Comparative paleoceanographical study using piston cores from Okhotsk Basin and Suiko Sea Mount

这项工作的目的是恢复末次冰期以来的古环境变化。为此，利用活塞式取样器在鄂霍次克盆地(长12.8m)和位于皇帝海山之一的绥歌海山山顶附近(长13.5m)获得了两个沉积岩芯。在鄂霍次克岩芯中，测定了沉积物的还原硫化物、生物蛋白石和元素组成。结果表明，鄂霍次克柱样中生物蛋白石和生物钡的含量在表层较高，随着岩心的下部逐渐降低，在8~10m深度达到最大值，与末次冰期最大年龄相对应。在地层以下，还原硫含量随岩心下移而逐渐增加。这些发现表明，鄂霍次克海的生物产量在冰期比间冰期要低得多。致岩元素铁、钛、铝、钙、镁在间冰期上部分布比较均匀，但随着岩心下部深度的增加而迅速增加，说明沉积物元素组成的这种变化是由于末次冰盛期冰排碎屑的大量供应所致。根据Narita等人的数据，2.5m深度的地层年龄估计为120KYR B.P.。(2002)。因此，该地区的生物生产量在末次冰期也出现了下降。

The object of this work is to reconstruct the change of paleo-environment after the last glacial age. For this purpose, two sediment cores were obtained using a piston corer in the Okhotsk Basin (12.8 m length) and at near the summit of Suiko Sea Mount (13.5 m length), which is one of the Emperor Sea Mounts. In the Okhotsk core, reduced suifur, biogenic opal and elemental composition of sediment were determined. In the Suiko core, biogenic carbonate and elemental composition of sediment were determined.In the Okhotsk core, the content of biogenic opal, as well as biogenic barium, was higher in the upper layer and gradually decreases with downcore, and has a maximum in the layer of 8-10 m depth, corresponding to the last glacial maximum age. Below the layer, the content of reduced sulfur gradually increases with downcore. These findings suggest that the biological production in the Okhotsk Sea is rather lower in the glacial period than in the interglacial age. On the other hand, the distributions of lithogenic elements, iron, titanium, aluminum, calcium and magnesium, were uniform in the upper interglacial period, but rapidly increased with downcore below the depth of 8-10 m. This implies that such the change of elemental composition of the sediment result from the greater supply of ice-rafted detritus in the last glacial maximum age.In the Suiko core, the concentration of biogenic carbonate varies from 4% to 94%, and the average was 69% in the whole core. The age of the layer of 2.5 m depth is estimated to 120 kyr B.P. on the basis of Narita et al. (2002). Therefore, it is suggested that the biological production in this area also has decreased during the last glacial age.