Wongan Hills
Following the intersection of significant supergene copper-gold mineralisation (44 metres grading 0.75% copper, with the last 5 metres, 75-80 metres, grading 3.79% copper and 1.87 g/t gold, and 36 metres grading 0.57% copper, including 6 metres grading 1.9% copper and 2.4 g/t gold) at Ninan North in 2005, the Wongan Hills project has been a exploration priority.
Strategies have involved surface geochemical sampling, systematic interface drilling, geophysical surveying and limited deeper drilling.
While previous geochemical sampling had outlined reasonably well defined anomalism in gold and copper, the data related to a variety of sample types and was often difficult to interpret. Sampling, undertaken during the year, utilising a mechanical auger to obtain more controlled sample types, and with these samples analysed for a wider range of elements, has outlined a series of more cohesive anomalies.
The data highlight both a major copper-gold trend and a separate lead-zinc trend with associated tin, bismuth and antimony anomalism. A further copper-zinc-lead-cobalt trend is also outlined. These trends demonstrate a zoning that, in general, parallels the geology (as interpreted from detailed magnetic data).
The interface drilling (designed to evaluate the zone of supergene mineralisation within the weathered material above the interface with relatively fresh bedrock) has been carried out to evaluate the copper-gold surface geochemical anomaly which comprises a 3 km by 1 km zone trending NE-SW from the Ninan North area and encompassing the Ninan Prospect, where significant copper-gold mineralisation had previously been intersected.
Significant copper mineralisation (+ 5m% Cu) is developed within two main sub-parallel zones with the more significant eastern zone extending over 500m (N-S) by 250m (E-W). Within this eastern zone there is a well defined richer core zone (+10m% Cu) extending over 250m x 100m. The original Ninan North ‘discovery’ intersection (44m @ 0.75% Cu) occurs at the centre of this core zone. Further significant intersections, including 44m @ 0.47% Cu (including 8m @ 1.28% Cu at the end of hole), 33m @0.38% Cu and 30m @ 0.31% Cu have also been returned.
The zone of + 5m% Cu extends for at least 2,000metres to the south where it has still only been evaluated by wide spaced interface drilling (traverses 1,000 metres apart) except in the Ninan Central area where previous (pre-Dominion) drilling has defined a zone up to 800 metres wide. Potential exists for the identification of a resource of supergene copper mineralisation within this zone.
Significant gold mineralisation (+5gm) at Ninan North is developed within broadly analogous zones to the copper mineralisation. The drilling has returned best intersections of. 15m @ 2.5 g/t (including 3m @ 6.3 g/t) and 15m @1.68 g/t (including 3m @ 6.67 g/t). This gold mineralisation could be a significant factor in any economic evaluation.
The discovery of this very extensive zone of ‘supergene’ mineralisation clearly also indicates a very significant potential for ‘primary’ sulphide copper-gold mineralisation in the underlying fresh bedrock. Initial reconnaissance Induced Polarisation (IP) surveying over the northern part of this zone has outlined a broad chargeability anomaly (potentially relating to sulphide mineralisation) coincident with the zone of regolith mineralisation but offset to the west, suggesting a westerly dip of the mineralized zone in bedrock.
Two diamond core holes were drilled to test this IP anomaly. Both of these holes (located on sections 100m apart) intersected very extensive (+ 200 metres intersected width) zones of chalcopyrite (copper sulphide) mineralisation and associated iron - rich alteration (pyrrhotite, magnetite, garnet and chlorite). Copper grades within the mineralized sections, are typically between 0.1% and 0.6% and locally exceed 1.0% over 1 metre intervals. Associated gold grades are more erratic up to 1 g/t Au.
It seems likely that this style of mineralisation is the source of the shallow supergene mineralisation intersected in the interface drilling. The style of this mineralisation and alteration may represent a volcanogenic massive sulphide (VMS) footwall system. Given the very large extent of the supergene mineralized zone (extending over a strike length of at least 3 km) there is a significant potential for economic mineralisation.
There is also believed to be a significant potential for VMS style lead – zinc (+ copper – gold) mineralisation, as is potentially indicated by an abrupt change from copper – gold to lead – zinc geochemical anomalism to the north west.
Perenjori Area
The most recent extensions to the reconnaissance surface geochemical coverage have been in the Perenjori Area. This area lies to the north of Wongan Hills and contains the Perenjori greenstone belt and several smaller greenstone belts. It is also adjacent to the greenstone belt that hosts the Golden Grove VMS deposits and several gold deposits.
The area is thought to be prospective for both gold and VMS deposits and the roadside sampling has outlined a number of gold and copper anomalies. Ten new tenement applications have been submitted to cover both these anomalies and also prospective geological settings interpreted from recently available regional magnetic data.
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