scholarly journals Supplemental Material: Thermotectonic events recorded by U-Pb geochronology and Zr-in-rutile thermometry of Ti oxides in basement rocks along the P2 fault, eastern Athabasca Basin, Saskatchewan, Canada

2021 ◽  
Author(s):  
Erin Adlakha ◽  
Keiko Hattori
Keyword(s):  
Data Set ◽  
Athabasca Basin ◽  
Ti Oxides ◽  
Basement Rocks ◽  
Zr In Rutile

Appendix figures and tables; U-Pb data set for rutile and anatase from the P2 fault.

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.

Geochemistry of the Athabasca Basin, Saskatchewan, Canada, and the Unconformity-related Uranium Deposits Hosted By It

2020 ◽  
Author(s):  
Paul Alexandre
Keyword(s):  
Chemical Composition ◽  
Large Data ◽  
Aluminum Phosphate ◽  
Enrichment Factors ◽  
Uranium Deposits ◽  
Average Chemical Composition ◽  
Data Set ◽  
Athabasca Basin ◽  
Ore Bodies ◽  
Five Elements

Abstract A large data set comprising near-total digestion analyses of whole rock samples from the Athabasca Basin, Saskatchewan, Canada (based principally on the Geological Survey of Canada open file 7495), containing more than 20,000 analyses, was used to define the average chemical composition of Athabasca Group sandstones and of unconformity-related uranium deposits hosted by the basin. The chemical composition of unaltered and un-mineralized Athabasca Group sandstones is dominated by Al (median Al2O3 of 1.14 wt.%), Fe (median Fe2O3 of 0.24 wt.%), and K (median K2O of 0.11 wt.%; Si was not measured), corresponding mostly to the presence of kaolin, illite, and hematite, in addition to the most-abundant quartz. The median concentration of U in the barren sandstones is 1 ppm, with 5 ppm Th, 3 ppm Pb, and 56 ppm ΣREE. Other trace elements present in significant amounts are Zr (median of 100 ppm), Sr (median of 69 ppm), and B (median of 43 ppm), corresponding to the presence of zircon, illite, and dravite. The elements most enriched in a typical Athabasca Basin unconformity-related uranium deposit relative to the barren sandstone are U (median enrichment of ×710), Bi (×175), V (×77), and Mg (×45), followed by five elements with enrichment factors between 20 and 30 (Co, Mo, K, As, and Ni). These correspond to the presence in the ore bodies of alteration minerals (dravite, kaolinite, illite, chlorite, aluminum-phosphate-sulfate minerals, and a suite of sulfide minerals) and are similar to what has been observed before. These elements are similar to the typical pathfinder elements described above known deposits, but their usefulness has to be assessed based on their relative mobility in the predominantly oxidizing Athabasca Basin sandstones.

Detrital zircon ages from Proterozoic, Paleozoic, and Cretaceous clastic strata in southern New Mexico, U.S.A.

2019 ◽  
Vol 54 (1) ◽  
pp. 19-32
Author(s):  
Jeffrey M. Amato
Keyword(s):  
New Mexico ◽  
Detrital Zircon ◽  
Rocky Mountain ◽  
Published Data ◽  
Data Set ◽  
Basement Rocks ◽  
Dakota Sandstone ◽  
Clastic Sedimentary ◽  
Detrital Zircon Ages ◽  
Combined Data

ABSTRACT U-Pb ages were obtained from detrital zircon grains from Proterozoic, Ordovician, Devonian, Pennsylvanian, and Cretaceous clastic sedimentary rocks in southern New Mexico and are compared to previously published data from Proterozoic, Cambrian, Permian, and other Cretaceous strata. This provides the first combined data set from most of the known pre-Cenozoic clastic formations in southern New Mexico, albeit in a reconnaissance fashion. Proterozoic quartzite, conglomerate, and lithic sandstone yield mostly 1.65-Ga zircon ages that were derived from the Mazatzal province, with minor 1.8–1.7-Ga zircon ages from the Yavapai province. The Cambrian–Ordovician Bliss Sandstone is dominated by Grenville-age grains and Cambrian grains inferred to be locally derived. Newly acquired ages from the Ordovician Cable Canyon Sandstone are dominated by 1.7–1.6-Ga Mazatzal province zircon grains, whereas new data from the Devonian Percha Shale indicate subequal contributions from 1.7–1.6-Ga and ~1.4-Ga sources, along with 1.8–1.7-Ga zircon ages. Both of these formations likely had mainly distal sources as the Precambrian basement in the region was largely buried by older Paleozoic strata. New data from a sandstone in the Pennsylvanian La Tuna Formation show mostly Yavapai grains and minor Paleozoic zircon grains, including Cambrian zircon grains sourced from the nearby Florida Mountains landmass postulated to have been exposed during Pennsylvanian time. The Permian ‘Abo tongue’/Robledo Mountains Formation of the Hueco Group has mostly Neoproterozoic and Grenville-age zircon grains and was derived from Ancestral Rocky Mountain uplifts that did not have a large ~1.4-Ga component. The Aptian Hell-to-Finish Formation of the Bisbee Group has mostly Yavapai-aged zircon grains in the pre-1000-Ma age group, but younger Albian- and Campanian-age sandstones have mostly Grenville-age zircon grains. New data from the Albian Beartooth Quartzite indicate syndepositional volcanic grains at 102 Ma and support correlations with the Mojado Formation rather than the younger Dakota Sandstone. Archean zircon ages are rare overall in all of the strata in southern New Mexico, but zircon grains with ages of ~2.74 Ga are most abundant. These grains could have been derived from basement rocks in the Wyoming or Superior provinces, or recycled from sediment originally derived from those sources.

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

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

A refined zirconium-in-rutile thermometer

2020 ◽  
Vol 105 (6) ◽  
pp. 963-971 ◽  
Author(s):  
Matthew J. Kohn
Keyword(s):  
Experimental Data ◽  
Stability Field ◽  
Careful Attention ◽  
Data Set ◽  
Natural Logarithm ◽  
Poor Understanding ◽  
Natural Data ◽  
Compositional Variability ◽  
Zr In Rutile ◽  
Combined Data

Abstract The zirconium-in-rutile thermometer enjoys widespread use, but confidence in its accuracy is limited because experiments were conducted at higher temperatures than many rutile-bearing rocks and calibration uncertainties have not been quantitatively assessed. Refined calibrations were developed using bootstrap regression to minimize residuals in the natural logarithm of the equilibrium constant, based on experiments only (n = 32) and on a combined compilation of experiments and natural data (n = 94, total). Rearranging the regression to solve for T, and expressing Zr concentration (C) in parts per million (μg/g), the calibrations in the α-quartz stability field are: Experimental data set: T ( C ∘ ) = 68740 + 0 . 441 · P ( bars ) - 0 . 114 · C ( ppm ) 129 . 76 - R · ln [ C ( ppm ) ] - 273 . 15 . Combined data set: T ( C ∘ ) = 71360 + 0 . 378 · P ( bars ) - 0 . 130 · C ( ppm ) 130 . 66 - R · ln [ C ( ppm ) ] - 273 . 1 . Thermodynamics of the quartz-coesite transition as applied to the calibration for α-quartz yields calibrations for the coesite stability field: Experimental data set T ( C ∘ ) = 71290 + 0 . 310 · P (  bars  ) - 0 . 114 · C ( ppm ) 128 . 76 - R · ln [ C ( ppm ) ] - 273 . 15 . Combined data set: T ( C ∘ ) = 73910 + 0 . 247 · P ( bars ) - 0 . 130 · C ( ppm ) 129 . 65 - R · ln [ C ( ppm ) ] - 273 . 15. Propagated temperature uncertainties are ±20–30 °C (2σ) for the experimental data set calibration, and ±10–15 °C (2σ) for the combined data set. Compared to previous experimental calibrations, the refined thermometer predicts temperatures up to 40 °C lower for T ≤ 550 °C, and systematically higher temperatures for T &gt; 800 °C. With careful attention to distributions of Zr in rutile grains, precisions of ±5 °C and accuracies ~±15 °C may be possible, although a poor understanding of how to select compositions for thermometry will typically lead to larger uncertainties. The ZiR calibration promises continued high-precision and accurate thermometry, and possibly improved thermodynamic properties, but the sources of compositional variability in rutile warrant further scrutiny.

3D electromagnetic modeling of graphitic faults in the Athabasca Basin using a finite-volume time-domain approach with unstructured grids

Geophysics ◽  
2021 ◽  
pp. 1-73
Author(s):  
Xushan Lu ◽  
Colin Farquharson ◽  
Jean-Marc Miehé ◽  
Grant Harrison
Keyword(s):  
Finite Volume ◽  
Time Domain ◽  
Tetrahedral Mesh ◽  
Late Time ◽  
Data Set ◽  
Athabasca Basin ◽  
Electric Model ◽  
Modeling Process ◽  
Transient Electromagnetic ◽  
Drilling Data

Uranium exploration in the Athabasca Basin, Canada, relies heavily on ground-based transient electromagnetic (TEM) surveys to target thin, steeply dipping graphitic conductors that are often closely related to the uranium ore deposits. The interpretation of TEM data is important in identifying the locations and trends of conductors in order to guide subsequent drilling campaigns. We present a trial-and-error modeling approach and its application to the interpretation of a data set acquired at Close Lake in the Athabasca Basin. The modeling process has two key tasks: building geo-electric models and computing their TEM responses. The modeling process is repeated with the geo-electric model being iteratively refined based on the match between three-component calculated and measured data from early to late times. To create geo-electric models, we first build a realistic geological model and discretize it using an unstructured tetrahedral mesh, with each mesh cell populated with appropriate resistivities. To calculate the TEM responses of the geo-electric model, we use a 3D finite-volume time-domain (FVTD) algorithm. We construct our initial model based on existing geologic information and drilling data. We show that this modeling process is flexible and can easily handle thin, steeply dipping conductive graphitic fault models with variable resistivities in the fault and background, and with topography. Our interpretation of the Close Lake data matches well with the trend and location of the main conductor as revealed by drilling data, and also confirms the existence of a smaller conductor which only caused noticeable anomalous responses in early-time horizontal-component data. The smaller conductor was suggested by previous electromagnetic data but was missed in a recent interpretation based on the modeling of only late-time vertical component data with plate-based approximate modeling methods.

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