Diatom Assemblage and Productivity Changes during the Last 340,000 Years in the Subarctic Pacific |
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| Authors: | Kota Katsuki Kozo Takahashi Makoto Okada |
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| Institution: | (1) Department of Earth and Planetary Sciences, Graduate School of Sciences, Kyushu University, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan;(2) Department of Environmental Science, Graduate School of Science, Ibaraki University, Bunkyo, Mito, Ibaraki 310-8512, Japan |
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| Abstract: | Diatoms represent the major part of the microfossils preserved in the subarctic Pacific sediments. During the warm climate
intervals the diatom accumulation rate (DAR) tended to increase, whereas it tended to decrease during the cold intervals.
Principal component (PC) analysis of the fossil diatom assemblages in Piston Core KH99-3 ES samples from the subarctic Pacific
was carried out to investigate the paleoceanographic conditions of the area. PC1 (59.9% of the total variance) was represented
by Neodenticula seminae, a characteristic species representing the high nutrient concentrations, which dominated during the interglacial periods.
The DAR and PC changes can be attributed to a global origin that is influenced by the nutrient change due to intermediate
water change and to a local one that is explained by the change of upwelling region. The analysis of PC2 (17.1% of the total
variance) indicates the change of water mass in the western subarctic Pacific. During Marine Isotope Stages (MIS) 2 and 3,
the western subarctic Pacific region was significantly influenced by the sea-ice, which may have been derived from the coastal
region or a proximal marginal sea.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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| Keywords: | Diatom western subarctic Pacific upwelling paleoceanography Quaternary |
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