Unca Creek Tenement
Introduction
KGL Exploration tenement EL28082, known as the Unca Creek (adjacent to the Jervois Project), nearly triples the size of the Jervois Copper Project area from 37.9 km² to 110.8 km². This tenement is located within the highly prospective Bonya Metamorphics, a sequence of metamorphic rocks known for hosting significant mineralisation. Unca Creek shares geological similarities with Jervois, particularly the northern strike extension of the sequence that hosts the Marshall-Reward deposits, which are a key component of KGL’s current resource base.
Figure 1. Geological map of Jervois and Unca Creek tenements showing prospects and mineral occurrence along the strike of J-fold and surrounding Unca Creek tenement.
Figure 2. Jervois Rang aeromagnetic.
Historical exploration by previous holders, including MIM, Normandy Poseidon, and NRE, demonstrated the tenement’s potential. Soil and rock chip sampling has confirmed continuous trends of copper mineralisation, with soil assays up to 2080 ppm and rock chip samples as high as 23% Cu. The tenement hosts multiple walk-up drill targets identified through geochemical sampling, reconnaissance mapping, and geophysical surveys.
Reconnaissance mapping has highlighted malachite occurrences and prospective host units extending north from the Boundary prospect, linking existing mineralisation at Jervois to new opportunities at Unca Creek. The integration of historical data with recent geophysical reprocessing has helped define clear exploration priorities.
Hamburger Hill: A Key Near-Surface Target
Hamburger Hill is a high-priority target located 2.9 km east of the Reward trend. This prospect features a sedimentary and volcanic host sequence that structurally resembles the Bellbird-Rockface area, suggesting it may represent a folded repetition of the Reward trend.
Hamburger Hill offers significant potential for near-surface oxide copper mineralisation in addition to deeper sulphide mineralisation. Historical wide-spaced (~200 m) RC and diamond drilling by Normandy intersected copper-lead-zinc mineralisation hosted in calcsilicate rocks, with notable results including:
- 7 m @ 1.28% Cu, 0.65% Pb, 0.34% Zn from 158.6 m (HHD-1A)
- 4.2 m @ 1.17% Cu from 115.8 m (HHD-3)
Reprocessing of SAM data by NRE has identified a significant Total Field Magnetometric Induced Polarisation (TFMMIP) anomaly. This central anomaly, over 1 km in length, is coincident with known mineralisation and indicates a northern extension that remains untested (Figure 3). The combination of near-surface oxide potential and robust geophysical anomalies positions Hamburger Hill as a standout exploration opportunity within the Unca Creek tenement.
Figure 3. Hamburger Hill SAM Induced Polarisation highlighting the high chargeability zones
Northern Prospects: Boundary, Becana, and Pioneer
The northern portion of EL28082 hosts a series of prospects along the Reward trend, extending from the Boundary prospect through Becana to Pioneer.
At the Boundary prospect, copper mineralisation is observed in outcrop and extends northward into the Unca Creek tenement. Soil and rock chip sampling have confirmed anomalous copper mineralisation, with soil values reaching up to 2080 ppm and rock chip assays up to 23% Cu. Aeromagnetic and IP data support a continuous mineralisation trend connecting Boundary to Becana and Pioneer.
Becana Prospect: Located 350 m north of Boundary, this prospect has yielded significant drill results, including:
- 9 m @ 2.3% Cu, 9.8 g/t Ag from 144 m (NRC011), including 2 m @ 8.1% Cu, 22.5 g/t Ag, 0.11 g/t Au.
- 2 m @ 1.2% Cu from 63 m (NRC013).
Pioneer Prospect: Situated 1.2 km north of Boundary, this prospect includes earlier results such as:
- 8 m @ 1.08% Cu from 198 m (J21, MIM).
- 8 m @ 1.5% Cu from 39 m (NRC001, NRE).
Geophysical reprocessing, including 3D inversions of IP chargeability and resistivity, has revealed a strong chargeability anomaly extending along this trend from Boundary through Becana to Pioneer (Figures 4 & 5). This anomaly highlights significant potential for expanding the known mineralisation.
Figure 4. 3D gravity inversion model over the northern Jervois prospects (Reward north and Boundary) and northern Unca Creek tenement (Becana and Pioneer).
KGL reprocessed an induced polarization (IP) survey originally conducted by MIM and performed 3D inversions of chargeability and resistivity. The analysis identified a significant chargeability anomaly extending from Boundary to Becana and further north to Pioneer. To enhance the resolution, additional 3D MIMDAS IP survey lines were incorporated in 2021, followed by the development of a refined 3D model (Figure 5).
Figure 5. Depth slice at 100m RL over northern prospects showing MIMDAS 3D_IP chargeability 2021.
Between the Reward trend and Hamburger Hill there is the Apex prospect within a tightly folded fold closure. Union Corporation mapped a malachite occurrence within folded calcsilicate units that coincides with a weaker parallel chargeability trend to the east of the main anomaly that is coincident with the Apex target where outcropping copper mineralisation has been observed. This prospect has no previous drilling.
Southern Prospects: Big J Trend
The southern portion of EL28082, below the J-shaped Jervois Range, remains underexplored but exhibits potential for tungsten-copper mineralisation along the “Big J trend.” This trend consists of four aligned tungsten-copper prospects hosted in sedimentary units, including calcsilicates and iron-rich sediments.
Recent 3D geological modelling by CSIRO suggests that this outer J-shaped trend may represent a folded repetition of the host sequence at Jervois, offering the potential for sulphide lenses. Although minimal historical exploration has been conducted in this area, it represents a promising frontier for future work.
Geophysical Advancements and Target Definition
A detailed gravity survey over the Unca Creek tenement has provided valuable insights into the subsurface geology. Gravity highs, indicative of magnetite- and garnet-altered rocks, correlate strongly with known mineralisation at Jervois, such as Marshall, Reward, and Rockface (Figure 6). These results have been integrated with existing drilling data, structural mapping, and geophysical surveys to define and refine drill targets across the tenement.
This combination of geochemical, geological, and geophysical data has significantly enhanced the understanding of EL28082, positioning it as a key area for future exploration.
Figure 6. Residual Bouguer gravity of the Jervois and Unca Creek tenements. Some of the most prospective prospects in Jervois and wider Unca creek tenement. Gravity highs(red/white) are often associated with iron rich units and gravity lows (blue/green) are often associated with the more felsic units.