Organic matter types of the Early Paleogene from the Sanshui Basin and its response to paleoclimate

Organic matter types of the Early Paleogene core sediments from the Sanshui Basin were analyzed using organic petrology method. The organic matter is dominated by type II. The type I organic matter intermittently occurs at some intervals and type III organic matter only has occasional occurrence. Organic matter of types I, II1 and II2 should be deposited under arid, drier and humid climate condition, respectively. The uppermost part of the Xinzhuang Formation is characterized by type II1, related to a dry climatic condition. Sub-member A of the Honggang Member is dominated by organic Type II2, sandwiched by Type I and II1, reflecting a prevailing humid climatic condition. Sub-member B is characterized by alternations of types II2 and II1 or I, suggesting rapid fluctuations of humid and arid climatic condition. Sub-member C shows type II1 and I in the lower part and shifts to type II2 in middle and upper parts, suggesting a dry climate condition followed by a prevailing humid climatic condition.