CHRONOSTRATIGRAPHIC DIVISION OF THE EARLY CRETACEOUS JIUFENGSHAN FORMATION IN HEIBAOSHAN-HANDAQI BASIN, HEILONGJIANG PROVINCE

The biostratigraphic characteristics of Jiufengshan Formation in Heibaoshan-Handaqi Basin of Heilongjiang Province are systematically summarized and compared to determine the climatic environment and age of its formation. The plants and their sporopollen fossils reflect the typical subtropical humid climate and age of Early Cretaceous. The diagenetic age of 119±0.89 Ma is obtained by the LA-ICP-MS zircon U-Pb isotopic dating of rhyolitic tuff in the lower part of Jiufengshan Formation. Combined with the paleontology and isotopic age, it is determined that Jiufengshan Formation was formed in the middle-late Aptian of Early Cretaceous, which provides accurate chronological basis for the correlation of Late Mesozoic regional strata, coal-forming ages and coal-bearing basins in Northeast China.