Geochemistry Characteristic and Origin of Paleogene Dolomite in Kuqa Depression, Tarim Basin

Key words: 
• Kuqa depression

Abstract: In order to analyze the dolomite origin of Paleogene dolomite(Kumugeliemu group)in Kuqa depression, this article take the thin slice to dye, trace element and stable isotope test as method, and system atically analyzed this set of dolomite geochemistry characteristic and their origin. The research indicated that the dolomite mainly divide into the creaming dolomite and micrite (powder crystal) dolomite. The trace element and the isotope characteristic of dolomite indicated that it forms in highsalinity, high Mg/Ca ratio, and the strong reducing water environment. The discontinuity ingression in Kuqa depression western area in early stage of Tertiary Period and the intense evaporation environment causes the water body salinity to be high, and the water has provided the magnesium ion for dolomite's formation in penecontemporaneous time. Combine the deposition and lithic facies characteristic of dolomite, we think the dolomite have two kinds of genetic types: the evaporation dolomitization and reflux dolomitization, creaming dolomite that stem from the evaporation dolomitization mainly distributes in supratidal flat(that is lowenergy environment), creaming micrite (powder crystal) dolomite or creaming dolarenite that stem from the reflux dolomitization distributes in subtidalthe lagoon (that is moderatelow energy environment).