The 810km2 Dexter Gold Project is located 140km south-southeast of Laverton in the southern part of the Burtville and Yamarna Terranes, 80km northwest of the Tropicana gold deposit. The Project straddles the intersection of the Yamarna and Dexter Shear Zones and includes 45km of the Yamarna Shear Zone and 90km of the Dexter Shear Zone. Thin aeolian sand and transported weathered Permian sediment overly the prospective Archean basement rocks.
Historically, partial-coverage soil geochemistry encountered anomalous gold-in-soil values up to 32ppb gold within E38/2695 in the northern part of the Project close to a prominent bend in the Yamarna Shear in the vicinity of a “syntectonic” domal granite that is interpreted to be mantled by previously unexplored greenstone. Follow-up drilling was not undertaken and the anomalous soil values are potentially significant as they are in sand, are open to the south and are comparable in magnitude to those encountered in early stage exploration at recent discoveries in the region. Transported cover is thin in the northern Project area (2m to 40m), and moderate to thick recent sediment in the central and southern areas (80m to 129m).
The Dexter Project is highly prospective due to a favourable structural setting, anomalous soils, multiple targets identified from new aeromagnetic data and the proximity to known mineralisation. Other exploration targets include the intersection of the Dexter Shear with the Sefton Lineament and the presence of long strike lengths of previously undrilled greenstone interpreted along the Dexter Shear. The intersection of these structures with numerous cross structures are also considered high value target areas for localising gold.
The Dexter Gold Project is Breaker’s main focus due to the size and magnitude of the gold-in-soil anomaly which to the Company’s knowledge has not been documented in similar areas of transported cover in Western Australia. Activities at Dexter have included reconnaissance and infill multi-element auger drilling, aircore drilling and RC drilling, together with interpretation of aeromagnetic data, environmental rehabilitation, rock chip and soil sampling.
The reconnaissance (1,600m x 400m) auger drilling identified a previously unknown gold trend with peak soil values up to 50ppb gold in several coherent anomalies over a 25km-long strike length with associated pathfinder gold elements including mercury, copper, zinc and silver. The strike length of the anomaly was subsequently increased to 32km following extension of the auger sampling to the north into the newly granted E38/2695, whilst remaining open to the south.
An infill (400m x 100m) auger program, targeting the northern half of the 32km-long soil anomaly, defined two priority prospects, each with different and distinct auriferous elements signatures consistent with an Archean bedrock source. The Three Bears Prospect, situated adjacent to the Dexter Shear Zone, comprises three anomalies up to 6km long in total with peak values of 298ppb gold and 17,415ppb silver. The Tallows Prospect, situated adjacent to the Yamarna Shear Zone, comprises a 14km-long anomaly with peak values of 130ppb gold.
In June/July 2013, reconnaissance auger drilling (1,600m x 400m) was extended to the south on the Dexter Shear Zone for a distance of 35km, and to as yet unsampled parts of E38/2695 to the north. In September 2013, this survey was successful in identifying a cohesive, 12km-long gold-in-soil anomaly of regional significance, designated the Sandshoes Prospect. The anomaly is in sand cover approximately 20km southwest of the Three Bears Prospect with peak gold values of 35ppb. The Sandshoes anomaly is situated near the intersection of the Sefton Lineament and a greenstone/granite contact near the western component of the Dexter Shear Zone. Significantly, the gold-in-soil anomaly appears to leak downslope from a granite/greenstone contact apparent in the aeromagnetic data over a 12km strike length, similar in some respects to the Three Bears Prospect.
Multi-element soil sampling was undertaken at the Dexter West area in March/April 2014 (E39/1745 and E39/1786) on a sample spacing of 400m on 1,600m-3,200m spaced lines, together with limited rock chip sampling. The assay results identified a significant anomaly measuring approximately 5km x 2km at >9ppb gold, with a maximum value of 31.7ppb. The anomaly overlies a discrete, high-amplitude, magnetic feature targeted by the soil sampling. The bedrock in the vicinity of the anomaly is estimated to lie beneath 20-30m of Permian cover.
A soil and rock chip sampling program was completed in the northern part of the Dexter Project (E38/2934) in July/August 2014, to investigate encouraging aircore drill results from the southeastern area of the Attila West Project.
A 23,073m aircore drill program, comprising 8,626m at the Three Bears Prospect and 14,447m at the Tallows Prospect, was completed in March 2013 with the objective of scoping the prospects’ anomalies in preparation for RC drilling. The drilling was conducted on a line spacing of 400m to 1,200m and a vertical drill hole spacing of 80m, closing to 40m in selected areas. Permian cover varied from 25m to 75m in thickness with approximately 65% of the drill holes reaching definitive bedrock. Penetration of fresh Archean bedrock was limited (generally <1m) and bottom-of-hole samples assaying up to 0.9g/t gold typically included some weathered material.
The aircore program identified two discrete zones of secondary (redox) gold enrichment in the weathered zone at the Three Bears and Tallows Prospects with a peak grade of 3m at 7.5g/t gold developed at a depth of 30m to 70m. These areas of redox gold enrichment occur in discrete areas within a larger coherent “channel” of gold-in-soil enrichment adjacent to the Dexter and Yamarna Shear Zones, suggesting restricted (Archean) bedrock sources consistent with recent research models. Bottom-of-hole bedrock geochemistry indicates anomalous levels of gold pathfinder elements including arsenic, tungsten, selenium and tellurium. Hematite- and sericite-altered syenite rocks were encountered at both prospects confirming a deep mantle link, considered a prerequisite in the formation of many large gold deposits.
A 2,121m aircore drilling program was conducted in mid-December 2013 comprising a total of 37 angled holes. The objective of the aircore traverses at Three Bears was to test several previously undrilled geochemical and structural targets. A total of 22 holes for 1,020m, at an average depth of 50m, was completed. The aircore drilling at Tallows was undertaken to clarify whether the main part of the redox gold anomaly identified extends to the east. A total of 15 holes for 1,101m, at an average depth of 68m, was completed. The drilling identified a maximum of 3m at 0.2g/t gold in a bottom of hole sample to the east of Tallows.
In April 2014 a further small aircore program was undertaken consisting of three traverses (~650m) to assess the Dexter Shear Zone over a 3km strike length to the north of the Three Bears Prospect and ~500m to assess an area located 5km to the west of the Three Bears Prospect. There were no results of any significance reported from the drilling to the west of Three Bears. Results to the north were inconclusive due to the presence of a hard basal conglomerate unit in the Permian cover rocks preventing drilling reaching the bedrock. RC drilling is now planned to test this target.
Wide-spaced aircore drilling to assess the Sandshoes and Dexter West Prospects commenced in late-August 2014. This program (120 holes; 6,034m) at the Sandshoes Prospect identified secondary redox gold anomalism however failed to reach bedrock. Reverse circulation drilling is planned to test the inferred bedrock source. Drilling (20 holes; 1,280m) at Dexter West turned up no significant gold values.
Reverse Circulation Drilling
An 8,426m RC drill program was completed in early July 2013 to test the bedrock below sub-surface redox gold enrichment identified in the weathered zone in the aircore program. The drill program consisted of 39 completed drill holes at the Three Bears Prospect (5,513m) and a further 13 drill holes (2,659m) at the Tallows Prospect. The RC drilling was partly funded by a grant from the WA Government’s Exploration Incentive Scheme.
At the Three Bears Prospect, initial drilling below areas of sub-surface redox gold intersected sericite- and hematite-altered syenite and granodiorite rocks. However, anomalous gold was restricted to the zone of weathering, indicating that the redox gold enrichment has moved geochemically downhill from the inferred bedrock source.
To assist in locating the bedrock source of the gold, 25 vertical “stratigraphic” drill holes (2,307m) were also completed upslope to the west of the initial area drilled in order to obtain a broader footprint of the redox gold enrichment, and to clarify the extent and nature of bedrock alteration. This drilling identified a 400m-wide zone of sheared and altered amphibolite on the Dexter Shear Zone with pyrite increasing noticeably to the south. A further seven angled RC drill holes (1,486m) were then drilled tracing the 400m-wide zone of sulphide-altered amphibolite along the Dexter Shear Zone to the south.
The final RC drill hole at Three Bears situated on the southern-most RC/aircore drill traverse intersected narrow 1m zones of anomalous gold assaying up to 0.3g/t in fresh pyrite-rich bedrock, suggesting that the inferred bedrock gold source is further south. This is consistent with elevated redox gold enrichments along the Dexter Shear, and converging tungsten and sulphur trends from bottom-of-hole aircore geochemistry. Gold and silver soil anomalies also converge in the area.
At the Tallows Prospect, 13 broadly spaced RC drill holes (2,659m) were completed over a 4km strike length to test the bedrock below areas of redox gold enrichment, developed at a depth of 30m to 60m over a 7km distance. These holes intersected hematite-altered granodiorite and syenite with localised areas of pyrite and sericite alteration. Anomalous gold was found to be restricted to the weathered zone suggesting that the redox gold enrichment is displaced from the inferred bedrock source, which is interpreted to be close to the area drilled, potentially in the Yamarna Shear Zone. Due to the large dimensions of the target areas involved, a decision was made to focus most of the RC drilling on the Three Bears Prospect where a tighter drill density enabled more detailed analysis.
On 29 November 2013 the Company commenced a 3,414m RC drilling program with the aim of zoning in on the likely bedrock source area at Three Bears. Drill targeting was undertaken based on the gold-in-soil anomaly location, previous results, bedrock alteration and multi-element geochemical studies.
At Three Bears, the program consisted of eight angled holes surrounding the most significant gold-in-soil anomalous area and a traverse of four wide-spaced vertical holes across structural and geochemical targets along the Dexter Shear to the south. RC drilling at the Tallows Prospect comprised three angled holes for a total of 994m with the purpose of targeting a potential bedrock gold source located on the Yamarna Shear upstream from multi-kilometre zones of redox gold enrichment identified by previous aircore drilling. The targeted area is situated in an area of structural complexity with favourable bedrock alteration characteristics highlighted by multi-element geochemistry and reflectance studies. No significant bedrock gold mineralisation was intersected however the resulting increase in density of multi-element bedrock data indicates a north-trending bedrock geochemical vector defined by several gold pathfinder elements such as tellurium and molybdenum. This suggests that the inferred bedrock source may be to the north of the Three Bears Prospect – in the direction of increasing weathered Archean bedrock – instead of south as previously thought.