Organic geochemical study on the relationship between primary productivity of palaeocean and evolution of marine invertebrates

在日本西南部的丹波和秩父山脉，含有二叠纪/三叠纪（P/T）界线的露头中，有富含有机质的黑色页岩夹层。考虑到它们的成熟度水平，初始有机碳浓度估计约为3%（平均值）。干酪根不含任何高等植物来源的碎屑，但主要由无结构的无定形碎屑组成。生物标志物表明，黑色页岩包括主要来自浮游生物的有机物质，以及与细菌活动有关的额外有机物质。黑色页岩形成时期古海洋相对活跃。在P/T转换期，由于构造和气候引起的活跃洋流系统，使具有发育良好的富营养化氧最小层的层结海洋间歇性地遭到破坏，导致了具有显著高初级生产力的上升流。晚二叠世氧最小层的扩张及其突然破坏可能是海洋无脊椎动物大规模灭绝及其演化的重要原因之一。

Outcrops containing the Permian/Triassic (P/T) boundary exposed in the Tanba and Chichibu terranes, Southwest Japan, have intercalated organic rich black shales. The initial organic carbon concentration was evaluated to be about 3% (average), considering their maturity levels. Kerogens do not contain any debris of higher plant origins, but are mostly composed of structureless amorphous ones. Biomarkers show that black shales comprise organic matter derived mainly from plankton with the additional organic matter related tothe bacterial activity. Palaeocean at the time of black shale formation was comparatively active. The stratified ocean with well developed oxygen minimum layr rich in nutrients was intermittently destroyed due to the tectonically and climatically induced active ocean current systems in the P/T transition time, resulting in upwelling for the remarkably high primary production. Expanding oxygen minimum layr in the Late Permian and its abrupt destruction can be one of crucial causes for the mass extinction of marine invertebrates and their evolution.