Lithic Facies And Geochemical Characteristics Of Cambrian Dolomite In The Bachu Uplift Belt,Tarim Basin

In this paper,the Cambrian dolomite in the Bachu uplift in the Tarim Basin is the research target.According to data analysis such as core observation,microscopic slice identification,and logging curves,the main type of sedimentary facies developed in the study area is the platform facies.Based on the mineral composition,rock characteristics,and sedimentary and diagenetic environment characteristics of the dolomite,15 types of dolomite lithofacies are identified and further classified into 10 categories: microbial dolomite facies,quasi-homogeneous cloudification facies,and latent permeability cloudification Diagenetic facies.Through geochemical analysis of typical dolomite samples,it was found that the active reflowed cloud diagenetic facies showed more Mg elements,and the contents of the three minor major elements of Fe,Al,and K in the dolomite showed a significant positive correlation.Due to the control of the relative content of Fe and Mn,the cathode luminescence intensity of dolomite is generally weak.The content of Sr is highest in the paste-bearing or gypsum-dolomite,while the content of Sr in the active reflux cloudification phase and karst breccia phase is obviously low.The quasi-syngenetic micrite dolomite has a high Th/U ratio due to some argillaceous in the deposition process.The diagenesis of the dolomite in the study area is determined as follows: dolomization,dissolution,recrystallization and cementation.On this basis,based on the results of dolomite lithofacies,diagenesis and diagenetic facies,10 models of dolomite diagenetic facies in the study area were established,and the distribution regularity map of dolomite diagenetic facies in four intervals was determined.