Summary:
The Kainantu region is in the north-eastern flank of the northwest trending Papuan Mobile Belt which is a major foreland thrust belt. The regional structural package of the Kainantu district is bounded in the northeast by the northwest trending Ramu-Markham Fault, a major suture zone that marks the northern margin of the Australian craton, and in the southeast by the Aure Deformation Zone. The belt is characterized by several north-northeast trending fault zones that commonly host major ore deposits.
The dominant host rock of the Kora - Judd - Irumafimpa vein systems (Kora was previously termed Kora Consolidated and made up of Kora, Kora North and Eutompi in earlier documents) is the highly sheared and deformed Bena Bena Formation, composed of low grade metamorphosed phyllites and amphibolites, intruded by Elandora type dacitic intrusives, marginal to the vein system.
Mineralization on the property includes gold, silver and copper in epithermal gold-telluride veins (Irumafimpa), gold, copper and silver sulphide veins of Intrusion Related Gold Copper (‘IRGC’) affinity (Kora and Judd) and also, less explored porphyry copper-gold systems (Blue Lake), and alluvial gold. The Kora vein systems have been demonstrated from K92ML’s drilling and surface mapping results to be a continuous mineralized structure. This mineralized structure occurs in the centre of a large, mineralized complex approximately 5 km x 5 km, in which drilling has identified several individual zones of IRGC and porphyry style mineralization.
The Mineral Resources for Kora and Irumafimpa occupy a broad northwest trending mineralized zone more than 2.5 km long and approximately 60 to 80 m wide with down dip continuity of over 1,000 m. The Kora mineralized zone comprises a series of individual veins and stringer vein systems named from west to east, as K2, Kora Link and K1. The parallel Judd vein system, which is located 90 to 150 m east of Kora, also comprises multiple veins, from J1W and J1 in the west to J3 in the east, although the J1W and J3 veins are yet to be thoroughly defined by drilling. The total width across the Judd vein system from J1W to J3 is between 60 to 80m. All of the vein lodes are composed of quartz-sulphide veins that vary in width throughout the vein packages from < 1 m pinch and swell structures at Irumafimpa to veins up to 10 m wide at Kora.
At Kora and to the northwest along strike at Irumafimpa, two stages of mineralization have been recognized in the same northwest-trending sub-vertical structure. There is an early copper sulphide dominant stage of mostly chalcopyrite overprinted by a later, quartz, pyrite dominant stage of mineralization including high grade gold associated with tellurides. The tellurides at Kora are minor and do not hamper processing, the gold and copper mineralization is significant and generates a significant revenue for the mine. The Kora deposit currently comprises two parallel, steeply west dipping, north south striking quartz-sulphide vein systems, K1 and K2. An additional structure, the Kora Link, has also been defined and provides a possible link between the two main vein systems. Drilling has confirmed that the overall system has a vertical extent greater than 1,000 m.
The dominant host rock of the Kora - Irumafimpa vein systems is the highly sheared and deformed Bena Bena Formation, composed of low grade metamorphosed phyllites and amphibolites, intruded by the Elandora porphyry at the northwest end of the vein system. Mineralization on the property includes:
1. Au-Cu-Ag mineralization in low sulphidation epithermal Au-telluride veins (Irumafimpa),
2. Au-Cu-Ag quartz-sulphide veins of Intrusion Related Gold Copper (“IRGC”) affinity at Kora,
3. Indications of porphyry Cu / Au systems (Blue Lake) and
4. Alluvial gold.
The Kora - Irumafimpa mineral zone occurs in the centre of a large mineralized system, approximately 5 km x 5 km in area, that has been subject to drilling in parts and comprises several individual zones of vein and porphyry-style mineralization. The Kora - Irumafimpa (including Kora, Eutompi and Kora North) vein deposits has been demonstrated from drilling results and underground development to be part of the same structural system.
The Kora vein system is a broad northwest trending structurally controlled mineralized zone more than 2.5 km long and up to 60 m wide. Individual veins vary from less than one metre wide with pinch and swell features over short distances to more continuous veins up to several metres wide. The mineralization is characterised by auriferous quartz-pyrite (chalcopyrite) lodes. There are gold telluride lodes at Irumafimpa.
The Kora mineral zone, includes the old Kora and Kora North mineralization, and comprises a K1 footwall lode and a K2 hanging wall lode separated by varying widths of 0 to 15 m. In parts there is interstitial mineralization between K1 and K2 known as the Kora Link lode. About 90 to 150 m to the east lies the parallel Judd lode system. comprising from grid west to east the J1W lode followed by the main J1 lode and then the J2 and J3 lodes. The mineralization associated with the Judd lodes appears to be a structural vein system similar to the Kora zone.
Major vein systems, similar to Kora and Judd, are apparent at Arakompa and Maniape, mostly within EL693 but also extending into the northern part of EL470. Both Arakompa and Maniape were drilled with a small number of short holes in the late 1980s and early 1990s and historical internal company reports indicate coherent mineralization were identified.
Peripherally to Kora mineralization, exploration activities both historically and those done by K92ML have also, identified further areas of vein and porphyry-style mineralization. A substantially sized, gold/copper mineralized porphyry system has been delineated by K92ML at Blue Lake (Kotampa). The drilling, mostly at 200m spacing, demonstrated the presence of a prominent silica-clay lithocap, overlying mineralized propylitic (epidote-chlorite) altered porphyry of dacitic composition, with higher copper and gold grades hosted by potassic alteration intersected in a number of holes.
Other less advanced prospects on the property include evidence for epithermal Au veins similar to Irumafimpa, IRGC veins similar to Kora, porphyry Cu-Au systems, skarn Cu, Pb and Zn mineralization and alluvial gold.
The Kora-Irumafimpa vein systems host two stages of mineralization. The earliest phase consists of pyrite/chalcopyrite-rich veining, followed by a quartz-rich, gold-dominant crustiform quartz vein system with telluride-associated high-grade gold. The dominant Stage 3 mineralization is characterized by crustiform, vuggy, and colloform quartz veins, quartz breccias, and xenomorphic pyrite. Gold occurs primarily as tellurides (calaverite, kostivite) at Irumafimpa, whereas at Kora and Judd, gold is found as fine particles associated with pyrite margins and is free milling. Native gold is observed locally, likely from telluride oxidation at Irumafimpa or as primary gold at Kora and Judd.
The Judd vein system, located 90–150 m east of Kora, consists of four narrow, steeply dipping veins (J1W, J1, J2, J3). J1 is the dominant vein, showing similarities to Kora with auriferous quartz-pyrite-chalcopyrite veins and breccias. Drilling by Barrick intersected up to 3 m @ 278 g/t Au, confirming a mineralized strike length of 2.5 km. The J1 lode, a 4–5 m wide intrusion-related quartz-sulfide vein, has been extensively developed over five levels with over 2,265 m of underground workings. It has provided significant mill feed and demonstrated strong geological continuity. Since its maiden Mineral Resource estimate in 2022, underground diamond drilling has focused on extending the J1 vein and further exploring J2 and J3.