Further Study of Transgression in Eastern Heilongjiang Basins in the Early Cretaceous: A Case Study of JD7 Well in Jixi Basin
黑龙江东部盆地群早白垩世早期海侵作用续探——以鸡西盆地鸡D7井为例

The Cretaceous basins in east Heilongjiang Province constitute a very important oil-producing region. In Early Cretaceous, lacustrine facies was the dominant facies, while different scales of transgression occurred at the same time. According to further study and comprehensive analysis of texture, structure, clastic constituents, comprehensive textual coefficient, cement and mineral arrangement of the Cretaceous sandstones, the double layers were found in Early Cretaceous strata, which constituted the typical structure in the subtidal zone. The main types of Cretaceous sandstones are debris-feldspar sandstones and feldspar-debris sandstones (quartz content ca. 25%), whereas cements are carbonate. Influenced by the transgression, the average value of comprehensive textual coefficient was 20.16 in Chengzihe period and 46.65 in Muling period, indicating that transgression influence was more obvious in Muling period. Moreover, more than 20 kinds of heavy minerals were found in Cretaceous sandstones, assuming banded enrichment. The characteristic minerals such as glauconite, authigenic monazite, framboid pyrite and native gold all show transgression characteristics. All of these characteristics provide abundant evidence for the transgression in the Cretaceous basins of east Heilongjiang Province.