Geology, Structural Analysis, and Paragenesis of the Arrow Uranium Deposit, Western Athabasca Basin, Saskatchewan, Canada: Implications for the Development of the Patterson Lake Corridor

2020 ◽  
Author(s):  
Sean Hillacre ◽  
Kevin Ansdell ◽  
Brian McEwan
Keyword(s):  
Structural Analysis ◽  
Uranium Deposit ◽  
Regional Scale ◽  
Structural Features ◽  
White Mica ◽  
Uranium Mineralization ◽  
Fault System ◽  
Thin Sections ◽  
Athabasca Basin ◽  
Quartz Veins

Abstract Recent significant discoveries of uranium mineralization in the southwestern Athabasca basin, northern Saskatchewan, Canada, have been associated with a series of geophysical conductors along a NE- to SW-trending structural zone, termed the Patterson Lake corridor. The Arrow deposit (indicated mineral resource: 256.6 Mlb U3O8; grade 4.03% U3O8) is along this trend, hosted exclusively in basement orthogneisses of the Taltson domain, and is the largest undeveloped uranium deposit in the basin. This study is the first detailed analysis of a deposit along this corridor and examines the relationships between the ductile framework and brittle reactivation of structures, mineral paragenesis, and uranium mineralization. Paragenetic information from hundreds of drill core samples and thin sections was integrated with structural analysis utilizing over 18,000 measurements of various structural features. The structural system at Arrow is interpreted as a partitioned, strike-slip–dominated, brittle-ductile fault system of complex Riedel-style geometry. The system developed along subvertical, NE- to SW-trending dextral high-strain zones formed syn- to post-D3 deformation, which were the focus of extensive premineralization metasomatism (quartz flooding, sericitization, chloritization), within the limb domain of a regional-scale fold structure. These zones evolved through post-Athabasca dextral and sinistral reactivation events, creating brittle fault linkages and dilation zones, allowing for hydrothermal fluid migration and resulting uraninite precipitation and associated alteration (white mica, chlorite, kaolinite, hematite, quartz veins). This study of the structural context of Arrow is important as it emphasizes that protracted reactivation of deep-seated structures and their subsidiaries was a fundamental control on uranium mineralization in the southwestern Athabasca basin.

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 Structural Controls of Uranium Mineralization in the Basement of the Athabasca Basin, Saskatchewan, Canada

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-30
Author(s):  
Antonio Benedicto ◽  
Maher Abdelrazek ◽  
Patrick Ledru ◽  
Cameron MacKay ◽  
Dwayne Kinar
Keyword(s):  
Regional Scale ◽  
Structural Data ◽  
Shear Zones ◽  
Uranium Mineralization ◽  
Uranium Deposits ◽  
Athabasca Basin ◽  
Structural Controls ◽  
The Right ◽  
Drill Holes

The occurrence of unconformity-related uranium mineralization requires the combination of three components: fluids with the right composition, geochemical traps with the right agents that produce precipitation, and structural traps with the right geometry. In the Athabasca Basin unconformity-related uranium deposits, while basinal brines are commonly accepted as the principal mineralized fluids and graphite and gases (CH4, CO2, and H2S) are well known as the reductants, only few case studies describing structural traps are published. A number of recent works, including numerical modelling, have improved the understanding of the role of inherited shear zones on fluid flow and the development of uranium deposits at a micro- and regional-scale. Nevertheless, there is still a lack of knowledge about the meso- or deposit-scale structural controls that lead to the present (and potentially predictive) localization of uranium deposits along a given shear zone. The present work examines new structural data from drill holes and deals with (i) the identification of mesoscale structural traps that lead to the formation of the Athabasca unconformity-related uranium deposits hosted within the basement and (ii) with the understanding of the role and mode of reactivation of the inherited shear zones. The Sue deposits (McClean Project), the Tri-Island showing (Martin Lake Project) in the Eastern Athabasca, and the Spitfire prospect (Hook Lake Project) in the Western Athabasca have been selected for a detailed analysis of structures and related uranium mineralization. The structural analysis performed brings new insights about the mesoscale structural controls, the role the inherited ductile fabric had on the mode of brittle reactivation and to trap mineralization, and the tectonic regime to which basement-hosted uranium deposits may be associated in the Athabasca Basin.

GEOCHRONOLOGY AND PETROGENESIS OF THE PUERTO ESCONDIDO-HUATULCO INTRUSIONS IN SOUTHERN MEXICO AND STRUCTURAL ANALYSIS OF THE WESTERN CHACALAPA FAULT SYSTEM

2019 ◽  
Author(s):  
Samantha Yahel García Hernández ◽  
◽  
Dante J. Morán-Zenteno ◽  
Barbara M. Martiny ◽  
Gustavo Tolson
Keyword(s):  
Structural Analysis ◽  
Fault System ◽  
Southern Mexico

The Coles Hill Uranium Deposit, Virginia, USA: Geology, Geochemistry, Geochronology, and Genetic Model

2022 ◽  
Vol 117 (2) ◽  
pp. 273-304
Author(s):  
S. M. Hall ◽  
J. S. Beard ◽  
C. J. Potter ◽  
R. J. Bodnar ◽  
L. A. Neymark ◽  
...  
Keyword(s):  
Shear Zone ◽  
Titanium Oxide ◽  
River Basin ◽  
Host Rock ◽  
Uranium Deposit ◽  
Uranium Mineralization ◽  
Late Triassic ◽  
Pb Isotope ◽  
Igneous Complex ◽  
Mineralizing Fluids

Abstract The Coles Hill uranium deposit, with an indicated resource of about 130 Mlb of U3O8, is the largest unmined uranium deposit in the United States. The deposit is hosted in the Taconian (approx. 480–450 Ma) Martinsville igneous complex, which consists of the Ordovician Leatherwood Granite (granodiorite) and the Silurian Rich Acres Formation (diorite). The host rock was metamorphosed to orthogneiss during the Alleghanian orogeny (approx. 325–260 Ma), when it also underwent dextral strike-slip movement along the Brookneal shear zone. During the Triassic, extensional tectonics led to the development of the Dan River Basin that lies east of Coles Hill. The mineralized zone is hosted in brittle structures in the footwall of the Triassic Chatham fault that forms the western edge of the basin. Within brittle fracture zones, uranium silicate and uranium-bearing fluorapatite with traces of brannerite form veins and breccia-fill with chlorite, quartz, titanium oxide, pyrite, and calcite. Uranium silicates also coat and replace primary titanite, zircon, ilmenite, and sulfides. Sodium metasomatism preceded and accompanied uranium mineralization, pervasively altering host rock and forming albite from primary feldspar, depositing limpid albite rims on igneous feldspar, altering titanite to titanium oxide and calcite, and forming riebeckite. Various geothermometers indicate temperatures of less than ~200°C during mineralization. In situ U-Pb analyses of titanite, Ti-oxide, and apatite, along with Rb/Sr and U/Pb isotope systematics of whole-rock samples, resolve the timing of geologic processes affecting Coles Hill. The host Leatherwood Granite containing primary euhedral titanite is dated at 450 to 445 Ma, in agreement with previously obtained ages from zircon in the Martinsville igneous complex. A regional metamorphic event at 330 to 310 Ma formed anhedral titanite and some apatite, reequilibrated whole-rock Rb/Sr and U-Pb isotopes, and is interpreted to have coincided with movement along the Brookneal shear zone. During shearing and metamorphism, primary refractory uranium-bearing minerals including titanite, zircon, and uranothorite were recrystallized, and uranium was liberated and mixed locally with hematite, clay, and other fine-grained minerals. Uranium mineralization was accompanied by a metasomatic episode between 250 and 200 Ma that reset the Rb-Sr and U-Pb isotope systems and formed titanium oxide and apatite that are associated and, in places, intimately intergrown with uranium silicate dating mineralization. This event coincides with rifting that formed the Dan River Basin and was a precursor to the breakup of Pangea. The orientation of late-stage tectonic stylolites is compatible with their formation during Late Triassic to Early Jurassic basin inversion, postdating the main stage of uranium mineralization and effectively dating mineralization as Mesozoic. Based on the close spatial and temporal association of uranium with apatite, we propose that uranium was carried as a uranyl-phosphate complex. Uranium was locally reduced by coupled redox reactions with ferrous iron and sulfide minerals in the host rock, forming uranium silicates. The release of calcium during sodium metasomatic alteration of primary calcic feldspar and titanite in the host rock initiated successive reactions in which uranium and phosphate in mineralizing fluids combined with calcium to form U-enriched fluorapatite. Based on the deposit mineralogy, oxygen isotope geochemistry, and trace element characteristics of uranium silicate and gangue minerals, the primary mineralizing fluids likely included connate and/or meteoric water sourced from the adjacent Dan River Basin. High heat flow related to Mesozoic rifting may have driven these (P-Na-F-rich) fluids through local aquifers and into basin margin faults, transporting uranium from the basin or mobilizing uranium from previously formed U minerals in the Brookneal shear zone, or from U-enriched older basement rock.

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.

Synchronous Eocene deformation recorded on either side of a major Miocene thrust bounding the Almyropotamos tectonic window in Evia, Greece

2021 ◽  
Author(s):  
Taylor Ducharme ◽  
Iwona Klonowska ◽  
David Schneider ◽  
Bernhard Grasemann ◽  
Kostantinos Soukis
Keyword(s):  
Regional Scale ◽  
Late Eocene ◽  
White Mica ◽  
Early Miocene ◽  
Lower Grade ◽  
Metamorphic History ◽  
Tectonic Window ◽  
Platform Carbonates ◽  
C 30 ◽  
Type 3

<p>Southern Evia in Greece exposes an inverted high pressure-low temperature (HP-LT) metamorphic sequence that has been loosely correlated with the Cycladic Blueschist Unit (CBU). On the island, the CBU is divided into the metavolcanic and ophiolitic Ochi Nappe and predominantly metacarbonate Styra Nappe. A lower-grade unit, the Almyropotamos Nappe, is exposed in the core of a N-S trending antiform and comprises Eocene platform carbonates overlain by metaflysch. The Almyropotamos Nappe occupies a tectonic window defined by the Evia Thrust, a brittle-ductile fault zone that emplaced the Ochi and Styra nappes atop the Almyropotamos Nappe. New multiple single-grain white mica total fusion <sup>40</sup>Ar/<sup>39</sup>Ar ages indicate that deformation occurred along the Evia Thrust at 25-23 Ma. White mica <sup>40</sup>Ar/<sup>39</sup>Ar data on either side of the tectonic window record Eocene dates between 40 and 32 Ma, consistent with previously published <sup>40</sup>Ar/<sup>39</sup>Ar dates and a single Rb-Sr age of c. 30 Ma. These ages broadly coincide with estimates for the timing of NE-directed thrusting of the Ochi Nappe over the Styra Nappe. Strain associated with thrusting localized as cylindrical folds in Styra marbles, with fold axes parallel to the stretching lineation and a clear strain gradient increasing toward the upper contact with the Ochi Nappe. The most prominent structures in the Ochi Nappe are a strong L-S fabric defined by acicular blue amphibole and type-3 refold structures with fold axes trending parallel to the NE-SW oriented stretching lineation. Whereas the Ochi Nappe and Styra Nappe locally preserve peak blueschist facies mineral assemblages, all three units commonly display evidence only for retrogressed initial HP-LT assemblages in the form of ferroglaucophane inclusions in albite porphyroblasts. Isochemical phase diagrams calculated in the Na<sub>2</sub>O-CaO-K<sub>2</sub>O-FeO-MgO-Al<sub>2</sub>O<sub>3</sub>-SiO<sub>2</sub>-H<sub>2</sub>O-TiO<sub>2</sub>±O<sub>2</sub> system support minimum peak metamorphic conditions of 12.5 ± 1.5 kbar and 465 ± 75 °C for an Ochi Nappe blueschist, and 6.0 ± 0.5 kbar and 315 ± 15 °C for an albite mica schist from the Evia Thrust. Peak P-T conditions for the Ochi Nappe support a metamorphic history more closely resembling that of the Lower Cycladic Blueschist Nappe, indicating that the entire section of the CBU exposed on Evia lies below the Trans-Cycladic Thrust. The Early Miocene ages from the Evia Thrust overlap with the proposed timing for the initiation of bivergent greenschist facies extension in the Cyclades. The remainder of the region, including high-strain corridors within individual nappes such as the Almyropotamos Thrust, uniformly records Eocene deformation ages. The similarity in <sup>40</sup>Ar/<sup>39</sup>Ar ages across the tectonic window contrasts with age relationships observed in similar tectonic packages on Lavrion, and suggests that regional scale deformation persisted until the Late Eocene before strain became localized in brittle-ductile corridors by the Early Miocene. </p>

Sign in / Sign up

Export Citation Format

Share Document