Japan Geoscience Union Meeting 2018

Presentation information

[EJ] Evening Poster

M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS06] Global climate change driven by the Southern Ocean and the Antarctic Ice Sheet

Mon. May 21, 2018 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Osamu Seki(Institute of Low Temperature Science, Hokkaido University), Akira Oka(Atmosphere and Ocean Research Institute, The University of Tokyo), Ryosuke Makabe(国立極地研究所, 共同), Ryu Uemura(University of the Ryukyus)

[MIS06-P03] Planktic foraminiferal assemblage in the Indian sector of the Southern Ocean since the last glacial

*Hiroki Matsui1, Minoru Ikehara1 (1.Center for Advanced Marine Core Research, Kochi University)

Keywords:Southern Ocean, Planktic foraminifera

Understanding the Antarctic Circumpolar Current (i.e., Antarctic polar front and Subantarctic front) is a key to climatic changes in the Southern Ocean and Antarctic ice sheets. Modern polar front ranges from 45°S to 60°S (Freeman et al., 2016), and the front position closely matches the boundary between carbonate and siliceous sediments (Dutkiewicz et al., 2015). Thus, the position of polar front can be estimated from the plankton assemblages of deep-sea sediments, which also provides insights into current systems related to the polar front (e.g., Agulhas current).
Here we performed planktic foraminifera census counts to reconstruct the position of polar front since the last glacial. Sediment samples are collected from DCR-1PC (46°S, 44°E, 2632 m water depth) located on the Del Caño Rise in the Indian sector of the Southern Ocean.
Planktic foraminifera were abundant during the Marine Isotope Stage (MIS) 1 compared to the MIS2. High latitude species such as Globigerina bulloides, Globorotalia inflata, Groborotalia truncatulinoides, Neogloboquadrina pachyderma comprised assemblages during the MIS1, and G. bulloides and N. pachyderma dominated during the MIS2. We show the reconstructed sea surface temperature based on foraminifera census data. The relative abundance of foraminifera species indicative of the Agglus current variation (Peeters et al., 2004) is also investigated. In addition, we examine foraminifera size distribution in relation to the environmental changes since the last glacial.