Results from a reconnaissance air core drilling campaign and data review have led Rumble Resources Ltd (ASX: RTR) to believe it has identified a large-scale copper-gold (with silver) mineralising system at the Munarra Gully Project in Western Australia.
Exploration work undertaken by Rumble has discovered copper, gold and cobalt mineralisation closely associated with a differentiated mafic sill horizon and a fine grain pyroxenite intrusion which are related to a regional structure (shear zone) that strikes over 34 km within the Munarra Gully Project.
Managing Director Shane Sikora added that recent research on historic drilling, located some 6km to the north of the White Rose prospect at Munarra Gully, has outlined widespread copper in basement mineralisation with significant gold over a strike of 7km with the system completely open.
“Rumble’s technical team developed a previously unrecognised exploration model for the region that identified the potential for significant mafic hosted Cu-Au deposits based on Rumbles exploration results at the White Rose Prospect (example 22m @ 1.00% Cu from 29m coincident with 19m @ 2.19 g/t Au from 33m),” Mr Sikora said.
“The White Rose Prospect mineralisation zone is up to 50m wide over a strike of 350m (faults have terminated strike continuity). Of importance, even with the significant sulphide intercept outlined above, the mineralised primary sulphide zone was not conductive when using ground and downhole TEM.
Using the newly developed regional exploration model, Rumble commenced regional exploration targeting for copper – gold bearing mafic sills that could potentially host a large-scale Cu-Au deposit(s).
“Detailed Open File review of historic exploration results has highlighted that the Amaryllis Cu-Au Prospect, which lies some 6km north of White Rose, is on the main regional structure associated with Cu-Au-Co mineralisation within the Munarra Gully Project. The historic exploration at the Amaryllis Cu-Au Prospect has shown previous explorers were focused on gold mineralisation rather than the copper potential, with limited copper assaying completed.
“Of note, the Amaryllis Cu-Au Prospect has the same style of mineralisation as the White Rose Prospect with true widths of over 50 metres (disseminated Cu with Au sulphide mineralisation), however, unlike the White Rose, which is constrained to a strike length of 350m, the large scale tonnage potential for multiple mafic hosted Cu-Au deposits at the Amaryllis Cu-Au Prospect is compelling with over 7km’s of Cu-Au strike identified and completely open.
“The Amaryllis Prospect has six historic diamond core drill holes that were designed to test for gold mineralisation and were only partially assayed for copper, however intersected significant widths of Cu-Au mineralisation including 74m @ 0.41% Cu, 0.29 g/t Au from 139m to EOH which included a higher-grade 5m @ 1.71% Cu, 0.82 g/t Au and 21.2 g/t Ag from 139m in mineralised primary sulphides (primary zone).
“Historic down-hole geophysical surveys were completed on four (4) of the diamond core drill holes in response to the level of sulphide intercepted, however, like the White Rose Prospect, the primary mineralised sulphides are not conductive.
Instead the results from the down hole survey indicate a flat lying conductor over 1km in strike (and open) at a depth of approximately 80m located above the significant widths of primary Cu-Au mineralisation.
Rumble has inferred the conductor may represent the secondary sulphide zone associated with supergene enrichment (supergene zone) above the mineralised primary sulphide zone outlined above.
“Of importance, typically the supergene zone is much higher grade than the underlying primary zone, and the historic diamond core drilling only intercepted the primary sulphide mineralisation while the potential higher-grade supergene zone remains to be drill tested. Rumble is now fast tracking the approvals to drill test the exciting supergene zone over the coming weeks.”