Study On The Types And Contributing Factors Of Microbialite From Mantou Formation In Dabeiwang

The development of Cambrian system in Xuzhou region was very complete.Hereinto,Mantou Formation represents the geological characters of south east formation in the North China plate.Based on a lot research of Mantou Formation profile in Xuzhou Dabeiwang area,it is concluded that the integral development of Cambrian system in Xuzhou region was developed from the sedimentary environment of platform-lagoon-tidal flat in the shoals of shallow water.According to the combination of different sedimentary facies symbols and rock symbols,fourteen macroscopical lithofacies have been divided and its microcosmic characters also are described.The analysis of the macroscopic morphological characters,microscopic cortex characters,microbial fossils and their calcification,and the formation and controlling factors of microbialites such as oncoids and thrombolites can provide evidences for the study on the spatial distribution and evolution of Cambrian microbial carbonates.Different types of microbial imprints on ooids from oolitie limestones are distinguishedand studied in this paper.And the study has obtained a Preliminary understanding on the roleof microbes during the formation of ooids.Microbial metabolism can change the physical-chemical conditions of microenvironments,which promote carbonate precipitation on ooidssurface andform various types ofconstructive deposition,also microbial activitiescan destroy the original structures of ooids by microboring and microbial micritization.