Sedimentary Environment and Geochemical Characteristics of Source Rocks from Later Carboniferous and Middle Permian in Santanghu Basin, NW China

Abstract

There is a long-term controversy on sedimentary environment of Late Carboniferous-Permian in Santanghu Basin. In this paper, we study on the geochemical characteristics of source rocks from Harjiawu Formation of Upper Carboniferous and Lucaogou Formation of Middle Permian in Santanghu Basin. The results show that the abundance and maturity of organic matter of source rocks in Harjiawu Formation are both high, which shows excellent source rocks. In contrast, the abundance of organic matter from source rocks in Lucaogou Formation is relatively low and the maturity of organic matter is between immature and mature, which suggests good-excellent source rocks. The organic geochemical characteristics indicate the freshwater lacustrine environment of Late Carboniferous, while Lucaogou Formation is the high salinity lacustrine environment. In addition, magmatic-hydrothermal activity may result in the water salinization of Permian.