Location and Access
The Dorian Miner project is located near Whitehorse, Yukon Territory, Canada.
Dorian Miner can be accessed by an All-Terrain Vehicle (ATV) trail extending from the end of the “CCC Road”, itself extending southeast from the South Klondike Highway (Yukon Hwy 2) about 8 km south of Carcross Corners (see Regional Location Map). The South Klondike Highway is a paved all-weather road, open year-round. The CCC Road is a dirt road, but is open year-round, due to permanent residences along its entire length. The ATV trail is locally rough and quite steep, requiring skilled ATV operators. The length of the trail from the CCC Road to the NI showing is 5.9 km. The trail is also accessible in winter by snowmobile.
The property area has a dry sub-arctic continental climate, with some intermittent moderation in winter caused by south winds originating from the Gulf of Alaska. Average high temperatures in July for Whitehorse stand at 20oC; average lows at 8oC. Average January high temperatures stand at -14oC; average lows stand at -22oC. Precipitation at Whitehorse averages about 10 inches (250 mm) per year, with the spring being the driest period, and the fall being the wettest. Temperatures are somewhat lower and precipitation somewhat higher on the property due to elevation.
Whitehorse (2013 pop. 28,028) is a full service city with an available workforce, including exploration and diamond drilling services. Whitehorse is serviced by an international airport and the Alaska and South Klondike highways. The White Pass and Yukon Railway is not operative north of Carcross.
The property covers a plateau with elevations ranging from about 1,200m to 1,400m, except for a stream valley in west-central areas which is somewhat lower. Most of the property is covered by taiga and buckbrush typical of areas along the tree line in the Whitehorse area, with hilltops slightly above tree line covered by dense buckbrush.
Outcrop exposure is good along ridgelines and hilltops in eastern areas but very sparse in western areas. Glacial till covers property areas without outcrop exposure, and attains a minimum thickness of 30 metres in western areas, particularly along the west-flowing stream valley.
Regional Geological Setting
The Dorian Miner property is located within the Whitehorse Trough, forming the northern portion of the Stikinia Terrane, consisting of mafic to intermediate volcanic flows and carbonate and mixed clastic-carbonate assemblages. The Whitehorse Trough is part of the island arc allocthonous terrane comprising the Intermontane Belt (Nicholson and Barron, 1996). In the property area, the Whitehorse Trough consists of three major groups: the Lewes River Group, Laberge Group and the Tantalus Formation. The Upper Triassic Lewes River Group consists of an island arc assemblage comprised of mafic volcanic and volcaniclastic rocks, including greywacke, siltstone, argillite and conglomerate, and an upper unit of grey limestone. The Laberge Group consists of a Lower to Middle Jurassic dominantly sedimentary assemblage; these are lithologically indistinguishable from Lewes River clastic sediments, but are stratigraphically higher. The Tantalus Formation is an Upper Jurassic to Lower Cretaceous sedimentary assemblage which locally hosts coal seams (Nicholson and Barron).
The Whitehorse Trough assemblages have been intruded by several plutonic suites; most notably the mid-Cretaceous Whitehorse Suite, consisting of grey, equigranular, medium to coarse grained felsic to intermediate and lesser mafic intrusions. The Whitehorse Batholith, within Whitehorse city limits on the southwest side of the Yukon River, is associated with numerous past-producing copper-gold skarn deposits of the Whitehorse Copper Belt. A second suite, the late Cretaceous Prospector Mountain Suite, consists of coarse grained equigranular quartz-hornblende-biotite granite; this is represented by the Mount Lorne Pluton directly south of the property. A third major suite is the early Cretaceous Teslin Suite, comprised of fine to coarse grained hornblende biotite granite, granodiorite and quartz monzonite (Gordey and Makepeace, 2001).
The regional structural orientation in the Whitehorse area is predominantly NNW – SSE, slightly oblique to the NW – SE orientation seen throughout most of southwestern Yukon. The orientation of the lithological units and stratigraphic setting is roughly parallel to the NNW – SSE structural tren.
The Dorian Miner property is underlain primarily by grey, semi-massive, locally foliated and locally carbonaceous limestone marking the upper member of the Lewes River group (Map 1). The southern property area covers the northern contact of the limestone with the Upper Cretaceous Mount Lorne Pluton, consisting of coarse grained, buff-coloured equigranular, hornblende-biotite granite (Figure 4). The limestone unit becomes progressively more coarsely crystalline towards the intrusion, indicating contact metamorphism.
The Ni showing is marked by at least three phases of dykes: a pulse of diorite (intermediate to mafic) dykes, locally feldspar porphyritic, to five metres in thickness (Figure 5); a set of biotite quartz monzonite dykes from 1-3m thick and containing up to 15% biotite crystals (Figure 7); and feldspar-hornblende phyrric intermediate dykes typically about 2m in width (Nicholson and Barron). Nicholson and Barron identified the set of diorite dykes as associated with the auriferous arsenical mineralization at the Ni showing. Elsewhere, fine grained mafic-intermediate dykes are fairly common, particularly near the Mount Lorne pluton, where dykes are typically limonitic after fine grained pyrrhotite and pyrite. Fine grained felsic dykes, locally weakly arsenical, also occur in southern property areas but are less abundant. Narrow coarse grained hornblende-biotite dykes occur directly north of the intrusion boundary, representing apophyses from the stock.
Nicholson and Barron mapped the northwest property area as underlain by calcareous black siltstone, and also identified narrow units in the trenched area. The siltstone is strongly calcareous and fissile, and commonly limonitic due to fine pyrite. The 1996 Nicholson report states that the fissile nature resulted in recessive weathering, and infers that the more prominent limestone units may be intercalated or interbedded with the siltstone beds. The northwestern area was not mapped in 2013.
Year-2013 property mapping revealed three major structural orientations: a NE – SW trending lineation (Figure 6); an east-west trending lineation and a NNW – SSE lineation, occurring primarily near the Mount Lorne pluton. The NE – SW lineation is marked by at least one arsenical occurrence at the NI showing, a pronounced lineament in the central property area, where it is associated with a weakly mineralized quartz vein, and by local stream drainages. The strike of local shear zones averages about 220o, typically dipping steeply to the northeast. The north-south lineation is marked by a fault zone extending at 345o - -85o across the north margin of the pluton, associated by strongly fractured to brecciated calc-silicated altered limestone and moderate shearing within the quartz-biotite granite. Mapping suggests this fault has caused a sinistral offsetting of stratigraphy of about 100 metres. Several smaller shear zones at comparable orientations occur elsewhere throughout the property. The east-west lineation is most evident in south-central property areas north of the intrusion, striking from 90o – 100o, dipping vertically or steeply southward. Although limited exposure inhibits the ability to conclusively determine dyke orientations, mapping in 2013 suggests many dyke orientations extend along this lineation.
The NE – SW lineation may be the dominant structural orientation on the property. Both this and the east-west lineation appear to predate emplacement of the late Cretaceous pluton; however, the north-south lineation either post-dates pluton emplacement or was re-activated during post-emplacement times.
Re-sampling of the Ni showing essentially confirmed the presence of gold-bearing arsenical mineralization, and also indicated the presence of at least three separate occurrences across a 100 x 60-metre area. The northwestern portion, indicated by Samples RE5881460 and RE5881461, consists of massive and banded arsenopyrite within a NE-SW trending shear zone hosted by grey limestone. Sample RE5881460 was a 1.2-metre chip sample which returned a value of 3.11 g/t Au with 0.9 g/t silver (Ag) and 1.47% arsenic (As) (Figure 8, Appendices 2 and 3). Sample RE5881461 was a select composite grab of arsenopyrite-rich material within the chip sampled interval; this returned 6.52 g/t Au, 5.5 g/t Ag and 4.82% As (Figure 9). Both samples returned anomalous bismuth (Bi) values of 27 and 83 ppm respectively, and antimony (Sb) values of 33 and 97 ppm respectively, roughly commensurate with the arsenic concentrations. Sample RE5881461 also contained anomalous cobalt (Co) and lead (Pb) values of 179 and 344 ppm respectively. Sample RE5881460 was the first chip sample taken from the Ni showing to return a value greater than 1.0 g/t gold.
Re-sampling of arsenopyrite veining in the mafic dykes about 100m to the east, previously returning values to 0.633 opt (21.7 g/t) gold, returned weakly elevated gold values only, with the exception of Sample RE5881462, which returned a value of 1.04 g/t Au with background Ag and 17.4% As. Pathfinder element values are low to background, with the exception of a value of 19 ppm Sb. Sample RE5881464, taken from weakly chalcopyrite-bearing skarn within an intermediate dyke returned a value of 0.024 g/t Au with 497 ppm As, 276 ppm Cu and 35.6 g/t Mo.
A composite grab sample of a mafic dyke about 60 metres south of Sample RE5881460 returned a value of 6.05 g/t Au with 0.4 g/t Ag, 2.59% As, 68 ppm Bi and 65% Sb. Grid soil sampling in 1996 returned a value of 31 ppb Au about 175m south of Sample RE5881460; the next three samples to the south (downhill) of this returned elevated arsenic and cobalt (Co) values, a similar signature to that of the 2013 chip and select composite grab samples. This suggests a separate occurrence with a similar geochemical signature exists near the sample returning 31 ppb Au.
The small copper occurrence was located in 2013. This consists of coarse crystalline chalcopyrite with lesser bornite, malachite and minor azurite and pyrite within granitic endoskarn directly along the north margin of the pluton (Figure 10). A composite grab sample returned a value of 9,440ppm (0.994%) copper (Cu), 6.6 g/t Ag, 0.026 g/t Au and 471 ppm Zn. Anomalous accessory element values include 2 ppm mercury (Hg), 8 ppm Sb, 152 ppm tin (Sn) and 20 ppm tungsten (W). The showing consists of a small pod traceable for only a few metres; however, other pyrite-pyrrhotite skarn occurrences were found along the intrusion contact. These returned background to near-background precious metal and pathfinder values, except for weakly anomalous copper values to 115 ppm.
Several moderately silicified pyrite and pyrrhotite-enriched limonitic mafic dykes were discovered and sampled in the south-central property area north of the intrusion (Figure 11). The best value returned was 0.039 g/t Au with 0.2 g/t Ag and 5 ppm Sb; other samples returned background to near-background gold and pathfinder values.
The ridgeline slightly north of the pluton margin is covered by abundant glacial float of mafic to intermediate dyke material, commonly mineralized with pyrite +/- pyrrhotite. Glacial movement was southeast to northwest; this suggests the presence of more and potentially abundant skarn occurrences, including other copper skarn showings.
A 1.1-metre chip sample of sheared chloritic +/- garnet skarn in limestone within the north-south trending shear zone directly north of the intrusion returned a tungsten value of 181 ppm, with a tin value of 60 ppm.
A quartz vein at least 16 metres long and up to 0.5m wide was discovered directly south of the pronounced NE-SW trending lineament in the central property area. The vein is weakly mineralized with arsenopyrite and sphalerite. The best value was returned from a 0.45-metre chip sample yielding 0.065 g/t Au, 2.4 g/t Ag, 251 ppm Pb, 42.5% cadmium (Cd) and 1,610 ppm (0.161%) Zn. A separate composite grab sample returned a value of 3,790 ppm Zn and 73.2 ppm Cd. A composite grab sample of nearby altered intermediate dyke rock returned 0.058 g/t Au, 0.5 g/t Ag and 865 ppm As.