Eagle River Exploration

Overview

The Eagle River Property remains largely unexplored despite 11 years of commercial production. Spanning 5250 hectares along an 18 kilometre strikelength, the Eagle River Property has to date produced over 650,000 ounces of gold, and is open at depth below 650 metres at the Eagle River Mine, as well as to the east and west.

The deposit at the Eagle River Mine has a 10 year history of replacing its reserves. Management is encouraged by this history and feels that systematic surface and underground exploration will add value as it as in the past. Below is an outline of the exploration potential of the Eagle River Property, beginning with an overview of the Regional Geology, followed by the specific characteristics of the deposit, as well as a look at the mineralization of each zone.

Regional Geology

The Mishibishu Lake greenstone belt is a broad arcuate syncline 55 kilometres long east-west and 16 kilometres wide north-south. This belt is part of the Wawa Subprovince of the Archean age Superior Province (Evans, 1942; Bennett and Thurston, 1977). Supracrustal rocks in the belt are dominated by greenschist facies mafic to intermediate volcanic rocks with lesser sedimentary rocks including iron formation and intermediate to felsic volcanic rocks. The belt is surrounded by Archean granitic rocks and includes two internal granitic batholiths occupying the central portion of the belt. Minor intrusions include synvolcanic stocks and sills of intermediate to felsic composition and an array of northeast and northwest striking late Precambrian diabase dykes. The northern limb of the belt is dominated by an assemblage of clastic sedimentary rocks, felsic tuffs and mafic flows. The southern limb, where the Eagle River property is located, is dominated by tholeitic basalts and calc-alkaline andesites with minor interflow clastic sedimentary rocks and lean chert-magnetite iron formation. In this area, the supracrustal rocks form a steeply north-dipping and north-facing sequence displaying moderate to steep eastward plunges defined by minor fold axes and mineral lineations. Gold in the Mishibishu Lake greenstone belt occurs primarily in quartz vein deposits located within regional zones of deformation (Sage and Heather, 1991). The Mishibishu Deformation Zone follows a volcanic-sedimentary contact in the north limb of the belt hosting the Magnacon and Mishi deposits while the Eagle River Deformation Zone hosts the Eagle River deposit along the south limb of the belt. Late northeast striking and lesser northwest striking faults and fractures offset the greenstone stratigraphy and deformation zones.

The Eagle River deposit is an Archean Greenstone Belt hosted vein-type deposit along a regional deformation zone with discrete brittle-ductile shears localized along lithological contacts (Heather 1986 & 1991). Due to 45º to 70º east-plunging lineations, he speculates on a simple shear model with oblique-slip displacement. Work by Johnston (1990), refutes Heather’s thesis by observing “There is no evidence of a continuous and mappable domain of relatively high strain referred to as the Eagle River Deformation Zone by Heather (1986)” (Johnston, 1990, page 25). Gold-bearing quartz is highly strained and recrystallized commonly displaying stylolytic textures. Gold occurs at the quartz grain boundaries and in the stylolites. Gold predates the straining of the quartz. Structural observations over the last ten years support Johnston’s view that deformation of the mineralized zones is attributable mainly to pure strain. The current structural model invokes progressive deformation of pre-existing veins by pure shear flattening in accordion-style folding to eventually reach their current tabular geometries.

The mineralized lenses occur at a spacing of 400 metres along a 2.4 kilometre strike length. They appear to be spatially related to a series of oblique 110º striking mafic dykes, which predate mineralization and preferentially occupy the shear zones. These dykes may have been important in creating competency and chemical anisotropies which promoted vein and gold deposition.

Mine Site Geology

Gold bearing quartz veins at the Eagle River deposit are predominantly hosted by sub-vertically dipping, east-west striking shear zones that constitute a structural corridor within an elliptical quartz diorite stock with dimensions of 1.8 kilometres east-west and 0.5 kilometres north-south. Zones 2,3,6,7 and 8 constitute different segments of the overall shear zone corridor and each have their own grade characteristic. The bulk of the historic production has come from Zone 8 and Zone 6, which are entirely within the intrusive quartz diorite, while Zone 2 mineralization is hosted in sheared mafic volcanic rocks just east of the stock.

Zone 8 is characterized by a series of thick, white laminated quartz vein lenses. The veins vary in thickness from one metre to 15 metres, but average about 2.5 metres. Commonly only portions of this vein system can be selectively mined with mining widths varying between 1.2 and 7.5 metres. Gold is concentrated in highly strained quartz of grey colour and in sericite-chlorite lamellae with accessory sulphide minerals including pyrite, pyrrhotite, galena, sphalerite, and chalcopyrite. The gold grade in Zone 8 has averaged about eight grams of gold per tonne with individual stoping blocks ranging from five to twelve grams of gold per tonne. Zone 8 is accompanied by a distinct, red, potassic fracture-controlled alteration in the immediate wall rocks of the veins. A distinct and discrete shear zone that forms a splay off the shear hosting Zone 8 hosts the Zone 6 mineralization. The vein varies in thickness from 0.5 metres to 2.0 metres. Locally the vein is folded back on itself forming tight S-folds or “ballrooms” which form plunging, pipe-like bodies 12 to 15 metres in diameter.

Zone 6 is high-grade averaging 12 to 18 grams of gold per tonne and has very competent wall rocks. Because of its high-grade character, Zone 6 has traditionally provided the economic backbone of the mine. The 650 Zone is in a sub-parallel southern splay from the shear hosting Zone 6, which continues eastward into volcanic rocks and hosts the 2 zone. Both the 650 and 2 Zones are characterized by sheeted veins of laminated white quartz ranging in thickness from 1.5 to 6.5 metres. These zones have good grades of ten to 15 grams of gold per tonne.

Zone 7 is a complexly folded white quartz vein located 100 metres north of the Zone 8 shear. It contains patches of coarse pyrite containing very high grades.

In addition to the zones that have been mined, a discrete yet persistent shear zone called the No Name Lake Zone occurs sub parallel and 400 metres to the south of Zone 8. The No Name Lake Zone dips 65º north and will meet the vertically dipping Zone 8 at depth. It consists of a 0.5 metre thick quartz vein in a 1.0 metre wide shear and has been traced by drilling over 600 metres of strike length, averages 7.0 grams of gold per tonne over 1.0 metre and remains open along strike and down dip. The No Name Lake Zone remains an attractive exploration target.