Ore-controlling factors and exploration indicators of alkaline magmatism related epithermal gold deposits: A case study of the Porgera gold deposit in Papua New Guinea

Epithermal gold deposits related to alkaline rocks possess a significant place in global metallogenic belts, especially in the Circum-Pacific metallogenic belt. Among them, the Porgera gold deposit located in the New Guinea orogenic belt is a typical deposit. The mineralization of the deposit is associated with alkaline Porgera intrusive complex and mostly occurs in the contact zone between the rock mass and the strata of Cretaceous Chim Formation. The ore-forming process can be divided into two stages, and the mineralization styles includes vein mineralization and breccia mineralization. The metallogenic materials and fluids of the deposit exhibit the characteristics of magma resources. The age of mineralization-related Porgera complex intrusion is 5.99Ma, which is consistent with the metallogenic epoch, and the magma of the intrusion originated from the metasomatic-enrichment type upper mantle. This kind of alkaline magma played an important role in gold concentration. The ore-controlling factors and indicators for the exploration of the deposits are summarized in this paper, which can provide guidance in search of similar deposits for China's mining enterprises.