Chronological and Geological Significance of Narigongma Plagiogranite Porphyry in the North Part of the Sanjiang Region

Located in the north part of the Sanjiang Region and composed of 6 small porphyry bodies, Narigongma porphyry belongs to high-K calc-alkaline series in petrochemistry. The REE diagram shows that the rock is enriched in LREE with rarely negative Eu anomaly. Zircon U-Pb dating method has determined for the first time that the diagenetic age of Narigongma plagioclase porphyry is about 41.0 0.18Ma in the Early Himalayan epoch. From the view of regional tectonic evolution, the formation of most granite ore bodies in the north part of the Sanjiang Region are closely related to the magmatic emplacement of Himalayan orogeny, as most of the isotopic ages concentrate in 21-66 Ma. Because Narigongma Cu-Mo deposit occurred in porphyry bodies, the granite porphyry has provided mineral sources for the deposit mineralization. Meanwhile, due to abundant occurrence of intermediate-acid magmatic bodies in the north part of the Sanjiang Region, the diagenetic age determination of Narigongma porphyry Cu-Mo deposit is of great theoretical and practical importance in porphyry Cu-Mo deposit prospecting.