|October 15, 2008|
GWR Reviews 2007 - 2008 Lac La Hache Exploration
|During 2007 - 2008, exploration of the Lac La Hache project area of GWR Resources Inc. comprised geological mapping, trenching and diamond drilling mainly on two tenures, ANN 1 which covers the Aurizon zone and ANN 2 within which lies the Peach prospect. Limited work was undertaken on the Murphy tenures in the southern part of the property and no work other than limited prospecting was carried out on other tenures that make up the Lac La Hache project area.|
The Lac La Hache project area is underlain by volcanic, volcaniclastic and associated strata of the Upper Triassic Nicola Group of the Quesnel belt, a 200+ million year old island arc that formed west of North America at that time. The Quesnel belt, or Quesnellia, along with a related belt, Stikinia, hosts a number of gold enriched copper porphyry deposits such as Ingerbelle-Copper Mountain, Afton, Mount Polley, Mount Milligan, Kwanika Creek, Galore Creek and Copper Canyon. All of these deposits have common characteristics such as mafic volcanic flows and breccias into which stocks of dominantly monzonitic composition have been intruded. Copper-gold mineralization is related to these intermediate to felsic intrusive complexes and is commonly hosted by magnetitite-rich hydrothermal breccia.
ANN 1 Exploration
As is typical of the region, the ANN 1 tenure is covered mainly by glacial and fluvioglacial deposits and exposed bedrock is extremely limited. Initial work that was carried out in the 1990's consisted of soil geochemical and geophysical surveying which resulted in low order geochemical and induced polarization anomalies. During subsequent prospecting activities a zone of disseminated native copper in monzonite was recognized in the central part of the ANN 1 tenure, a zone which is now referred to as the Aurizon zone.
In late 2006, a ten-hole drilling programme was initiated over the Aurizon zone which resulted in the discovery of chalcopyrite-bornite mineralization that was enriched in gold, beneath the previously recognized zone of native copper mineralization. In 2007, a trenching programme was undertaken across the northern part of the ANN 1 tenure which exposed bedrock which, in places, contained anomalous copper and gold. Mineralization exposed in the trenches comprised two groups, one that confirmed mineralization of the Aurizon zone and a second which suggested the presence of a copper-gold zone to the northwest of the Aurizon zone.
In the spring of 2007, a diamond drilling programme was begun, initially to the north of the Aurizon zone (drill holes AZ07-11-18) and then within and adjacent to the Aurizon zone (approximately 50 drill holes). This initial drilling was aimed at defining the nature of the Aurizon zone, the distribution of mineralization within the zone, its size and configuration, the types and distribution of hydrothermal alteration assemblages, the relationship between alteration assemblages and mineralization and solving the structural complexities that were recognized at an early stage. Later drilling was designed to test an additional area of interest in the northwestern part of the ANN1 tenure, an area that trenching results suggested was prospective for copper-gold mineralization. Results of this drilling were inconclusive as many of the holes drilled here were to define the geology of the area and not to define copper-gold mineralization per se. The Company's drilling permit for the ANN 1 tenure was exhausted by summer of 2008, at which time 95 drill holes had been completed for a total of almost 30,000 metres of drilling.
The most encouraging result from exploration of the ANN 1 tenure during 2007-2008 was the recognition that the Aurizon zone, as currently defined, consists of copper-gold mineralization hosted by a hydrothermal breccia pipe that plunges steeply to the north within a larger zone of potassically altered monzonite. The dimensions of the breccia pipe have not been fully defined: its near surface expression is about 100 metres in diameter but it increases in size down plunge and is truncated both to the north and the south by northwesterly-striking faults. Limited drilling to the north and the south strongly suggests that both a northerly and southerly continuation of mineralization exists as hydrothermally altered monzonite, along with anomalous copper-gold mineralization, has been intersected in reconnaissance drill holes both to the north and the south of the breccia pipe.
Statistical studies of the distribution of copper-gold mineralization indicates that there are two copper and gold populations within the Aurizon zone. Hypogene mineralization consists of copper and gold in which the two metals are intimately related in a ratio of 2:1 in that gold, expressed as grams per tonne, is usually double the copper grade expressed as a percentage. On the other hand, there is no spatial relationship between copper and gold in the supergene environment where copper, manifested as native copper and as chalcocite, is spatially separate from gold which ranges in grade from less than one gram per tonne up to over 15 grams per tonne. This spatial separation of copper and gold is probably a reflection of the differing mobilities of the two metals in the supergene environment. Mineralization of the Aurizon zone is similar to that of Afton, a developing mine near Kamloops to the south, in that both deposits are hosted by magnetite-rich hydrothermal breccia and both have abundant native copper as a supergene component. This differs from deposits such as Mount Polley to the north where supergene copper is dominated by copper carbonates - malachite and azurite.
ANN 2 Exploration
The ANN 2 tenure encompasses a number of significant copper-gold prospects, Peach 1, Peach 2, NK and Ann North, amongst others. The first integrated exploration of the ANN 2 tenure was conducted by ASARCO in 1994-1995, who carried out tenure-wide soil geochemical and geophysical surveying, geological mapping, trenching and limited percussion drilling. Results of this work suggested that several zones of copper-gold mineralization exist within the ANN 2 tenure of which none had been adequately evaluated. ASARCO's trenching and drilling results demonstrated the presence of copper mineralization within the Peach prospects but did not define the extent of mineralization in either. In 2007, GWR excavated a north-trending trench across the Peach 1 zone from which analyses returned 65 metres of about 0.22% copper. Subsequently, the Company initiated a drilling programme of 22 holes, totalling over 7,000 metres which confirmed copper-gold mineralization over a distance of over 300 metres in an east-west orientation but which has not yet defined the spatial limits of the zone. A feature of this initial drilling programme was the intersection of 86 metres of 0.50% copper and 0.42 g/t gold, including 42 metres of 0.86% copper, at depth beneath the zone of relatively low grade copper-gold mineralization.
Unlike the Aurizon zone where copper-gold mineralization is hosted by hydrothermal breccia developed with a monzonite stock, Peach 1 mineralization, for the most part, occurs within volcanic rocks cut by numerous monzonite dykes at the margin of a monzonite pluton. However, the initial, relatively high grade, copper-gold intersection was entirely within hydrothermally-altered monzonite.
Mineralization at Peach 1 occurs within an envelop of propylitic alteration - chlorite-magnetite-calcite-albite - and is intimately associated with potassium feldspar-epidote-actinolite veins and irregular masses. This style of mineralization is in contrast to the Aurizon zone where copper-gold mineralization is within hydrothermal breccia, reflecting, possibly, the differing mechanical properties of the two rock types, that is monzonite-hosted mineralization at Aurizon and volcanic-hosted mineralization at Peach 1.
Work to date at Peach 1 seems to suggest that supergene processes have not been as significant as within the Aurizon zone. Nonetheless, so far no work has been undertaken on the mineralogy of Peach 1 mineralization in order to enable characterization of supergene and hypogene species and their relative distributions.
The potential of the Lac La Hache project area for the definition of economic copper-gold mineralization is obviously very high when one considers the number of prospective areas that host significant copper-gold mineralization but which have yet to be adequately tested. The two most important aspects of exploration of the project area that have yet to be fully understood are i) the post-mineralization structural history of the project area and ii) the distribution of hydrothermal alteration assemblages that are related to copper-gold mineralization. In the past, monzonite that had been pervasively potassium feldspar altered had often been mapped as syenite whereas now it is recognized that this is an alteration phenomenon that is often related to copper-gold mineralization. There several "syenite" bodies within the Lac La Hache project area that need to be re-examined from this point of view.
A feature of the project area that has not yet been considered in the past is the relationship between magnetite alteration and copper-gold mineralization. Because the hydrothermal solutions that transport copper-gold mineralization in alkalic porphyry systems are oxygen-rich, there is a common association of magnetite with copper-gold sulphides. Consequently, past explorers often focused their exploration activities on those areas in which the rocks exhibited high magnetic susceptibility. It is now known, however, that bornite mineralization, which is usually of higher grade than chalcopyrite mineralization, is often accompanied by only small amounts of magnetite or none and, thus, magnetic highs may not necessarily be an indicator of mineralization. Similarly, because of the low total metal content of some zones of high grade copper mineralization because of the absence of iron sulphides and magnetite, induced polarization responses may also be weak. Areas underlain by intrusive rocks that exhibit low magnetic and induced polarization response but moderate to intense hydrothermal alteration are not uncommon within the Lac La Hache project area and elsewhere within the Quesnel belt in general. An example of such is that of Mount Polley's Northeast Zone, amongst the richest copper-gold mineralization so far discovered by Imperial Metals within its Mount Polley project area but which has very weak induced polarization response and very low magnetic susceptibility.
The use of soil geochemistry as an indicator of possible copper-gold mineralization in bedrock will also be re-examined. There are large areas of low soil copper and gold values within the project area that have been dismissed as having no potential. However, there has been no characterization of the nature of the overburden on which the soils developed. If, for example, the overburden consists of lodgement till, this effectively geochemically masks any mineralization that may exist in the underlying bedrock.
Thus, it is considered that despite many years of exploration within the Lac La Hache project area, there are many aspects of the project that have yet to be fully evaluated within the terms of modern exploration concepts and ore deposit models.
Ongoing and Future Exploration
The Company now has three drill rigs operating within the Lac La Hache project area. One drill is continuing exploration of the Peach 1 zone, a second is testing the Peach 2 prospect located a few hundred metres to the southeast of Peach 1 and which may be a fault-displaced part of Peach 1, while a third drill is working on the Aurizon zone in an attempt to define the extent, dimensions and grade of the zone.
A deep induced polarization survey has also been carried over the ANN 1 tenure, the eastern part of the ANN 2 tenure and the JACK 2 tenure to the east of the northern part of ANN 1 and which has seen no exploration in the past. Preliminary induced polarization results indicate that conductive rocks that may be indicative of copper-gold mineralization are present beneath and to the south of the known Aurizon mineralization and beneath an upper pyrite zone at Peach 2. Geophysical surveying is ongoing.
Modeling of the Aurizon zone indicates gaps in grade information that need to be filled in before a resource estimate of this zone can be made. Consequently, a resource estimate has not yet been carried out despite hopes that it could be completed within the current year. The main problem, unforseen early in 2008, was the extent and nature of faulting within the zone. It is hoped that the current drilling programme at Aurizon and future drilling, for which a permit should be received before the end of the year, will resolve this issue.
In 2009, it is expected that work on the Aurizon zone will be completed and emphasis will be placed on those prospects that have additional bulk tonnage potential. The Ann North prospect to the northwest of Aurizon and immediately north of GWR's NK prospect is of high priority in this respect. Other targets will present themselves from ongoing review of early work and a planned geological mapping and trenching programme.
A listing of all drilling results from the ANN 1 and ANN 2 tenures and which includes the Aurizon and Peach 1 zones is available on the Company's website at www.gwrresources.com. A updated geological map of the Aurizon zone that also shows drill hole locations is also available on this website. Those unfamiliar with the geological nomenclature used in this news release, please refer to a geological dictionary available at www.webref.org/geology.
David G. Bailey, Ph.D., P.Geo. is the Qualified Person as defined by National Instrument 43-101 who is responsible for the technical aspects of this news release.
Responsible Officer: Irvin Eisler, President
Telephone Number: (604) 687-0789
The TSX Venture Exchange has not reviewed and does not accept responsibility for the adequacy or accuracy of this release.
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