Genetic Mineralogy Research Of Dolomite And Calcite In Xingshutai Mining Area, Hebei Province

Xingshutai mine is located in Zanhuang ridge south of the new mining area exposed Archean zanhuang group Shijialan group. Mining metamorphic rocks were generally NW-SE extension tendency NE, moderate inclination. Through field investigation, study light thin section, major elements, trace elements, rare earth elements, carbon and oxygen isotope, fluid inclusion analyzes the forming fluid characteristics Xingshutai mining dolomite, genesis and mineralization mechanism.Field geological prospecting and laboratory testing research, understanding main achievements are:Dolomite mineralization of pre-magmatic hydrothermal, while the same period dolomite mineralization and mineralization period after the product is derived from the meteoric water and mixing zone recrystallization of carbonate rocks. Dolomite mineralization After mineralization of the same period and has a weak negative Eu anomaly, indicating that it is formed in the relatively open and oxidizing environment. The La / Yb ratio hydrothermal dolomite often less than 100. The mining dolomite La / Yb ratio of less than 100, indicating that this mine belongs to hydrothermal dolomite.Through this area chalcopyrite sample Rb-Sr dating that Xingshutai formed copper era 1844 Ma, belonging to the Proterozoic, and mainly from the lower crust as minerals, a small amount of mantle material is added; Xingshuai mining dolomite types of fluid inclusions in two main types: liquid two-phase liquid-rich inclusions(V-L-type) and liquid fluid inclusions(L-type). Test results show that the temperature of fluid inclusions range from 154.2 ℃ ~ 439.8 ℃, the average temperature is 271.56 ℃, belong to the medium and high temperature region; Changes in salinity range 4.03%- 23.18%, belongs to the middle and high salinity; density in the range of 0.7326 ~ 1.001 g / cm3, belongs to the medium and low density; metallogenic pressure range of 91.264 ~ 262.008 MPa, belong to the high-pressure region; a mining depth in the range of 3.446 ~ 9.892 km, are deep into the depth of mineralization. By trace elements Xingshutai dolomite mining, rare earth elements, C, O isotopes homogenization temperature and salinity of fluid inclusions, etc. show as medium and high temperature、Medium and high salinity、Magmatic hydrothermal genesis, the Medium and low density and high pressure is generated in the plutonic environment. Mine wall rock alteration evident, carbonation and copper relationship is remarkable. In summary, Xingshuai copper mine belonging to the Proterozoic high temperature magmatic hydrothermal deposits, and Xingshutai pyrite(Archean) does not belong to the same era.