The Grizzly occurrence area is underlain by a structurally complex assemblage of various Upper Triassic sedimentary and volcanic rocks that have been intruded by Juro-Cretaceous diorite and an array of Tertiary-Cretaceous felsites and porphyritic dikes. The sediments consist of conglomerates, sandstones, shale, limestone and minor carbonate breccia. The volcanics are comprised of tuffs, lithic tuffs which have been hornfelsed locally.

A substantial gossan covers the area of interest. It contains pyrite, limonite, pyritic shears and highly bleached rock. Within the pyrite zone is an area of chloritic, carbonate rich, chalcopyrite-pyrite bearing volcanics about 50 by 200 metres in extent. Distinctive coarse syenite porphyry dikes are spatially associated with the mineralization. Fine biotite is present as are traces of galena and molybdenite. Disseminated and veinlet chalcopyrite mineralization occur in a prophylitic-pyrite alteration zone associated with potassium feldspar porphyry syenite dikes of probable late Triassic to early Jurassic age. Host rocks are Upper Triassic sandstone and siltstone of the Stuhinin Group.

Eleven chip samples were taken across some of the more highly mineralized areas. They returned a weighted average of 0.3 per cent copper, 1.71 grams per tonne silver and 0.41 gram per tonne gold over an average sample width of 5.7 metres (Assessement Report 9041).

Although surface mapping in the Grizzly area showed strong copper-gold mineralization in historic trenching, the 2008 Grizzly drilling intersected only sub-economic grades over moderate widths, including 38.63 metre at 0.15 gram per tonne gold (GRZ08-05) and 53.73 metre at 0.19 gram per tonne gold and 0.11 per cent copper (GRZ08-11)(Assessment Report 30723). Strong K-feldspar alteration and carbonate veining and alteration were encountered in the drilling, as on surface. The mineralization in the Grizzly Showing area appears to be associated with these carbonate veins and the alteration halos surrounding them.

Work History

Assessment Report 9041 reports that Newmont Mining Corporation had carried out geological and geochemical work in 1970 and drilled two short holes, but could not locate their collars and provided no further information on Newmont’s work. The Little Les 1-24 claims were held by Newmont in 1971.

In 1980, Teck Corporation did the first work filed for assessment on the Grizzly property, reporting coincident copper and gold soil anomalies associated with syenite dikes intruding volcanic rocks and carbonate-chlorite-pyrite alteration. Teck’s best chip sample averaged 0.30 per cent copper and 0.41 gram per tonne gold across 5.7 metres within what is now termed the Grizzly Showing.

In 1989, Skeena Resources staked their Arctic claims over felsic Hazelton Group stratigraphy, from the current Grizzly property south along More Creek, focusing on exploration for a Eskay Creek-style VMS deposit. They carried out reconnaissance mapping, prospecting and geochemical sampling over the entire area covered by the current Grizzly property in 1990 (as reported in Assessment Report 30723), describing the Grizzly Showing as traceable for a length of 250 metres over a width of about 15 metres, consisting of “2-5 per cent disseminated chalcopyrite with 1 to 3 per cent disseminated and fracture fill pyrite”. Grab samples from the Grizzly Showing assayed up to 5.9 per cent copper and 13.1 grams per tonne gold. In addition, Skeena found several boulders in the glacial moraine 4 kilometres north of the Grizzly Showing (the “Northeast Cirque”) with elevated gold, silver, copper and/or As values, including one with 4500 parts per billion gold and 74.6 parts per million silver and a second with 9034 parts per million copper (as reported in Assessment Report 30723).

In 1991, Skeena Resources focussed on the Grizzly Showing, with trenching and geophysical surveys. Skeena believed the mineralization to be associated with a 050° structure on the northwest side of Grizzly Creek, and traced its associated alteration zone for 390 metres along strike. The best trench averaged 0.87 per cent copper and 1.51 grams per tonne gold across 20 metres, and the IP survey showed a distinct chargeability anomaly up to 50 metres wide and 300 in length.

Rimfire Minerals Corporation and its joint venture partners began exploration of the RDN property to the south of the Grizzly property in the late 1990s, using an Eskay Creek VMS exploration model and focusing on the Hazelton Group stratigraphy. Over the years, the RDN property was enlarged to the northward over favourable stratigraphy, including the acquisition of most of the current Grizzly property in 2005 from J. Fleischman. In 2005 Rimfire Minerals and Northgate Minerals acquired the property, known then as LL, to add to their RDN property. They reported average results from trench sampling of 0.55 per cent copper, 0.76 gram per tonne gold over 4.8 metres (Rimfire Press Release Dec 16, 2005, www.sedar.com).

In 2006, Rimfire and Northgate Minerals commissioned an airborne EM/magnetic survey over most of the Grizzly property. A geophysical signature similar to the Hazelton Group stratigraphy, with low resistivity and relatively low magnetic response, was present over the low-lying ridge (“Mirko’s Knob”) two kilometres northwest of the Grizzly. A soil grid (the “Mirko Grid”) over this area yielded highly anomalous, coincident Copper, gold and molybdenum values over a northerly-trending area of 1100 x 2300 metres, which remained open in each direction. Rimfire and Northgate also mapped and chip sampled the Grizzly Showing. Ninety-eight chip samples were collected from previously sampled trenches and from large areas not previous sampled so rigorously. Their best chip sample averaged 0.74 per cent copper and 1.09 grams per tonne gold across 38.0 metres (Assessment Report 28789).

In 2007, Northgate relinquished its option on the portion of the RDN property without Hazelton Group stratigraphy. Rimfire split this property up from their RDN property and renamed it the Grizzly Property to be owned 100 per cent by Rimfire. This portion called the Grizzly property was optioned by Rimfire to Inmet Mining Corporation in January 2008.

In 2008 Inmet Mining Corporation entered into an option agreement with Rimfire to conduct an exploration program, which commenced in June 2008. The 2008 Inmet Mining program consisted of 2127.26 metres of BTW drilling on two zones, Mirko’s Knob and the Grizzly Showing, and 31.13 line kilometres of IP and magnetic surveying (Assessment Report 30723). Additional work on the property consisted of mapping and prospecting and collection of 611 grid-based and contour soil samples. Moderate chargeability and intermediate resistivity with (or without) a localized magnetic response were targeted by drilling in the Grizzly and Mirko’s Knob areas.

See RDN (104G 144) for related work history details.