South West Yilgarn

Regional Database

Dominion has developed a very significant geochemical database, including over 150,000 surface geochemical samples, throughout an area of over 100,000sq km of the South West Yilgarn district. During 2006, increased industry focus has been directed to this district as a result of the release of regional magnetics and geochemical datasets by government bodies.

The geochemical dataset, released by CRC LEME, has highlighted prospective regional mineralised trends on the basis of regional sampling at an average density of 1 sample per 9 square kilometres. Dominion’s in-house sampling has an average density of more than 1 sample per 1 square kilometre and has given a much more detailed definition of these and other trends.

Dominion’s database is the basis of ongoing ground selection and target generation. The newly available datasets, and in particular the detailed magnetics, are being integrated into this selection process.

Newdegate Area Gold Anomalies

The Lake Magenta South target is a very large 17 kilometre long arcuate surface gold geochemical anomaly coincident with a major arcuate discontinuity, as defined by detailed airborne magnetics, along the Yandina Shear Zone.

Previous interface drilling (drilling designed to evaluate the relatively soft, weathered material extending down to the interface with the relatively hard and unweathered bedrock) had outlined a series of continuous zones of bedrock mineralisation (+ 100 ppb gold), each between 850 and 1,700 metres long, respectively termed the Western Zones 1 and 2 and the Eastern Zone.
Induced Polarisation (IP) surveys had defined a series of anomalies coincident with these mineralised trends, and initial deeper reverse circulation (RC) drilling of two of these anomalies intersected extensive sulphide mineralisation and associated alteration. Gold values within these mineralised zones, although locally elevated, were sub economic.
During the current year further interface drilling defined significant extensions to the Eastern Zone with bedrock mineralisation now extending continuously along a 6 kilometre long zone which is still open.

Initial wide spaced drilling of the Hinge Zone (the arcuate link between the Eastern and Western Zones) also outlined bedrock mineralisation with a best base of hole intersection of 3 metres @ 1.54 g/t gold. Interface drilling also outlined extensions to Western Zone 2.

Two diamond core holes were drilled to evaluate the geological setting of Western Zones 1 and 2. They intersected successions of mixed mafic and felsic gneissic rocks, intruded (cut) by porphyritic (granitic) material.

The holes encountered extensive sulphide mineralisation and alteration which is anomalous in a range of elements including copper, lead, zinc, silver, tungsten, cobalt, bismuth and molybdenum. While only sub economic gold values have been returned, the style of the sulphide mineralisation and associated alteration is typical of other gold mineralised districts (eg, Boddington and. The Southern Cross belt) and is believed to significantly enhance the prospectivity of this very large gold anomaly.

The zones of bedrock gold mineralisation are of a truly impressive extent and clearly reflect the continuity and trend of the surface gold geochemical anomaly. There is, however, a consistent pattern of gold depletion between the surface and interface gold anomalism and the potential for shallow, ‘regolith hosted’, orebodies has been downgraded.

This depletion is believed to relate to the combined effects of highly saline and acidic groundwater, the latter effect probably reflecting the weathering of very large amounts of sulphide mineralisation.

Nevertheless, results to date have outlined a major exploration opportunity. Considering the extent of the defined target, there has been very little drilling to evaluate the fresh bedrock underlying the depleted regolith and systematic deeper drilling is warranted.

However, the initial focus will be to complete systematic shallower interface drilling to define the ‘hot spots’ along the semi-continuous 17 kilometre long bedrock anomaly. These hotspots will then be selectively targeted with follow up deeper drilling.

(Return to top of page)