CHALLENGER WEST PROJECT
THE CHALLENGER WEST PROJECT
The Challenger West Prospect (Figure 1) lies c.190 km northwest of the Highway Prospect and approximately 135 km southwest of Coober Pedy. The tenements are accessible from the Commonwealth Hill Road, off the Stuart Highway to the east. The Commonwealth Hill airport lies centrally between the two prospects and is 78 km east of the Challenger West properties. From the Commonwealth Airport, the tenements are accessible by track (cf. Figure 1).
Figure 1. Taiton Resources Challenger West Project
Challenger, and the gold deposits near it, lie on gravity ridges in the Mulgathing Province of the gneissic Christie Subdomain and Christie Mineral Field (Figure 2). Taiton was the last new entrant to the area and has extensive coverage of gravity ridges west of Challenger. Arguably, the area has been artificially sterilised as Challenger was discovered by calcrete sampling. Prolific calcrete sampling across SA followed in the next 15 years. More recently, limitations have been identified in that approach. Taiton has yet to acquire any new data but has re-processed the existing gravity data to better highlight the relationship of the mineralisation to gravity gradients (Figure 3).
Figure 2. Simplified lithotectonic map of the Gawler Craton, South Australia, showing the location of the Challenger Gold Mine with respect to the surrounding subdomains and their inferred boundaries (Gum, op. cit.). The Christie Subdomain is highly metamorphosed.
Figure 3. Bouger anomaly map (isocontours along the 10mGal band) showing locality of the Challenger West Prospect, in relation to the Challenger Gold Mine. The presence of addition gold occurrences and mines along a gravity high boundary and a mirrored gravity ridge to the west, attests to the high prospectivity of this ground (dashed yellow lines). Major gold mines highlighted.
The Challenger West Prospect is located west of the Challenger Mine, approximately 150 km southwest of Coober Pedy. The Archaean para- and orthogneisses with mafic to ultramafic intrusive and extrusive rocks of the Sleaford and Mulgathing Complexes form an older basement cropping out sporadically in the western and north-western parts of the Craton. The deposit hosts >500,000 oz of gold in granulite facies gneisses and pelitic migmatites.
Challenger may more realistically be interpreted as a metamorphosed gold deposit and that the distribution and grade of pre-existing gold mineralization was strongly affected by high-temperature deformation, partial melting, and melt migration during the Palaeoproterozoic granulite facies metamorphism event that affected the region. Formation of a polymetallic melt thereby enabled extensive mobilization of gold, which produced leucosomes enriched in gold. It is interpreted that concurrent migration of polymetallic and silicate melt allowed concentration of gold into a series of dilational structures which developed within the larger scale fold geometry. The Challenger deposit represents a new deposit type. Other deposits around the world, such as Renco and Griffins Find, are hosted in granulite facies-grade rocks, but Challenger is the first reported example of leucosome-hosted gold in migmatites.
Textural relationships indicate that gold was present prior to peak metamorphism. Visible gold is now restricted to migmatitic leucosomes and, to a lesser extent, melanosomes. The gold-bearing leucosomes are believed to have been formed during the metamorphism of the Challenger deposit which resulted in partial melting of the gold bearing pelitic host rock and formation of silicate and polymetallic gold-rich melts which were synchronously redistributed to accumulate as leucosomes during development of a stromatic migmatite.
Gold-rich shoots at Challenger parallel the plunge of ptygmatically folded leucosomes that are shown to be parasitic to a larger scale fold geometry which appears to be structurally related to the ore shoots. It has been interpreted that concurrent migration of polymetallic and silicate melt allowed concentration of gold into a series of dilatational structures which developed within the larger scale fold geometry, which appears to be structurally related to the ore shoots.
Taiton is a new entrant to the area. The Company’s primary source of confidence in being situated in the Challenger region, besides its proximity to an existing mining district, is due to the presence of gravity highs (isocontours in the 10Mgal Band) found in the same basement terrane setting as the Challenger deposit (cf. Figure 18). As mentioned, the regolith of the area is extremely prospected, based on the discovery of Challenger by sampling calcrete carapaces and regolith. This approach led to a flurry of district-scale calcrete sampling for over a decade. More recently, limitations have been identified in that approach. The Challenger gold camp is well understood, and Taiton is well-placed to capitalise on the vast amount of historic data available in the public domain and on SARIG. Taiton has only recently acquired it ground holdings at Challenger West and has not acquired any new data in the interim, other than to reprocess the gravity data to produce higher resolution Bouger anomaly maps that clearly highlight the relationship of the mineralisation to the gravity gradients (cf. Figure 3).
The Company believes that the existing data, which has a good historical indicator of district-scale mineralisation, supports a strategy for a new discovery at Challenger West. The Bouger gravity model supporting gold deposits developing marginal to a metamorphosed gravity ridge, is a compelling concept. The mirror-imaged gravity ridge boundary located in the west of the tenement EL 6785 bodes well for similar mineralisation to other significant and neighbouring gold deposits (cf. Figure 1).