Abstract The richest uranium deposits in the world are unconformity-type deposits of the Proterozoic Athabasca Basin, Saskatchewan, Canada.

However, about 55 km east of the Key Lake uranium mine, uraniferous granitic pegmatites and leucogranites intrude into a shear zone

at the contact between deformed Paleoproterozoic Wollaston Group metasedimentary rocks and Archean orthogneisses. The uranium

mineralization is directly related to these igneous rocks, and the aim of this project is to determine whether these represent a distinct

target for uranium exploration in Saskatchewan or if the mineralization is related somehow to unconformity-type uranium deposits.

The magmatic-hosted deposits (Fraser Lakes Zones A and B) are in NE-plunging regional fold noses adjacent to a 5 km long folded EM

conductor (i.e. graphitic pelitic gneisses). The more prospective Zone B sits within an antiformal fold nose, from which several drill

holes have intersected multiple intervals of uranium and/or thorium mineralization (up to 0.183% U3O8 over 1.0 m in drill core). The

zones are cross-cut by a number of E-W-, NNE-, and NNW-trending structures. Associated with the uranium are thorium and LREE

mineralization with elevated amounts of pathfinder elements including Co, Cu, Mo, Ni, Pb, V, and Zn.

Drill core observations revealed the existence of multiple generations of granitic pegmatites, including mineralized (generally

subcordant to gneissosity, and believed to be syndeformational) and nonmineralized (discordant to gneissosity, and probably post–

tectonic) varieties, with some of the pegmatites showing compositional zoning due to igneous AFC processes.

While this is a magmatic-hosted U-Th deposit, the presence of clay alteration and structural features in Zone B drill core similar to that

of basement-hosted unconformity uranium deposits (e.g. Millennium, P Patch, Eagle Point, and McArthur River Zone 2) raises the

possibility that altered remobilized parts of the Fraser Lakes zones formed at the same time as unconformity-type mineralization in the

Athabasca Basin. This project will integrate field observations and geological, geochemical, and geophysical datasets so to develop a

metallogenetic model for the Fraser Lakes deposit, and clarify its relationship with the rich uranium deposits in the Athabasca Basin

(e.g. U protore).

WYL-09-50

Fig. 1 Location of JNR’s properties in northern

Saskatchewan, including the Way Lake Property

(modified from map on JNR Resources Inc. website)

Fig. 2 Topographic map showing the location of the Fraser Lakes Zones A and B

deposits, the folded EM conductor, and drill hole collars.

Fig. 3 Total field aeromagnetic image and trace of the EM conductor in the

Fraser Lakes area, location of Fraser Lakes Zones A and B, and drill holes.

Comparisons to other types of Uranium Deposits Several unconformity-type uranium deposits in the Athabasca Basin contain peraluminous leucogranites and pegmatites in the

basement rocks (Annesley et al., 2000a, 2000b, 2005, 2009; Annesley and Madore, 1999; Madore et al., 2000; Portella and Annesley,

2000) that have similarities to the pegmatites at the Fraser Lakes deposits, including host rocks, mineralogy, and presumed origin.

As well, drill core observations (Zone B) indicated the presence of chlorite and hematite alteration similar to that in basement-hosted

unconformity deposits (Annesley et al., 2009), indicating that there was possibly Athabasca hydrothermal fluid movement through the

Fraser Lakes area and remobilization of the uranium and thorium mineralization.

The Fraser Lakes uranium-thorium-LREE deposits are also similar to some of the pegmatite-, vein– and skarn-hosted uranium deposits

in the Grenville Province (Lentz, 1991), and are believed to have a similar origin (partial melting at deep to moderate crustal levels).

The authors acknowledge the financial support of JNR Resources Inc., NSERC (Discovery Grant to Ansdell) and the University of Saskatchewan (Graduate Scholarship to Austman). Thanks to Blaine Novakovski for

preparing the thin sections, to Kimberly Bradley from JNR Resources Inc. for her assistance with petrography, and the Saskatchewan Research Council for the geochemical results.

The Fraser Lakes Zones A and B uranium deposits are located in JNR Resources Inc.’s

Way Lake Property in northern Saskatchewan, Canada, ~25 km southeast of the

Athabasca Basin (location of the highest-grade uranium deposits in the world) and

55 km east of the Key Lake U mine.

The Way Lake Property is underlain by Paleoproterozoic Wollaston Group

metasedimentary rocks (including graphitic pelitic gneisses) and Archean orthogneisses

that underwent complex deformation, intrusion, and metamorphism during the Trans-

Hudson Orogen (~ 1.8 Ga). An approximately 65 km long electromagnetic (EM)

conductor runs across the property, with the Fraser Lakes deposits hosted adjacent to a

5 km section of the conductor (see Fig. 2 and 3) in NE-plunging synformal (Zone A) and

antiformal (Zone B) fold noses. The mineralization consists of uraniferous pegmatites

and leucogranites that intrude the highly deformed contact between the basal Wollaston

Group metasedimentary rocks and the Archean granitoids. It is estimated that the

Athabasca sandstone/basement unconformity was about 200-250 m above the presently

exposed outcrop (Annesley et al., 2009).

Analytical Methods Drill core from the Fraser Lakes Zone B deposit was examined for this study, with several samples from drill hole

WYL-09-50 taken for petrography. After drilling, each hole was probed using a gamma-ray probe to test for radioactivity.

Whole rock geochemical analysis on selected samples from each drill hole was completed by the Saskatchewan Research

Council Geo-Analytical Laboratories in Saskatoon.

Introduction

The purpose of this M.Sc. study is to develop a metallogenetic model for the Fraser Lakes deposits, and clarify their

relationship with the rich uranium deposits in the Athabasca Basin.

Examination of the drill core, combined with down hole gamma logs and geochemical analysis indicated the presence of elevated radioactivity due to uranium and thorium mineralization in pegmatites, leucogranites and migmatitic leucosomes (Fig. 5, 6, 7, pegmatites are the red unit, with the gamma probe results in blue alongside the logs) Pegmatite emplacement is controlled by the NE-plunging antiformal fold, with the pegmatites being concentrated in the fold nose area The deposit is also cross-cut by an E-W dextral ductile-brittle structure and a number of later NNW– and NNE-trending brittle faults (Annesley et al., 2009) Up to 0.453 % U3O8 was found in surface samples in a 500 m x 1500 m area and up to 0.183% U3O8 over 1.0 m in drill core (WYL-09-50) Multiple generations of pegmatites with variable mineralogy, some containing uranium mineralization with others barren (Fig. 8, 9, 10, 11, 12) Zonation of the pegmatites is common due to igneous assimilation fractional crystallization (AFC) processes (Fig. 8, 10, 11) Several features indicative of partial melting are also found in the drill core, including diatexitic migmatites and boudined felsic melt pods (Fig. 9, 13, 14) U– and Th– mineralization is accompanied by LREE enrichment and elevated amounts of pathfinder elements including Co, Cu, Mo, Ni, Pb, V, and Zn (see Fig. 15—17) Chlorite and hematite alteration similar to that found in basement-hosted unconformity deposits is found in several drill holes

Fig. 24 (PPL) + 25 (XPL) Granitic pegmatite (215.8 m) with Cal-Fl-Qtz

veining and alteration of feldspar to Ep, Hem, Chl, Cal, and Musc.

Fig. 26 Granitic pegmatite (166.2 m)

with alteration and fracturing.

Examination of several thin sections from drill hole WYL-09-50 indicated that the mineralized pegmatites and leucogranites contain

varying amounts of quartz, feldspar, biotite, +/- garnet, +/- muscovite, +/- magnetite, +/- ilmenite, +/- pyrite, +/- titanite, +/- zircon, +/-

allanite, +/- apatite, +/- monazite, +/- fluorite, +/-sphalerite, +/-molybdenite, +/- uraninite, +/- thorite, +/- uranothorite (Fig. 18 –26)

Textures associated with the mineralization include pleochroic halos around radioactive inclusions and radiation cracks radiating from

the radioactive minerals into the surrounding crystals (Fig. 20, 23, 24).

Fig. 8 Drill core from WYL-09-50 showing fractionation from quartz-rich to

feldspar-rich in the granitic pegmatite core (158.7 - 62.7m).

The presence of epidote, hematite, fluorite, calcite, and chlorite alteration associated with weak to locally strong brittle fracturing

(Fig. 23 - 26) indicates the likelihood of post-crystallization hydrothermal fluid flow through the rocks.

Fig. 22 Biotite-rich section of

granitic pegmatite (216.5 m).

Fig. 23 Granitic pegmatite (215.8 m)

containing zircon and allanite.

Fraser Lakes Zone B

Acknowledgements

Fig. 9 Drill core from WYL-09-524 (15.6—19.8 m) with boudinaged crustal

melt pods and granitic pegmatites.

Fig. 10 Granitic pegmatite in WYL-09-40 (116.5 -127.9 m)

showing fractionation from feldspar-rich to quartz-rich due

to igneous assimilation-fractional crystallization (AFC)

processes.

Fig. 11 Quartz-rich (up to 80%) pegmatite (121.3 to 149 m)

further down in drill hole WYL-09-40 than the feldspar-rich

granitic pegmatite shown in Fig. 10.

Fig. 14 Diatexitic migmatite with hematite

alteration in WYL-09-42 (~ 88.5 m)

Fig. 12 Granitic pegmatite (96.8 m) in WYL-09-41 with hematite

staining, and up to 2100 cps.

Fig. 13 Boudinaged felsic melt pods with garnet

cores in WYL-09-37 (188.1 to 192.6 m)

THE FRASER LAKES URANIUM DEPOSITS: FIELD RELATIONSHIPS, PETROGRAPHY,

AND GEOCHEMISTRY OF URANIFEROUS PEGMATITES AND ASSOCIATED ALTERATION AUSTMAN, Christine L.

1, ANSDELL, Kevin M.

1, and ANNESLEY, Irvine R.

1,2

(1) Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK, Canada S7N 5E2 (E-mail: christine.austman@usask.ca);

(2) JNR Resources Inc., Saskatoon, SK, Canada S7K 0G6

Conclusions Structurally controlled, basement-hosted U, Th, and LREE mineralization in Hudsonian-aged leucogranites and granitic pegmatites

that intrude Paleoproterozoic graphitic pelitic gneisses at the unconformity with Archean granitoids.

Zone B has up to 0.183% U3O8 over 1.0 m in drill core, and up to 0.453% U3O8 in outcrop grab samples.

Pegmatites have similar mineralogy to migmatitic leucosomes in the drill core, indicating that the pegmatites may be the products of

partial crustal melts.

Post-crystallization alteration and fluid flow through the rocks raises the possibility of post-crystallization uranium remobilization

Fraser Lakes U-deposits are similar to several basement-hosted U-deposits in the Athabasca Basin, including the Eagle Point, McArthur

River Zone 2, Millennium, and P-Patch deposits.

The Fraser Lakes deposits also show similarities to pegmatite--hosted uranium deposits in the Grenville Province.

The potential exists for finding basement-hosted unconformity-type mineralization in the Fraser Lakes area.

Future work will include: petrographic examination of other drill holes, electron microprobe work, further whole-rock geochemical

analysis, Pb-isotope studies, REE-analysis, Cl-analysis, and U-Pb chemical age dating of the mineralization and the development of a

metallogenetic model and examination of the potential for future discoveries in the area.

References Annesley, I., Cutford, C., Billard, D., Kusmirski, R., Wasyliuk, K., Bogdan, T., Sweet, K., and Ludwig, C. (2009) Fraser Lakes Zones A and B, Way Lake Project, Saskatchewan: Geological, geophysical, and

geochemical characteristics of basement-hosted mineralization. Proceedings of the 24th International Applied Geochemistry Symposium (IAGS), Fredericton, NB. Conference Abstract Volume 1. p. 409-414.

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Lentz, D. (1991). U-, Mo-, and REE-bearing pegmatites, skarns and veins of the Grenville Province, Ontario and Quebec. Can. Journal of Earth Sciences, 28, 1-12.

Madore, C., Annesley, I. and Wheatley, K., (2000) Petrogenesis, age, and uranium fertility of peraluminous leucogranites and pegmatites of the McClean Lake / Sue and Key Lake / P-Patch deposit areas,

Saskatchewan. GeoCanada 2000, Calgary, Alta., May 2000, Extended Abstract 1041. (Conference CD).

Portella, P. and Annesley, I.R. (2000a) Paleoproterozoic tectonic evolution of the eastern sub-Athabasca basement, northern Saskatchewan: Integrated magnetic, gravity, and geological data. GeoCanada 2000, Calgary,

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Fig. 18 + 19 Granitic pegmatite (~ 191.6 m) with abundant zoned zircons (with

primary cores and metamict rims), apatite, and monazite in a cluster of biotite.

Fig. 20 (PPL) + 21 (Reflected light) Finely disseminated uraninite grains in an altered

allanite with pleochroic halo. Granitic pegmatite at ~ 232.9 m.