Open AccessTill geochemical signatures of the Kiggavik uranium deposit, Nunavut
Author(s) -
S V J Robinson,
R C Paulen,
C W Jefferson,
M B McClenaghan,
Daniel LaytonMatthews,
David Quirt,
Peter Wollenberg
Publication year - 2014
Language(s) - English
Resource type - Reports
DOI - 10.4095/293857
Subject(s) - geology , outcrop , prospecting , geochemistry , bedrock , uranium , basement , geomorphology , metallogeny , pyrite , archaeology , geography , materials science , metallurgy , sphalerite
In 2010, a drift prospecting study was initiated over the Kiggavik uranium deposit under the Geomapping for Energy and Minerals (GEM) Program. The objective of this study was to document the till geochemical signatures of the Kiggavik uranium deposit and to applythese geochemical characteristics for future exploration for buried, drift-covered uranium deposits. The study area is within the zone affected by the migration of the Keewatin Ice Divide of the Laurentide Ice Sheet. Mineralized bedrock and surface till samples (n=71) were collected directlyoverlying, up-ice, and at various distances (50 m, 100 m, 200 m, 500 m, 1 km, 2 km, 3 km, 5 km, and 10 km) in a fan-shaped pattern down-ice from the deposit with respect to the dominant north-northwest, northwest, and west ice-flow directions. Samples containing the highest metal contents werelocated directly to the west of the deposit in locally derived, basement-dominated grey till, which markedly contrasts with the regional red till dominated by material eroded from the Baker Lake and Wharton Groups of the Dubawnt Supergroup. Till geochemistry exhibits a polymetallic dispersalsignature down-ice of the Kiggavik Main Zone outcrop. Uranium, Bi, Mo, Au, Ag, Co, Cs, Pb, and W range from elevated to anomalously high concentrations up to 1 km down-ice of the Main Zone and thus can be utilized as pathfinder elements. These pathfinder elements are also present down-ice from otherU deposits within the Kiggavik camp, demonstrating their broad applicability to U exploration in basement rocks near the Thelon Basin. Analysis of the <0.063 mm and <0.002 mm fraction of the till matrix shows that elemental abundances are significantly greater in the finerfraction, indicating a strong geochemical partitioning based on grain size. Laboratory gamma-ray spectrometry, Pb isotopic analysis, and X-ray diffraction were conducted on the till samples. Results show that eU and Pb isotope ratios (206Pb/204Pb, 207Pb/204Pb, 207Pb/206Pb) in the till matrix share astrong correlation with U content in till and can be used as a geochemical tool for U exploration. The clay mineralogy of samples with elevated to anomalously high U is enriched in illite and kaolinite relative to quartz. Pebble lithological and Pb isotope ratio analyses have trends that can beapplied to deciphering till matrix provenance.