皖南震旦纪-早寒武世沉积岩有机碳、氮元素记录

安徽南部晚震旦世蓝田组、皮园村组和早寒武世荷塘组主要由黑色页岩和硅质岩组成。分析结果表明，蓝田组和荷塘组的总有机碳(可达10％--18％)和总有机氮(可达2．0‰--2．6‰)的高含量，应归于富有机质埋藏所致，反映新元古代末次冰期后和早寒武世海洋浮游生物处于大发展时期。由于海洋植物的光合作用产生大量O2，并消耗大量CO2，导致大气中O2／CO2比率明显增加，为震旦纪晚期多细胞真核生物的辐射、后生动物的出现和‘寒武纪生物大爆发’提供了条件。蓝田组黑色页岩中部的有机碳与有机氮含量大体呈现正比例增加，并且分别达到17．74％和2．66‰的最高值，与该剖面发现的蓝田植物群相对应；荷塘组黑色页岩的有机碳和有机氮垂直分布曲线之间呈现相互背离，即有机氮含量与时增加，而有机碳含量与时减少，与扬子地台相应的地层层位产生的澄江动物群相对应，表明TON和TOC分布特征有可能与早期生物演化历程相关。

ORGANIC CARBON AND NITROGEN RECORDS IN THE SINIAN -EARLY CAMBRIAN SUCCESSION OF SOUTHERN ANHUI, CHINA

Organic carbon and organic nitrogen analyses in the Sinian-Early Cambrian succession of southern Anhui Province, China, show that the high contents of both total organic carbon (TOC: up to 10 %-18%) and total organic nitrogen (TON: up to 2.0‰-2.6‰) may reflect a great increase of organic matter burial and consequent rise in O2 concentration in the atmosphere and the upper ocean. It, in turn, may be attributed to a high primary productivity in the ocean, which resulted from a rise of major global temperature and enhanced tectonism after the Late Neoproterozoic glaciation. Warm climate and the rise in O2 concentration of the atmosphere may have triggered the radiation of multicellular eukaryotes in the Doushantuo time, development of the metazoan in the late Sinian and 'Cambrian Explosion'. In addition, the TON and TOC vertical distribution characteristics may be asso ciated with the early life evolution.