Framework geophysical modelling of granitoid versus supracrustal basement to the northeast Thelon Basin around the Kiggavik uranium camp, Nunavut

Tschirhart, V; Morris, William A.; Jefferson, C W

doi:10.1139/cjes-2012-0149

Cited by 10 publications

(13 citation statements)

References 10 publications

(14 reference statements)

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“…Major ENE-trending dextral strikeand oblique-slip faults, including the Thelon-Fault ( Fig. 1 Ma supracrustal rocks of the Woodburn Lake Group , and a distinctive package of 2620-2580 Ma felsic volcanic and related hypabyssal rocks known as the Snow Island suite (Jefferson et al, 2011a(Jefferson et al, , 2011bMcEwan, 2012;Tschirhart et al, 2013Tschirhart et al, , 2017Peterson et al, 2015a;Johnstone et al, 2016). These rocks, together with overlying Paleoproterozoic (2300-2150 Ma) rocks of the Ketyet River Group (Rainbird et al, 2010), include a prominent unit of orthoquartzite (Zaleski et al, 2000).…”

Section: Regional Settingmentioning

confidence: 99%

The Contact uranium prospect, Kiggavik project, Nunavut (Canada): Tectonic history, structural constraints and timing of mineralization

Grare

Benedicto

Lacombe

et al. 2018

Ore Geology Reviews

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Uranium mineralization in the Kiggavik area, on the eastern border of the Thelon basin (Nunavut, Canada), hosts significant uranium resources within the basement and its understanding is critical to comprehending the genesis of unconformity-related deposits' structural controls and therefore exploration of these types of deposits in this prospective district. This article deciphers the complex multiphase fracture network associated with uranium mineralization of the most recently discovered, basement-hosted prospect in the Kiggavik area, named Contact. The Contact prospect is located along the Andrew Lake Fault (ALF), a major NE-SW fault corridor in the area. This study combines field work, drillcore logging, sampling, and macro-to micro-petro-structural analyses. Key results from this study highlight that the NEtrending ALF, along with the ENE-trending Thelon (TF) and Judge Sissons (JSF) faults, formed early during intracratonic rifting and deposition of the Baker Lake and Wharton groups (ca. 1850-1750 Ma) in response to the Thelon and Trans-Hudsonian orogeny. The ALF was affected by a strong silicification-brecciation event that likely developed at ca. 1750 Ma, and partitioned later deformation and fluid circulation. In the Contact prospect, the ALF was reactivated multiple times and mineralized in three stages with distinctive secondary fracture patterns, alteration, and mineralization types. Ten fracture stages have been identified at the Contact prospect, f1 to f10. The first stage of mineralization, coeval with f5, is related to fluids of unconstrained origin that circulated through E-W faults in the area that locally re-activated quartz veins of the brecciation event at the intersection with the ALF. Mineralization at this stage is polymetallic and associated with weak clay alteration. The second stage of uranium mineralization occurred coeval with transtensional reactivation of the NE-SW trending ALF (f6c) and in relation to circulation of oxidizing basinal brines within the fault zone. Mineralization at this stage is monometallic and associated with illite and sudoite alteration. Later reactivation of the inherited fracture network (f8) led to strong illitization and bleaching of the host rock, with local reworking of the ore body. Finally, reactivation of the fracture network during f9 and 10 lead to circulation of meteoric fluids that remobilized mineralization in a third stage of uranium re-concentration along redox fronts, with strong illitization and bleaching of the host rock. Unlike the classic unconformity-related uranium deposits in the Athabasca Basin where clay alteration halos occur around the ore bodies related to mineralizing processes, in the Contact prospect the strongest clay alteration event (f8) postdates both main stages of mineralization. Along with uranium remobilization, the basement-hosted Contact prospect is likely a relict of what was once a larger deposit.

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Section: Regional Settingmentioning

confidence: 99%

The Contact uranium prospect, Kiggavik project, Nunavut (Canada): Tectonic history, structural constraints and timing of mineralization

Grare

Benedicto

Lacombe

et al. 2018

Ore Geology Reviews

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“…The drill-hole and gravity data show that the apparent decrease in magnetic susceptibility is not a result of increased distance from magnetic source to sensor but rather is the result of post-dyke (<1.75 Ga) hydrothermal destruction of magnetite (Tschirhart et al 2014). Similar demagnetization effects characterize the Kiggavik camp that is also intersected by numerous hydrothermally altered, reactivated faults, has a markedly decreased magnetic susceptibility toward the Thelon Fault, and is at surface (Tschirhart et al 2013c;Fuchs et al 1986).…”

Section: Discussionmentioning

confidence: 89%

“…Cross Section 4 ( Fig. 9) extends 80 km southeast to almost the TF, which was modelled by Tschirhart et al (2013c). At the north end of section 4, the multiple-fold Amer Group and RA (density 2.74 g/cm 3 ) are unconformably overlain by undivided Amarook and Thelon Formations.…”

Section: Cross Sectionmentioning

confidence: 97%

“…The Thelon Formation and Wharton Group unconformably overlie older rocks, starting with the 1.83 Ga Hudson Suite (Peterson et al 2002;van Breemen, Peterson, and Sandeman 2005) of granite and syenite that intrude earlier Paleoproterozoic (<2.2 to <1.9 Ga Amer and Ketyet River groups) and Archean supracrustal rocks (Woodburn Lake Group, Marjorie Hills assemblage) (Pehrsson et al 2013;Jefferson et al 2015). The Hudson Suite forms thick, gently west-dipping slabs of the magnetically intense Schultz Lake Intrusive Complex (SLIC; Miller and Peterson 2015;Scott et al 2015;Tschirhart, Morris, and Jefferson 2013c) that intrudes the Neoarchean Marjorie Hills assemblage on the southeast side of the sub-basin .…”

Section: R E G I O N a L S E T T I N Gmentioning

confidence: 99%

“…The main 075°TF offsets the 1.83 Ga SLIC by 18 km. The TF also has a north-down, dip slip offset of at least 400 m Tschirhart et al 2013c).…”

Section: R E G I O N a L S E T T I N Gmentioning

confidence: 99%

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Basement geology beneath the northeast Thelon Basin, Nunavut: insights from integrating new gravity, magnetic and geological data

Tschirhart

Jefferson

Morris

2016

Geophysical Prospecting

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Current models for unconformity‐associated uranium deposits predict fluid flow and ore deposition along reactivated faults in >1.76 Ga basement beneath Mesoproterozoic siliciclastic basins. In frontier regions such as the Thelon Basin in the Kivalliq region of Nunavut, little is known about the sub‐basin distribution of units and structures, making exploration targeting very tenuous. We constructed a geological map of the basement beneath the unconformity by extrapolating exposed features into the subsurface. The new map is constrained by detailed geological, geophysical, and rock property observations of outcrops adjacent to the basin and by aeromagnetic and gravity data over the geophysically transparent sedimentary basin. From rock property measurements, it is clear that the diverse magnetic and density characteristics of major rock packages provide quantitative three‐dimensional constraints. Gravity profiles forward modelled in four cross sections define broad synforms of the Amer Belt and Archean volcanic rocks that are consistent with the structural style outside the basin. Major lithotectonic entities beneath the unconformity include: supracrustal rocks of the Archean Woodburn Lake group and Marjorie Hills meta sedimentary gneiss and associated mixed granitoid and amphibolitic gneiss; the Amer Mylonite Zone and inferred mafic intrusions oriented parallel and sub‐parallel; other igneous intrusions of 2.6 Ga, 1.83 Ga, and 1.75 Ga vintage; and the <2.3 Ga to >1.84 Ga Amer Group. Four main brittle regional fault arrays (040°–060°, 075°–90°, 120°, and 150°) controlled development and preservation of the basin. The reactivated intersections of such faults along fertile basement units such as the Rumble assemblage, Marjorie Hills assemblage, Nueltin igneous rocks, and Pitz formation are the best targets for uranium exploration.

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Geochemistry and geochronology of the Kiggavik uranium deposit, Nunavut, Canada

et al. 2020

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Framework geophysical modelling of granitoid versus supracrustal basement to the northeast Thelon Basin around the Kiggavik uranium camp, Nunavut

Cited by 10 publications

References 10 publications

The Contact uranium prospect, Kiggavik project, Nunavut (Canada): Tectonic history, structural constraints and timing of mineralization

The Contact uranium prospect, Kiggavik project, Nunavut (Canada): Tectonic history, structural constraints and timing of mineralization

Basement geology beneath the northeast Thelon Basin, Nunavut: insights from integrating new gravity, magnetic and geological data

Geochemistry and geochronology of the Kiggavik uranium deposit, Nunavut, Canada

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