Mineralogy and U/Pb, Pb/Pb, and Sm/Nd geochronology of the Key Lake uranium deposit, Athabasca Basin, Saskatchewan, Canada

1992 ◽  
Vol 29 (5) ◽  
pp. 879-895 ◽  
Author(s):  
C. Carl ◽  
E. von Pechmann ◽  
A. Höhndorf ◽  
G. Ruhrmann
Keyword(s):  
Uranium Deposit ◽  
Time Span ◽  
Radiometric Dating ◽  
Age Difference ◽  
High Grade ◽  
Uranium Deposits ◽  
Isotopic Data ◽  
Athabasca Basin ◽  
The Past ◽  
Preparation Techniques

The Key Lake deposit is one of several large, high-grade, unconformity-related uranium deposits located at the eastern margin of the Athabasca Basin in northern Saskatchewan, Canada. The deposit consists of the Gaertner orebody, now mined out, and the Deilmann orebody, which is presently being mined. In the past, radiometric dating efforts yielded an age of oldest ore-forming event of 1250 ± 34 Ma at the Gaertner orebody and 1350 ± 4 Ma at the Deilmann orebody. This unlikely age difference called for further investigation. Innovative preparation techniques were used to separate the paragenetically oldest U mineral, an anisotropic uraninite. Ore microscopy and U/Pb isotopic data show that the oldest event of uranium emplacement occurred simultaneously at the two orebodies, at 1421 ± 49 Ma. The primary ore-forming phase was followed by younger generations of U mineralization and periods of remobilization. Sm/Nd data of Key Lake uraninite form an isochron corresponding to an age of 1215 Ma. This is interpreted as the age of a uranium remobilization or a new mineralizing event. The lead found in the Athabasca Group above the Deilmann deposit and in galena appears to be a mixture of a common lead and radiogenic lead mobilized from the orebody over a time span of at least 1000 Ma.

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.

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.

scholarly journals How Can Technical Aspects Help Improving K-Ar Isotopic Data of Illite-Rich Clay Materials into Meaningful Ages? The Case of the Dominique Peter Uranium Deposit (Saskatchewan, Canada)

Geosciences ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 285
Author(s):  
Norbert Clauer
Keyword(s):  
Analytical Procedure ◽  
Uranium Deposit ◽  
Isotopic Data ◽  
Athabasca Basin ◽  
Isotopic Methods ◽  
Circular Structure ◽  
Combining Data ◽  
Two Generations ◽  
Host Rocks ◽  
Clay Materials

Previously published K-Ar dating results of <2 μm illite separates from uranium-hosting and associated barren rocks from Dominique Peter district of the Carswell circular structure in the Athabasca Basin (Canada) were considered to trace four distinct tectonic-thermal events at 1447 ± 45, 1282 ± 40 and 1184 ± 15 (all errors at ± 2 Ma, with a younger, less constrained episode at ~900 Ma. Recent analyses of K-Ar ages of additional <0.2 μm illite fractions from a few initial samples demonstrate that the intermediate ages at ~1280 and ~1185 Ma result, in fact, from mixing of two generations of illite that precipitated at ~1450 and ~900 Ma. They have, therefore, no stratigraphic value, while the two tectonic-thermal episodes at 1448 ± 48 and 937 ± 39 Ma appear to be historically sound. In fact, the analytical procedure of isotopic dating clay materials is of more importance than is often stated. For instance, a safe way to evaluate and constrain best numerical isotopic data of clay separates into ages is combining data of two size splits from several samples. If such age data, especially from size fractions of indurated host rocks, are scattered and point towards the higher data of the coarser fractions, they are potentially enriched in earlier crystallized K-rich components, and should consequently be discarded. The occurrence of detrital or early-crystallized components in clay-rich separates becomes a serious concern when comparing ages generated by various isotopic methods on mineral separates of various whole rocks. It is especially verified in very old, metal-rich deposits such as the uranium-rich deposits of the Saskatchewan Basin. These deposits and their host rocks were studied extensively by a large spectrum of isotopic methods on many types of rocks in a widely dispersed area, and for which the numerical statistics became, sometimes, more central in the interpretation than the specificity of the successive events in the host rocks.

Paleomagnetism and the evolution of fluids in the Proterozoic Athabasca Basin, northern Saskatchewan, Canada

1992 ◽  
Vol 29 (7) ◽  
pp. 1474-1491 ◽  
Author(s):  
T. G. Kotzer ◽  
T. K. Kyser ◽  
E. Irving
Keyword(s):  
Fluid Flow ◽  
High Temperature ◽  
Fault Zones ◽  
Time Span ◽  
High Grade ◽  
Lateral Migration ◽  
Athabasca Basin ◽  
Precambrian Rocks ◽  
Late Precambrian ◽  
Low Intensity

In the Athabasca Basin, diagenetic hematite of variable paragenesis occurs throughout the sandstones and underlying paleoregolith. This hematite carries three distinct, single-component magnetizations: A (D = 158°, I = 62°, α95 = 5°, n = 21); B (D = 11°, I = −36°, α95 = 7°, n = 6); and C (D = 18°, I = 79°, α95 = 3°, n = 27). In some areas of the sandstones, such as near reactivated fault zones, the diagenetic hematite has been altered to goethite which yields a very low-intensity, incoherent D magnetization. Ages for the A, B, and C magnetizations, inferred from comparisons with paleomagnetic directions in Precambrian rocks whose ages are known approximately, are 1750–1600, 1600–1450, and about 900 Ma, respectively. The A magnetization is carried by the earliest formed hematite, and its estimated age compares well with U–Pb ages of 1650–1700 Ma for early diagenetic apatite. U–Pb and Rb–Sr ages of approximately 1500 and 900 Ma for uraninite and illite coeval with hematite that carries the B and C magnetizations compare well with their ages estimated from paleomagnetism. The development of B magnetization appears to be coeval with high-grade, unconformity-type uranium mineralization.Petrographic and field relationships indicate that the A magnetization is carried by hematite formed during initial diagenesis of the Athabasca sandstones, the B magnetization is carried by hematite formed during peak diagenesis, and the C magnetization is carried by hematite formed during subsequent high-temperature hydrothermal alteration. The incoherent D magnetizations have resulted from degradation of hematite to goethite as a result of incursion of low-temperature meteoric waters along fault zones that have been continuously reactivated since the late Precambrian. δ18O values of clay minerals and of the coeval hematite which carries the B and C magnetization indicate that they were formed from a fluid having temperatures of 150–200 °C and δ18O values near 1.0‰. Fluids that deposited the early formed hematite carrying the A magnetism are relatively 18O depleted, with values of approximately 0.8‰ and somewhat lower temperatures of 120–160 °C. Intermingling of A, B, and C magnetizations indicates either that hematite may be deposited by one fluid and reprecipitated by a subsequent fluid, or that fluid flow was controlled by local variations in permeability. Evidently, fluid flow has been episodic and basin wide and has occurred over a time span on the order of 108 years. It is suggested that the stratigraphy of the sandstones controlled the basin-wide lateral migration of the basinal fluids and that faults facilitated interformational fluid flow.

Stable isotope constraints on the role of graphite in the genesis of unconformity-type uranium deposits

1989 ◽  
Vol 26 (3) ◽  
pp. 490-498 ◽  
Author(s):  
T. K. Kyser ◽  
M. R. Wilson ◽  
G. Ruhrmann
Keyword(s):  
Fluid Flow ◽  
Stable Isotope ◽  
Uranium Deposit ◽  
Shear Zones ◽  
Limited Range ◽  
Hydrothermal Fluids ◽  
Uranium Deposits ◽  
Athabasca Basin ◽  
Ore Zones

The Key Lake unconformity-type uranium deposit occurs in a shear zone where it intersects the unconformity between Archean and Aphebian gneisses and the overlying Proterozoic Athabasca Group sandstones. The roots of the Key Lake and many other unconformity-type uranium deposits in the Athabasca basin are close to gneisses rich in graphite and most deposits have small amounts of carbonaceous materials (bitumen and hydrocarbon buttons) within and around altered basement and sandstone ore zones. In many Athabasca uranium deposits, hydrothermal fluids have destroyed graphite disseminated in the strongly altered gneisses in the vicinity of the deposits, prompting some to suggest that graphite was converted to CH4, which reduced and precipitated the uranium and partially condensed to form bitumen. The δ13C values of graphite collected from unaltered and altered gneisses around the Key Lake deposit have a limited range (−25 ± 5) and are not a function of distance from the mineralization or the intensity of alteration or deformation. The uniformity of these δ13C values suggests that the destruction of graphite was due predominantly to oxidation by basinal fluids from the sandstone and that the graphite near the deposits did not react to form substantial amounts of 12C-rich phases such as CH4. Most of the bitumen samples, which have higher H/C ratios than the graphite, have δ13C values identical to those of the graphite (−25 ± 5). The similarity in the isotopic compositions of carbon in the bitumen and in the graphite indicates that the bitumen formed from degradation of graphite as a result of reactions with no significant isotopic fractionations, such as ones involving radiolysis of graphite. The hydrocarbon buttons and a few samples of bitumen have petrographic relations and 13C/12C ratios (δ13C values less than −30) that are indicative of reduction of graphite by H2 produced from water by radiolysis. Graphite in these deposits did not play a central role as a reducing agent for uranium, rather it represents a critical structural factor by providing shear zones along which fluid flow can be focussed.

Geometallurgical ore characterization of the high-grade polymetallic unconformity-related uranium deposit

2021 ◽  
Vol 59 (5) ◽  
pp. 813-845
Author(s):  
Andrew J. Kaczowka ◽  
T. Kurt Kyser ◽  
Tom G. Kotzer ◽  
Matthew I. Leybourne ◽  
Daniel Layton-Matthews
Keyword(s):  
Uranium Deposit ◽  
Mineral Chemistry ◽  
Molar Ratio ◽  
High Grade ◽  
Tectonic Structures ◽  
Athabasca Basin ◽  
Significant Control ◽  
Mine Effluent ◽  
Ore Characterization

ABSTRACT Cigar Lake is a polymetallic, unconformity-related uranium deposit with complex geochemistry and mineralogy located in the eastern Athabasca Basin of northern Saskatchewan, Canada. Variable concentrations and spatial distributions of elements of concern, such as As, Mo, Ni, Co, Se, and Zr, associated with the high-grade tetravalent uranium ores [UO2+x; U(SiO4)1–x(OH)4x] present unique mining, metallurgical, and environmental challenges. Sulfide and arsenide minerals have significant control over As, Mo, Ni, Co, and Se abundances and have properties that affect element of concern mobility, thus requiring consideration during mineral processing, mine-effluent water treatment, and long-term tailings management. The U-bearing (uraninite, coffinite) and metallic arsenide (nickeline, often called “niccolite” in the past), sulfarsenide (gersdorffite, cobaltite), and sulfide (chalcopyrite, pyrite, galena, bornite, chalcocite, sphalerite, pyrrhotite) minerals provide the main controls on the distributions of the elements of concern. Arsenic, Ni, and Co occur primarily in a reduced state as 1:1 molar ratio, Ni-Co:As, arsenide, and sulfarsenide minerals such as gersdorffite, nickeline, and cobaltite. Molybdenum occurs within molybdenite and uraninite. Selenium occurs within coffinite, sulfide, and sulfarsenide minerals. Zirconium is found within detrital zircon and coffinite. The spatial distribution and paragenesis of U-, As-, and S-bearing minerals are a result of the elemental composition, pH, and redox conditions of early formational and later meteoric fluids that formed and have modified the deposit through access along lithostratigraphic permeability and tectonic structures. Using the holistic geometallurgical paradigm presented here, the geochemistry and mineral chemistry at Cigar Lake can be used to optimize and reduce risk during long-term mine and mill planning.

Smart Estimation Ver-H.1.0

2018 ◽  
Author(s):  
Sigit Haryadi
Keyword(s):  
Sample Size ◽  
Confidence Level ◽  
Time Span ◽  
Regression Equation ◽  
Weight Factor ◽  
The Past ◽  
Level Of Confidence ◽  
The Future ◽  
Future Value ◽  
The Difference

We cannot be sure exactly what will happen, we can only estimate by using a particular method, where each method must have the formula to create a regression equation and a formula to calculate the confidence level of the estimated value. This paper conveys a method of estimating the future values, in which the formula for creating a regression equation is based on the assumption that the future value will depend on the difference of the past values divided by a weight factor which corresponding to the time span to the present, and the formula for calculating the level of confidence is to use "the Haryadi Index". The advantage of this method is to remain accurate regardless of the sample size and may ignore the past value that is considered irrelevant.

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