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

The purpose of this paper is to clarify the main diagenetic model of the Lower Paleozoic Ordovician dolomite in the central uplift of the Tarim Basin.Physical methods such as observation through the core and microscopic observation of the rock flakes,and geochemical characteristics analysis method for determination of elements such as trace elements and carbon and oxygen isotopes.Firstly,the main types of Ordovician dolomite in the central uplift of the Tarim Basin were classified,including Micritic structure dolomite?Gray patch structure gray matter dolomite or dolomite with gray matter?Crystalline dolomite with relic structure?Tectonic breccia dolomite.According to the diagenesis of dolomite and the sedimentary structural characteristics of the target layer in the study area,the diagenetic facies of these types of dolomite are obtained Quasi syngenetic dolomitization facies?Hidden permeable dolomitized facies?Active reflux dolomitization facies and Tectonic fracture facies.Finally,diagenetic facies of each type of dolomite are summarized,including Quasi syngenetic dolomitization facies:It is rich in Fe,Mn and other elements representing the surface environment;Hidden permeable dolomitized facies:Sr content is higher,but V,Fe and Mn content is lower;Active reflux dolomitization facies:Rich in Fe?Mn?Mo and U;Tectonic fracture facies:The rare earth element is very low,and the oxygen isotope composition value is significantly negative.