Cathodoluminescence characteristics and dolomitization of Qrdovician Majiagou Formation in Jingbian Gasfield,Ordos Basin

By studying the cathodoluminescence and geochemical characteristics of Ordovician Majiagou formation dolomite,it is found that there is a positive correlation between the cathodoluminescence intensity of the dolomite and Mn/Fe ratio and the dolomite is of low content Na,Mn and Sr and high content of Fe as a whole.Micrite dolomite is characterized by low order degree of 0.67 in average, high content of Na(302.3×10~(-6)),δ~(13)C of 0.6‰~ - 1.58‰(PDB)(-1.5‰in average),which indicates that the micrite dolomite is penecontemporaneous dolomitization.Fine crystal dolomite is characterized by the average order degree of 0.71,δ~(13)C average value of - 1.55‰and higher content of Mn than the micrite dolomite,which indicates the great effect of leaching and burial diagenesis. Medium-coarse dolomite has a relative high average degree order of 0.84,anomaly high Fe content of 11 617.2×10~(-6) and relative low values of δ~(13)C andδ~(18)0,which indicates the medium-coarse dolomite is formed in the burial diagenesis.