borehole database, (2) the descriptions of lithofacies and N-values were standardized, (3) the irregularly scattered values of lithofacies indexes and N-values were horizontally interpolated to obtain regularly gridded datasets in each altitude, and (4) the datasets were stacked vertically. The three-dimensional distribution of lithofacies and N-values shows the three-dimensional distributions of sedimentary bodies, such as meandering river channel fills, natural levee to backmarsh deposits, deltaic mud bodies, and sand spit deposits.