Geochemistry, geochronology, and geological implications of the granitoids associated with the Dongfengshan gold deposit, Heilongjiang Province, NE China

Abstract

The Dongfengshan gold deposit in Heilongjiang Province of China is located at the western margin of the Jiamusi Massif. The mineralization is closely related to the intrusion of the Permian granite porphyry. In this paper, we present new zircon U–Pb ages and whole‐rock geochemical analyses of the granitoids from the Dongfengshan deposit. They are classified as peraluminous high‐K calc‐alkaline to shoshonitic A‐type granites, with enrichment in the large ion lithophile elements (e.g., Rb, U, and Th) and depletion in the high field strength elements (e.g., Nb, P, Ti, and Zr) and clear negative Eu anomalies. The zircons from the granite porphyry are both magmatic and hydrothermal, with the former yielding ages of 281.7 ± 3.3 and 282.1 ± 3.5 Ma that represent the timing of crystallization of this Early Permian pluton. The hydrothermal zircons yield an age of 280.5 ± 0.3 Ma, representing the hydrothermal age, which coincide with the emplacement of the igneous rocks. These data suggest that the Early Permian magmatic and mineralization event led to the formation of the Dongfengshan gold deposit. In comparison, zircons from the monzogranite yield a weighted age of 523.0 ± 6.4 Ma, indicating that magmatism of the study area occurred in the Early Cambrian. On the basis of the regional geological history and the new geochemical and isotopic data from intrusions, we suggest that diagenesis and mineralization of the Dongfengshan gold deposit took place in a postcollisional extensional tectonic setting during the Early Permian.