THE STRATIGRAPHIC AGE AND RELATIONSHIP WITH MOLYBDENUM OF THE WUDAOLING FORMATION IN HEILONGJIANG PROVINCE

The Wudaoling Formation, which is closely related to mineralization, is a set of significant continental volcanic strata in Heilongjiang Province. Arguments have long existed about its geological age. Based on new isotopic data, with geochronological study on the granitoids that are closely associated with the Wudaoling Formation, as well as the geochemical comparison of the volcanic rocks and associated granites, this paper proposes a new recognition that the Wudaoling Formation can be defined from Late Triassic to Early Jurassic epoch. It is also identified that the molybdenum deposits in the area were formed closely related to the volcanic rocks of Wudaoling Formation and the Late Triassic-Early Jurassic granites in an approximately same geologic period. The Wudaoling volcanic formation was formed by earlier continental volcanic eruption, followed by multistage intrusion of granitoids, and then the molybdenum deposits were formed in the later stages of comagmatic evolution. The volcanic rocks of Wudaoling Formation and the Late Triassic-Early Jurassic granitoids are products of a single source at different evolution periods and depths. Therefore, there is a clear consistency in the space-time relationship, petrochemistry, trace elements, REE patterns and isotopic composition between them. The close space-time and genetic relationship between the Wudaoling Formation, the associated granitoids and the molybdenum deposits can be applied in the assessment for molybdenum metallogenic prospective areas.