Geochemical characteristics of carbonate source rocks of Taiyuan Formation in Southern North China Basin

CAO Gaoshe; LIU Huihui; XING Zhou; XU Guangming

Abstract：In order to clarify the essential features of the carbonate source rocks of Taiyuan Formation in Southern North China Basin and analyze the special background of the organic matter enrichment in these source rocks,through selecting the carbonate source rocks of Taiyuan Formation samples from full-coring coal boreholes in Luoyang area,Pingdingshan area and Yongcheng area at the edge of the Southern North China Basin,it was systematically analyzed and evaluated the samples,and it is revealed the organic matter enrichment background of these source rocks on the basis of the mineralogical analysis and the sedimentary environment analysis of the carbonate source rocks of Taiyuan Formation.The mean organic carbon contents are all greater than 1.00％ in Taiyuan Formation source rocks in different areas of the Southern North China Basin,however,the contents of the generating hydrocarbon potential and chloroform bitumen "A" is relatively smaller,the mean contents are smaller than 1.0 mg/g and 0.01％ separately.The main organic microstructure composition of kerogen in these source rocks is vitrinite,and it is generally more than 50％,while exinite is usually between 20％ and 50％.Inertinite is a little,and sapropelinite is rarely contained.The vitrinite reflectances (Ro) have large differences in different districts,and the mean values of Ro are respectively 4.57％,2.1％,1.14％ and 1.97％ in Luoyang area,Yuzhou area,Pingdingshan area and Yongcheng area.The carbonate source rocks of Taiyuan Formation in the Southern North China Basin not only have greatly different from common marine carbonate source rocks` features.The higher organic content of Taiyuan Formation limestone is mainly related with the large amounts of carbon dust,and the reason is related to the strong erosion to the underlying coal bed or carbonaceous mudstone by the limestone which was formed by sudden transgression.