The thin section identification method,scanning electron microscope(SEM),energy dispersive spec-trometer(EDS),and CT tests,along with the examination of chemical elements and carbon and oxygen isotopes are utilized to analyze meticulously the petrology and geochemical characteristics of dolomite with varying sandifi-cation degrees along the route in Yuxi section of the Central Yunnan Water Diversion Project.The present paper concludes as follows:within diverse diagenetic environments encompassing recrystallization,cementation,dolomiti-zation,and dolomite dissolution,it is observed that the higher the degrees of sandification are,the more both pore development and void occurrence are.During the process of sandification,a distinct elemental migration is wit-nessed,characterized by the loss of calcium(Ca)and magnesium(Mg),alongside the enrichment of silicon(Si)and aluminum(Al).The characteristics of migration and evolution patterns of major elemental constituents exhibit a discernible correlation with the sandification process of dolomite.The content of ∑LREE,∑HREE,and ∑REE gradually decreased from severely to weakly sandy dolomite,indicating that dolomite experienced a certain degree of leaching loss during the sanding process;the concentration of rare earth elements decreases,and the degree of fractionation increases with the enhancement of sandification degrees.The average Marine-Terrestrial environmental indicator values(Z)value is 143.0‰,the average salinity(S)value is 30.0％,and the average temperature(T)of 35.5 ℃ are calculated out through the content of δ13CPDB and δ18OPDB in the carbon and oxy-gen isotopes.It proved that the formation of sandy dolomite is of marine origin without the impact of meteoric wa-ter in the research area,and both the environmental salinity and seawater temperature are higher during the for-mation of dolomite.The result has shown that the geochemical behaviors of major and trace elements during the process of dolomite sandification are well correlated.
关键词
滇中引水工程/砂化白云岩/岩石学/地球化学
Key words
Central Yunnan Water Diversion Project/sandy dolomite/petrology/geochemistry
维普
万方数据