Post by
megacopper on Jan 31, 2007 11:20am
Athabasca Basin vs Sibley/Nipigon Basin
The Athabasca Basin is home to the largest high grade uranium deposits in the world.
These similarities have long been recognised and led to a modest amount of exploration for uranium in the area in the late 1970s and early 1980s. From a geological standpoint, similarities between the Athabasca and Sibley/Nipigon basins include:
Both areas are unmetamorphosed, continental sedimentary basins;
Both basins were formed during the Helikian age (the Athabasca Formation 1,350 my, Sibley Group 1,339 my);
Both basins have well developed deep paleo-weathering of basement rocks at the unconformity where the sediments overlie Archean to early Proterozoic basement rocks;
Both basins overlie basement rocks with high background uranium contents and/or zones of uranium enrichment;
Both basins have been intruded by Helikian-age mafic magmatic activity (e.g. diabase dykes and sills in the Atha-basca Basin; the Nipigon sills in the Nipigon Basin);
The basement rocks under both basins contain chemical traps (such as graphitic units) that are capable of reacting with uranium-bearing groundwater to precipitate and concentrate uranium mineralization.
The southern part of the Nipigon Basin, between Lake Nipigon and Lake Superior, is the most favourable for uranium exploration. In this area, Sibley Group sediments overlie "uraniumrich" metasediments and granitic intrusives of the Quetico subprovince.
At the northern margin of the Quetico rocks, the basement rocks change to metavolcanics and metasediments of the Wabigoon subprovince, containing abundant graphitic units, sulphide zones and iron forma-tions, all of which represent potential chemical traps for uranium.
The southern part of the Nipigon Basin is very accessible, with an extensive network of logging roads, which allow overland access to most areas for exploration purposes. Recent government airborne radiometric and magnetic surveys and high-density lake sediment surveys have provided an excellent database to guide project selection and regional exploration.