The change in redox condition of the Japan Sea since its birth based on trace element geochemistry of sediment cores and sulfur isotope ratio of framboidal pyrite.

从日本海日本盆地的高硫层柱状岩心（KH77-3-L4′）中分离出草莓状黄铁矿球粒，测定了黄铁矿-硫的硫同位素比值。硫同位素比值低至50*，表明含氧底水为同生形成的草莓状黄铁矿，可有效区分含氧底水为同生形成的草莓状黄铁矿，也可通过成岩硫酸盐还原作用区分含氧底水为同生形成的草莓状黄铁矿与成岩形成的草莓状黄铁矿。用加速器质谱法测定了岩心高有机碳层有机碳的C-14年龄。采用中子活化法测定了27种主要元素和微量元素的含量以及有机碳、氮和硫的含量。根据这些化学参数，特别是氧化还原敏感元素的化学参数的精确垂直剖面，估计了近35000年来日本海深水氧化还原条件的变化。对取自日本海盆地的深海钻井岩心（Leg 127 Site 795岩心）的123个样品进行了有机碳、氮、总硫和27种主要元素和微量元素的分析。分离出草莓状黄铁矿球粒，测定了它们的硫同位素比值。根据这些化学参数，估计了约15 Ma前日本海诞生以来深水氧化还原条件的变化。这些结果表明，自2.4 Ma以来，高氧条件和高还原条件之间的循环变化变得明显。

Framboidal pyrite spherules were isolated from high sulfur layrs of a piston core (KH77-3-L4') sample collected from the Japan Basin of the Japan Sea and sulfur isotope ratios of the pyrite-sulfur was measured. The sulfur isotope ratios show as low as-50* indicating the syngenetic formation of framboidal pyrite under euxinic bottom waters and its validity to distinguish the formation of framboidal pyrite under euxinic bottom waters and its validity to distingnish the formation of framboidal pyrite between syngenetic formation under euxinic bottom waters and diagenetic formation through diagenetic sulfate reduction. The C-14 ages of organic carbon were measured at high organic carbon layrs of the core by accelerator mass spectrometry. Twenty seven major and trace element contents were also measured for the core by neutron activation analysis in addition to organic carbon, nitrogen and sulfur. Based on the precise vertical profiles of these chemical parameters, especially of those of redox sensitive elements, the changes of redox conditions of the deep water of the Japan Sea were estimated for the last 35000 years.Organic carbon, nitrogen, total sulfur and 27 major and trace elements were analyzed for 123 samples from and Deep-sea Drilling Core, Leg 127 Site 795 Core, from the Japan Basin of the Japan Sea. Framboidal pyrite spherules were also isolated and the their sulfur isotope ratios were measured. Based on these chemical parameters, the changes in redox conditions of the deep water since the birth of the Japan Sea, ca.15 Ma ago, were estimated. According to these results, the cyclic changes between highly oxic and highly reducing conditions have become significant since 2.4 Ma ago.