Gold Mountain identifies porphyry system in PNG

Gold Mountain (ASX: GMN) has identified a new epithermal/porphyry system on its Mamba Creek target in Papua New Guinea.

A stream sediment and rock chip sampling programme was carried out successfully at Mamba Creek with epithermal type gold mineralization found and copper and Pathfinder element anomalies indicating a porphyry system.

Highlights

• Epithermal vein style mineralization found in a creek with gold workings and weakly mineralized probable outer porphyry zone intrusive rocks.
• A zonal pattern of copper, zinc and bismuth recognised, indicating a porphyry system is present.
• A magnetic high surrounded by a magnetic low is present suggesting a magnetite destructive zone is present which is also indicated by iron analyses.

Future Workplan

• Additional more detailed stream sediment sampling will be undertaken to close off the anomalies found so far at Mamba Creek.
• Ridge and spur soil sampling will be undertaken in the Cu/Zn ratio and bismuth anomaly area and follow up to find the mineralised epithermal vein float will be undertaken.
• Potential for both epithermal and porphyry mineralisation has been demonstrated and detailed geochemical sampling and mapping is required to focus on the centres of mineralisation.

The Wabag tenements lie within the highly productive Papuan Fold Belt which contains several world class porphyry copper deposits, several large, world class epithermal gold deposits and is grossly underexplored.

Regionally, deposits are mainly associated with Miocene to Pliocene intrusives of the Maramuni Intrusive Suite.

The Wale Intrusive Complex in the GMN tenements is part of the Maramuni intrusive suite and consists of a composite body ranging from gabbro to diorites and tonalites.

The Timun Conglomerate is a well-known gold bearing conglomerate, that contains gold nuggets which come from an epithermal source or sources.

The main rock types in the conglomerate include pyroxene gabbro, diorite and tonalite, rock types that are common in the Wale Batholith north of Crown Ridge where GMN recovered epithermal gold nuggets.

These are the same rock types mapped while sampling at Mamba Creek. At least two different intrusive bodies were interpreted to be present as well as basalts.

An epithermal gold bearing clast composed of massive magnetite – pyrite – chalcopyrite was found in the headwaters of Mamba Creek, part of the interpreted catchment of the gold bearing Timun Conglomerate that has produced some spectacular specimens of alluvial epithermal gold.

A magnetic high surrounded by a magnetic low was interpreted from helicopter airborne data acquired and reported on by GMN in 2017. High copper, Cu/Zn and bismuth (Bi) were found to lie in the magnetic low surrounding the magnetic high with iron analyses focussed on the magnetic high which is a common feature in porphyry systems.

This geophysical signature combined with the geochemical data is strongly suggestive of a porphyry and epithermal system being present.