LAUSR

Abstract Heihuashan is a newly discovered porphyry Cu-Mo prospect in Heilongjiang Province, northeastern China, with considerable Cu and Mo mineralization. Until now the ages of the Cu-Mo ores and the causative granite porphyry, the magma origin and characteristics, as well as the mineralization potential at depth are still unclear. In this contribution, whole rock geochemical and Sr-Nd isotopic compositions, zircon U-Pb ages and Hf isotopes, and molybdenite Re-Os dating, are presented to constrain the timing of the magmatism and mineralization, and the petrogenesis of the causative intrusion. The results also provide an opportunity for evaluating the potential of the deep Cu-Mo mineralization. Zircon U-Pb dating using LA-ICP-MS yields a crystallization age of 146.4 ± 1.8 Ma for the Heihuashan granite porphyry, which is consistent with the molybdenite Re-Os isochron age of 143.7 ± 3.1 Ma. These results indicate that the porphyry Cu-Mo mineralization at Heihuashan occurred at late Jurassic to early Cretaceous. The whole rock geochemical data suggest that the ore-related intrusion is mildly peraluminous and belongs to the high-K calc-alkaline series, I-type granitoids. The granite porphyry samples are enriched in Rb, Ba, Th, U, and Sr, but depleted in Nb and Ta, showing typical arc magma affinities. They also have initial 87Sr/86Sr ratios of 0.70546–0.70550 and eNd(t) values between +0.4 and +0.7. The zircon eHf(t) values for the granitic intrusion range from +3.5 to +9.2, with two-stage Hf model ages of 977–614 Ma. The geochemical and Sr-Nd-Hf isotopic compositions suggest that the parental magma was dominantly derived from the slab-metasomatized mantle, which could have mixed with some lower crust components. The Fe2O3/FeO ratios of the Heihuashan granite porphyry are relatively high, ranging from 0.52 to 1.17, indicating a high magmatic oxidation state. This is also supported by the high zircon Ce/Ce*, Eu/Eu* and Ce/Nd ratios (33–2433, 0.22–0.70 and 2.4–44.0, respectively) and the high magmatic ΔFMQ values (+0.1 to +3.5 with an average of +2.1) calculated using the zircon trace elements. The intrusion has relatively high Sr/Y ratios (40–94) and displays negligible Eu anomalies (Eu/Eu* = 0.68–1.07); the zircons from the intrusion have high (Eu/Eu*)/Y (mostly > 0.0001) and (Ce/Nd)/Y ratios (mostly > 0.01), but low Dy/Yb ratios (generally