Laser probe 40Ar/39Ar and conventional K/Ar dating of illites associated with the McClean unconformity-related uranium deposits, north Saskatchewan, Canada

1987 ◽  
Vol 24 (1) ◽  
pp. 10-23 ◽  
Author(s):  
C. J. Bray ◽  
E. T. C. Spooner ◽  
C. M. Hall ◽  
D. York ◽  
T. M. Bills ◽  
...  
Keyword(s):  
Hydrothermal Alteration ◽  
Uranium Mineralization ◽  
Complete Agreement ◽  
Time Interval ◽  
Uranium Deposits ◽  
Class Interval ◽  
Laser Probe ◽  
Alteration Halo ◽  
Sheet Silicates ◽  
Sedimentary Layer

The McClean group of uranium deposits consists of elongate pods of high-grade uranium mineralization (width = ~ 15–40 m) tightly confined to within ±40 m of the basal unconformity. Uraninite–coffinite–sulphide/arsenide–chlorite–siderite mineralization at McClean is surrounded by a muscovite/illite ± haematite hydrothermal alteration halo,which can contain coffinite–pararammelsbergite (NiAs2) – muscovite/illite nodules. Ten laser probe 40Ar/39Ar dates, two of which are step-heat runs showing good plateaus, and 10 conventional K – Ar dates for this material show a distribution with asharp beginning at ~ 1320 Ma, a marked peak in the 1250–1200 Ma class interval, and a tail to dates as young as 1002 ± 33 (1σ) Ma. These determinations are in complete agreement with direct (U–Pb and Sm–Nd) dates on uraninite at the Midwest (e.g., 1328 ± 9 and 1110 ± 28 Ma), Key Lake (e.g., 1350 ± 4 and 1281 ± 6 Ma), and Collins Bay B deposits(e.g., 1281 ± 80 Ma). Since estimated depositional ages for the Athabasca sedimentary sequence are in the 1470 ± 15 to1428 ± 15 Ma range, uranium mineralization and associated hydrothermal alteration started ~ 100–150 Ma after Athabasca sedimentation, a result consistent with fluid-inclusion data, which indicate that mineralization took place at ~ 160–220 °C beneath ~ 3000 m of cover at a relatively advanced stage in the evolution of the basin. It is suggested that the similar initiation dates for uranium mineralization might reflect a widespread faulting event that affected the eastern part of the basin. A muscovite/illite closure temperature calculated from a measured argon diffusion activation energy of 36 ± 4 kcal/mol(1 kcal = 4.1868 kJ) indicates that the base of the Athabasca Basin in the McClean area has not been disturbed by temperatures greater than ~ 140 °C for 1.1–1.0 Ga. It is suggested that mineralization ceased when fracture permeability had been sealed by crystallization of secondary minerals. The duration of mineralization may have been ~ 150 Ma, a relatively long time interval not unreasonable for the base of a sedimentary basin.Secondary illites interstitial to quartz grains from the HLM1 stratigraphic borehole give 40Ar/39Ar ages of 1459 ± 4, 1341 ± 4, and 1113 ± 11 Ma, indicating that formation of diagenetic sheet silicates predated uranium mineralization. Recrystallization or formation of sheet silicates in relict sedimentary layers and in subunconformity altered basement referred to as "regolith" started at approximately the same time, since dates of 1484 ± 55 Ma (sedimentary layer), 1482 ± 49 Ma (regolith), and 1453 ± 49 Ma (regolith) have been obtained. Resetting of interstitial, sedimentary layer, and regolith sheet-silicate dates continued to ages of, for example, 1113 ± 11 Ma (interstitial) and 1038 ± 55 Ma (sedimentary layer), which exactly coincide with the youngest ages obtained for the alteration halo associated with mineralization.The youngest date obtained is a 40Ar/39Ar plateau age of 673 ± 3 Ma. The sample (2045-517) was obtained from within 2 mm of a concentrated pitchblende nodule and may have been disturbed in some way by its proximity to uranium.

The age of unconformity-related uranium mineralization in the Athabasca Basin, northern Saskatchewan

1992 ◽  
Vol 29 (8) ◽  
pp. 1623-1639 ◽  
Author(s):  
G. L. Cumming ◽  
D. Krstic
Keyword(s):  
Uranium Mineralization ◽  
Time Interval ◽  
Lake Area ◽  
Uranium Deposits ◽  
Athabasca Basin ◽  
Major Exception ◽  
Vein Deposits ◽  
Eagle Point ◽  
The One ◽  
Almost All

Age data are presented for major Athabasca Basin uranium deposits at Cigar Lake, Cluff Lake, Collins Bay, Dawn Lake, Eagle Point, McArthur River, Midwest, and Rabbit Lake, as well as for several minor or undeveloped deposits, including Hughes Lake and Nisto. The best constrained data indicate that almost all the deposits formed in a restricted time interval between about 1330 and 1380 Ma. This range of ages is believed to be real and not the result of uncertainties in the calculation of ages based on discordant data. The one major exception is the recently discovered NiAs-free deposit at McArthur River, for which a well-determined age of 1514 ± 18 Ma (2σ) has been obtained. Even this deposit yields an age in the1330–1380 Ma range for some material. Periods of reworking–redeposition occurred at ~1280, ~1000, ~575, and ~225 Ma. These may be basin-wide, affecting to some degree all the deposits that we have studied. Other times of redeposition are less well determined, but may be present as well. No ages that approach the ~1700 Ma age of the Athabasca Group have been found to date for unconformity-related deposits, and the Athabasca Basin mineralization is unrelated to the ~1750 Ma pitchblende vein deposits in the Beaverlodge Lake area.

Precipitation of Uraninite in Chlorite-Bearing Veins of the Hydrothermal Alteration Zone (Argile De Pile) of the Natural Nuclear Reactor at Bangombé, Republic of Gabon

1994 ◽  
Vol 353 ◽  
Author(s):  
P. Eberly ◽  
J. Janeczek ◽  
R. Ewing
Keyword(s):  
Hydrothermal Alteration ◽  
Nuclear Reactor ◽  
Energy Dispersive ◽  
Alteration Zone ◽  
Backscattered Electron Imaging ◽  
X Ray ◽  
Alteration Halo ◽  
Sheet Silicates ◽  
Backscattered Electron ◽  
Electron Imaging

AbstractThis paper describes the mineralogy of a phyllosilicate/uraninite/galena-bearing vein located within the hydrothermal alteration halo associated with the Bangombé reactor. Phyllosilicates within the vein include a trioctahedral Al-Mg-Fe chlorite (ripidolite), Al-rich clay (kaolinite and/or donbassite) and illite. Textural relations obtained by backscattered-electron imaging suggest that ripidolite crystallized first among the sheet silicates. Uraninite is spatially associated with ripidolite and probably precipitated at a later time. While energy-dispersive x-ray analyses suggest that the uranium phase is predominantly uraninite, coffinite or other phases may also be present.

scholarly journals Uranium deposits of Franceville basin (Gabon): Role of organic matter and oil cracking on uranium mineralization

2020 ◽  
Vol 123 ◽  
pp. 103579
Author(s):  
Andreï Lecomte ◽  
Raymond Michels ◽  
Michel Cathelineau ◽  
Christophe Morlot ◽  
Marc Brouand ◽  
...  
Keyword(s):  
Organic Matter ◽  
Uranium Mineralization ◽  
Uranium Deposits ◽  
Oil Cracking

scholarly journals Paragenetic and petrographic study of uranium mineralization along the Midwest Trend, Northeastern Athabasca Basin

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Daniel Peter Ferguson ◽  
Guoxiang Chi ◽  
Charles Normand ◽  
Patrick Ledru ◽  
Odile Maufrais-Smith
Keyword(s):  
Mineral Resource ◽  
Genetic Model ◽  
Uranium Deposit ◽  
Current Model ◽  
Uranium Mineralization ◽  
Mining District ◽  
Uranium Deposits ◽  
Athabasca Basin ◽  
Technical Report ◽  
Petrographic Study

The Athabasca Basin in northern Saskatchewan is host to many world-class uranium deposits associated with the unconformity between the Paleoproterozoic sandstone of the basin and the underlying crystalline basement (Jefferson et al., 2007).  While the style and tonnage of these deposits vary, the current genetic model for unconformity-related uranium deposits has been a practical tool for exploration in the Athabasca Basin. However, the factors which control the location and formation of these deposits is still not fully understood. A paragenetic and petrographic study of mineralization along the Midwest Trend, located on the northeastern margin of the Athabasca Basin, aims to refine the current model and to address the general problem: What are the factors which control mineralization and non-mineralization? The Midwest Trend will be used as a "modèle réduit" for uranium mineralization, as it displays many features characteristic of unconformity type deposits. The Midwest Trend comprises three mineral leases that encompass two uranium deposits, the Midwest Main and Midwest A (Allen et al., 2017a, b). Mineralization occurs along a NE-trending graphitic structure, and is hosted by the sandstone, at the unconformity, and in much lesser amounts in the underlying basement rocks. Petrographic observations aided by the use of RAMAN spectroscopy and SEM-EDS, have been used to create a paragenetic sequence of mineralization (Fig.1). Future work will focus on fluid inclusion studies using microthermometry, LA-ICP-MS, and mass spectrometry of contained gases. References:Allen, T., Quirt, D., Masset, O. (2017a). Midwest A Uranium Deposit, Midwest Property, Northern Mining District, Saskatchewan, NTS Map Area 741/8: 2017 Mineral Resource Technical Report. AREVA Resources Canada Inc. Internal Report No. 17-CND-33-01. Allen, T., Quirt, D., Masset, O. (2017b). Midwest Main Uranium Deposit, Midwest Property, Northern Mining District, Saskatchewan, NTS Map Area 741/8: 2017 Mineral Resource Technical Report. AREVA Resources Canada Inc. Internal Report No. 17-CND-33-01. Jefferson, C.W., Thomas, D.J., Gandhi, S.S., Ramaekers, P., Delaney, G., Brisbin, D., Cutts, C., Portella, P., and Olson, R.A., 2007: Unconformity-associated uranium deposits of the Athabasca Basin, Saskatchewan and Alberta. Geological Survey of Canada, Bulletin 588, p. 23–67.

scholarly journals New kinetic analysis of the Fenton reaction: Critical examination of the free radical – chain reaction concept

2019 ◽  
Vol 44 (4) ◽  
pp. 289-299
Author(s):  
Mordechai L Kremer
Keyword(s):  
Free Radical ◽  
Fenton Reaction ◽  
Critical Examination ◽  
Complete Agreement ◽  
Time Interval ◽  
Second Phase ◽  
Chain Reaction ◽  
Rapid Phase ◽  
Two Phases ◽  
Radical Model

Using [H2O2] in the molar range, the reaction with Fe2+ has two phases: in the first rapid phase, only a small fraction of the total O2 is evolved; the bulk of the gas is formed in a slow second phase. In interpretations based on the free radical model of Barb et al., the first phase has been identified with the ‘Fenton reaction’ (reaction of Fe2+with H2O2), while the second with catalytic decomposition of H2O2 by Fe3+ ions. This interpretation is not correct. A new analysis of the model shows that (1) it is a chain reaction having no termination steps and (2) the ‘Fenton part’ alone consists of two phases. It starts with rapid evolution of O2 via a five-membered chain reaction (first phase). When [Fe2+] becomes low, evolution of O2 continues in a three-membered chain reaction at a greatly reduced rate (second phase). In later stages of the second phase, Fe3+ catalysis contributes to O2 evolution. Thus, the amount of O2 formed in the rapid phase cannot be identified with the total amount formed in the ‘Fenton reaction’ but only with that formed in its first phase. Computer simulations of O2 evolution based on the model of Barb et al. and rate constants show a definite dependence of this quantity on the initial [H2O2] – in contrast to the experimentally found independence. More satisfactory, but not complete, agreement with measured data could be reached in simulations using a non-radical model. Some of the difficulty has been due to the determination of the exact position of the end of the first phase. The transition between the two phases of the reaction occurs in a short, but finite time interval. It has been shown that the quantity ‘total amount of O2 evolved in the Fenton reaction’ (subtracting the part due to Fe3+catalysis) is not accessible to experimental determination nor to theoretical calculation.

scholarly journals INTEGRALS OVER PRODUCTS OF DISTRIBUTIONS FROM PERTURBATION EXPANSIONS OF PATH INTEGRALS IN CURVED SPACE

2002 ◽  
Vol 17 (15) ◽  
pp. 2019-2050 ◽  
Author(s):  
H. KLEINERT ◽  
A. CHERVYAKOV
Keyword(s):  
Singular Integrals ◽  
Equations Of Motion ◽  
Path Integrals ◽  
Complete Agreement ◽  
Time Interval ◽  
Perturbation Expansions ◽  
Curved Space ◽  
Infinite Time Interval ◽  
Definition Of ◽  
Products Of Distributions

We show that the requirement of coordinate invariance of perturbatively defined quantum-mechanical path integrals in curved space leads to an extension of the theory of distributions by specifying unique rules for integrating products of distributions. The rules are derived by using equations of motion and partial integration, while keeping track of certain minimal features stemming from the unique definition of all singular integrals in 1 - ∊ dimensions. Our rules guarantee complete agreement with much more cumbersome calculations in 1 - ∊ dimensions where the limit ∊ → 0 is taken at the end. In contrast to our previous papers where we solved the same problem for an infinite time interval or zero temperature, we consider here the more involved case of finite-time or temperature amplitudes.

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

The Paleoproterozoic Kombolgie Subgroup (1.8 Ga), McArthur Basin, Australia: Sequence stratigraphy, basin evolution, and unconformity-related uranium deposits following the Great Oxidation Event

2021 ◽  
Vol 59 (5) ◽  
pp. 1049-1083
Author(s):  
Eric E. Hiatt ◽  
T. Kurtis Kyser ◽  
Paul A. Polito ◽  
Jim Marlatt ◽  
Peir Pufahl
Keyword(s):  
Large Scale ◽  
Sedimentary Basins ◽  
Uranium Mineralization ◽  
Coarse Grained ◽  
Uranium Deposits ◽  
Burial Diagenesis ◽  
Fine Grained ◽  
Braided Rivers ◽  
Tectonic Events ◽  
Regional Tectonic

ABSTRACT Proterozoic continental sedimentary basins contain a unique record of the evolving Earth in their sedimentology and stratigraphy and in the large-scale, redox-sensitive mineral deposits they host. The Paleoproterozoic (Stratherian) Kombolgie Basin, located on the Arnhem Land Plateau, Northern Territory, is an exceptionally well preserved, early part of the larger McArthur Basin in northern Australia. This intracratonic basin is filled with 1 to 2 km-thick, relatively undeformed, nearly flat-lying, siliciclastic rocks of the Kombolgie Subgroup. Numerous drill cores and outcrop exposures from across the basin allow sedimentary fabrics, structures, and stratigraphic relationships to be studied in great detail, providing an extensive stratigraphic framework and record of basin development and evolution. Tectonic events controlled the internal stratigraphic architecture of the basin and led to the formation of three unconformity-bounded sequences that are punctuated by volcanic events. The first sequence records the onset of basin formation and is comprised of coarse-grained sandstone and polymict lithic conglomerate deposited in proximal braided rivers that transported sediment away from basin margins and intra-basin paleohighs associated with major uranium mineralization. Paleo-currents in the upper half of this lower sequence, as well as those of overlying sequences, are directed southward and indicate that the major intra-basin topographic highs no longer existed. The middle sequence has a similar pattern of coarse-grained fluvial facies, followed by distal fluvial facies, and finally interbedded marine and eolian facies. An interval marked by mud-rich, fine-grained sandstones and mud-cracked siltstones representing tidal deposition tops this sequence. The uppermost sequence is dominated by distal fluvial and marine facies that contain halite casts, gypsum nodules, stromatolites, phosphate, and “glauconite” (a blue-green mica group mineral), indicating a marine transgression. The repeating pattern of stratigraphic sequences initiated by regional tectonic events produced well-defined coarse-grained diagenetic aquifers capped by intensely cemented distal fluvial, shoreface, eolian, and even volcanic units, and led to a well-defined heterogenous hydrostratigraphy. Basinal brines migrated within this hydrostratigraphy and, combined with paleotopography, dolerite intrusion, faulting, and intense burial diagenesis, led to the economically important uranium deposits the Kombolgie Basin hosts. Proterozoic sedimentary basins host many of Earth's largest high-grade iron and uranium deposits that formed in response to the initial oxygenation of the hydrosphere and atmosphere following the Great Oxygenation Event. Unconformity-related uranium mineralization like that found in the Kombolgie Basin highlights the interconnected role that oxygenation of the Earth, sedimentology, stratigraphy, and diagenesis played in creating these deposits.

Ferriferous and vanadiferous kaolinites from the hydrothermal alteration halo of the Cigar Lake uranium deposit (Canada)

Clay Minerals ◽  
1996 ◽  
Vol 31 (3) ◽  
pp. 291-299 ◽  
Author(s):  
C. Mosser ◽  
M. Boudeulle ◽  
F. Weber ◽  
A. Pacquet
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Alteration ◽  
Uranium Deposit ◽  
Octahedral Sheet ◽  
Vanadyl Ion ◽  
Alteration Halo ◽  
Sem And Tem ◽  
Oriented Samples ◽  
Epr Measurements

AbstractThe uranium deposit (1350 Ma) of Cigar Lake (Canada) is surrounded by a late hydrothermal alteration halo (330 Ma) containing Fe-illites and kaolinites. Crystallochemical characterization of the kaolinites has been carried on the microscale using XRD, electron microscopy (SEM and TEM) coupled with EDX spectrometry and EPR. The large, well-crystallized particles show large amounts of Fe (0.9–1.8%) and V (0.3–0.5%). According to EPR measurements performed on both random powders and oriented samples, V occurs as the vanadyl ion VO2+, in substitution within the octahedral sheet of the kaolinite structure in the same way as Fe3+. Kaolinite growth proceeded through the hydrothermal alteration of anterior phyllosilicates devoid of V, induced by fluids which leached V-rich titano-magnetites in the surrounding sandstones.

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