| Affiliation: | (1) School of Earth and Environmental Sciences, Seoul National University, 151-742 Seoul , Korea;(2) Marine Environment and Climate Laboratory, Korea Ocean Research and Development Institute, Ansan P.O. Box 29, 425-600 Seoul , Korea;(3) Graduate School of Environment and Earth Science, Hokkaido University, 060-0810 Sapporo , Japan;(4) Present address: FB5 Geowissenschaften, University of Bremen, Klagenfurter Strasse, 28359 Bremen, Germany |
| Abstract: | We investigated the biogenic components (biogenic opal, calcium carbonate, and organic carbon) of the marine sediments in core TY99PC18 recovered from the southeastern part of the Ulleung Basin, East Sea (Japan Sea). Our results indicate that primary productivity by diatoms increased after the last glaciation (15,000 14C years b.p.) probably because of the onset of vertical mixing of seawater and nutrient supply from the deep water. Between 5,000 and 10,000 14C years b.p. a shift in the dominant primary producer, i.e. from diatoms to coccolithophores, coincides with decreased productivity, which could be related to the influx of warm, low-nutrient waters at that time. During the late Holocene (after 5,000 14C years b.p.) the productivity of diatoms increased once more probably due to renewed ventilation and vertical mixing. |
