Application of Radiation-Induced Defects in Quartz to Exploration for Uranium Deposits: A Case Study of the Maw Zone, Athabasca Basin, Saskatchewan

Abstract The nature and distribution of radiation-induced defects (RIDs) in quartz from the Maw Zone, a yttrium- and rare-earth-element-enriched sandstone breccia complex exhibiting intense hydrothermal alteration, have been investigated by electron paramagnetic resonance (EPR) spectroscopy. EPR spectra show that detrital quartz in sandstone, from five diamond drill holes intersecting the Maw Zone and one above the crest of the so-called Quartzite Ridge, contain only background-level RIDs, indicating that Ubearing fluids were absent in this area. However, close to the sandstone-basement unconformity, in hole WR-194 immediately west of the Quartzite Ridge, the concentration of RIDs in detrital quartz is significantly above background but at least an order of magnitude lower than those at the Key Lake and McArthur River deposits. Widespread drusy quartz at the Maw Zone, which signifies intense hydrothermal alteration, is associated with hematite-, sulfide- and carbonate-bearing mineral assemblages, which exhibit complex crosscutting relationships. EPR spectra of drusy quartz in all three types of mineral assemblages are low in RIDs as well, supporting the EPR evidence that fluids at the Maw Zone did not carry significant U. These EPR results suggest that, in spite of intense hydrothermal alteration and favorable structural geology, the Maw Zone is unlikely to host any significant U mineralization. Moreover, this study shows that the EPR technique is potentially a useful exploration tool, capable of determining whether individual alteration zones in the Athabasca Basin were associated with U-bearing fluids or not.
Keywords: quartz EPR, radiation-induced defects, hydrothermal alteration, uranium exploration, Athabasca Basin
Résumé La nature et la distribution des défauts induits par rayonnement (DIR) dans le quartz de la zone Maw, un complexe de brèche dans des grès enrichi en yttrium et en terres rares qui présente une altération hydrothermale intense, ont été étudiés par spectroscopie de résonance paramagnétique électronique (RPE). Les valeurs des spectres RPE montrent que le quartz détritique dans les grès provenant de cinq forages au diamant traversant la zone Maw et d’un forage situé au-dessus de la crête de Quartzite Ridge, se situent au niveau du bruit de fond en matière de DIR, ce qui indique que les fluides uranifères étaient absents dans ce secteur. Cependant, près de la discordance entre le grès et le socle, dans le trou WR-194 situé immédiatement à l'ouest de Quartzite Ridge, le concentration des RID dans le quartz détritique est nettement plus grand que le bruit de fond, tout en demeurant moindre à ce que l’on observe aux gisements de Key Lake et de McArthur River par un ordre de grandeur. On note une abondance de quartz drusique dans la zone Maw, ce qui indique une altération hydrothermale intense, en association avec des assemblages minéraux présentant de l’hématite, des sulfures et des carbonates et lesquels présentent des relations de recoupement complexes. Les spectres RPE du quartz drusique dans les trois assemblages minéraux sont faibles en DIR eux-aussi, ce qui va dans le même sens que les données de RPE qui suggèrent que les fluides dans la zone Maw ne transportaient pas de quantités significatives d’U. L’information fournie par la RPE suggère qu’en dépit d'une altération hydrothermale intense et de la présence de structures favorables, il est improbable que la zone Maw contienne des minéralisations significatives en U. De plus, cette étude montre que la RPE est un outil d'exploration potentiellement utile, capable de déterminer si des zones d'altération individuelles dans le bassin d'Athabasca ont été associées ou non avec des fluides uranifères
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Summary: We use the results of new bedrock mapping, combined with geochemical point data and airborne radiometric data (in particular equivalent uranium concentrations) to help determine which geological units in the Paleoproterozoic Great Bear magmatic zone (GBmz) contain elevated uranium. The data collectively indicate that the highest primary uranium concentrations are in equigranular granites and subvolcanic/volcanic porphyries. Notably, these rocks host the majority of known uranium-bearing...
Publication: Exploration & Mining Geology
Author(s): LUKE OOTES, JEFF HARRIS, VALERIE A. JACKSON, BRONWYN AZAR, AND LOUISE CORRIVEAU
Keywords: Wopmay orogen, Great Bear magmatic zone, bedrock geochemistry, IOCG, unconformityrelated uranium
Issue: 1
Volume: 21
Year: 2013
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Summary: A 10-cm thick clay-rich layer near the top of the Manitou Falls Formation of the Athabasca Group is unusual in its breccia texture, alteration, and detrital mineral composition relative to the adjacent overlying and underlying sedimentary beds. This layer is composed of angular quartz grains set in an illite >> kaolinite + dickite matrix. Deformed clay-rich fragments within the layer have very similar mineral assemblages. The presence of euhedral accessory minerals including Ti-oxides and...
Publication: Exploration & Mining Geology
Author(s): JEANNE B. PERCIVAL, SEAN A. BOSMAN, ERIC G. POTTER, PAUL RAMAEKERS, KATHERINE E. VENANCE, PAT A. HUNT, WILLIAM DAVIS, AND CHARLES W. JEFFERSON
Keywords: microbreccia, hydrothermal alteration, hydraulic fracturing, uranium mineralization
Issue: 1
Volume: 21
Year: 2013
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Summary: The use of CR-39 plastic polymer as a solid state nuclear track detector in the textural analysis of radioactive minerals in geological samples was first described by I.R Basham in 1981. CR-39 autoradiographs provide a detailed, high-resolution image of the in situ distribution of the radioactive minerals within geological samples on both the macroscopic and microscopic scales. This technique is an inexpensive and effective means of obtaining detailed textural information that provides...
Publication: Exploration & Mining Geology
Author(s): G.W. SPARKES
Keywords: uranium, CR-39, autoradiograph, Labrador, uraninite
Issue: 1
Volume: 21
Year: 2013
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Summary: The U-Th-REE mineralization at Fraser Lakes Zone B is hosted by granitic pegmatites and leucogranites, which lie along the deformed contact between Paleoproterozoic metasedimentary gneiss of the Wollaston Group and Archean orthogneiss, approximately 25 km from the southeastern edge of the Athabasca Basin. The pegmatites/leucogranites are subcordant to concordant with the regional foliation and are concentrated within a northeast-plunging antiformal fold nose, the study area, which lies west...
Publication: Exploration & Mining Geology
Author(s): CHRISTINE L. MCKECHNIE, IRVINE R. ANNESLEY , AND KEVIN M. ANSDELL
Keywords: U-rich pegmatites, Th-REE-rich pegmatites, Fraser Lakes Zone B, Wollaston Domain, Athabasca Basin, U metallogeny
Issue: 1
Volume: 21
Year: 2013
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Summary: A new method for mapping faults within basement rocks underlying the Thelon Formation and glacial overburden was developed and tested in the Aberdeen Sub-basin. This method utilizes newly acquired aeromagnetic data, the Blakely algorithm for defining magnetic source edges, a calculated dip-direction map, a digital elevation model (DEM) derived from the Canadian Digital Elevation Database, and the positions of identified, inferred and newly mapped faults that are within and adjacent to this...
Publication: Exploration & Mining Geology
Author(s): VICKI TSCHIRHART, BILL MORRIS, AND CHARLES JEFFERSON
Keywords: faults, uranium, Thelon Basin, source edge detection, lineament analysis
Issue: 1
Volume: 21
Year: 2013
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Summary: The Dragon Lake Zone (uranium prospect) comprises a N160º trending vein that is approximately 110 m long, up to 5 m wide and from 1 to 40 m high. The zone is mostly within altered sandstone of the Fair Point Formation, the basal unit of the Paleoproterozoic Athabasca Group, but it also extends downward (up to 3.5 m) into basement rocks that occupy the northerly trending Maybelle River Shear Zone (MRSZ). This subvertical shear zone separates graphitic paragneiss and weakly deformed granitoid...
Publication: Exploration & Mining Geology
Author(s): K. WHEATLEY AND C. CUTTS
Keywords: uranium, unconformity, Alberta, Maybelle River, Dragon Lake, Athabasca
Issue: 1
Volume: 21
Year: 2013
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Summary: Lac Cinquante is a mineralogically simple, vein-hosted uranium deposit in Archean basement rocks (Angikuni greenstone belt) that originally were unconformably overlain by Proterozoic sedimentary and volcanic rocks of the Baker Lake Group (BLG). Basement rocks are mainly pillowed and massive tholeiitic lavas (N-MORB) with interbedded tuff; overlying sedimentary rocks comprise a basal talus/fault breccia that grades upward into fluvial sedimentary rocks and subaerial, trachytic volcanic rocks;...
Publication: Exploration & Mining Geology
Author(s): N.J. BRIDGE, N.R. BANERJEE, S. PEHRSSON, M. FAYEK, C.S. FINNIGAN, J. WARD, AND A. BERRY
Keywords: NW Hearne, Archean basement, Baker Lake Group, Angikuni subbasin, vein-hosted uranium, graphite
Issue: 1
Volume: 21
Year: 2013
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