Abstract:

Papua New Guinea (PNG), which is located at the convergence edge between the Pacific plate and the Indo-Australian plate, consists of three tectonic units. There are two main types of gold mineralization in PNG: epithermal and porphyry. National-scale geochemical mapping was conducted in PNG between 2015-2018, using 1399 stream sediment samples collected from the Highland Region, Papua Peninsula, and New Guinea Islands. In this preliminary study we analyzed the geochemical background, spatial distribution characteristics and metallogenic potential of gold in PNG. The gold concentration ranged between 0.2-6188.0 ng/g, with a median value of 1.5 ng/g, which is higher than the gold upper crustal aboundance, and slightly lower than the gold geochemical baselines of China and Australia. The Central Arc-Land Collision Zone—consisting of the Papuan Fold Belt, the New Guinea Thrust Belt, Finisterre Terrane, the Aure Fold Belt, the Eastern Fold Belt, the Eastern Papuan Composite Terrane, and the Finisterre Terrane, with widespread development of medium-acidic intrusive rocks, alkaline intrusive rocks, and alkaline volcanic rocks—has a higher median value of gold than the Melanesian Arc. The calc-alkaline intrusive complex of the New Guinea thrust belt, and the calc-alkaline intrusive complex and the potassium-rich volcano-intrusive complex of the Melanesian magmatic arc strongly correlate with higher gold concentration. Altogether seven gold geochemical provinces and nine gold anomalies with epithermal or porphyry mineralization potential are delineated.

Key words: national-scale geochemical mapping, gold, anomaly, epithermal, porphyry, Papua New Guinea