Project boosts search for uranium in Alberta

EXTECH IV study sees potential for unconformity-type deposits

Approximately 10% of the Athabasca Basin is in northeastern Alberta, but this region has yet to yield a uranium deposit comparable in size to the McArthur River or Cigar Lake mines, which are in the basin but in neighbouring Saskatchewan. This is partly because of the remoteness of northeastern Alberta but also because of a lack of new geoscientific data. With the completion of the EXTECH IV Athabasca uranium multidisciplinary study (EXTECH IV), knowledge has been gained and exploration for uranium in Alberta is on the rise.

The 3-year EXTECH IV study was designed to update and expand the understanding and improve the geological, geophysical and geochemical database. It was also conceived to stimulate uranium exploration, particularly in less explored portions of the basin, such as those in northeastern Alberta.

The invitation to participate in the EXTECH IV study was too good for the Alberta Geological Survey (AGS) to pass up. The study provided a treasure trove of information at a relatively low cost. According to Dr. Reg Olson, an EXTECH co-ordinator and Leader of the Minerals Section of the AGS, the AGS’s $150,000 expenditure provides “considerable leverage for the information to which Alberta gained access, including information provided by both Cameco (CCO-T) and Cogema Resources.”

Results of the study suggest Alberta’s portion of the Basin has great potential for large, unconformity-type uranium deposits. Specifically, the study indicates that the basal Athabasca Group in Alberta now appears to be as potentially favourable for hosting uranium deposits as in Saskatchewan. In addition, the basement rocks underlying the basin in Alberta have lithological and structural similarities to basement rocks underlying Saskatchewan’s rich uranium mines. Finally, the alteration and mineralization at one study area, known as the Maybelle River prospect, show similarities to some uranium deposits in Saskatchewan.

The Maybelle River prospect is 200 km northeast of Fort McMurray and was first investigated in 1988 with a drill hole that intersected a 5-metre interval averaging 21% U3O8. More recently at Maybelle River, three sub-projects of the EXTECH IV study were completed; these included relogging and re-analyzing 15 drill cores along with stratigraphic, alteration and organic geochemical studies in the vicinity of the high-grade intersection. At the same time, Cogema was conducting its own drill program.

EXTECH IV indicates that Maybelle River is a north-to-northwest-trending structural zone of highly deformed metasedimentary rocks. This zone is associated with a basement conductor related to graphitic mylonite. In addition, there are several parallel, fault-related mylonite structures nearby.

The Maybelle River graphitic mylonite cuts granitoid gneisses, and geochemical evidence suggests the granitoid gneisses at the Maybelle River prospect are similar to those of Cigar Lake. The basement rocks at Cigar Lake include granitic pegmatites and some other rocks with high background uranium content. One of several hypotheses for the origin of unconformity uranium deposits invokes uranium-rich pegmatites as the source. An alternative hypothesis is that the uranium is derived from sandstones of the Athabasca Group.

Fair Point formation

Mineralization at Maybelle River is hosted in a coarse pebbly conglomeratic sandstone and pebbly sandstone with abundant (up to 15 volume per cent) interstitial clay. These sandstones, known as the Fair Point formation, were once thought to be less permeable and therefore not as likely to host uranium mineralization, yet at Maybelle River they host the prospect. The formation, which ranges from 30 to 50 metres in thickness, also exhibits other types of alteration commonly exhibited in large uranium deposits.

For Alberta, one of the more tangible benefits resulting from EXTECH IV has been the increased level of permitting or staking. In late 2001, following the release of interim results of the EXTECH IV program, 395 sq. km of Alberta’s portion of the Athabasca Basin was staked. Previous to the release, this area was largely open. While government reports concede that some of this ground was staked for diamond exploration, most of the activity is thought to have been related to uranium exploration.

This permitting activity has involved primarily junior exploration companies, such as Valley Gold, Cogema, Cameco and JCU (a consortium of Japanese nuclear energy companies). Junior companies typically have not been involved in uranium exploration, owing to the high cost of drilling targets buried beneath hundreds of metres of sandstone. The EXTECH IV study, however, has helped to level the playing field to the juniors’ benefit, who can now use the results to develop a first order understanding of their properties.

As the results of EXTECH IV are assessed and integrated into exploration programs, better, more efficient, and more economic applications of technology will result. This will allow both senior and junior companies to explore the as-yet-ignored portions of the basin in the quest for large unconformity-type uranium deposits.

— The author is a Toronto-based freelance writer specializing in mining and investment issues.