STRATIGRAPHIC CLASSIFICATION OF THE WUDANG GROUP AND ITS AGE ASSIGNMENT

The Wudang Group is widespread and up to more than ten thousand metres in thickness, and is represented by an acid volcanic-clastie sedimentary rock series. It exhibits the obvious character of polyphase deformation, and its metamorphic grade reaches greenschist facies. According to the volcanic cycles and sedimentary rhythms, a stratigraphie sequence has been established. The group may be divided in ascending order into the Yaoping Formation, Yangping Formation and Shuangtai Formation and may be further divided into 12 subformations. In the light of the age of the overlying strata andunconformable relationship as well as the acritareh assemblage contained in the Wudang Group and isotopic geochronological data, the age of its formation has been determined to range between 1400 and 1044 Ma, being equivalent to middle Proterozoic, so the group may be assigned to the Jixian System.