Zircon LA-ICP-MS U-Pb Ages and the Hf Isotopic Composition of the Ore-Bearing Porphyry from the Yanghuidongzi Copper Deposit, Heilongjiang, China, and Its Geological Significance

Abstract

The Yanghuidongzi copper deposit is a typical porphyry copper deposit located at the eastern margin of the Xing’anling-Mongolian Orogenic Belt (XMOB). While much attention have been paid to the ore-forming age of the deposit and the magma source of the ore-bearing porphyry, this paper approaches this issue with the methods of the LA-ICP-MS zircon U-Pb dating and Lu-Hf isotopic composition of the Yanghuidongzi porphyry copper deposit. The results reveal that the Yanghuidongzi porphyry copper deposit was formed in the Early Jurassic (189.6 ± 1.0 Ma), which corresponds to the time of magmatic activity in this region. The background studies of ore-forming dynamics indicate that the formation of the Yanghuidongzi copper deposit is related to the subduction of the Paleo-Pacific plate. The Yanghuidongzi ore-bearing porphyry zircons have a positive εHf(t) value (4.4–7.0), a high 176Hf/177Hf ratio (0.282786–0.282854), and a two-stage Hf model ages (TDM2) ranging from 783 Ma to 943 Ma, all of which suggest that the Early Jurassic granodiorite porphyry of the Yanghuidongzi deposit was formed by the partial melting of newly grown crustal material from the depleted mantle in the Neoproterozoic.