Skarn geochemistry of the Huangshaping W-Mo polymetallic deposit in Hunan and its geological significance

Abstract：The Hangshaping large-size W-Mo polymetallic ore deposit lies in the Nanling metallogenic belt. The authros chose the skarn as well as wall rocks（limestone and marble）and ?granite porphyry related to the skarn to conduct component analysis. The result shows that the major elements (Fe, Al, Mg and Si) migrated between the granite porphyry and the skarn, and the content of SiO2 shows linear descending relationship with the content of MgO, MnO, CaO and Fe2O3+FeO in the skarn. The skarn is enriched in LREE and depleted in HREE, with obvious Eu negative anomalies. The granite porphyry has the same REE distribution patterns as the skarn. The precise Re-Os dating of the molybdenite from skarn-type ore yielded an ore-forming age of 158.4±1.3 Ma. which is the same as the age of the granite porphyry, suggesting their relationship in petrogenesis. The poorly-developed Ce anomalies in skarn rocks imply that the fluids for the formation of skarn were mainly derived from the magma and mixed with meteoric water. Combined with the geochemical characteristics of different rocks, intense differentiation of LREE and HREE and Eu negative anomalies, the authors infer that the skarn in the Huangshaping ore deposit was formed by fluid metasomatism.