Studying elemental geochemistry of hypogene sulphides can discriminate the hydrothermal fluids responsible for ore formation. To determine whether Golpu porphyry Cu-Au deposits are related to the Nambonga North porphyry system which is located 2.5 km apart in the Wafi-Golpu Mineral District, Papua New Guinea, we compare the trace element compositions of drill core chalcopyrites and pyrites analysed using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS). The results for the Golpu chalcopyrites revealed high concentrations of Au, As, Se, Mo, Sb, Te and Bi and lower concentrations of Ag and Zn compared to those from Nambonga. Pd and Pt were below the detection limit in chalcopyrites for both deposits. The results for the Golpu pyrites indicated high concentrations of Pt, Au, Se, Mo, Sb, and Te and lower concentrations of Cu, Zn, As, Ag, Pb, Pd and Bi compared to those from Nambonga North. Au concentrations in the pyrites from both the porphyry deposits were higher compared to chalcopyrites, which mean that pyrite is the Au-bearing sulphide responsible for the higher Au content. In contrast, Cu values in pyrites from Nambonga North are higher than those from Golpu. Overall, it is envisaged that the ore fluids were exsolved at different times during the evolution of both porphyry deposits, although these porphyry centres may be related in space and time.

Papua New Guinea is one of the least studied regions in the Southwest Pacific, and large areas of the country, such as the Fly Plat-form, remain poorly understood due to limited exposure and access constraints. This study presents the first documentation of basaltic volcanism on the Fly Platform, based on new field discoveries at Mea-hill and Yemsigi, two areas located approximately 25 km apart. Inte-grated field observations, petrography, mineral chemistry, and whole-rock geochemistry show that both basalt suites were derived from a similar magma source but record contrasting emplacement histories. Meahill basalts, which include welded tuffs and highly ve-sicular basalt units, reflect rapid magma ascent, vigorous degassing, and locally explosive activity. In contrast, the massive, less vesicular porphyritic basalts at Yemsigi preserve a quieter emplacement history, but with more extensive post-magmatic alteration. Geochemical sig-natures from least altered rocks of both suites support an intraplate origin with similarities to Pliocene-Pleistocene lava fields of Northeast Queensland. The origin of the intra-plate basaltic magmatism is enig-matic, but both young volcanic provinces correlate spatially with a lower mantle anomaly that may represent residual slab material and a seated-seated magma source. These findings provide further insight into the tectono-magmatic evolution of the Fly Platform region and highlight the need for continued geological investigation in this underexplored district.

Papua New Guinea (PNG) remains one of the least studied regions in the Southwest Pacific, and the tectono-magmatic evolution of extensive areas such as the Fly Platform remains poorly constrained. This study presents the first investigation of basaltic volcanism on the Fly Platform based on the discovery of two previously unrecognized volcanic centres, Meahill and Yemsigi, located approximately 13 km apart along a northeast–southwest alignment. Integrated field observations and petrographic studies reveal contrasting eruptive and emplacement histories. Yemsigi is characterized by coherent porphyritic basalts, whereas Meahill comprises highly vesicular porphyritic to micro-porphyritic basalts indicative of explosive volcanism. Mineral chemistry and whole-rock geochemistry indicate that both basalt suites were derived from a common magma source. The K–Ar age of 0.57 ± 0.09 Ma for the Meahill basalts suggests that volcanism on the Fly Platform represents a late-stage magmatic event that post-dates the Maramuni Arc and Central Highlands magmatism on the PNG mainland. These findings provide the first evidence for Middle Pleistocene volcanism on the Fly Platform and place new constraints on the tectono-magmatic evolution of southern PNG.