Geochemistry of the Yangla volcanic rocks and its relationship to Cu mineralization in the Yangla copper deposit, western Yunnan, China

The Yangla copper deposit is a recently discovered, giant copper deposit with an estimated Cu reserve of about 1,200,000tons. Development is now underway. Previous studies have reported that the Yangla copper deposit is a VMS-type deposit related to the Yangla volcanic rocks. Volcanic bulk-rock analyses shows high contents of Si (49.3%–58.7%), Na2O (Na2O=3.3%–4.9%), MgO (MgO=3.7%–8.6%), and CaO(CaO=6.8%–9.0%), low TiO2 (TiO2=0.9%–2.1%) and K2O(K2O=0.2%–1.4%) contents. The geochemistry of the volcanic represent forearc basalts. Four molybdenites samples from the ore bodies in the deposit yield Re–Os model ages ranging from 229.7±3.3Ma to 233±3.4Ma. The REE distribution patterns and the primitive-mantle-normalized trace element patterns of the volcanic rocks are similar to the ores, indicating the Yangla copper deposit are closely associated with the Yangla volcanic rocks. The results contribute to our understanding of the genesis of the Yangla copper deposit and will guide further exploration in the region.