Will rush to Yukon spill into Alaska?
A century-old rivalry continues as these northern neighbors draw prospectors, miners to the world-class terranes shared by both
Last updated 11/20/2011 at Noon
Is the "Yukon Gold Rush" about to spill into Alaska? Since the 1896 discovery of gold on the aptly named Bonanza Creek sparked a stampede of fortune seekers to the rivers and streams of the Klondike, these world-class mining jurisdictions that share a common geological and mineralization history have been engaged in a cross-border rivalry of drawing prospectors and miners to their mineral-rich deposits.
While 19th Century miners seeking their fortunes in Alaska's Fortymile and Circle mining districts were the first to answer the call when gold was discovered in the Klondike, three short years later the tides reversed as thousands of prospectors in the Yukon pulled up stakes and stampeded across the breadth of Alaska to make their fortune on the gold-rich beaches near Nome. This ebb and flow of prospectors and miners has continued through the decades.
During a presentation at the Alaska Miners Association 2011 Annual Convention in Anchorage, Patrick Sack, an economic geologist at the Yukon Geological Survey, outlined a banner year for the Yukon's mining industry and pointed to the geology shared by the territory and its stateside neighbor to the west.
$600M of exploration
Whether it was a matter of logistics or a manifestation of the neighborly rivalry between Yukon and Alaska, Sack's update on exploration and mining in the Yukon was the lead presentation of the "Issues Affecting Alaska Miners" session at the early November convention.
Sack informed his Alaska audience that exploration expenditures in the Yukon are expected to near the C$300 million mark - 69 percent of which was spent on the search of gold. This is almost double the previous record of nearly C$160 million spent in 2010 and some 40 times the C$7.2 million spent on exploration in the territory a decade ago.
The economic geologist said incessant claim-staking is keeping the territory's recorders office swamped. During the first eight months of 2011, more than 94,000 new hard rock claims were staked in the Yukon, bringing the total claims in good standing to around 250,000, nearly triple those held in 2009.
Sack's stateside counterpart - Alaska Department of Natural Resources Division of Geophysical Surveys Senior Minerals Geologist David Szumigala - told Mining News that exploration spending in Alaska will also be up around US$300 million, or slightly higher than the US$264 million spent in 2010.
While final tallies from either jurisdiction will likely not be calculated for several months, 2011 may mark the first year in modern times that the Yukon came out on top in terms of exploration spending. Whether it is Alaska or Yukon that claims the title of most exploration dollars spent in 2011, combined more than half-a-billion dollars is being invested to investigate the mineral potential of these two world-class mining jurisdictions.
The recent exploration rush to the Yukon can largely be attributed the the 2008 White Gold discovery in the Dawson Range. This 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 Gold and Kinross Gold Corp.'s White Gold.
In the Yukon, the Dawson Range stretches from around Rockhaven Resources Ltd.'s Klaza property northwest through Radius Gold Inc.'s Sixty Mile property. Without regard to international borders, this swath of deposits, prospects and placer gold mines carries into Alaska's Fortymile, a placer mining district that predates the Klondike discovery by about a decade.
While more than 30 exploration companies have descended on the White Gold District, Full Metal Minerals Ltd. and Millrock Resources Inc. are the only companies that have said they are currently seeking similar Dawson Range prospects in the Fortymile District.
Mike Burke - who was head of Minerals Services Division of the Yukon Geological Survey before joining the private sector as chief geologist for Golden Predator Corp. - attributes the current lack of interest in chasing White Gold-style mineralization into Alaska to proximity.
"Really, it is 'close-ology' - the closer you are to the new discovery, the better the odds of finding something similar and eventually that spreads out further and further," Burke told Mining News during a recent interview. "We look for parallels a little further away but usually we look for parallels nice and close."
The geologist drew parallels to a similar situation where the discovery of the Pogo gold deposit drew a rush of explorers into Alaska but never expanded across the border into the Yukon.
"When you look at it, you could say the same thing about when Pogo was discovered. It's kind of in the Dawson Range; it's around Cretaceous intrusions, so same intrusions; and you are in Yukon-Tanana Terrane that comes across the border into the Yukon," he explained.
Burke said a handful of people looked around the Yukon, hunting for Pogo-style gold but did not turn up anything significant.
"But in Alaska it was going nuts all around Pogo," he recalled. "So, the same thing with White Gold -they are working within that trend as close as they can and slowly moving outward."
When pressed on details about the prospectivity of eastern Yukon and western Alaska, Burke quipped, "I am not a government guy anymore - I don't want to reveal any secrets."
What is not a secret is that the modern "Yukon Gold Rush" has expanded to the Alaska border. Radius is seeking gold at its Sixty Mile project immediately across the border from the Fortymile District.
In late October, Radius reported intersections of high-grade gold over narrow widths at Sixty Mile. Hole DDH11-08 which cut 19 grams per metric ton gold over 1 meter and DDH11-10 cut 132 g/t gold over 1.5 meters. Another seven holes from this year's program are pending.
Adjacent to the east and south of Sixty Mile, Ryan Gold Corp. is seeking White Gold-style mineralization on its Fifty Mile claims. The company - of which Shawn Ryan is president - has completed mapping, geophysical surveys and detailed geochemical soil sampling to evaluate the potential of this project.
"The Fifty Mile Project has potential to host mineralization similar to that at the White Gold deposit of Kinross Gold Corp. based on similar geological setting and geology (including Devonian-Mississippian orthogneiss, and ultramafic rocks), favorable airborne magnetic geophysical signature, gold-in-soil anomalies with significant alteration and mineralization, and presence of placer creeks," Ryan Gold posts on its website.
Rolling Thunder, a grassroots program Full Metal initiated in 2010, is seeking White Gold-style mineralization as the source of more than half a million ounces of placer gold recovered from streams draining the rolling hills of the Dawson Range on Alaska's side of the border.
Full Metal - which shared its managers and geologists with Underworld Resources Inc. during that junior's exploration of White Gold - is applying its firsthand understanding of the geologic controls, geochemistry and targeting methods that led to discoveries at White Gold to its Rolling Thunder claims.
The company said its reconnaissance sampling and mapping has identified multiple areas of strong alteration and quartz veining reminiscent of White Gold.
Millrock has completed similar prospecting at its some 23,000 hectares (57,000 acres) of claims in the Fortymile district and the project-generating explorer said it is looking for a partner to continue this exploration.
While the White Gold discovery helped spark the exploration rush to the Yukon, Sack told Mining News that the Dawson Range and the Yukon-Tanana Terrane in which it is hosted is not the only Yukon-Alaska-shared geology and may not be the most prospective.
The government geologist suggests the Selwyn Basin, also known as the North American Basinal Terrane, could hold more promise for explorers seeking minerals in Alaska.
In the Yukon, the Selwyn Basin hosts a multitude of styles of mineralization. Renown for its SEDEX silver-zinc-lead deposits, this terrane has recently come into the spotlight for hosting the only known Carlin-style gold mineralization outside of Nevada.
While Sack is reluctant to officially deem ATAC Resources Ltd.'s Rackla Gold discovery as "Carlin-style," most geologists familiar with the find agree the parallels are hard to ignore.
Additionally, the Yukon's Selwyn Basin hosts other carbonate replacement-style gold deposits, such as Atac's Tiger zone; orogenic gold, such as Northern Tiger Resources Inc.'s 3Ace property; polymetallic vein systems, such as Alexco Resources Corp.'s Bellekeno Mine; and intrusion-related gold, such as Victoria Gold Corp.'s Eagle Gold deposit.
This mineral-rich terrane stretches from southeast Yukon across the breadth of the territory along the north side of the Tintina Fault. While only a small portion of the contiguous terrane north of the Tintina Fault pokes into Alaska, some 120,000 square kilometers (46,000 square miles) of the terrane assemblage that lies south of the continental scale fault has been displaced in Alaska as the Tintina Gold Belt drifts westward.
This chunk of misplaced Selwyn Basin-like terrain dominates Alaska's Eastern Interior. Geologists familiar with both the Eagle Gold deposit in the Yukon and Kinross Gold Corp.'s Fort Knox Mine in Alaska have drawn close comparisons between the two intrusion-related deposits.
Eagle Gold and Fort Knox are found in a once continuous belt of mid-Cretaceous intrusions known as the Tombstone Plutonic Suite. This subset of the Selwyn Basin is also home to Golden Predator's Brewery Creek project, Ryan Gold's Ida Oro discovery and Atac's 1,600-square-kilometer (620-square-mile) Rackla Gold property.
The Circle Mining District, situated about 130 kilometers (80 miles) northeast of Fort Knox, is part of Alaska's portion of the Tombstone Suite immediately south of the Tintina Fault. The streams of this historical district have produced more than 1 million ounces of placer gold but a significant hardrock source has yet to be found here.
Applying similar exploration techniques that have been successful in making gold discoveries in Yukon's Dawson Range, Full Metal completed soil sampling across its 27,502 hectares of mineral claims it staked in the Circle District in 2011. This initial investigation has uncovered several promising zones. The explorer is planning an aggressive follow-up program during the 2012 field season, including trenching and diamond drilling.
While the Dawson Range and Selwyn Basin have nabbed the spotlight, a small contingent of explorers has quietly moved into southwestern Yukon, a region that shares multiple geological relationships with Alaska.
"It is well-tied to Alaska," Sack told the AMA crowd.
Prophecy Platinum Corp.'s platinum group metal-nickel project in southwestern Yukon is an ultramafic-associated deposit similar to the Man PGM-nickel project being explored by Pure Nickel Inc. at its Man project, which is also located in the Wrangellia Terrane about 400 kilometers (250 miles) west.
From the south, the Alexander Terrane - which hosts a series of volcanogenic massive sulfide deposits that includes Hecla Mining Company's silver-rich Greens Creek Mine - continues into southwestern Yukon.
Sack, who wrote a paper on the geology and geochemistry of Greens Creek while earning his doctorate at the University of Tasmania, is familiar with this VMS-belt that stretches along the Southeast Alaska Panhandle north into the Yukon.
Based on recent field investigations of this corner of the territory, Steve Israel of the Yukon Geological Survey has proposed that this region has close ties to the Juneau Gold Belt, a prolific orogenic gold-producing region known to host such high-grade deposits as Coeur d'Alene Mine Corp.'s Kensington Mine and the renowned Treadwell Mine.
"A package of schists here called the Kluane Schists that are bounded (to the north) by the Denali Fault and tectonically, stratigraphicaly very similar to the area around Juneau and have garnered some exploration interest for orogenic gold," Sack explained. "The Ruby project, otherwise known as Killer Gold, is probably the best example of this."
Additionally, companies are exploring southwestern Yukon for porphyry copper-gold and intrusive-related gold deposits. Among these companies are Tarsis Resources Ltd. and Teck Resources Ltd., which are exploring adjacent properties in the White River region about 30 kilometers (19 miles) east of the Alaska border.
"The things that we are looking for are porphyry-style deposits or deposits that are related to that type of mineralization," said Tarsis President and CEO Marc Blythe. "We like them because they are potentially large - and potentially large means bigger companies will be interested in them."
While Tarsis has found both copper and gold on its White River claims, Teck said it is looking strictly for gold in the Yukon.
"Our work in the Yukon is gold-only, and a fair bit of it is going back into our historical exploration files and coming up with some very encouraging stream sediment anomalies for gold," Teck Resources VP of Exploration Fred Daley told Mining News. "So, over the last two years we have gone back to the Yukon and staked a couple of large properties and this year we are following up with some soil surveys and additional rock sampling."
From atop a ridge where Tarsis' White River copper-gold-silver discovery was made, Blythe pointed out that from this vantage Alaska could be seen on the horizon to the west. Gazing over the hills that rolled westward, the Tarsis CEO said he is considering looking for new prospects in neighboring Alaska.