Research On Dolomite Diagenesis Of Cambrian Formation In Central Uplift Belt,Tarim Basin

The study area of this paper is the Centre Uplift Belt of Tarim basin and the target horizon is Cambrain of Lower Paleozoic.Based on the combination of core observation and microscopic slice identification and previous research results,the paper considered that the sedimentary facies types in the study area are evaporation platform,restricted platform,open platform,platform margin,slope and basin six types of sedimentary facies.Combined with field investigation,core description,microscopic study and samples' examining analyses of study area,rock types are identified as four major categories which are residul-grained dolomite,Mud crystal dolomite,siliceous rock and evaporite.Microscopic petrography was used to select typical samples for geochemical dolomite experiments which included general and trace elements,carbon and oxygen stable isotopes,and full-rock X-ray diffraction experiments to determine various characteristics of lithofacies.Through the above research combined with the dolomite diagenetic environment and diagenetic type,the study shows three main diagenesis that are dolomitization,burial recrystallization and dissolution.According to diagenetic environment and diagenesis,there are three main types of diagenetic facies of dolomite which are penecontemporaneous dolomitization,active reflux dolomitization and weathering crust karst.In the end,according to the diagenesis of dolomite and the results of diagenetic facies,the diagenetic facies model of dolomite is determined into three categories in the study area: penecontemporaneous dolomitization,active reflux dolomitization and weathering crust karst.