Mineralogical Characteristics for the Sediments around Dokdo, East Sea, South Korea

Abstract

There is little understanding of clay mineralogical depositional environment for the subseafloor sediments around Dokdo, East Sea, South Korea, because clay minerals are scarce for the previous expedition (2016.09.07 ~ 2016.09.08). The recent site (132° 00.371’, 37° 24.252’) in the basin-like topography that will collect the clay minerals, was explored to understand clay mineralogy, elemental composition of smectite, grain size distribution of smectite, sedimentary phaseand relative proportion of clay minerals. The change of depositional environment has influenced the mineralogical characteristics of the marine sediment around Dokdo during the interglacial and glacial period. Grain size distribution showed a variation in the proportion of clay, silt and sand size which consistent with the change of sedimentary facies. During the interglacial period bioturbated mud is dominant, while laminated mud is dominant during the glacial period. Variation in the relative proportion of clay minerals such as smectite, illite, chlorite and kaolinite also reflects the change of depositional environments during the glacial-interglacial period. During the interglacial period, smectite is moreabundant than the glacial period. In this study, the interpretation of paleo-depositional environments around Dokdo will be discussed.