PRELIMINARY STUDY OF GEOCHEMICAL CHARACTERISTICS AND FORMATION-OF ORGANIC MATTER RICH STRATIGRAPHY OF XIAMALING-FORMATION OF LATER PROTEROZOIC IN NORTH CHINA
华北新元古界下马岭组富有机质层段的地球化学特征及成因初探

Xiamaling Formation of Qingbaikou System of later Proterozoic in North China is relatively more abundant in organic matter in marine sedimentary stratigraphies from Proterozoic to later Paleozoic in North China area. The content of organic matter is beyond 16% at most. The analyzing result of main elements, trace elements and organic matter content of Xiamaling Formation shows that the content of SiO_2 is apparently higher in organic matter rich mud rock than organic poor mud rock, the content of SiO_2 has a positive correlation with TOC content, and has a negative correlation with TiO_2 content (indicator of land matter input). The ratio of Si/(Si Al Fe) has a positive correlation with TOC content, too. In organic matter rich stratigraphy, there is apparently higher element content of P, Cu, Zn, Co, Ni, V which are related to thermal fluid activity in ocean floor, and the ratio of Ba/Sr is far more than 1. These characteristics indicate that during the organic matter rich stratigraphy of Xiamaling Formation was depositing, there is thermal fluid activity in ocean floor at the same time. The activity of thermal fluid can provide organism a lot of nutrition, such as N, P, K, SiO_2 and so on, it also can provide much energy for organism to grow. As a result, it leads to apparently better accumulation of organic matter in depositional stratigraphy of thermal fluid active area in ocean floor.