Migration of brines in the basement rocks of the Athabasca Basin through microfracture networks (P-Patch U deposit, Canada)

Lithos ◽  
2010 ◽  
Vol 115 (1-4) ◽  
pp. 121-136 ◽  
Author(s):  
Julien Mercadier ◽  
Antonin Richard ◽  
Marie-Christine Boiron ◽  
Michel Cathelineau ◽  
Michel Cuney
Keyword(s):  
Athabasca Basin ◽  
Basement Rocks

Geological environment of the Cigar Lake uranium deposit

1993 ◽  
Vol 30 (4) ◽  
pp. 653-673 ◽  
Author(s):  
P. Bruneton
Keyword(s):  
Uranium Deposit ◽  
Transitional Zone ◽  
Uranium Deposits ◽  
Athabasca Basin ◽  
Structural Framework ◽  
Basement Rocks ◽  
Metamorphic Basement ◽  
Basement Ridge ◽  
Archean Basement ◽  
East West

The Cigar Lake uranium deposit occurs within the Athabasca Basin of northern Saskatchewan, Canada. Like other major uranium deposits of the basin, it is located at the unconformity separating Helikian sandstones of the Athabasca Group from Aphebian metasediments and plutonic rocks of the Wollaston Group. The Athabasca Group was deposited in an intra-continental sedimentary basin that was filled by fluviatile terrestrial quartz sandstones and conglomerates. The group appears undeformed and its actual maximum thickness is about 1500 m. On the eastern side of the basin, the detrital units correspond to the Manitou Falls Formations where most of the uranium deposits are located. The Lower Pelitic unit of the Wollaston Group, which lies directly on the Archean basement, is considered to be the most favourable horizon for uranium mineralization. During the Hudsonian orogeny (1800–1900 Ma), the group underwent polyphase deformation and upper amphibolite facies metamorphism. The Hudsonian orogeny was followed by a long period of erosion and weathering and the development of a paleoweathering profile.On the Waterbury Lake property, the Manitou Falls Formation is 250–500 m thick and corresponds to units MFd, MFc, and MFb. The conglomeratic MFb unit hosts the Cigar Lake deposit. However, the basal conglomerate is absent at the deposit, wedging out against an east–west, 20 m high, pre-Athabasca basement ridge, on top of which is located the orebody.Two major lithostructural domains are present in the metamorphic basement of the property: (1) a southern area composed mainly of pelitic metasediments (Wollaston Domain) and (2) a northern area with large lensoid granitic domes (Mudjatik Domain). The Cigar Lake east–west pelitic basin, which contains the deposit, is located in the transitional zone between the two domains. The metamorphic basement rocks in the basin consist mainly of graphitic metapelitic gneisses and calcsilicate gneisses, which are inferred to be part of the Lower Pelitic unit. Graphite- and pyrite-rich "augen gneisses," an unusual facies within the graphitic metapelitic gneisses, occur primarily below the Cigar Lake orebody.The mineralogy and geochemistry of the graphitic metapelitic gneisses suggest that they were originally shales. The abundance of magnesium in the intercalated carbonates layers indicates an evaporitic origin.The structural framework is dominated by large northeast–southwest lineaments and wide east–west mylonitic corridors. These mylonites, which contain the augen gneisses, are considered to be the most favourable features for the concentration of uranium mineralization.Despite the presence of the orebody, large areas of the Waterbury Lake property remain totally unexplored and open for new discoveries.

The origin of Ti-oxide minerals below and within the eastern Athabasca Basin, Canada

2020 ◽  
Vol 105 (12) ◽  
pp. 1875-1888
Author(s):  
Erin E. Adlakha ◽  
Keiko Hattori ◽  
Mitchell J. Kerr ◽  
Brandon M. Boucher
Keyword(s):  
Regional Metamorphism ◽  
Hydrothermal Activity ◽  
Geological History ◽  
Epma Data ◽  
Athabasca Basin ◽  
Basement Rocks ◽  
History Of ◽  
Oxide Minerals ◽  
High Concentrations ◽  
Late Diagenesis

Abstract Titanium oxide minerals along the P2 fault in the eastern Athabasca Basin are characterized to constrain their origin and the geological history of the area. Two types of rutile are recognized in the basement rocks. Early rutile is disseminated in graphitic metapelite and quartzite, and it formed during regional metamorphism and post-metamorphic hydrothermal activity. Late rutile occurs as a needle-like alteration product of mica and likely formed during retrogression of the basement. In graphitic metapelite, early rutile commonly occurs with an assemblage of oxy-dravite, quartz, graphite, zircon, pyrite, biotite, and muscovite. In quartzite, rutile occurs with quartz, sillimanite, muscovite, and zircon. Metamorphic rutile is characterized by high Nb/Ta ratios (up to 47) with high concentrations of U (up to 126 ppm) and V4+ (up to 1.44 wt%; V valance calculated from EPMA data). Hydrothermal rutile contains distinctly low Nb/Ta (as low as 4.80) with high Ta (≤3050 ppm), and relatively low V (as V 3+; as low as 0.02 wt%) and U (as low as 9.06 ppm), reflecting fluids in reduced oxidation conditions. Anatase forms small anhedral (rarely coarse and euhedral) grains in the basal sandstones and altered basement rocks. In sandstones, anatase occurs with the late diagenetic mineral assemblage, whereas in basement rocks it commonly occurs with the clay-sized minerals related to uranium mineralization. In both rocks, anatase likely formed through the dissolution of rutile and/or other Ti-bearing minerals. Anatase is characterized by variably high Fe (up to 0.99 wt%; possibly contributed by hematite micro-or nanoinclusions) and U (up to 180 ppm). The mineral assemblages and composition of anatase suggest its protracted crystallization from relatively low temperature, oxidizing, acidic, uraniferous fluids of the sandstones during late diagenesis and hydrothermal activity. Therefore, the occurrence of anatase records the incursion of basin fluids into the basement, and the interaction of basement rocks with fluids responsible for the formation of the McArthur River uranium deposit. The results of this study confirm that Ti-oxides are useful in unraveling the geological history of an area that underwent prolonged hydrothermal activity.

Structural evolution and related implications for uranium mineralization in the Patterson Lake corridor, southwestern Athabasca Basin, Saskatchewan, Canada

2020 ◽  
pp. geochem2020-030
Author(s):  
Dillon Johnstone ◽  
Kathryn Bethune ◽  
Colin Card ◽  
Victoria Tschirhart
Keyword(s):  
Structural Evolution ◽  
Uranium Mineralization ◽  
Ductile Deformation ◽  
Normal Faults ◽  
Uranium Deposits ◽  
Content Type ◽  
Athabasca Basin ◽  
Basement Rocks ◽  
Transfer Faults ◽  
Dextral Strike Slip

The Patterson Lake corridor is situated along the southwest margin of the Athabasca Basin and contains several basement-hosted uranium deposits and prospects. Drill core investigations during this study have determined that granite, granodiorite, mafic and alkali intrusive basement rocks are entrained in a deep-seated northeast-striking subvertical heterogeneous high-strain zone defined by anastomosing ductile to semi-brittle shears and brittle faults. The earliest phases of ductile deformation (D1/2), linked with Taltson (1.94–1.92 Ga) orogenesis, involved interference between early fold sets (F1/2) and development of an associated ductile transposition foliation (S1/2). During subsequent Snowbird (ca. 1.91–1.90 Ga) tectonism, this composite foliation was re-folded (D3) by northeast-trending buckle-style folds (F3), including a regional fold centered on the Clearwater aeromagnetic high. In continuum with D3, a network of dextral-reverse chloritic-graphitic shears, with C-S geometry, formed initially (D4a) and progressed to more discrete, spaced semi-brittle structures (D4b; ca. 1.900–1.819 Ga). Basin development (D5a; <ca. 1.819 Ga) was marked by a set of north-striking normal faults and related east- and northeast-striking transfer faults that accommodated subsidence. Primary uranium mineralization (D5b; ∼1.45 Ga) was facilitated by brittle reactivation of northeast-striking basement shears in response to west-southwest - east-northeast-directed compressional stress (σ1). Uraninite was emplaced along σ1-parallel extension fractures and dilational zones formed at linkages between northeast- and east-northeast-striking dextral strike-slip faults. Uranium remobilization (D5c) occurred after σ1 shifted to west-northwest – east-southeast, giving rise to regional east- and southeast-striking conjugate faults, along which mafic dykes (1.27 Ga and 1.16 Ga) intruded.Thematic collection: This article is part of the Uranium Fluid Pathways collection available at: https://www.lyellcollection.org/cc/uranium-fluid-pathways

scholarly journals Basement rocks to the Athabasca Basin, Saskatchewan and Alberta

2007 ◽  
Author(s):  
C D Card ◽  
D Panã ◽  
P Portella ◽  
D J Thomas ◽  
I R Annesley
Keyword(s):  
Athabasca Basin ◽  
Basement Rocks

Interpretation of buried basement in the southwestern Athabasca Basin, Canada, from integrated geophysical and geological datasets

2020 ◽  
Vol 21 (1) ◽  
pp. geochem2019-061
Author(s):  
Victoria Tschirhart ◽  
Sally Pehrsson ◽  
Colin Card ◽  
Eric G. Potter ◽  
Jeremy Powell ◽  
...  
Keyword(s):  
Potential Field ◽  
Physical Property ◽  
Drill Hole ◽  
Airborne Gravity ◽  
Content Type ◽  
Athabasca Basin ◽  
Basement Rocks ◽  
Gravity And Magnetic ◽  
Geophysical Surveys ◽  
Lineament Analysis

Recent discoveries of basement-hosted uranium deposits in the Patterson Lake corridor in the southwestern Athabasca Basin of Canada have brought vigorous exploration interest to the region. New lithostratigraphic constraints, geochronology and airborne geophysical surveys have dramatically improved the understanding of the host basement geology, warranting a re-examination of the remote predictive mapping and geophysical responses of the buried basement rocks. This study took a two-step approach to examine the regional basement geology and architecture. First, a mosaic of the long-wavelength response of potential field (gravity and magnetic) datasets was examined to divide the basement into regional domains based on bulk physical property variations. The interpretive geological model was then refined using textural and lineament analysis of new airborne gravity and magnetic datasets, geological drill hole logs and magnetic susceptibility measurements. The new basement map identifies and updates major features including a crustal-scale structure that separates the southern Tantato Domain from the newly defined eastern Taltson Domain. This structure may have played a role in localizing fluid flow in the Patterson Lake corridor, defining the spatial extents of structurally controlled buried felsic intrusions, and redefines the boundaries of the Taltson, Clearwater and Tantato Domains. In addition, the potential field enhancements delineated significant regional faults that controlled the geometry of Paleoproterozoic cover sequences and have implications for understanding the crustal architecture of the southern Rae Province. These new interpretations shed light on the tectonic history of the region to support on-going exploration activities and delineate regionally prospective areas in this understudied area of the Canadian Shield.Thematic collection: This article is part of the Uranium Fluid Pathways collection available at: https://www.lyellcollection.org/cc/uranium-fluid-pathways

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