FORTYMILE – The storm clouds responsible for the torrential rains that recently washed away long sections of the Taylor Highway are not the only source of rumbling in the Fortymile region of eastern Interior Alaska. Full Metal Minerals Ltd. has launched the Rolling Thunder Project here this summer. The staking and exploration initiative is targeting the lode source of more than half a million ounces of placer gold recovered historically from the streams draining the rolling hills of the Fortymile Mining District.
The discovery of the yellow metal in the region ignited Interior Alaska’s first gold rush in 1886, a decade before the stampede to the Klondike a few miles to the east.
Though Fortymile – like most of the placer gold producing districts scattered across the Tintina Gold Belt – has been investigated by geologists and prospectors seeking the source of the alluvial deposits, an economic lode has yet to be discovered in this historic placer-producing region.
Full Metal’s website quotes Hungarian-born biochemist Szent-Gyorgyi as saying, “Discovery consists of seeing what everybody has seen and thinking what nobody has thought.”
This adage and the Vancouver B.C.-based junior’s firsthand understanding of the geologic controls, geochemistry and targeting methods successfully applied by Underworld Resources Inc. at its White Gold deposit about 60 miles, or 100 kilometers, to the southwest in the Yukon Territory could be keys to unlocking this 125-year-old mystery.
“Full Metal and Rolling Thunder is in a unique position for advancing exploration in the area. Our relationship with Underworld Resources has provided the Rolling Thunder technical staff with exploration techniques that were successfully used on the White Gold property,” Rolling Thunder Project Manager Chris Siron told Mining News.
Underworld connectionsFull Metal’s top executives, Rob McLeod and Michael Williams, along with former Placer Dome exploration manager Adrian Fleming formed Underworld in 2008. In less than two years, the seasoned team of geologists transformed the White Gold prospect into a major a new gold deposit with a resource of 1.41 million ounces averaging about 3 grams per metric ton gold, which resulted in Kinross Gold Corp. buying the young junior and its assets for C$139.2 million.
The White Gold discovery sparked a claim-staking rush to the Yukon Territory’s Dawson Range. The mineral belt – commonly referred to as the White Gold District – includes porphyry copper and epigenetic gold deposits such as Northern Freegold Resource Ltd.’s Freegold Mountain, Northern Tiger Resources Inc.’s Sonora Gulch, Kaminak Gold Corp.’s Coffee and Kinross’ White Gold.
Without regard to international borders, this swath of Cretaceous-age deposits, prospects and placer gold mines stretches northwest from Capstone Mining Corp.’s Minto copper-gold-silver mine in central Yukon across the border into Alaska.
While more than 30 companies are investigating the White Gold District, Full Metal is the only company currently seeking similar prospects in the Fortymile region.
“White Gold has an unusual geologic and geochemical signature as it relates to gold mineralization. The Rolling Thunder staff has recognized White Gold’s unique geologic architecture and is taking an analogous approach toward exploration on the Alaska side of the border, although, we’re not exclusively targeting White Gold-style deposits,” Siron explained. “Rather, the Rolling Thunder staff is taking an open-ended approach toward gold exploration.”
Seeking the lodeThe Rolling Thunder claims blanket around 34,000 hectares, or 84,000 acres, of the hills that rise above some of the most prolific placer gold-bearing streams in Fortymile, including Chicken Creek, which alone produced more than 100,000 ounces of the precious metal.
“We look for recent and historic placer mining that occurs in drainages of prospective targets,” Siron explained.
Full Metal geologists are using a proprietary geochemical data set compiled from historical exploration and their firsthand knowledge of White Gold mineralization as they traverse nine blocks of Rolling Thunder claims that stretch from the Yukon-Alaska border to the company’s Fortymile silver-zinc-lead property about 60 miles, or 100 kilometers, to the northwest.
Using the alluvial gold deposits to vector their search, Rolling Thunder geologists are seeking rock formations similar to those that are found in and around the White Gold mineralization.
“Lithologies similar to Golden Saddle and Arc-Zone – such as amphibolite-grade felsic orthogneiss and metasedimentary host rocks; spatially associated mafic and ultramafic units, which may behave as fluid seals; areas of favorable structure such as thrust faults, structural corridors and fault intersections; breccia zones, including lode and stockwork quartz veining – are being targeted.”
Applying the Ryan methodLike the White Gold District in the Yukon, the Fortymile region has not experienced glaciation. The gradual weathering and lack of ice flows scouring the surface means potential gold-bearing lode sources of the alluvial deposits in the streams are mostly hidden beneath a layer of sub-Arctic tundra. The best rock exposure can be found near the tops of the rolling mountains common to the areas. For this reason Full Metal geologists are traversing the hilltops and ridges as they do a first-pass sampling and mapping of the Rolling Thunder claims.
McLeod, Full Metal’s CEO and vice president of exploration, explained that while the exposed weather resistant rocks provide geological information for mapping, they are not necessarily the host of the gold being sought. Consequently the explorer is depending on soil sampling, a technique that was successfully utilized by Dawson City prospector Shawn Ryan in the discovery of the Golden Saddle and Arc zones at the White Gold property.
“Rolling Thunder staff has spoken with Shawn Ryan directly about sampling protocols and methodologies used at White Gold. These methods are being employed at our claims,” Siron explained.
“This reconnaissance sampling and mapping has already identified multiple areas of strong alteration and quartz veining reminiscent of White Gold.”
At the 20X prospect, grab samples from oxidized quartz veins returned 5.5 and 4 grams per metric ton gold, with anomalous molybdenum and other pathfinder elements similar to the White Gold Property. Nine samples collected from the 20X claim-block ranged from 0.014 to 5.5 g/t gold and averaged 1.53 g/t gold.
A grab sample from a one meter wide quartz vein trending onto Full Metal claims at the Tweeden prospect graded 52.2 g/t gold. Secondary structures splaying off of main structure returned assays between 1 and 2 g/t gold within sheeted quartz veins.
According to Siron, early results from the soil sampling also are returning promising results.
“Results from a majority of the first-pass reconnaissance soil lines are still pending, however, encouraging results have been received,” the Rolling Thunder manager said. “White Gold-style geochemical signatures are recognized at several of our claims.”
Rolling Thunder geologists are returning to these more prospective areas to conduct more thorough sampling.
“Followup work has begun targeting geochemical anomalies by means of infilling soil sampling and gridded soil surveys,” Siron explained.
A leg-up in the FortymileFull Metal has been exploring its LWM silver-zinc-lead deposit in the Fortymile region for nearly four years. This experience, along with the rapport the junior has built with people of the area, gives the company a leg-up on other explorers that may decide to seek out White Gold-style mineralization as it trends into Alaska.
“The Full Metal technical staff has a fond geologic knowledge of the Fortymile District of Alaska. In addition, we have established relationships with organizations working in the area, including the USGS (United States Geological Survey). We are also participants in the Yukon Gold Project, an industry consortium developed to improve the geologic understanding of the region and to promote successful exploration,” Siron explained.
The Yukon Gold Project that Siron referred to is a two-year study aimed at gaining a better understanding of the geology and geochemistry of the Dawson Range.
It is being conducted by the Mineral Deposit Research Unit, a collaborative venture between the mining industry and the University of British Columbia.
The project consists of six modules:
• Tectonic and Structural Setting
• Magmatic Evolution & Geochronology
• Exploration Geochemistry
• Targeting with Placer Gold
• Metallogeny and Deposit Studies
• Fluid Geochemistry and Ore Genesis
Full Metal, as a sponsor of the project, is privy to the information that it generates and plans to apply the findings at its Rolling Thunder Project on the Alaska side of the border.
The explorer is also putting together a library of placer gold from the Fortymile region. This collection, which is being tested for its geochemistry and fineness, will assist the geologists to vector in on the lode source of gold still being recovered from streams in the district.
“The Fortymile is a difficult place to explore; however, the foundation we’ve established and our persistence and aggressive approach towards grassroots exploration has given us a strategic position in an area that is undoubtedly a forefront for upcoming exploration by many companies,” Siron said.
Storms flood FortymileThe Fortymile District, known for its hot, dry summers, has experienced unusually wet conditions this summer, which made exploration at Rolling Thunder particularly challenging.
The area, which normally receives an average of about 10 inches of annual precipitation, was hit by a 3.2-inch downpour over 24 hours starting July 10. This deluge sent the Fortymile River over its banks and it crested at the highest levels ever recorded. The flooding washed out the Taylor Highway, stranding travelers and miners along the 42-mile-, or 68-kilometer-, stretch of road between the community of Chicken and the Alaska-Yukon border.
During the torrent, Full Metal’s Fortymile crews were forced to stay near its camp located on the historic Chicken Creek about a mile upstream from the community with the same name. However, many of the Rolling Thunder claims are accessible with all-terrain-vehicles, allowing geologists to continue working even when helicopter travel is prevented by the uncommonly frequent thunderstorms rolling through the Fortymile.
“The weather has been very uncooperative. We’ve had some flooding issues near camp and we had a day where the field crews could not go out. But our operation has been running smoothly, considering the circumstances. Access hasn’t been too restricted aside from the main road, which washed out in several places,” Siron told Mining News July 14.