Paragenesis and Isotopic Composition of some Gangue Minerals from the Uranium Deposits of Eldorado, Saskatchewan

Sassano, G. P.; Fritz, P.; Morton, R. D.

doi:10.1139/e72-012

Cited by 17 publications

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“…Many of the uranium deposits are known to have been reworked at various stages throughout their history, but to what extent this is due to circulating groundwater or metamorphic or magmatic fluids depends on temperatures of deposition and the time of re-working. Temperature estimates for the vein-type deposits are in excess of 400~ (Robinson, 1955;Sassano et al, 1972) while significantly lower values have been suggested for the unconformity-type deposits.…”

mentioning

confidence: 97%

“…Because the 1740 Ma figure is based on whole-rock Rb-Sr isochron data it is thought to represent the average age of a distinct magrnatic event and not just a figure that reflects an updating of older granites by the Hudsonian Orogeny. Whole-rock Rb-Sr isochron dates from lamprophyre dykes of 1740___ 70 Ma in the northwestern part of the province have been documented by Sassano et al (1974).…”

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confidence: 99%

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A review of the geochronology of the Precambrian of Saskatchewan—some clues to uranium mineralization

Bell

1981

Mineral. mag.

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Assessment of available geochronological information, as well as new whole-rock Rb-Sr data from several granitoid rocks of Saskatchewan, shows a close relationship between magmatic-metamorphic events in the Hudsonian orogen and uranium mineralization. Most uranium deposits lie to the west of the Needle Falls Shear Zone and occur as either: (i) vein-type deposits or (ii) unconformity-type deposits close to the contact between the Athabasca sediments and their basement. At least two metamorphisms have affected the pre-Athabasca rocks: the Kenoran at about 2500 Ma ago, and the more pervasive ‘main’ Hudsonian event at 1740 Ma. A much younger thermal event (perhaps associated with uplift and cooling) at 1540 Ma is also indicated. The post-Kenoran K-Ar dates suggest prolonged thermal activity from about 1900 Ma through to about 1500 Ma ago. Granitoid events at 1870 Ma and 1740 Ma ago are outlined by both U-Pb zircon and Rb-Sr whole-rock isochron data. Whole-rock Rb-Sr data from the unmetamorphosed Athabasca sediments suggest an approximate depositional age of 1450±50 Ma, a figure that is consistent with the age of the underlying Hudsonian basement and the truncation of the sediments by the Cree Lake diabase dyke swarm at about 1200–1300 Ma ago. Although several episodes of uranium deposition have been documented, the main ones seem to have occurred at 1860 Ma (syngenetic uraninite in pegmatites), 1740 Ma (the Beaverlodge vein-type deposits) and between 1300 and 800 Ma (the epigenetic uranium of the unconformity-type deposits). Whereas the two earlier episodes can be correlated with periods of either magmatic or metamorphic activity, the late Proterozoic episodes cannot. The close agreement between the age of the Cree Lake dyke swarm and the late Proterozoic mineralization suggests that at about 1300 Ma ago possible hydrothermal activity from relatively deep-seated fractures may have been responsible for the solution and transportation of the uranium of the unconformity-type deposits. The period 1300 Ma to about 900 Ma, in other parts of the Canadian Shield, was a time of crustal rifting, basic magmatism, carbonatite activity, and intense deformation. Prior to the deposition of the Athabasca sediments uranium was concentrated by Hudsonian magmatic and metamorphic processes whereas subsequently, transportation and intermittent deposition of the unconformity-type deposits were related to fairly long-lived, low-temperature hydrothermal activity.

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confidence: 97%

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A review of the geochronology of the Precambrian of Saskatchewan—some clues to uranium mineralization

Bell

1981

Mineral. mag.

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“…According to Robinson (1955), Koeppel (1968), Tremblay (1968), Beck (1969Beck ( , 1970 and Sassano et al (1972) the following geological features of the Beaverlodge deposits can be observed:…”

Section: Beaverlodgementioning

confidence: 99%

“…(10) Studies of fluid inclusions and stable isotopes (13C, lsO) by Sassano (1972) of dolomite, calcite and quartz from ore of the Fay and Bolger mines, indicate a cooling sequence from the initial phase of mineralization at 440 ± 30 °G down to the final stages at around 80 + 10 °C. Five generations of carbonate can be distinguished in the ore veins.…”

Section: Beaverlodgementioning

confidence: 99%

Uranium occurrences in northern Saskatchewan, Canada, and their mode of origin

Dahlkamp¹

1979

Phil. Trans. R. Soc. Lond. A

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Mineralogical, petrographical, geochemical, tectonic and palaeoclimatological studies suggest the following sequence of events in the formation of the Key Lake ore bodies: (1) Uranium was deposited in Aphebian sediments surrounding Archaean cores; (2) the Hudsonian orogeny metamorphosed the sediments, perhaps further concentrating the uranium; (3) Middle Proterozoic weathering processes mobilized the uranium and nickel; (4) both elements migrated into tectonic traps, where they were concentrated; (5) the basement was covered by the Athabasca formation to a thickness of 1000 m and more; (6) diagenetic processes mobilized and redeposited the uranium more or less in situ destroying the original radiogenic equilibrium and simultaneously forming a new ‘primary ’ generation of uranium oxide with a rejuvenated age of about 1100 Ma; (7) episodic uplift resulted in erosion of the overlying Athabasca formation, leading to the formation of new generations of uranium minerals (sooty pitchblende, coffinite). An alternative explanation is that the weathering cycle of stages (3) and (4) can be disregarded and the uranium enrichment, involving mobilization, transportation and redeposition, attributed entirely to diagenetic processes. Published data of similar deposits in Saskatchewan/ Canada are compared with the Key Lake geological setting. They contain metallogenic parameters comparable with those of Key Lake indicating that all these orebodies or mineral occurrences probably belong to the same vein type of deposit.

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“…the Fay and Verna Mines by G. P. Sassano, from Eldorado Nuclear Limited, augmented these with underground dike samples (Sassano 1972;Sassano et al 1972a). The structural relations shown in the mine workings are discussed by Morton and Sassano (1972).…”

Section: Introductionmentioning

confidence: 99%

Rb-Sr Age of the Late-Kinematic Phase of the Hudsonian Orogeny in the Beaverlodge Area, Saskatchewan

Sassano¹,

Baadsgaard²,

Burwash³

1974

Can. J. Earth Sci.

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The Tazin Complex, north of Lake Athabasca, shows widespread development of mylonites associated with northeast trending faults. Hudsonian metamorphism has caused recrystallization of cataclastic rocks with post-crystalline deformation forming narrow zones of later mylonites. Syenitic lamprophyre dikes which, with very few exceptions, are undeformed, form the latest intrusive rocks in the area, filling dilatant fractures developed during crustal uplift. R b S r whole rock dating of eight samples of the dikes in the Beaverlodge area, yield an isochron of 1779 i-72 m.y. (initial ratio = 0.709 0.001, MSWD = 0.39. x("Rb) = 1.39 X 10-U/yr). The late-kinematic phase of the Hudsonian orogeny, therefore, occurred around 1780 m.y. ago, at which time the uplift of the northwestern sector of the Churchill structural province took place. It is also believed that the date is close to the time of final movement of the St. Louis Fault.Le complexe de Tazin, au nord du Lac Alhahasca. montre un dbveloppement Ctendu de mylonites associees B des failles de direction nord-est. Le mktamorphisme hudsonien a causC la recristallisation des roches cataclastiques avec la deformation post-cristalline formant rles zones etroites de mylonites tardives. Des dykes de lamprophyre syknitique qui sont, sauf de rares exceptions, non dCformCs. constituent les roches intrusives les plus tardives dans la rkgion, remplissant les fractures de dilatation dCvelopp6es pendant le soul&vement de la croQte. La datation (roche totale) au R b S r de huit tchantillons des dykes pris dans la rkgion de Beaverlodge, donne un isochrome de 1779 rt 72 millions d'annees (rapport initial = 0.709 2 0.001, MSWD = 0.39, A("Rb) = 1.39 X 10-"/an). La phase tardi-cinkmatique de I'orogine hudsonienne, par conskquent, s'est dkroul6e il y a 1780 millions cl'ann6es environ, au moment oh le soul&venient du sectour nord-ouest de la province structurale de Churchill prenait place. On pense aussi que le mouvement final de la faille de St. Louis s'est produit vers cette date. praduit par le journal]

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Paragenesis and Isotopic Composition of some Gangue Minerals from the Uranium Deposits of Eldorado, Saskatchewan

Cited by 17 publications

References 0 publications

A review of the geochronology of the Precambrian of Saskatchewan—some clues to uranium mineralization

A review of the geochronology of the Precambrian of Saskatchewan—some clues to uranium mineralization

Uranium occurrences in northern Saskatchewan, Canada, and their mode of origin

Rb-Sr Age of the Late-Kinematic Phase of the Hudsonian Orogeny in the Beaverlodge Area, Saskatchewan

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