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Modern and past processes of ocean-atmosphere-climate interactions in the low-latitude western Pacific and Indian Ocean
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Paleoenvironmental changes in the NW South China Sea over the Last Glacial-Interglacial Cycle inferred by fossil diatom assemblages
Wednesday 9th @ 1030-1050, Conference Room 1
Jinpeng ZHANG* , Guangzhou Marine Geological Survey
Michal Tomczak, University of Szczecin
Andrzej Witkowski, University of Szczecin
Jan Harf, University of Szczecin
Hongjun Chen, Guangzhou Marine Geological Survey
Presenter Email: jinpenggmgs@sina.com |
| The paleoclimatic and paleoceanographic records during interglacial and glacial cycles in the East Asian monsoon zone are one of cutting edge in the marine geosciences. In this one of the most climatically sensitive regions shaped by the land-ocean-atmosphere interactions between the western Pacific and eastern Indian Ocean systems the fossil record of diatoms preserved in biofacies help to reconstruct environmental changes over the last glacial-interglacial cycle that took place at the continental margin of the northwestern South China Sea (SCS). The results of a diatomolgical investigation of a piston core (111 PC) shown diatom flora dominated by tropical-subtropical planktonic and coastal species, that could be classified into 6 diatom assemblage zones, coinciding with oxygen isotope stages inferred by foraminifera assemblages (correlated to LR04, Lisiecki & Raymo, 2005). The diatom biostratigraphy based on the indication of key diatom species among their assemblages and oxygen isotopic stages. Shifting of diatom abundances and species in the core profile response to the glacial and interglacial climate fluctuations in this sea area. Concentrations of diatom covers were relatively high in the late Warm glacial stage and then decaying during the mid-Warm glacial stage and postglacial stage (Marine Holocene). While the abundances were significantly lower during the Riss glacial stage and early Warm glacial stage. The characteristic of diatom abundance distribution in northwest SCS differ to southwest SCS, and in extent is similar to northeast SCS. Fossil diatom recorded climatic changes during the turning stage between Riss glacial stage and Riss-Warm interglacial stage, although this mechanism is not fully explained. Species distribution revealed an in the middle Warm glacial stage early warm period present. The irregular distributions of diatom species in the core reflected dynamic oceanographic conditions and sedimentary environments during specific geological periods, particularly in the period of late MIS 4 to early MIS3 and the transition of MIS 3 to MIS 2 in last glacial stage. This study provides a detailed record of regional paleoenvironmental changes and their impact on the silicious organisms (mainly diatoms), that has a key importance in marine and near coast ecosystems.
Keywords: Diatom, NW South China Sea, Glacial-Interglacial cycle.
References: Lisiecki, L. E., Raymo, M. E. A Pliocene-Pleistocene stack of 57 globally distributed benthic d18O records, Paleoceanography, 2005, 20, PA1003.
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