Tracing the ore forming process of Dahenglu copper-cobalt deposit with the rare earth elements and isotopic compositions of tourmaline and calcite
The Dahenglu copper-cobalt mine is classified as a large cobalt deposit in China,which has experienced complex sedimentary-metamorphic effects and has long been considered a typical sedimentary-metamorphic deposit.However,the late-stage hydrothermal mineralization may have been underestimated.In this study,we proved that the magmatic-hydrothermal fluid was involved in the mineralization process through detailed petrographic-mineralogical observations,in addition to metamorphic fluids mineralization.In-situ calcite strontium isotope,tourmaline boron isotope was analyzed.Boron isotope varies from the vein(ca.-4‰)to the matrix(ca.-14‰).Strontium isotope does not show differences between tourmaline and calcite,with the average of 1.0896 and 1.0948,respectively.Both of which are slightly lower than that of whole rock.Although it is impossible to quantitatively estimate the contribution of magmatic-hydrothermal fluids to mineralization currently,this study shows that the hydrothermal fluid driven by the magmatic heat promotes the oxidation,activation,and migration of cobalt by in-situ calcite strontium isotope,tourmaline boron isotope,and trace elements techniques.Then the fluid was reduced and precipitated in the calcite-quartz veins,which was the most important way of mineralization during the magmatic hydrothermal ore-forming stage.However,the magmatic-hydrothermal fluid did not contribute significantly to mineralization in the aspect of cobalt source,and no evidence of marine evaporites participating in mineralization was found in this study.Therefore,the trace element and isotopic compositions of calcite and tourmaline are important indicator minerals for the reconstruction of hydrothermal mineralization.
Ore forming processBoron isotopeStrontium isotopeTourmalineCalciteRare earth elements
万方数据
维普
