Grain size partitioning in loess–paleosol sequence on the west coast of South Korea using the Weibull function

Abstract

This study aims to partition the grain size of the loess–paleosol sequence on the west coast of South Korea and investigates the limitations and applicability with the partitioning method, through the help of a laser diffraction grain size analyzer. Two to four components, depending on the samples and theories employed to convert the laser diffraction data to grain size data, are identified through the partitioning process. However, the identification of one component is thought to be contingent upon the theories employed, rather than natural processes. The partitioning results reveal that the sequence consists mostly of fine and coarse components transported by the same mechanisms as in the Chinese Loess Plateau and shares common source areas with the Chinese Loess Plateau. The sequence also contains a small quantity of material from the local sources, and this component is expected to provide crucial information about paleoclimatic variations in Korea. This study suggests that considerations of the theories are essential in modeling processes of grain size because the theories greatly influence the results of grain size analysis and the number of components and that conversions using the Fraunhofer Approximation seem to provide more reliable results than those using the Mie Theory.