West Wyalong – a joint venture with Argent Minerals (ARD)
GCR’s West Wyalong tenement (EL5915) is located over the township of the same name in central NSW, 430 km west of Sydney. GCR owns the property 100%, subject to a 2.5% net smelter return royalty to Barrick.
A joint venture agreement has been negotiated with Argent Minerals Limited (AM) whereby it can earn a 70% interest in the West Wyalong project by spending $1.3 million by July 2013.
Geology and Mineralisation
The exploration licence is host to a magnetic, magmatic complex of Ordovician age located on the Gilmore Suture within the Lachlan Fold Belt. Geological and geophysical interpretations indicate three domains – the Gidginbung Volcanic domain (comprising highly sheared andesitic rocks); the Gidginbung Intrusive domain (comprising a variety of dioritic intrusions with Gidginbung volcanics); and the Bland Diorite domain (where diorite bodies intrude basaltic volcanic rocks). A number of significant gold and copper-gold deposits have been identified regionally along the Gilmore Suture.
The West Wyalong Goldfield – hosted by the Ungarie Granite – is the principal area of known mineralisation in the West Wyalong area. The gold occurs within narrow quartz veins that average about a half-metre thick, but vary considerably from a few centimetres to 3 metres thick in lens-like shoots dipping steeply east and pitching to the south. Up to 25 lenticular veins are recognised in the West Wyalong Goldfield.
Historic production of high grade gold was recorded at more than 440,000 ounces prior to 1920. In the period of peak mining activity from 1894 to 1907, 371,000 ounces of gold was produced with an average grade of 44 g/t.
The discoveries of the Lake Cowal Deposit (in excess of 2.5 million ounces) 30 km to the north, and Marsden (115 million tonnes at 0.4% copper and 0.15g/t gold) 20 kilometres to the northeast, provide encouragement that large intrusion/volcanic-related hydrothermal systems exist in the area. This, in addition to the recent discoveries at Cadia (near Orange), and Northparkes (near Parkes) showed that the Ordovician age magmatic arc complexes in NSW remain highly prospective for copper and gold.
Within the GCR tenement, Geopeko delineated a sulphide-rich hydrothermal system at Narragudgil (mid 1980s) by testing magnetic anomalies beneath alluvial cover, and further to the south Gold Mines Australia discovered the Mandamah porphyry complex in the mid-1990s.
Due to West Wyalong’s poor outcropping, and deep alluvial and saprolite cover, GCR reviewed geophysical data, which has greatly enhanced the knowledge of sub-surface geology in the area.
GCR has reviewed geophysical data from the West Wyalong tenement, which is essential as the area features poor outcropping, and deep alluvial and saprolite cover. Geophysical modelling indicated that a 21-miligal gravity anomaly in the Pines prospect area was caused by a deep, dense, non-magnetic body – probably a gabbro. This body is about 600m to the top. The magnetic features observed are shallow, near-surface responses and are located above the dense (gabbro) body and within the diorites and basalts of the Bland Domain.
Residual gravity shows a distinctive hole in the gravity high southeast of the Pines, which is interpreted to be a body of less dense rock cross cutting the gabbro. This area is roughly circular and 3 km in diameter, named the “Intrusive Centre”. Interpreted together with all the compiled drill hole and bedrock geochemistry, a broadly concentric pattern is formed at the “Intrusive centre”.
In late 2007, ARD drilled three vertical RC holes to test anomalous gold and copper geochemical anomalies and intersected what may be a previously unmapped gold reef. The drilling was planned around the Intrusive Centre. One hole, APG003, intersected 2m at 19.1 g/t gold from 106m downhole. Holes were also drilled under old workings on five gold reefs, looking for possible depth extensions. This strategy was successful at the Mallee Vale reef in the north of the property, with an intersection of 4m at 6.11 g/t gold from 28m. The Pine Ridge reef, in the west of the property, was also intersected, returning 2m at 1.48 g/t gold from 36m.
In 2010, ARD announced that their follow-up drilling indicated three possible gold reefs at West Wyalong. AWGC002 and AWGC003 were drilled to intersect the same porphyry gold mineralisation encountered by the vertical hole AWGC001 (2m @ 22.7g/t Au).
AWGC002 intersected a 6m void from 20m downhole – assumed to be old workings – and assayed 0.48g/t gold at the bottom of the void. The hole then intersected 2m @ 4.29g/t gold which suggested another possible gold reef, sub-parallel to the reef represented by the void. The anticipated gold mineralisation (from AQGC001) was then intersected for 2m from 56m downhole, and assayed 8m @ 1.94g/t gold.
The third hole, AWGC003, was drilled at a right angle to AWGC002 and intersected the expected 2m of mineralisation grading 2.05 g/t gold. AWGC003 did not extend deep enough to intersect the possible westerly reefs.
The results indicate three narrow, steeply dipping sub-parallel gold reefs, trending north northeast.
Reviewed, updated September 2012.