The Late Sinian Dengying Formation at Xiejiadian in Suizhou

Hubei Province is dominated by deep-water carbonate deposits of slope basin facies.Dolomitas develoved well in study area

and are characterized by fine crystals

poor crystal forms

stable lateral distribution and well horizontal lamination.The isotope analysis of carbon and oxygen show that the salinity decreases with the increase of water depth

indicating that the dolomites were the products of penecontemporaneous dolomitization

the Mg

2+

was dervied from high salinity water in platform.According to above mentiioned

model of dolomitization has been established.