THE ANALYSIS OF MICROFACIES OF THE MANTOU FORMATION OF DABEIWANG SECTION IN XUZHOU

The Mantou Formation of Dabeiwang section, in Xuzhou,Jiangsu Province, is an ideal section for the study of the Early Cambrian carbonate rock because of the near perfect occurrence and fascinating sedimentary formation. In this paper, microfacies analysis is used, the microfacies characters of the carbonate rock, such as the biotic assemblage, grain composition, the type and texture of the matrix, have been deeply studied. According to types of grains, sedimentary structures and fossils, the carbonate rocks can be recognized as three types consisting of ten kinds of microfacies: grainstone(MF1 to MF5 microfacies), wackstone(MF6 to GM8 microfacies) and mudstone(MF9 and MF10microfacies). Each microfacies corresponds a designated sedimentary environment and its evolution. It is inferred from the microfacies division and microenvironmental analysis that the Early Cambrian strata were deposited in the lagoon, restricted platform,open platform and the organic sand at platform edge environments. A facies model has been constructed for the above-mentioned depositional environments. the late Early Cambrian, Mantou Formation inherited the characteristics of the Early Cambrian, transgression continued to expand.