Rau Trend Geology
The Rau Trend lies within a band of regional-scale thrust and high angle reverse faults that imbricate rocks of Selwyn Basin and Mackenzie Platform. Selwyn Basin stratigraphy consists of regionally metamorphosed, basinal sediments of Neoproterozoic to Paleozoic age. Mackenzie Platform stratigraphy comprises dominantly shallow water carbonate and clastic sediments that were deposited from Mid-Proterozoic through Paleozoic times. Both packages of sediments were deposited on the western margin of ancestral North America.
Stratigraphy along the Rau Trend generally consists of a package Cambrian to Devonian aged dolostones, silty limestones and fossiliferous limestones interbedded with thin mafic volcaniclastic flows. In addition a 63 million year old felsic intrusion was emplaced along the Rau Trend. The carbonate stratigraphic package is bounded to the south by the Dawson Thrust and to the north by the Kathleen Lakes Fault. All units have been deformed into open folds that are aligned parallel to the thrusts and plunge gently to the southeast. Several high angle faults, which parallel the general structural trend, occur on the property and may have acted as mineralizing fluid conduits. The volcaniclastic flows, while insignificant volumetrically appear to have played an important role in localizing the mineralization within the underlying carbonates by acting as an impermeable cap and source of soluble iron for the deposition of gold enriched pyrite.
Rau Trend Mineralization
Several types of mineralization are known to occur on the Rau property including:
- -Carbonate replacement, intrusion related, gold (sediment hosted gold mineralization): Tiger, Bengal, Caracal, Cheetah, Condor, Cougar, Jaguar, Panther, Puma and Serval targets ;
- -Scheelite Tremolite-Actinolite Skarns (tungsten skarn mineralization: Hogsback, Ridgecrest, Flat Top, Bobcat and Blue Lite showings; and,
- -Gold-Bearing Quartz-Boulangerite Vein: Now showing.
Carbonate Replacement, Intrusion Related, Gold
Sediment hosted gold mineralization has been the primary focus of exploration. To date several showings have been identified with the Tiger Deposit being the best understood and most aggressively explored.
The Tiger Deposit is a thick northwesterly trending body of carbonate replacement style gold mineralization hosted within a moderately northeast dipping horizon. Mineralization is developed within and adjacent to a 40 to 150 m wide zone of small scale folding and shearing. The geometry of the mineralized system is a series of stacked and folded limestone horizons interbedded with locally extensive mafic flows and volcaniclastic units.
Gold occurs in both sulphide and oxide facies rocks. Sulphide mineralization is accompanied by, and developed within, limestone which is replaced by ferruginous dolomite and iron carbonate minerals. Sulphide minerals consist of disseminated to banded pyrite, with subordinate arsenopyrite and pyrrhotite and minor bismuthinite and sphalerite. Small amounts of disseminated scheelite are also present. The main sulphide minerals exhibit at least three stages of mineralization. The best intersection from sulphide bearing mineralization averaged 4.04 g/t gold over 96.01 m from hole Rau-09-66.
Oxide mineralization is completely devoid of sulphide minerals and ranges from very competent, weakly porous limonitic mud to rubbly porous limonitic grit. The oxide appears texturally amorphous within most intersections but occasionally exhibits residual color banding that may represent relict sulphide textures. Complete oxidation extends up to 250 m from surface. Highlight oxide grades (RAU-09-19 which returned 24.07 g/t gold across 28.04 m) and deepest oxidation occur where northerly trending extensional faults intersect the regional structural corridor. Sulphide mineralization at the Tiger Zone remains open to extension along strike and down dip at both ends of the known zone, as well as at depth across a normal fault that locally defines the southwest margin of the favourable structural corridor.
Scheelite Tremolite-Actinolite Skarns
Six known tungsten skarn showings occur within the Rau Trend in fairly close proximity to the Rackla Pluton. These skarn showings are represented as a combination of scheelite-tremolite and actinolite skarns containing varying concentrations of pyrite, pyrrhotite and rare chalcopyrite. The skarn showings have associated moderate to strong tungsten, gold and copper soil geochemical anomalies. These skarn targets have yet to be drill tested.
Gold-Bearing Quartz-Boulangerite Vein
The Now Showing is situated within a pronounced northwest trending gully located where little outcrop is exposed, but abundant float occurs along a more than 400 m area. Mineralization was first discovered in 1969 and followed up in the 1970's. Prospecting by ATAC in 2009 returned 1.03 g/t gold, 447 g/t silver and 13.45% lead from a float sample. The bedrock source of this mineralization is still unknown. Three holes were drilled at the Now Showing but due to poor ground conditions the holes were terminated before they reached the targeted depth of mineralization.
The Ocelot discovery was first identified in 1978. It is marked by a 110 m long, 25 m wide surficial gossan, which formed by the precipitation of iron oxides containing silver, lead and zinc from solutions traveling upward from a massive sulphide deposit. The gossan has a northwest orientation and parallels an adjacent topographic linear feature. A total 4,918 m in 24 holes was drilled at Ocelot.
Ocelot was first diamond drilled in 2010 and 2011 and returned sulphide mineralization that is contained within a steeply dipping northeast trending fault. Mineralized drill intercepts included 14.82 m of 400.18 g/t Ag, 20.44 % Pb and 9.50 % Zn from hole OC-11-11. The full limits of this mineralized structure are not yet known and are still open for expansion.
The Kathy Showing
comprises a 40 m wide by 30 m long surficial gossanous ferricrete slab, located approximately 750 m southeast of the Rackla Pluton. The gossan is situated downhill of a thrust fault that places shale, to the south, over carbonates to the north. It is believed that the gossan is formed by fluids traveling along this thrust fault and mineralization similar to the Ocelot discovery may be present.