Provenance of late Quaternary sediments on the southwestern slope of the Ulleung Basin, East/Japan Sea

Abstract

The provenance of fine-grained sediments deposited since the late Quaternary was recovered from drill site UBGH2-1_1 on the southwestern slope of the Ulleung Basin, East/Japan Sea. Based on geochemical analyses, including rare earth elements (REEs), the fine-grained sediments could be interpreted as mixtures of sediments from China via various pathways and sediments discharged from the Nakdong River (NRS). A comparison of variations in REE fractionation factor with Marine Isotope Stages (MISs) indicated that the provenance of the fine-grained sediments on the southwestern slope of the Ulleung Basin was controlled by global eustatic sea-level change. During glacial periods, most of the fine-grained sediments were supplied via the atmospheric pathway by an intensified East Asian Winter Monsoon, and sediments from Chinese rivers (CRS) transported into the Ulleung Basin through the Korea Strait were limited due to the morphological characteristics of the Korea Strait and low sea-level. During interglacial periods, The CRS transported into the Ulleung Basin through the Korea Strait increased with sea-level rise and eolian dust inputs decreased due to attenuated East Asian Winter Monsoon. Simultaneously, NRS also should have been deposited when sea-level was higher than −40 m relative to present sea-level during MIS 1 and MIS 5. In particular, during MIS 1, signals of NRS were revealed since 11 ka; thus, it can be suggested that the present coastal current system around the southeastern coast of Korea became established by around 11 ka.