Abstract: The Dongwodong copper deposit, located in the east of the Duolong oreconcentrated district, is a newlydiscovered porphyry copper deposit in the BangonghuNujiang metallogenic belt in Gerze County, Tibet. Zircon UPb dating results show that the granodioriteporphyries intruded at (1210±12) Ma and the graniteporphyries intruded at (1215±10) Ma, which are similar to those of the orebearing porphyries from Duolong oreconcentrated area. These porphyries are systematically more enriched in largeion lithophile elements and LREE, relatively depleted in high strength elements and HREE, and have middle negative Eu anomalies, high Al and Sr, low Mg, Ti, Y and Yb, which are consistent with those of arctype magmas worldwide. These porphyries have similar ages and geochemical features to those of ore bearing porphyries from Duolong oreconcentrated area, suggesting that they were formed in a common magma chamber. The orebearing intrusions are characterized by high TZr ranging from 7796 to 8445 ℃. Additionally, they have varying εHf(t) values ranging from +34 to +111, T2DMC values ranging from 467 to 963 Ma. According to the obtained data, we proposed that the studied porphyries were generated by partial melting of juvenile crust under the background of BangonghuNujiang Tethys oceanic crust subducting northward to Qiangtang massif and the BangonghuNujiang oceanic basin was significant sizes during the Early Cretaceous. Besides, based on field geological surveys, we suggest that this deposit show typical porphyry copper deposit alteration characteristics. Its rock composition, mineralization and alteration, ages of diagenesis and mineralization, and tectonic environment and material source are consistent with those of the deposits in Duolong oreconcentrated area. Comprehensive analysis indicates that Dongwodong copper deposit shares a great potential to discover superlarge epithermalporphyry Cu (Au, Ag) concealed ore body.

Key words: BangonghuNujiang metallogenic belt, Dongwodong copper deposit, zircon UPb age dating, geochemistry, magmatic evolution, Tibet