The Doolgunna Project covers 1,100km2 and is located approximately 110km northeast of Meekatharra and some 10km southwest of Sandfire’s DeGrussa discovery. The project is considered prospective for volcanogenic massive sulphide (VMS) and stratabound base metals, and mesothermal stockwork gold.
Previous exploration activities completed by Enterprise over the Doolgunna Project have included; aeromagnetic/radiometric and VTEM surveys, extensive soil/rock chip sampling, geological mapping, induced polarisation surveys and aircore/RC drilling.
Exploration activities during 2012 have focussed on the Vulcan Prospect, (12km SW of the DeGrussa copper-gold deposit), where coarse visible gold was first identified in a shallow pit associated with an area of ferruginous laterite. The gold occurs within angular ferruginous fragments, some of which displayed “gossanous” textures, see Figures 2 & 3. (ENT:ASX Announcement 7 June 2012).
Follow-up costeaning was then completed aimed at providing sub-surface geological/ structural data and information regarding the character and setting of the visible gold. An estimated 500 tonnes of material was excavated from the costean and a total of 47 ounces of coarse gold recovered. This figure applies to the coarse “detectable“ gold portion only, and does not take into account the presence of any “fine” gold.
Six follow-up aircore holes adjacent to and beneath the costean were then undertaken returning the following results.
|DNAC069||3m @ 2.03 g/t Au from 1m|
|11m @ 0.58g/t Au from 92m|
|DNAC132||2m @ 1.26g/t Au from 16m|
|DNAC133||15m @ 2.03g/t Au from 35m|
|Incl.||7m @ 3.66g/t Au from 42m|
|14m @ 1.01g/t Au from 54m|
Infill soil sampling over Vulcan then defined a 1,500m long NE trending zone of copper, with anomalous gold. A strong base metal multi-element association comprising gold, silver, arsenic, lead, zinc, molybdenum, antimony and cadmium was also identified on the open, eastern margin of Vulcan, see Figure 4.
A rock chip sample with visible gold, located northeast of the Vulcan costean within the copper/gold soil anomaly, returned 810g/t Au, 0.1% Cu, 18.3g/t Ag, 1.0% Bi, 132ppm Mo and 2.7ppm Sb, supporting the base metal prospectivity of the area, see Figure 4. This gold/base metal association is similar to the VMS pathfinder elements reported from the DeGrussa deposit 13km to the NE. Both DeGrussa and Vulcan are hosted by the Narracoota Formation volcanics, adjacent to major regional faults.
An aircore drilling program in the area surrounding Vulcan, comprising 134 holes for 7,790m, with holes at 200m spacing along lines 1km apart, was then completed. The drilling was targeting a supergene copper-gold enrichment “blanket”, which may be developed below a “leached cap”, and above deeper primary sulphide copper-gold mineralisation within the Narracoota Formation volcanics. Anomalous gold results were returned from the drilling as shown below.
|DNAC050||8m @ 0.84g/t Au from 26m|
|DNAC066||2m @ 16.48g/t Au from 72m|
|Incl.||1m @ 30.60g/t Au from 73m|
|DNAC136||6m @ 4.85 g/t Au from 49m|
|Incl.||1m @ 19.00g/t Au from 49m|
A 260 hole aircore drilling program at the Vulcan prospect and surrounding area is planned testing previous gold intersections and multi-element geochemical anomalies. This program is designed to enhance Enterprise’s understanding of both the bedrock geology and the distribution of gold, copper and pathfinder elements in the regolith, with the ultimate aim of delineating VMS and gold mineralisation in the primary (fresh rock) zone.
A regional aircore drilling program comprising 250 holes for 10,000m along 12 traverses has also been designed, focussing on possible copper/gold mineralisation associated with the Southern Boundary Fault and Doolgunna Formation. The traverses will test a combination of geochemical and geophysical targets over a 60km strike length located southwest of Vulcan.