Geochronology and geochemistry of granitoids of the Yanghuidongzi porphyry Cu deposit, Heilongjiang Province: Implications for petrogenesis and metallogenic setting during the Early Jurassic in the Northeast of China

Abstract

The Yanghuidongzi Cu deposit is a newly discovered porphyry Cu deposit in the eastern segment of the Central Asian Orogenic Belt. The Cu mineralization is associated with granodiorite porphyry and granodiorite. This paper presents new zircon U–Pb dating, Hf–O isotopes, whole‐rock major and trace elements data for this deposit, to constrain the ore‐forming age and the magma source of the granitoids. LA–ICP–MS U–Pb dating of zircons from granodiorite porphyry and granodiorite samples yielded ages of 192.8 ± 1.7 Ma, and 198.1 ± 1.4 Ma, respectively, which are interpreted as the emplacement ages of granitoids. These age data confirm that the granodiorite porphyry is associated with the porphyry Cu deposit, and both granitic intrusion and Cu mineralization were associated with the Early Jurassic magmatism in NE China. The granodiorite porphyry has high SiO2, Al2O3, and Sr contents together with low concentrations of Y and Yb. It is enriched in LILE, and depleted in HFSE, classified as adakitic. The granodiorite has high SiO2 and K2O, enriched in LILE, depleted in HFSE, and is classified as high‐K calk‐alkaline I‐type granite. The granodiorite porphyry and granodiorite have variable εHf(t) values (5.2 to 9.5), Mesoproterozoic two‐stage Hf models (TDM2) of 629–905 Ma, and δ18O values (4.26‰ to 7.50‰). These geochemical data and zircon Hf–O isotopes suggest that the granodiorite porphyry originated from the partial melting of thickened juvenile crustal materials and granodiorite derived from the partial melting of juvenile crustal materials with an additional of mantle‐derived magmas input. Combining our new data with the regional tectonic setting, the Yanghuidongzi Cu deposit and the related granitoids formed in a compressional tectonic setting associated with the subduction of the Paleo–Pacific Plate beneath the Eurasian continent.