New Copper-Gold Mineralisation Defined at Munarra Gully
Exploration Target: Multiple copper-gold bearing mafic (norite) intrusions.
- The style of mineralisation is likely magmatic and is atypical with respect to mineralised mafic intrusive systems due to high Cu:Ni ratios, high Au and Ag, low S and elevated PGM's.
- The style is similar to known large copper rich mafic intrusive (ortho-pyroxenite) historical deposits in Brazil (Caraiba mining district - 96Mt @1.82% Cu reserve and production) and South Africa (Okiep mining district - Koperberg - 94Mt @ 1.75% Cu historic production). Gold, silver and PGM's are associated with these copper deposits.
M51/122 - White Rose Prospect Background (New Cu-Au Discovery Aug 2018, see figure 1 in link below)
In August 2018 four (4) RC drill-holes returned significant copper-gold mineralisation from a fine to medium grain intrusive pyroxenite (norite) at the White Rose Prospect (ASX announcement - Significant Cu-Au Discovery at Munarra Gully - 30 Aug 2018). All four RC drill-holes intercepted significant copper-gold mineralisation over 160m of strike which is completely open (along strike and depth). See image 1 for significant intercepts. Results included:
o 22m @ 1.00% Cu from 29m coincident with 19m @ 2.19 g/t Au from 33m - WRRC001.
Air Core Drilling Completed December 2018 (see Figure 1 in link below)
During December 2018, five shallow air core drill traverses tested for potential strike extensions to significant copper-gold mineralisation discovered by RC drilling (refer ASX announcement 30 August 2018).
A total of 50 angled air core holes (blade refusal only) for 1099m were completed. The average drill hole depth was only 22m (15m vertical), as the programme was designed to highlight the copper - gold geochemistry in the upper weathered basement. The White Rose Prospect has undergone an extended period of alluvial gold mining. This historical work has disturbed the surface and therefore doesn't allow for traditional soil/lag sampling methods.
From composite sampling (4m and 2m composites), a 1000 ppm Cu (0.1% Cu) contour has outlined copper mineralisation in the surface/upper basement zones. The air core drilling has extended copper mineralisation some 300m to the northeast of the open cuts with anomalous gold (using 100ppb Au). Copper anomalism occurs over a width up to 80m. The trend is potentially open to the northeast as low order Au (50ppb contour) and elevated Cu (400ppm) were encountered with very shallow drilling. Immediately west of the open cuts at White Rose, a large north-northeast trending mafic dyke has intruded along a fault zone and the copper-gold mineralisation has been displaced some 200m to the north. Strong copper - gold mineralisation was encountered on the westernmost air core drill traverse over a width of 70m. Intercepts include:
- WRAC037 - 33m @ 0.17% Cu from surface (entire hole)
o includes Cu to 0.38% and Au to 0.74 g/t
- WRAC036 - 33m @ 0.15% Cu from surface (entire hole)
o includes Cu to 0.35% and Au to 0.21 g/t
The air core drilling intercepted highly weathered mafic and ultramafic intrusives under shallow hardpan (1 to 2 m depth). Discrete areas of strong silica alteration were encountered along with late dolerite to gabbro dykes. Copper anomalism with Au has been defined over a strike of 800m and is completely open to the west and is potentially open to the northeast.
New Target Type: A north trending magnetic anomaly was tested by (4) four air core holes on the eastern side of M51/122 (see figure 1). Highly weathered pyroxenite was intercepted in shallow drilling. Moderate nickel anomalism was encountered with elevated copper (Ni to 4008 ppm and Cu to 1061 ppm). No gold was associated with the pyroxenite.
Lag Sampling Completed December 2018 (see figure 2 in link below)
Infill and extension lag sampling (344 samples) complimented previous orientation lag sampling (107 samples) for a total of 451 samples and were collected on 200m by 50m and 200m by 100m spacings over a strongly magnetic northeast trending sequence of mafic volcanics with ultramafic and mafic intrusions. Four (4) significant, coherent copper anomalies have been highlighted, some with gold anomalism.
1. Copper A1 Anomaly - 600m strike, up to 400m wide with copper to 437 ppm
2. Copper A2 Anomaly - 500m strike with copper to 444 ppm
3. Copper A3 Anomaly - 2000m strike with copper to 620 ppm and gold to 35 ppb
4. Copper A4 Anomaly - 200m strike with copper to 916 ppm and gold to 19 ppb
The copper in lag anomalism occurs over a strike of 3.6 km and is open to the northeast under cover towards the White Rose Prospect. Note: Approximately 4km of potential strike is under cover between the copper in lag anomalism and the White Rose Cu - Au mineralisation. This is a target that will be tested with future aircore drilling, to test for strike at depth.
Significance of Air Core Drilling and Lag Sampling Results
Extending strong copper with gold anomalism geochemistry (800m strike) northeast and west from the White Rose Cu - Au mineralisation has significantly added size and scale potential to the Munarra Gully Project. The previous RC drilling at White Rose had defined significant copper-gold mineralisation within a 40 to 50m wide >1000 ppm Cu halo. The current air core drilling has highlighted >1000 ppm Cu over widths of 70m and 80m.
Lag sampling to the southwest of White Rose has generated copper anomalism to 916 ppm. Orientation sampling (pXRF) over the White Rose Prospect returned <100 ppm Cu. Hardpan and disturbed surface soils have masked the copper mineralisation. Copper in lag (soil) results >300 ppm (wet analysis) are considered very significant.
Airborne Magnetic Survey
Rumble has commenced an airborne magnetic survey over the main copper anomalous trend at Munarra Gully. Previous airborne magnetic surveys were completed on east west lines on 200m and 400m line spacing with a sensor height of 60m. The main mineralisation at White Rose is approximately east-west, sub-parallel to the flight lines. The proposed survey will have flight lines at 330deg (optimum to main magnetic units), line spacing at 100m and a sensor height at 45m. The survey will provide better resolution and definition to aid in identifying the main host unit for the copper-gold mineralisation, assist in understanding the structure and any future drill targeting.
Aircore and slimline RC drilling Drilling is planned in March 2018 to:
- Extend the 800m strike of known Cu-Au mineralisation at the White Rose prospect with air core drilling.
- Test the recently defined zones of copper-gold mineralisation with deeper RC drilling.
- Complete air core drilling traverses over the recently defined copper in soil targets.
- Complete air core drilling traverses over the approximate 4km of potential strike under cover between the copper in lag anomalism and the White Rose Cu - Au mineralisation.
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About Rumble Resources Ltd
Rumble Resources Limited (ASX:RTR) (FRA:20Z) is an Australian based exploration company, officially admitted to the ASX on the 1st July 2011. Rumble was established with the aim of adding significant value to its current gold and base metal assets and will continue to look at mineral acquisition opportunities both in Australia and abroad.
Rumble Resources Ltd