ALASKA & THE YUKON — Copper Ridge hot on Scheelite Dome — Drilling aimed at proving up gold target in Yukon

Increasingly, Copper Ridge Explorations (KRX-V) is of the opinion that its Scheelite Dome property represents one of the better mineralized plutonic-related gold targets in north-central Yukon. The company’s enthusiasm is supported by several factors, including a large alteration and mineralization system, widespread soil geochemical anomalies and positive trench and drill results.

Situated 25 km northwest of Mayo, the road-accessible property is currently being subjected to a 15-hole, $375,000 drill program. Once the 11,600-ha project reaches the feasibility stage, Kennecott Canada Exploration, a division of London-based Rio Tinto (RTP-N), will acquire a 49% back-in right or a 2% net smelter royalty. The original vendor also holds a 2% NSR.

Scheelite Dome is one of five exploration-stage properties Copper Ridge recently acquired from Kinross Gold (K-T) in exchange for 1 million shares. As a result, Kinross holds about 26% of Copper Ridge. The properties formerly belonged to La Teko Resources, which merged with Kinross last February on the basis of its advanced-staged Ryan Lode and True North gold deposits, near Fairbanks, Alaska.

“We first looked at the Scheelite Dome property two years ago,” says Gerald Carlson, president of Copper Ridge. “We had a good summer last year, and managed to get a small drill program going. We feel we’re in elephant country for gold deposits, and we’ve got some great properties.”

Prior to the merger, La Teko conducted reconnaissance soil geochemistry and prospecting at Scheelite Dome, delineating a coincident gold-arsenic-antimony anomaly measuring 4 by 1.5 km. This was followed by a widely spaced induced-polarization (IP) survey, further soil sampling and seven drill holes. Drill targets were selected by integrating anomalies generated by IP and resistivity geophysics and gold-in-soil anomalies.

The best hole, No. 12, intersected 7.7 metres averaging 3.67 grams gold per tonne in the upper oxidized portion, including a 1.5-metre section of 10.56 grams. Hole 11, collared 400 metres to the northeast, cut a 0.8-metre section of 1.65 grams gold and ended in mineralization. Copper Ridge believes hole 11 may have been stopped just short of the mineralized structure encountered in hole 12.

Two holes in the current program were drilled as 25-metre stepouts from last year’s hole 12, while two others were drilled close to last year’s hole 11. When The Northern Miner visited the property in early October, Copper Ridge was drilling hole 8, designed to test northwesterly trending structures roughly 250 metres northeast of hole 12.

The company also plans to drill at least one hole beneath the northeasterly striking Hawthorne trench, which averages 0.3 gram gold per tonne over its entire length of 750 metres. Assays from the first few holes are expected shortly.

Exploration in the area dates back to the turn of the century, when gold placers were worked in Highet and Johnson Creeks. Records indicate that about 50,000 oz. were mined from these placers, and several small-scale placer miners are active there even today.

The first hard rock discoveries were reported in 1916, around the time the Hawthorne vein was discovered. This vein and others like it were explored until the early 1940s, when, with tungsten sought as a strategic metal for the war effort, the focus shifted to the source of placer scheelite. In 1942, the Geological Survey of Canada discovered a scheelite occurrence on the northern side of the Scheelite Dome, and several companies explored for more scheelite occurrences until 1981.

During the late 1980s, after the discovery of the Fort Knox deposit, exploration shifted to intrusion-hosted gold mineralization. Kennecott assembled the present-day Scheelite Dome property and, between 1994 and 1997, carried out soil geochemical sampling, geological mapping, airborne geophysics, extensive excavator trenching and two drill campaigns.

In 1997, La Teko entered into an option with Kennecott to earn a 100% interest.

Scheelite Dome is underlain by a siliciclastic unit of Upper-Proterozoic/ Lower-Cambrian-aged rocks. The metasedimentary rocks include highly foliated, interlayered muscovite-chlorite phyllites, as well as quartz-feldspathic and micaceous psammites. Marble and calc-silicate rocks are generally found as pods and boudins throughout the property. The igneous rocks on the property are believed to be part of the Late Cretaceous-aged Tombstone plutonic suite, and these consist of hornblende- and biotite-bearing granodiorite and diorite.

The Tombstone plutonic suite represents a group of intrusions that form a narrow, 50-km-wide, east-westerly trending belt stretching 550 km from Dawson City to the border with the Northwest Territories. The intrusions are spatially and genetically associated with a wide range of base and precious metal occurrences.

The Scheelite Dome property is on the southerly dipping limb of the southwesterly trending antiform. Deformation is believed to be Jura-Cretaceous in age. A strong, northeasterly trending, southeasterly dipping foliation affects the metasedimentary rocks and is the most prominent fabric on the property. Small-scale isoclinal folds and crenulations are also common. The foliation is crosscut by three sets of moderate to steeply dipping faults, shears, fractures and joint structures.

Alteration and mineralization are directly related to the intrusive bodies of the Tombstone plutonic suite. Mineralization occurs in several styles, including structurally controlled quartz-sulphide veins, disseminated sulphides, skarn and replacement.

“It’s a big system, which is mineralized thoughout,” says Copper Ridge Vice-President Mark Fields. “You can find gold mineralization anywhere on the property; the challenge we face is finding the high-grade areas.”

The primary target is the structurally controlled quartz-sulphide veins, which crosscut both the metasediments and the Scheelite Dome stock. The gold grades are thought to be tied to the density of veining; therefore, areas with closely spaced sheeted veins, stockwork zones and breccia zones tend to have higher grades. The veins both occur in and are external to the contact metamorphic aureole that surrounds the Scheelite Dome intrusion.

Disseminated sulphides are hosted in both the intrusive and metasedimentary units. Most of the sulphides are found outside the intrusive units. Areas of disseminated mineralization are typically altered by sericite and silica (or, less commonly, by biotite) and are often found surrounding the quartz-sulphide mineralization.

Zones of gold-enriched garnet-wollastonite-quartz-tremolite skarn with disseminations and blebs of pyrrhotite, scheelite and chalcopyrite exist on the northern side of the Scheelite Dome intrusive.

Sulphides, specifically arsenopyrite, replace lime-rich bands in metasediments — a type of mineralization found in the central portion of the property.

Most of Scheelite Dome lies about 1,370 metres above sea level.