Sedimentary fabric on deep-sea sediments from KODOS area in the eastern Pacific

摘要

An anisotropy of magnetic susceptibility (AMS) study on three sediment cores taken from the Korea Deep Ocean Study (KODOS) area in eastern Pacific was carried out to understand the relationship between magnetic fabric patterns and paleo-depositional conditions of deep-sea sediments. Most AMS measurements reveal normal sedimentary fabric patterns indicating a stable sedimentation mode.However, some intervals show deformed AMS patterns (magnetic lineation), and this anomalous fabric is mainly observed at the boundary where sediment color changes. The abrupt change of AMS parameters at this boundary provides evidence that the linear fabric was induced by input of intensified bottom currents.Based on the trend of microfossil occurrences, it is interpreted that the discontinuous color boundary was formed by hiatus between Tertiary and Quaternary age. The change of magnetic fabric at the topmost color boundary coincides with the time of prevailed antarctic bottom water (AABW) activity. In this study, the AMS properties are shown to be useful tools for making inferences concerning the paleoenvironment of abyssal basins.