Heavy mineral characteristics and provenance analysis of Chengzihe and Muling Formations in Dasanjiang basin group,East Heilongjiang Province

Although Dasanjing basin group is a residual basin at present,there existed a huge oil and gas potential in the uniform lake basin in Early Cretaceous,especially in the Chengzihe and Muling Formations,which now serve as important exploration strata.Based on mathematical statistics and Q type cluster analysis,the authors analyzed the heavy mineral ZTR indexes,stability coefficients and assemblage characteristics of the sandstones from Early Cretaceous Chengzihe and Muling Formations distributed in 20 drill holes in the main basins of Dasanjiang basin group,and then determined the direction of the provenance.The heavy mineral ZTR index contour maps of Chengzihe and Muling Formations are characterized by the gradually increasing trend from the edge towards the center,while their heavy mineral stability coefficients are relatively low,reflecting a lower heavy mineral stability at the early stage of the basin formation.According to the heavy mineral distribution,the study area can be divided into 6 heavy mineral assemblage zones.A comprehensive analysis shows that the provenance directions of Chengzihe and Muling Formations in Dasanjiang basin group did not change significantly,and both of the formations actually had an inheritance relationship.There mainly existed three provenance systems:the west and northwest provenance from Xiao Hinggan Mountain-Zhangguangcai Mountain,the east provenance mainly from Baoqing Block and Dongsanjiang uplift area and the southeast provenance mainly supplied by Xingkai Block.Nadanhada Block and Yanji fold belt provided source materials for northern Hulin Basin and southern Jixi Basin respectively,but the influence was limited.