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

Abstract

An anisotropy of magnetic susceptibility (AMS) study on three sediment cores taken from the Korea Deep Ocean Study(KODOS) area in eastern PaciÆc 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 astable sedimentation mode.However, some intervals show deformed AMS patterns (magnetic lineation), and this anomalous fabric is mainly observed atthe boundary where sediment color changes. The abrupt change of AMS parameters at this boundary provides evidence that thelinear fabric was induced by input of intensiÆed bottom currents.Based on the trend of microfossil occurrences, it is interpreted that the discontinuous color boundary was formed by hiatusbetween Tertiary and Quaternary age. The change of magnetic fabric at the topmost color boundary coincides with the time ofprevailed antarctic bottom water (AABW) activity. In this study, the AMS properties are shown to be useful tools for makinginferences concerning the paleoenvironment of abyssal basins.q2000 Elsevier Science B.V. All rights reserved.