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The origin, structural style, and reactivation history of the Tabbernor Fault Zone,
. Saskatchewan, Canada
BY
James R. Davies
A thesis submitted to the Faculty of Graduate Studies and Research
in partial fulfillmeot of the requirements for the degree Master of Science
Department of Earth and Planetary Sciences McGill University, Montreal
@James Davies, 1998
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Frontispiece
Wollaston Lake at sunset, summer of 1996
Abstract
The Tabbernor ~ a u n zone (TFZ) in Saskatchewan is a >1500krn geophysical,
topographie and geological lineament that trends approximately northward dong
the province's eastern boundary. Detailed field mapping and petrographic
analyses, coupled with remote sensing and geophysical evidence have shown
that the TFZ is a fundamental structure within the Trans-Hudson Orogen (THO),
separating and offsetting severai lithotectonic domains.
Eariiest deformûtion presewed within the TFZ in the Wollaston Lake area is the
transposition of a regionai gneissic foliation ont0 a northeast-trending fiattening
piane, within north-trending sinistral shear zones. The transposed fabnc is
characterized by folded and attenuated remnants of the gneissic foliation.
together with boudinaged leumgranitic sheets and dykes. Within these shear
zones a shear fabric is developed parailel to the margins in several locations.
The shear fabric offsets dl earlier foliations with consistent sinistrai offset.
Adjacent to the shear fabric, structures are reoriented to lie dose to the shear
plane.
The fault and its associateci structures controlleâ the intrusion of grmitic and
pegrnatitic dykes which were subsequently weakiy deformed. These intrusives
relate to a regionai magmatic episode assouated with the culmination of the
second tectonornorphic event in the THO at 181 5Ma. Post-collisional
adjustments caused localized reactivation of stnictures and assoaated
retrogresive metamorphism.
Brittle overpnnting of ductile fault features is widespread. Mineralized fault planes
display well-developed slickenlines which formed during more than one
reactivation episode. Reactivation may have been coevai with the age of
formation of large uranium deposits in the irnmediately adjacent Athabasca
Basin. Structural similafiaes between the TF2 and rninerdized areas suggest that
the fault may have had a control on the location of minerakation.
Sedirnentary features, apatite fission track data, and uranium mineralogical
studies ail show that the TFZ was readvated at least twice in Phanerozoic times.
Late Devonian tectonic events associated with the Antler Orogen caused
reactivation of the TF2 dong much of its length. In southern Saskatchewan fault
reactivation cuntrolled depositional patterns and structures within the Williston
Basin. Further north. fault reactivation resulted in the widespread rernobilization
of uranium-bearing minerais. Reactivation in the Eady Cretaceous Pefiod,
associated with Cordilleran orogenic activity. had similar affects. The
identification of multiple reactivations of an intracratonic structure calls into
question the model of a 'stable' craton.
La zone de la faille de Tabbemor (ZFï). situde en Saskatchewan, reprdsente un
lineament g6ologique. topographique et gdophysique de plus de 1500km. Elle
présente une orientation nord, longeant la frontière Est de la province. Une
cartographie detailiee et une Btude petrographique, jumelés aux donnees de
télédetedion et aux Bvidences geophysiques illustrent dairement qu'il s'agit
d'une structure fondamentale au sein de I'orogène Trans-Hudsonienne (THO)l
séparant et décalant plusieurs domaines lithotectonics.
Dans la region du Lac Wollaston, les premieres evidences de d6formations
observées au sein de la ZFT sont caracterisees par la transposition d'une
foliation gneissic regionale dans un plan nord-est. Ce plan est situ6 A l'intérieur
d'une zone de cisaillement qui est orienté vers le nord et & ddplacement
sénestre. La fabrique transposee est caracteris& par des plis et des traces
résiduelle de la foliation gneissk accompagne de feuillets leucogranitique et de
dykes boudin&. A d i f fhn t endroits. plusieurs de ces zones de deformation
possedent une fabrique de cisaillement paraiMe aux marges, deplaçant les
foliations precedentes avec un mouvement s6nestre. Aux abords des plans de
cisaillement, les structures sont rborientées de façon à être similaire aux
fabriques de cisaillement.
La faille de Tabbernore ainsi que les structures associées contrôlent l'intrusion
de dykes granitiques et pegrnatitiques qui furent par la suite faiblement
déformés. Ces intrusions sont associées à un épisode magmatique régional.
associé avec la culmination du second 6venement tectonomorphique dans la
THO. à 181 5Ma. Des ajustements post-collisionnaux? ont causé la réactivation
des différentes structures ainsi qu'un mdtamorphisme rétrograde.
iii
La superposition de structures cassantes sur les zones de faille ductile est trbs
fr6quente. Les pians de failles min6raJises possèdent des "did<enlinesn bien
développes formés lors de diffdrentes périodes de rdacüvation. La r&acüvation
des plans de failles est probablement contemporaine la formation de grand
d6pôts d'uranium dans le bassin adjacant d'Athabasca. Les similarit6s
structurales entre la ZFT et les zones rnin&ralis&es suggdrent que la faille puisse
avoir un contrôle sur la localisation de la rnindralisation uranifbre.
Les caractéristiques s6dimentaires. les donnees de fission de I'apatite? ainsi que
les résultats des Btudes sur la minhiagie des min6raux uranifhres démontrent
tous que la rbactivation. Phan6rozoïque de la ZFT semble s'être produite a deux
reprises. Les Bvenements tectoniques du DOvonien tardif associés B IOrogéne
d'Antier, ont causds la r6activation de la ZFT sur presque toute la longueur de
celle-ci. Dans le sud de la province du Saskatchewan. la réactivation de la faille
contrôle les patrons de ddpdt ainsi que les structures a I'intdrieur du bassin de
Williston. Plus au nord. la rdactivation de la faille a produit une rembilisation
génerale des mineraux d'uranium. Cette rembilisation des mineraux uranifhres
s'est aussi produite lors de la r6activation de la ZFT au Crétace Inférieur lors de
I'Orog8ne CordilliBflenne. L'identification de plusieurs phases de rdactivation
d'une structure intracratonique remets en question le modele d'un craton
"stable".
This thesis consists of four chapters, the second and third of which are in
manuscript form. and are intended for submission to a refereed journal. In
accordanœ with McOill thesis preparation guidelines the candidate is required to
make an explicit statement on the authonhip of dl work submitted as part of the
thesis:
The analyses of two rock sarnple suites from the Wollaston Lake and Neilson
Lake areas were undertaken by Dr. Barry Kohn, at the Australian Geodynarnics
Cooperative Research centre. La Trobe University, Bundoora, Victoria. The
samples were analyzed to provide an apatite fission track age for each sample.
As well as the results, Dr. Kohn also provided a preliminary interpretation of the
fission track age data within the context of the North Amencan continental
history. Ail subsequent interpretetion of the data in relation to the cunent study is
the work of the author. The Neilson Lake sample suite was collected by Colleen
Elliott. Ail other data collection, preparation. analyses and presentation within the
thesis was conducted entirely by the author. The thesis supervisor, Colleen Elliott
of Concordia University. has reviewed both manuscri pts.
Acknowledgements
The author would like to acknowledge the role of his field assistants Luke Willis,
Gary Smith, and Rami Mirshak for their patient and diligent work dunng two
summers of fieldwork on Wollaston Lake. Additional field logistics were supplied
by Gary Delaney, Tom Sibbald and Bruno Lafrance (dl Saskatchewan Energy
and Mines). Laboratory preparation and results of fission track analyses on two
sample suites was provided by Barry Kohn at La Trobe University. Victoria.
Supervision of the Masten program was undertaken by Colleen Elliott of
Concordia University. Colleen Elliott aiso gave review and cornments that greatly
improved the organization 'and preparation of the two manuscripts. French
translation of the thesis abstract by tissa Morotti and Annick Chouinard is gratefully acknowledged.
I am especially indebted to Gary Delaney, lnhne Annedey (Saskatchewan
Research Council), Don Baker, and Andrew Hynes (both McGill University) for
their continued comments and advice during the cornpletion of this project.
Funding for this project was provided by a LITHOPROBE supporting
geosciences grant awarded to Colleen Elliott.
To al1 the additional friands, family, and ailleagues who go unmentioned here but
without whom this thesis would have gone unfinished, "1 wish you al1 that you
would wish yourselves!".
Table of Contents
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Résume iii
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Preface v
. . . . . . . . . . . . . . . . . . . . . . . . . Table of Contents vii
. . . . . . . . . . . . . . . . . . . . . . . . . . List of Figures x
. . . . . . . . . . . . . . . . . . . . . . . . . . . List of Tables xii
. . . . . . . . . . . . . . . . . . . . . . . . . . . List of Plates xiii
Chapter 1 : Thesis Introduction . . . . . . . . . . . . . . . . . . 1
Generai Statement . . . . . . . . . . . . . . . . . . . . . . . 1
. . . . . . . . . . . . . . . . . . . . . Objectives of Research 2
. . . . . . . . . . . . . . . . . . . . Review of Previous Work 2
Chapter 2: Structural Investigation of the Tabbernor Fault Zone. Wollaston Lake: Implications toi Regional Deformation Associateâ with Post-collisional Tectonics In the Tnns-Hudson Otogen . . 5
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
. . . . . . . . . . . . . . . . . . . . . . . . . 1 . Introduction 7
2 . Regional Geology . . . . . . . . . . . . . . . . . . . . 8
3 . Previous Work on the Tabbernor Fault Zone . . . . . . . . . . 11 3.1 Geometry . . . . . . . . . . . . . . . . . . . . . . . 11 3.2 Deformational Character . . . . . . . . . . . . . . . . . 12 3.3 Offset . . . . . . . . . . . . . . . . . . . . . . 12 3.4 Timing of Movernent . . . . . . . . . . . . . . . . . . . 13
. . . . . . . . . . . . 4 Previous Work in the Wollaston Lake area 14 4.1 Stratigraphy . . . . . . . . . . . . . . . . . . . . . . 14 4.2 Structure . . . . . . . . . . . . . . . . . . . . . . . . 16 4.3 Timing and Metamorphism . . . . . . . . . . . . . . . . 18
vii
. . . . . . . . . . . . . . . . . . . . . . 5.CunentWork;. 20 . . . . . . . . . . . . . . . . 5.1 Geophysical Interpretaüon 20
. . . . . . . . . . . . . . . . . . . . . . 5.2 Field Mapping 23 . . . . . . . . . . . . . . . . . . 5.2.1 Hidden Bay area 23
. . . . . . . . . . . . . . . . 5.2.2 Compulsion Bay area 28 5.2.3 Small-scale Reactivation Features cornmon to both Hidden Bay and Compulsion Bay . . . . . . . . . . . . . 31
. . . . . . . . . . . . . . . . . . . . 6 . lnterpretation of Data 33 6.1 Ductile Defoimation Associated with the Trans-Hudson Orogen 33
. . . . . . . . . 6.2 Briffle Reactivation of Hudsonian Features 38
. . . . . . . . . . . . . . . . . . . . . . . . . . 7 Discussion 40
. . . . . . . . . . 8 Importance of the TFZ to Uranium Exploration 43
. . . . . . . . . . . . . . . . . . . . . . . . . 9 Conclusions 46
Link: The Rob of Proterozoic Fault Delormtion in Controlling Phanerozoic Fault Reactivation . . . . . . . .
Chapter 3: Evidence for Orogeny-drfven Phanerozoic Reactlvations of the Tabbernor Fault Zone. Saskatchewan. Canada . . . . . . 49
. . . . . . . . . . . . . . . 3 . Reactivations in Western Canada 52 3.1 Regional Stratigraphy . . . . . . . . . . . . . . . . . . 53 3.2 Dnving Mechanisms for Tectonic Deformation . . . . . . . 55
4 . The Tabbernor Fault Zone . . . . . . . . . . . . . . . . . . 57 . . . . . . . . . . . . . . . . . . . . . . . 4.1 Introduction 57
. . . . . . . . . . 4.2 Deformational Character and Geometry 58 4.3 Geophysical Characteristics . . . . . . . . . . . . . . . 60
. . . . . . . . . . . . . . . . . . . . . . . . . 4.4 Offset 61 4.5 Absolute Ages of Movement . . . . . . . . . . . . . . . 62
viii
. . . . . . . . . . . . . . . . 5 Phanerozoic History of the TFZ . . . . . . . . . . . . . . . . . . . . . 5.1 Previo~s Work
. . . . . . . . . . . . . . . . . 5.2FissionTrad<Anal~*s. . . . . . . . . . . . . . . . . 5.3 Williston Basin Deposition
5.4 Geochronology and Isotope Systematics from Uranium Deposit . . . . . . . . . . . . . . . . . . . . . . . . . Mineralogy
. . . 5.5 Field Evidence of Phanerozoic Reactivation of the T E
. . . . . . . . . . . . . . . . . . . . . . . . . 6 . Discussion . . . . . . 6.1 Timing of Phanerozoic Basement Reactivations
. . . . . . . . . . 6.2 Cause and Mechanisms of Reactivation
Chapter 4: Summary and Conclusions . . . . . . . . . . . General Conclusions . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . Contributions to Knowledge
References and Bibliography . . . . . . . . . . . . . . . .
List of Figures
Figure 2.1
Figure 2.2
Figure 2.3
Figure 2.4
Figure 2.5
Figure 2.6
Figure 2.7
Figure 2.8
Figure 2.9
Figure 2.10
Simplified Geologicaî map of the exposed THO and
boundary regions.
lnterpretation of the internai geometry of the THO.
Age constraints on ductile deformation within the
Tabbernor Fault Zone in the Neilson and Wollaston Lake
areas.
Simplified geological map of the southern Wollaston Lake
area showing the location of the data collection areas.
Schematic stratigraphie column for the Wollaston Lake
area of the Wollaston Dornain.
lnterpreted vertical gradient aeromagnetic map of the
NENIAEA Athabasca test area.
Fom Surface map of the Hidden Bay area.
Contoured stereographicai projections of structural data
from the Hidden Bay area.
Stereographical projections of fold data from the Hidden
Bay area.
Location rnap of the Compulsion Bay mapping area.
Figure 2.1 1 Stereographical projections of structural data from the
Compulsion Bay area.
Figure 2.1 2 Detailed field map of the location 520201.
Figure2.13 Stereographical projection of fold data from the
Compulsion Bay area.
Figure 2.14
Figure 2.1 5
Figure 2.16
Figure 2.1 7
Figure 3.1
Figure 3.2
Figure 3.3
Figure 3.4
Figure 3.5
Figure 3.6
Figure 3.7
Figure 3.8
Stereogiaphicai projections of bnttle fault data from the
Hidden Bay area.
Stereographicai projections of brime fault data from the
Co mpufsion Bay area.
lnterpretative cartoon showing the evolution of the THO.
Compilation map of a selected area of northern
Saskatchewan showing the relationship between
aeromagnetic lineaments that define the trace of the TFZ
and major lithotedonic boundaries.
Phanerozoic elements of the western North American
continent.
Tectonic domains of the western Canadian basement.
Constraints on the development of a ciassicai foreland
basi n.
Simplified Geologicaî map of the exposed THO and
boundary regions.
Simplified geological map of the Athabasca Basin and
adjacent basement domains.
lnterpretation of the internai geometry of the THO.
Age constraints on ductile deformation within the
Tabbernor Fault Zone in the Neilson and Wolfaston Lake
areas.
Location and apatite fission-track ages of sarnples
collected dong the Neilson Lake transect.
Figure 3.9 Location and m e fission-track ages of sarnples
collectecl dong the Hidden Bay transect, Wollaston Lake.
Figure 3.1 0 Isopach map of the Woodbend (374370Ma)-Winterbum
(370-362Ma) and equivalent groups of the Upper Devonian
Period, Saskatchewan.
Figure 3.1 1 lsopach map of the Cretaceous Upper Manville Group (and
equivalents) in Saskatchewan. Paleogeographical
reconstruction of Cretaceous middle Upper Manville Group
(and equivalents) geography in Saskatchewan.
Figure 3.1 2 Secondary isochron plots of =pb?pb and p7~b1204~b
ratios in sulfide and sulfate rninerals of varying paragenesis
from the Athabasca Basin.
List of Tables
Table 3.1 Compilation of Phanerozoic radiogenic age data derived
from U-Pb dating rnethods on uranium minerakation.
xii
List of Plates
Plate 2.1
Plate 2.2
Plate 2.3
Plate 2.4
Plate 2.5
Plate 2.6
Plate 2.7
Plate 2.8
Second-generation pegmatite dyke, north shore of Pow
Bay.
Developrnent of foliation boudinage at location 21071.
southeast shore of Parker Island.
Small-scale ductile faul t with adjacent st rong sinist r d drag . location 2 1 041 , southeast shore of Parker Island.
Extensive boudinage of pegmatitic materiai within well-
foliated, fine-grained biotitequartz gneiss. location 25021 .
Closely-spaced shear deavage in Archean gneiss of the
Johnson River Inlier, location 520201, west of Compulsion
Bay.
Granite dyke intruded into the shear deavage, location
520201, same as plate 2.5.
Photomicrograph of the margin of a dyke in t~ded into the
shear deavage, from location 520201.
Photornicrograph of quartz from a vein intnided into a fault
plane.
xiii
Chapter 1
Thesis Introduction
General Statement .
It can be reasonably assumed that a person who has lived for 80 yean will have
had more life expeiienœs than a child of 5 or 6. The same can be said for faults.
Thus, if the tectonic conditions are right, it should corne as no surprise to find
many ancestral faults have a repeated history of reactivation.
The processes that accompany the formation of faults. both ductile and brittle.
assure that the structures will never regain the same strength as the previously
unaltered rock. Mineralogical weakening of fault zones has been shown to
dramatically reduœ the strength of a fault (Wintsch et al.. 1995), and may be the
cause of seismic activity in modem strike-slip faults such as the San Andreas
Fault, which fail under stress conditions lower than those expected by modeling.
The fundamental loss of strength is espeaall y true of deep-rooted fault structures
such as interplate transform faults. During continental assembly these fault
structures may becorne situated within the cratonic interior but their inherent
incornpetence means that they will aiways be among the weaker parts of the
crust. These faults m y in fact focus intraplate stresses far from the cratonic
margins because of their predisposition for reactivation (Heller et al., 1 993).
Over the last decade or more the study of fault reactivation has become more
prevalent in structural geology. Advances in the field have culminated in recent
publications, such as the thematic set ansing from the Tectonic Studies Group
meeting (Butler et al.. 1997) held at Budington House, 6-7 March 1996. Fluid
processes. both during and after initial fault formation. also have a very important
role in the evolution of a fault system. An exceilent review of the involvement of
fluids in faulting can be found in Hickman et al. (1 995. and references therein).
Objectives of Research This project was formulateci with the goal of expanding and refining cunent
knowiedge of the Tabbemor Fault zone (TFZ). The study is part of a larger
research program ai- at working out the timing and kinemtic hidory of the
Tabbernor Fault, and adjacent structures. in the context of the assembly of the
North American continent. Phanerozoic reactivation of the fault was known to
have occurred pnor to the undertaking of this thesis (Byen, 1 962; Elliott. 1 995),
and the research group aiso covered this aspect of the fault's history. The
fieldwork component of the project was restncted to the fault where it is exposed
on Wollaston Lake, Saskatchewan. Exposures of the fault to the south have been
examined by Prof. Colleen Elliott. Spedfic goals established at the outset were to
evaluate kinematics and significanœ of dudile fabrics dong the fault in the
Wollaston Lake area, and to assess the potential links between faulting and U-
mineralization in the Athabasca Basin. Subsequent to the start of the project it
became clear that there was the potential for a strong causai Iink between
Phanerozoic fault reacüvation and remobilization of mineralization within many of
the major uranium deposits. The project was wnsequentiy expanded to explore
this avenue of research.
Review of Previous Work The Tabbemor Fault has been identified as a s1500km geophysicai (Green et
al., 1985; Jones and Craven, 1990) and topographie (Elliott and Giroux. 1996)
lineament that extends from the Northwest Territories to North Dakota, with a
north-south trend. Earliest geologicai studies to indude parts of the Tabbernor
Fault (Budding and Kirkland, 1956; Wailis, 1971 ; Scott, 1973; Sibbald, 1978;
Lewry et al., 1981) ail canduded that the fault had a sinistral sense of
displacement but did little to darify the kinematic history. Recent studies have
initiated much debate over the significance of the fault in the regional tectonic
framework of the Trans-Hudson Orogen. Lewry (1981) suggested that the
Tabbernor Fault was a transform junction between t ha Glennie Microcontinent
and the Kisseynew Domain. More recently, Lewry et al. (1990) downplayed the
importance of the Tabbernor Fault, suggesüng that eafly ductile mylonites seen
in the exposed southem segment of the fault are only locally coincident with the
fault. lnstead they suggest that these rnylonites relate to an eailier refolded, and
over-steepened, high-strain nappe d e . Uliott (1 994a. 1995) used the kinematics
of the eady ductile deformation, in relation to dated deformed intrusives to
bracket the timing of movement between 1848+6/-5Ma and 1737eMa. Elliott
(1996b) also suggested that the combination of geophysical evidence and well-
developed kinematic features indicate that the Tabbernor Fault did have an
important role in the evolution of the Trans-Hudson Orogen.
Reviews of the regional geology assocjated with the Trans-Hudson Orogen are
numerous, but the rost comprehensive can be found in Lewry and Stauffer
(1 990, and references therein). Lucas et al. (1 993), and Clowes (1 997, and
references t herein).
The Phanerozoic history of the Western Canadian Sedimentary Basin is covered
by excellent publications such as Mossop and Shetson (1994), Savoy and
Mountjoy (1 995), and Macqueen and Leckie (1992). For tectonic modelling of the
Western Canadian cratonic rnargin the reader is re fend to Leckie and Smith
(1 992), Fermor and Moffat (1 9W), Quinlan and Beaumont (1 984), and Stockmal
et al. (1 992). More speafic studies of the role of the Tabbernor Fault in the
Phanerozoic eon c m be found in Byen (1962), Gerhard et al. (1987). Haidl
(1 988), and Elliott (1 995).
The process of fault reactivation, and its recognition. is covered by Butler et al.
(1 997, and references therein) and Heller et al. (1 993).
The study of unconformity-type uranium deposits. as found in the Athabasca
Basin, immediately adjacent to the Wollaston Lake field area is extensive. Recent
reviews concentrate on the geochemistry and origin of ore-forming luids and
associated alteration minerakation (Kotzer and Kyser, 1993, 1995; Komninou
and Sverjensky, 1996; Fayek and Kyser, 1997). Previous work (Cameron, 1983;
Sibbald and Petruk, 1985; Evans. 1986) mncentrated more on the structural and
stratigraphic settings of the deposits. as well as paragenetic minerai studies.
Varying aspects of the deposits are stress& in individuai studies but it is
probably true that structure9 fluid composition, lithology. and alteration al1 have an
important role in determining the position and composition of the deposits.
Chapter 2
Structural Investigation of the Tabbernor Fault Zone, Wollaston
Lake: Implications for Regional Deformation Associated with
Post-collisional Tectonics in the Trans-Hudson Orogen J. R. Davies, Dept. of Earth and Planetary Sciences, McGill University, 3450
University Street, Montre al, QC. H3A 2A7, CANADA.
Abstract The Tabbernor Fault zone (TFZ) in the area of Wollaston Lake. northern
Saskatchewan, is a series of poorl y defined NNE-trending sinistral shear zones
with a repeated history of fault mwement. The region is within the northwestern
hinteriand of the Trans-Hudson Orogen VHO). An eaily episode of regional
orogenic deformation (Dl) resulted in an extensive, EN€-stfiking, moderately to
steeply S-dipping, gneissic foliation (SI). This eady fabric is transposed ont0 a
NE-striking. steeply SE-dipping, flattening foliation ( S . Transposition is
characterized by folding and boudinage of the original gneissic foliation and is
limited to Tabbemor-related shear zones such as the Parker Island shear zone
(PISZ). These can be tracad back to the main fault in the Reindeer zone. Within
the highest strain zones the S2 foliation is modified by the development of a
coeval NNE-striking, verticai sinistral shear deavage. Metre-scale ductile and
brittle-ductile faults parallel the main shear zones. Previousl y identified TFZ fault
zones, that are N-trending and show little offset. are probably synthetic 'Riedel'
faults. Regionally, D2 deformation probably occuned dunng or after terminai
collision in the THO, and was concentrated in shear zones which allowed post-
collisional orogenic shortening and 'escape' tectonics.
Intrusion of leucogranitic and pegmatitic sheet-like dykes into the sinistral shear
fabrics postdates the bulk of 0 2 deformation. These intrusives are similar to
1815Ma Hudsonian granites seen elsewhere in the Wollaston Dornain and
bracket the lower limit of lming of Dt deformation. Continued ductile detonnation
during late Hudsonian deformation events caused restrided sinistral shearing.
Brittle overprinting of the dudile shear zones is a cornmon feature and consists
of brecaation and th8 development of slickensided fmlt planes. Two generations
of cogenetic faults have ben identified by the fault-slip inversion method. Brittle
fault features are accompanied by mineral growth that suggests extensive ffuid
circulation accornpanied fault rnovement.
1. Introduction Anal ysis of LITHOPROBE THOT seismk line 9 (Hajncil el al.. 1 992; Lucas et al..
1993) has show that the western margin of the Trans-Hudson Orogen (THO) in
Saskatchewan is dominated by a sucœssion of westedy to noithwesteily dipping
juvenile tenanes. subducted beneath the eastern mrgin of the Hearne Province
(Figs. 2.1 and 2.2). Above, and to the wst of th8 subduction zone, sediments of
the Wollaston Group were deposited in a rift to continental margin setting. Dunng
oblique collision events that cha*iderized the dimax of the THO, Wollaston
Group sediments were complexly folded and metamorphased. The nature of
deformation and metamorphic events within the Wollaston Domain (containing
Wollaston Group rocks as well as exposed Archean inliem. and Hudsonian-age
intrusives) is not well defined. Neither is the relationship between deformation in
the Wollaston Dornain, and deformation elsewhere in the THO.
This study atternpts to explain some of the structural relationships in the
Wollaston Lake area of the Wollaston Domain (Fig. 2.1). The lake is on the
eastern margin of Athabasca Basin, the western world's largest uranium
producing region. 01 particular interest is the age and nature of defomtion
associated with the Tabbemor Fault system (TFZ). The TFZ crossaits and
borders several distinct tedonic domains of the THO (Le- et al., 1990). It is a
longitudinal geophysical and topographical lineament which is c1500krn long
(Elliott and Giroux, 1996). Its noithern limits can be traced to the northern border
of Saskatchewan, and airphoto anaiysis shows that the southem limits extend
under the Phanerozoic cover into North Dakota (Giroux. unpublished M.Sc.
thesis). In addition there are a number of extensive regional lineaments, parallel
to the TFZ. which occur in Saskatchewan and Manitoba (Elliott, 1996a). The
study was organized with the goal of fitting Tabbemor-related deformation into
the larger picture of deforrnation in the Wollaston Domain and the THO.
Figure 2.1. Simplltkd Gwloglcat map of the exposed THO and
bounda y mglons. Lithotectonic zonas are sub-dlvldd lnto
domalns e.g. Flin Flon, Klsseynew etc. Abbnvlatlons: C.S.B.Z. = Churchill - Superlor Boundary Zone; f.FZ. = Tabkrnor FauHZone;
N.F.SZ = Needk Falls Shnr Zone; B.R.S.B. = Blrch Raplds
StraigM Bdt; S.82. - Stanley Shear Zone; P.L.SZ. = Parker Lake . Shear Zone; 8.T.Z = Snowblrd Tedonlc Zone. Red dots ma*
locations dlscuuod In the tex-; 1 = Wollaston Lake; 2 - Nelkon
Lake. Nok that only major TF2 huit splays am shown In tha
northern half of.the map. By lncludlng mlnor TFZ splays the
longltudinal extent of the fault zone exbndr for approxlmatoly
170km. Map k adapted after Lewry et al. (1890); Iithotactonlc
dlvislons as of Clowes (1997).
Flgum 2.2. InterpmWIon of the Intemal geometiy of the THO.
A)GeoIoglcal cross-sect lon showlng pr lnc lpa l
tectonostmtlgmphlc unltm of the Tmns-Hudson Orogen (fmm HaJnal et al.. 1992). The medon 1s con.tn1n.d by THOT reflectlon
praflk B. 6) Inamt of the migrated wlsmlc profile. The sectlon is /
from O to 12 wconds (TWT), and aquat.. to a dapth of
approxlmately 36km. The TFZ k charadmalzed by a zone of low refiectance. Note that althouah decton In the lomr crust appear to truncate the TFZ they am not contlnuous acrosr the fiult wlth
the samo mfioctance.
2. Regional Geology The THO is a 500km-wide belt of exposed Eaily Proterozoic orogenic rocks. The
western segment of the orogen has an arcuate form that changes from s- trending in Saskatchewan and western Manitoba, through th8 'Big Bend' to W-
trending across northern Manitoba and into Hudson Bay. Subsurface extensions.
buried beneath Phanerozoic rocks of the Western Interior Platform. continue
southward into North Dakota and Montana (Nelson et d., 1993). Recent
summaries of the THO have divided the geology up into 4 distinct lithotectonic
zones:
The Churchill-Superior Boundary Zone (CSBZ) (Fig. 2.1) is a narrow foreland
zone, bordering the Superior Craton to the southeast. The zone is composed of
reworked Archean rocks of the Superior Craton. together with Paleoproterozoic
supracrustai rocks of the Thompson belt and vanous Hudsonian-age intnisives.
To the northwest the CSBZ is fault-contacted with the Reindeer Zone that
composes the juvenile core of the THO (Fig. 2.1). It is subdivided into sevenl
domains distinguished by rock type, structural continuity, radiornetric age and
style of deformation within. Geochernicai and isotopic work suggests that most of
these rocks evolved in an oceanic to transitionai. subduction-related an: setting
(Clowes, 1997). The age of the Reindeer Zone jwenile rocks is arca. 1.9-1.8Ga
(Clowes, 1997). Beneath these juvenile domains there is strong geophysical and
geochemical evidence for an Archean crustctl block, termed the Sask Craton
(Lucas et al., 1993; Ansdeil et al., 1995) (Fig. 2.2). This Archean 'micro-continent'
does not appear to be connected to either the Superior or Rae/Hearne
Provinces, and where exposed in 'basernent windows', such as the Pelican
Window (Lewry et al., 1989). structurai evidence suggests that the juvenile
terranes were thrust southwestward over the Sask Craton at cira. 1.81Ga
(Heaman et al-, 1995).
The Wathaman-Chipewyan Batholith (Fig. 2.1 ) is an Andean-type m g mt i c arc. The southern margin of the batholith forrns the northem and western boundary of the Reindeer Zone. The batholith fomied as a result of continued westerly
subduction of oceanic material beneath the continental rnargin. It is a moderately
heterogeneous granite-granodiorite body, and contacts between the batholith
and the Reindeer Zone appear intrusive (Lewry and Collenon, 1990).
Emplacement of the batholith is though to have ocairred in a restricted
geological time frame, at approximately 1855Ma (Mayer et al., 1992).
The western boundary of the THO is forrned by the Northwestern Hinterland
Zone (NHZ) (Fig. 2.1). As with the CSBZ, it is a mmbination of reworked
Archean basernent rocks, overiain by Paleoproterozoic sediments. Unlike the
CBSZ, the NHZ is a wide belt, dominated by defomed matasedirnentary rocks of
the Wollaston Group. These were deposited in a rift to miogeodinal setting
(Money, 1968; Ray, 1979; Delaney, 1995). Where the orogen is N- to NE-
trending in Saskatchewan, the contact between the NHZ and the Wathaman
batholith is marked by a 400km-long dextral fault, the Needfe Falls Shear Zone
(NFSZ) (Fig. 2.1). Studies show that the NFSZ was active somewhere between
1857Ma and 1760Ma. with ductile kinematics (Stauffer and Lewry, 1993;
Fedorowich et al., 1995), and later with ductile-brittle to britüe shearing. West of
the 'Big Bend' the contact relationship between the batholith and the NHZ
appean to be largely intrusive (Lewry and Collenon, 1990).
lntraplate transcurrent faults and sub-horizontal shear zones dissect the entire
orogenic belt into thrust sheets (Lewry et ai., 1990). It has been suggested that
many of these steep faults and detachment shear zones were active lata in the
main phase of orogenic activity, allowing orogen-parailei extension (Hoffman,
1 988; Stauffer and Lewry, 1993; Hajnal et al., 1996). or orodinal rotation of the
southern part of the orogenic belt (Symons, 1991, 1994). In the modal of Hajnal
et al. (1996) the escape of the central-western Reindeer zone to the southwest,
dunng these orogenic adjustments, was facilitated by dominantly dextral stnke-
slip shear dong omgen-parailel shear zones on the western margin (eg. NFSZ),
and sinistrai strike-slip movement on the Tabbernor Fault (TFZ). All of this
ocarrred in response to contraction aaoss the Reindeer Zone. due to oMique
convergence with the Superior craton during postcollisional deformation (Bleeker. 1990; Stauffer and Lewry, 1993)
3. Previous Work on the Tabbernor Fault Zone
3.1 Geometry
The TFZ is one of several largescale shear zones and linear belts which help to
subdivide the THO into lithotectonic domains (Fig. 2.1). What is unusual about
the TFZ is that it is oMique to main fabric trends in the orogen. Between the
Glennie Domain and the Hanson Lake Block the TF2 is a domain boundary, but
in other places, such as the Wollaston Domin, the fault crosscuts domains. The
effect is to deflect and offset eartier fabrics within a domain. It is well documented
that the fault offsets eariier Hudsonian structures in both the central Neilson Lake
area (Elliott, 1994a) and further north in the Wollaston Lake area (Wallis. 1971 ;
Davies, 1996). with a consistently sinistrd sense.
Seismic imaging of the TFZ, as part of the LfTHOPROBE Trans-Hudson Orogen
Transect, has revealed the TFZ to be a wide vertical zone of low reflectance
(Hajnal et al., 1 992; Lucas et a/., 1 993) (Fig. 2.2b). Strong reflecton terminate at
the TFZ through much of the crustai profile. Hajnai et al. (1992) interpret the TFZ
as -terminating on a shailowiy dipping lower crustal retlector, probably a detachment thrust, and therefore suggest that it is not a through-going crustai
structure (Fig. 2.2a)..The migrated profile published in their paper, and that of
Lucas et al. (1993). is incondusive and aithough reflecton seem to correlate on
both sides of the fault they are not cantinuous with the same reflectance right
across the fault zone. Nemeth and Hajnal (1 996) suggest that veloàty anisotropy
in the upper-lithospheric mantle beneath the northern Reindeer Zone and NHZ
can be attributed to reonentation of the mantle fabnc by the TFZ and adjacent
NFSZ. This would suggest that the TFZ is a through-going cnistal structure.
penetrating the Moho boundary, although this may not necessarily have always
been the case during its evolution.
3.2 Deformational Chwactar The character of the TF2 changes dong its length. Between the Glennie Domain
and Hanson Lake Bock the eailiest fabrics developed in the fault are
characterized by sinistral ductile shear and development of eafiy, upright,
mylonites (Elliott, 1 994a). Minerai lineations within the mylonitic fabric change
orientation acrosç the fault. They are Werately to steeply S-plunging in the
east, changing to Werately N-plunging in the west. These two distinct domains
are separated by a bnttle to semi-brittle fault trace with subhonzontal slickenside
lineations t hat overprint the eariier ductile fabrics (Elliott, 1 994a).
As the fault progresses northward its mrphology changes from a single. or
several anastornosing, splay(s) with restncted longitudind extent. to a bifurcating
array of discrete fault splays and topographical lineaments which extend from
1 02OW to 1 OSOW (Fig. 2.1 ). This is a width of approximatel y 1 70km. compared to
maximum width of 2km in the Neilson Lake area (Elliott, 1994a). in the Reindeer
Zone. The change in style of the fault coincides with the transition from where the
fault separates the Glennie Domain from the Hanson Lake Bock and Kisseynew
Domain, to where it penetrates into the La Ronge Dornain and extends northward
to the Wollaston Domain (Fig. 2.1).
3.3 Offset
Magnitude of offset across the TF2 varies with location but the sense is
consistently sinistral. Offset of a north-east dosing fold hinge, across a single
Tabbernor splay in the Neilson Lake area, was documented to be 2km (Elliott.
1 994a). From this it was argued that the offset across the main fault trace was
greater than 2km. Further north, in the Wollaston Lake area, offsets across individual fault splays have been suggested to be <500m-3000m+ (Wallis. 1971).
based on field mapping augmented by aeromagnetic interpretations.
Metamorphic isograds mapped by Sibbald (1978) and Wilcox (1991) in the
Neilson Lake\ Pelican Narrows area suggest post-metamorphic sinistral
displacement across the entire fault of 6-8km. although these isograds are
argued to be controlled by lithology (Elliott. 1994a) and not to reflect tnie
displaœment.
3.4 Timing of Movernent. Timing of fault movement is not well understood. Deformation associatecl with the
formation of the mylonitic strain zone in the Neilson Lake area is constrained by
cross-cutting relationships between 1848+6/-5Ma and 1737&2Ma (Elliott. 1995)
(Fig. 2.3). The only constraint on movement along the TFZ in the Wollaston
Domain is that it is younger than the Hudsonian fabncs that it deflects and
offsets. The earliest Hudsonian deformation accurred at approximately 1840-
1850Ma (see below). Brittle deformation in both locations overpnnts ductile
fabrics and is therefore younger. Reactivation of the TFZ is known to have
occurred at least once during the Phanerozoic eon (Byers, 1 962; Elliott. 1 995).
Current work suggests that there hava been severai reactivation events. the most
significant of which occuned dunng the Late Devonian and Early Cretaceous
penods (Davies. in press b). No ages have been determined to more preasely
constrain early ductile or bnttle movement along the TFZ.
Despite its dimensions and evident regional significanœ, the importance of the
TF2 has been downplayed by several recent authors (Lewry et el., 1 990. Tran et
al., 1996. Maxeiner, 1996) due to the lack of significant offset of lithologies.
Flgure 2.3. Aga constralnts on ductlk ddonnatlon wlthln the
Tabbernor Fauk Zona In the NeIlson and Wollaston Lake areas. Tho
aga constralnts In tha NaIlson Lakm ana am from the NeIlson Lake pluton and a crosscuttlng pogmatite (Elllott, 1O95); aga
constralnts In the Wollaston Lake ana am bamd on the dlsruptlon . of D, fabrltr In the vlclnity of Tabkmor Fault .play.. D,
deformation has bwn dateâ at 1 .a54 . M a (Annerley et al., 1996.,
1897). In southam Saskatchewan, kmk movementr on the TF2 are known to have occumd afbr depositlon of aarly Sllurlan strata
(Elllott, 1 B9S).
4. Previous Work in the Wollaston Lake area
4.1 Stratigraphy
Much of the previous work in the Wollaston Lake area was driven by the
discovery of the Rabbit Lake uranium deposit in 1968 (located on figure 2.6). and
subsequent need for better understanding of the Wollaston Domain geology
beneath the Athabasca basin (Fig. 2.4). The firçt detailed mapping of the
basement geology in the area was undertaken in the Hidden Bay (64L - 4) area
(Wallis. 1971) at 1 :63 360. Together with work to the south of Hidden Bay in the
Nekweaga Bay (west half) (64E - 13 - W) and Morell Lake (west half) (64E - 12 - W) areas (Chadwick. 1966, 1967). and subsequent work southwest of Hidden
Bay in the Compulsion bay area (part of area 64E - NW) (Lewry et al., 1981). it
has produced a dear picture of the local stratigraphy (Fig. 2.5). The idealized
stratigraphic succession starts with the Archean basement gneisses and
granites. Above the basement rocks a 'basal' pelite forms the lowest unit of the
Aphebian Wollaston Group supracrustai rocks. lnterbedded with the pelites are
semi-pelites. metaquaitrites and cabsilicate horizons. Above the pelites is a
thick sequence of arkosic rocks that contains more quartz-rich horizons. Locafly
t hase are intnided by abundant pegmatites (Lewry et al., 1 981 ; Thomas. 1 983).
In the Hidden Bay area Wallis (1971) identified the Hidden Bay assemblage that
consists of meta-quartzite overiain by biotite psammite, rneta-arkose, garnet-
amphibole rock, marble and cabsilicate rock. In the study of the Compulsion
Bay area (Lewry et al.. 1981 ) no similar package of rocks was found. Wallis
considered this to be a distinct package of sedimentary rocks. overlying the
pelites and quartzites. Alternatively it has been suggested that the Hidden Bay
assemblage either represents the uppermost part of the Wollaston Group,
equivalent to other mixed sedimentary rocks seen elsewhere (Lewry and Sibbald,
1980), or the lateral faaes equivaient of the psamrnitic rocks found elsewhere in
the upper Wollaston Group (Ray, 1979). In 1978 an area north and northwest of
Hidden Bay was chosen as the site of the NEA/IAEA test area, a multidisciplinary
exploration study for uranium deposits assoaated with the unconformity-type
Ffgum 2.4. Slmplitkd goologlcil nup of th. .outhm Wollamton
Lake arw showlng th. Iowtlon d t h d.h odl.ctlon amu.
the cores of m Jor rtructuril dom# W h rn rmglonal no*adrrly
trend. Aphebianrgo mdasdlmontary gnebm (no pitbni)
unconformably wdk th. Ardian gri.k.w. and t#m th.
majority of t h m oxposd roda In the Wollaston Domain.
Hudsonlan-ige Inttllalv# (cm88 p.tbni) mm 8 common fadur, of
the rma and occur at al1 scdos. Flat-lylng wdlnnntiry rodu dthe Athabasca Group (mndom stlpplm) unœnformIibly o v d k roda of the Wollaston Domaln in th. wmst of thm map ama. Tho Hlddan Bay
and Compulsion Bay d . b wlloctlon m I k . am shown by the huavy black boxas. Addltlonal data wlkctlon amam away fbm the maln
Hldden Bay a m am Indi- by th0 wrouin. Also shown am the
the locatlon of ne* Idontltlod, Tabkrnor~lated, Wult splays
(solid lines). Identification 1s basd on g.ophyslcal anomaly
patterns and mapplng whero Ilmlted expomun allowa.
Abbmvlatlons: S.I.G. - &ndy klinds Gmbbm complox; R.L.T. - Rabbit Lake Thnist; TwNmGm - Tmut N8mows Gmnlk; K.L.G. - Kldd
Lake Granlt.; HwIwGm = Hocton Island Gmnb; K.L.F. = Kldd Lake
Fault; and JrnRrnIm - Johnson R k w Inlier. Map b adapteâ from Chadwlck (1 0; Lowry et al. (1981); and Thomas (1 B83).
I I Wollaston 1 ! Lake
Flgun 2.5. Schmmatlc stmtlgmphlc column for #a Wollaston Lakm
ana of the Wollaston DomaIn. A d a m afbr Lowry etml. (1081) and
Slbbald (1O83). Tho column Ir not to s#k.
Athabasca Group, fluviatile quartz sandstones and conglomerates
Ulc '
'Hidden Bay assemblage' dominated by quartzite and amphibolite rocks, minor metaarkoses, semipelites, calc
A
. . . . . . . . < . . . .
nudsonian intrusives . . . . . .- . ;_
. . . . . : . . Arkosic sequences, thick meta- arkose and biotite-rich psammite, interbedded with pure quartrites, . . . . .
plagioclasites and calc-silicate horizons
. . , i . - - i. - i.
Pelites, 'basal' pelite in part graphitic, grading into semipelites with interbedded metaquartrites and calc-silicate horizons
Basement gneiss, foliated, exposed in the cores of basement domes such as the Johnson River Inlier and Trout Narrows Granite; hig hly strained at contact with unconformably overlying Aphebian pelites
model (Fig. 2.4; Carneron, 1 983). Wolk on the geology of the test area (Si Wald.
1979, 1983). induding the Hidden Bay area, has done much to improve the
understanding of the Hidden Bay assemblage leading to the recognition of a
varied st ratig raphy, folded and faulted du ring pol yphase deformations.
Many Hudsonian-age intnisives have been reporteci in the area. Most are granitic
or leucogranitic in composition. but more mafic intrusions, such as the Sandy
Islands Gabbro cornplex (Madore and Annesley. 1996), are aîso present (Fig.
2.4). The main phase of granitic intrusions is interpreted to be synchronous with
the end of peak rnetamorphism circa. 181 5Ma (Annesley et al., 1 997; Madore
and Annesley; 1998). There is some evidence that the intrusives are deforrned
along their margins suggesting that they were intruded into active shear zones
(Heine, 1986; Madore and Annesley. 1992; Annesley pen. corn. 1998).
The Wollaston Group is overlain by the Paleohelikian Athabasca Group (Figs. 2.4
and 2.5). which is interpreted to have been deposited unconfombly on top of
the basement rocks at circa. 1 700Ma (Cumming et al., 1 987; Kotzer et al., 1 992).
It is composed of fluvial to marine dastic sediments. dominantly sandstones
(Ramaekers, 1983). At the base of the sandstones a well-developed basement
regolith is present in some paieo-depressions. The thidviess ranges from O-Som.
The regolith is a major host of unconfomity-type uranium minerakation
(Saskatchewan Geologicai Survey, 1994). Several large, SW-trending diabase dykes intrude the Wollaston Domain and Athabasca Basin. They rarely outcrop in
the area but their traces are deaily seen on the verticai gradient aeromagnetic
maps (Kornik, 1983. Fig. 2.6). Diabase is also found in drillare from the Midwest
Lake uranium deposit (Fig. 2.6. Ayres et al., 1983). The dykes are assumed to
belong to the Mackenzie dyke swarm, dated at 1267I2Ma (Cumrning and Kntic,
1992, and references therein).
4.2 Structure
The earîiest regional Hudsonian-age deformation event preserved is the
development of an early gneissic foliation parallel to the basement-cover contact
in the Archean gneisses. and the sedimentary layering in the Wollaston Group
rocks. This foliation development has been suggested to have resulted from the
rise of a sub-horizontal thermal front eaily in the THO (Lewry and Sibbdd, 1980).
This early gneissic foliation is folded into a senes of northeasterly trending.
shallowly doubly-plunging domes by a second major deformational event. It is in
the cores of these domes that Archean basement rocks are exposed, such as the
Trout Narrows Granite (Wallis. 1971) and the Johnson River lnlier (Lewry et al.,
1981) (Fig. 2.4). A third minor deformational event was reported by Wallis (1 971).
In the Hidden Bay area (Fig. 2.4) two prominent foliations have been
distingukhed (Wallis, 1971). The first foliation, SI, typidly trends 070'. and is
defined by compositional layering and by biotite and amphibole preferred
orientations. The second foliation, Sp, also ocairs as compositionai layering and
as an orientation fabric. but trend is typically doser to 050". Wallis (1 971) noted
tha-t where only one of the fabrics is present there are no distinguishing criteria.
The SI fabnc is commonly seen axial planar to FI folds, but F2 fol& are only
rarely seen with a well developed axial planar fabric. More typically the F2 folds
are distinguished by the occurrence of the SI foliation folded about Fz fold
hinges. FI axial planes typically strike 060-070°, whereas F2 axial planes are
more variable about a strike of 040-050'. F g folds are minor, smali-scaie
concentric folds or kinkfolds. with the axial plane variable about a trend of 320°.
No axial planar foliation is associated with these folds.
In the Compulsion Bay area (Fig. 2.4) two foliations were also recognized. The
first, Si, is cornposed of transposed primary layering, gneissic segregation, and
preferred orientation of biotite, amphiboles, sillimanite, feldspar, gamet and
cordiente. SI is axial planar to FI folds, that are generally isoclinal and commonly
have disconnected fold noses (Lewry et al., 1981). The Si foliation is refolded
about minor F2 isodinal folds, commnly plunging at low to rnoderate angles to the southwest. S2 axial planar sdiistosity is rare except for the more pelitic
interlayers.
Thus, DI and D2 events observed in the Wollaston Lake area, both in the
Compulsion Bay and Hidden Bay areas. appear to cornelate with the DI and Dt
regionai deformation events for the Wollaston Dornain described above. Similar
late small-sale folding. such as the 0 3 event of Wallis (1971) is seen elsewhere
in the Wollaston Domain (Scott. 1 973; Delaney et al., 1995)
Faulting in the Wollaston Lake area is widespread. and is of vanous styles and
presumabiy ages. The eailiest fault structures observed by Wallis (1971) are a
series of NE-trending, SE-dipping, ouique reverse faults. such as the Kidd Lake
fault (Fig. 2.4). At Kidd Lake, faulting produced a new penetrative foliation in the
highly deforrned footwall rocks. Fault slickenlines, quartz rods and fold axes of
minor folds in the imparted foliation trend 2Q8Ol plunging 1 1 OS. This suggests that
movement was dominantly sinistrai with a small, reverse. east side-up
component.
Two roughly E-trending faults have been located in the Hidden Bay area. The
most important is the Rabbit Lake T h ~ s t (the name 'Pow Bay Fault" was given
to the structure by Wallis (1971). but was renamed by Sibbald. 1983) that
regionaily strikes 075" and passes through the Rabbit Lake pit (Fig. 2.4 and
2.6b). Where exposed in the pit walls the fault strikes 06S0. dipping 35-65"
southeast. It consists of a black gouge, in part graphitic, varying in width from 1 - 35m. The amount and sense of displacement on the fault is not known (Heine,
1 986).
The second fault forms the topographic low between Ashley lnlet and Otter Bay
(Fig. 2.4 and 2.6b). It is well exposed along the south shore of the Ashley lnlet
and on the south shore of m e r Bay. The fault strikes 090°, and dips 35"s.
Kinematic indicators suggest sinistral rnovement (Wallis. 1 971 ).
Many authors have reported the occurrence of Tabbernor-related faults in the
Wollaston Lake area (Chadwick 1966, 1967; Wallis, 1971 ; Chandler, 1978; Ray,
1 978; Lewry et al., 1 981 ; Sibbald, 1 983). N-trending topographic lowç, steep diffs
and bluff sections. and intense brecciation define the most prominent fault
splays. In the Compulsion Bay area there is a very conspicuous N-trending linear
bay to the west of Compulsion Bay itself (Figs. 2.4 and 2.10). This trend
continues southward of the bay as a nanow area of swamp and muskeg, and a
narrow linear lake. Such N-trending topographic features are also common in the
Hidden Bay area. Both Wallis (1971) and Sibbald (1983) reported prominent
north-south fault depressions and abrupt bluffs at Pow Bay, Dragon Lake, north
of Ahenakew Lake, and the west shore of Otter Bay (Fig. 2.4 and 2.6b). At these
localities the rocks are strongly brecciated but no new foliation is imparted
(Wallis, 1971). The breakdown of feldspan to kaolin and widespread
hematization are also common features. Sibbald (1983, p. 10) noted that
- ". . .quartrites intersected..[by north-trending faults]..are strongly fractured,
hematized and permeated by microcrystailine opalescent quartz", whereas,
"rocks intersected by reverse faults tend to be extensively affected by argillic and
chloritic aiteration". Offset along the former faults is deemed to be sinistral,
ranging from 500m-3000m+ (Wallis, 1971). No kinematic indicators were
recorded to indicate the displacement vector.
4.3 Timing and Metamorphism
The basement rocks of the Wollaston Domain record a polyphase metamorphic
history. The earliest. metamorphic event produced a high-grade metamorphic
assemblage across most of the Wollaston Lake area. Both Sibbald (1 983;
Hidden Bay) and Lewry et al. (1981 ; Compulsion Bay) conduded that the first
metamorphic event attained upper arnphibolite - lower granulite faaes conditions
at low to medium pressure (700-750°C, 5-6kban). The first rnetamorphic event
Ml, was synchronous with. or imrnediately postdatecl, the 01 deformational event.
These metamorphic conditions amtinued through to the end of the Do
deformational event (Lewry et al., 1981). In contrast, Wallis (1971) suggested
that metamorphic grade in the Hidden Bay area only reached mid-amphibolite
facies th tempe rature and pressure at 600-65û°C and 3kbars. respectivel y.
Retrograde metamorphisrn accompanied minor Da deformation that is seen
locally in the Hidden Bay area (Wallis, 1971 ; Hoeve and Sibbald. 1978).
Recent worù (Madore and Annesley, 1993; Madore et al., 1996; Annesley et cil.,
1996a, 1997) has conœntrated on the tectonotherml history of the Wollaston
Dornain, especiaify in the Wollaston Lake area Madore and Annedey's study
area is essentiaily the same as the current rnapping area, augmented by drillcore
samples from basement rocks to the immediate west. They condude that the
Wollaston Domain underwent three rnapr thermotectonic events (using the
notation of Mn1-3 and D~1.3). The first event MHI, occurred at 1840-1850Ma,
synch ronous wit h, or immediatei y proceeding DH~. Peak pressures of 5-8kban
were obtained duting MHI. Granulite-faaes peak metamorphic conditions were
attained dunng MH~, a e v i with DH~, at 1812-1830Ma. Pressures and
tempe ratures reached 4-6kban and 725-77S°C, respdvely. The third event,
MH~, occurred between 17751795Ma. This was an amphibolite-facies,
retrograde metamorphic event that ocairred during uplifi-driven decompression,
and tranpressional shearing. Retrograde metamorphisrn continued with uplift
through untii 1752Ma. and a minor greenschist to lower amphibolite-facies
rnetamorphic event, M H ~ (Annesley et al., 1997). Thus, it is noted that with the
addition of several refinernents by the later studies, the metamorphic conditions
indicated here are broadly sirnilai to those proposed by Lewry et al. (1981) and
Sibbald (1 983).
5. Current Work
5.1 Geophysical Interpfetation To help in the interpretation of the structural history of the Wollaston Lake area it
was decided to try and reevaluate the geophysical data available. The whole of
northern Saskatchewan is covered by aeromagnetic field data collected dong
flight lines with a 350m line spaang. and pubiished by Saskatchewan
Department of Mineral Resourœs. It shows the broadly NE-trending grain of the
Wollaston Domain. It aiso shows magnetic highs that correspond to the outcrop
patterns of the douôly-plunging basement gneiss domes, which core the fold
patterns in the domain. The Archean basement gneiss has a high magnetic
response in cornparison to the metasedimentary rocks of the Wollaston Group.
Although this gives a broad picture of the structurai styie in the Wollaston Domain
it does not help resolve srnaller-scale fault and fold structures.
As part of the NWIAEA study extensive aeromagnetic surveys were flown over
the test area to aid in the interpretation of basement geology ôeneath the
Athabasca Group and later Quaternary cover. Line spacing on the survey was 300m, flown east-west, with readings taken every 0.5 seconds, equivalent to
approximately 40m. The results of the survey are discussed in Komik (1 983). In
an attempt to improve the resolution of basement fault features the raw data file
from the original survey was obtained from the GSC Regional Geophysics
branch.
Two sets of readings were taken in the sunrey, total magnetic field (nT) and
vertical gradient (nT/m). The vertical gradient reading provides better resolution
of near surface magnetic features, and thus was chosen for interpretation of
surface geology. A map of the contoured vertical gradient data is shown in figure
2.6a. The disadvantage of the vertical gradient measurement sh~ws in the
western half of the rnap where up to 300m of sandstone cover decreases the
resolution and amplitude of top to basement anomalies. The colour scheme
Figure 2.6. lnterpreted vertical gradient aeromagnetic map of the
NENIAEA Athabasca test area. A) shaded relief map of the vertical
gradient data. See text for explanation of colour scheme. 6)
interpretation of the underlying geology based on the magnetic
response of the rocks coupled with knowledge of geology from
previously published and unpublished reports. Abbreviations:-
(structures) P.I.S.Z. = Parker Island Shear Zone; R.L.F. = Rabbit
Lake Thrust; C.B.F. = Collins Bay Thrust; M.L.F. = Moffat Lake
Thrust; (Locations) H.B. = Hidden Bay; O.B. = Otter Bay; A.P. = Ashley Peninsula; B.I. = Black Island; PB. = Pow Bay; P.I. = Parker
Island; N.I. = North Island; H.P. = Harrison Peninsula; S.I. = Snowshoe Island; K.L. = Kewen Lake. Shading:- red indicates high
magnetic response, probably Archean basement gneisses;
unshaded indicates moderate to low magnetic response,
dominantly Aphebian paragniesses with subordinate Hudsonian
intrusives; solid blue lines indicate position of diabase dykes;
horizontal green stripes indicates limits of the P.I.S.Z.; thin green
Iines indicate possible position of additional Tabbernor-related
fault zones. Red dots show the locations of major uranium
deposits: 1 = Midwest Lake; 2 = Dawn Lake; 3 = JEB; 4 = McClean
Lake; 5 = Sue; 6 = RavenlHorseshoe; 7 = Rabbit Lake; 8 = Collins
Bay 'B' zone; and 9 = Eagle Point.
chosen for the map is not related to a linear increase in the vertical g&ent. but
is modified to best pi& out the changes in field patterns assodated with
basement fault features. Thus no d e is show and no inferences about the
absolute value of the verticai gradient should be drawn. Reds and oranges
represent relatively high values, and Mues and greens represent low values. The
east-west 'stripes' are an artifact of the greater line spaang than sample spaang
along the lines.
The map is dominated by a NE-trending high in the centre. and similady trending
lows to the northwest and southeast. The high has been interpreted as the axial
trace of a Dz antiform with Archean rocks creating the high. This fold in fact
contains two separate cores termed the Hanison and McClean massifs
(nomenclature of Suryam. 1984). The abrupt deep lows on the north and west
sides of the basement doms, as compared to the mare graduai change in field
to the south and east, suggests that the antiform is not upright. The axial plane
appears to strike northeast and dip to the southeast, with the sense of vergance
to the northwest. As noted above, Tabbemor-related fault features show intense
oxidation and brecciation of the basement rocks associated with them. Because
of this the faults should appear on the map as a decrease in the vertical gradient.
Cornparison of the known topographie lows that coinude with the rnapped
Tabbernor Fault traces (at Ahenakew Lake, Dragon Lake and Pow Bay) to the
vertical gradient map shows that there is no offset of the dominant northeasterly
trend across these faults. within the resolution of the rnap (compare figures 2.6a
and 2.6b). There is certainly not the 3000m+ suggested by Wallis (1971). There
is however a small decrease in the vertical gradient assoaated with the faults.
This is in agreement with the observation of oxidation and breakdown of the
rnagnetic rninerals in the vicinity of the fault.
The most obvious feature affecting the regionai trend of the vertical gradient map
is a zone 1 -3km wide, trending 01 5-025' aiong the western shore of Otter Bay.
through Black Island, Harrison Peninsula, and Snomhoe Island (Fig. 2.6a). It is
characterized by a visiMe sinistral displacement of the magnetic highs and a lowering of the gradient field in cornparison to those rocks either side dong
strike. This feature is herein after refened to as the Parker Island shear zone
(PISZ) (Fig. 2.6b), as it is at this locality that the features related to its structural
history are best devdoped. lopographidly the PIS2 is hidden beneath the
waters of Wollaston Lake for much of its length. Where it does intersect the shore
it is usually in areas of liffle or no exposure. There are several other wïde
basernent zones that trend approximately 020° and appear to offset the regional
trend sinistraily (Fig. 2.6a). The rnost prominent of these is a 2km wide zone.
5km west of Kewen Lake. These zones are not as well defined as the PISZ but
this is probably due to the greater Athabasca Group cover to the west.
There are also severai visibie lineaments in the Harrison massif on the north
shore of Collins Creek (Fig. 2.6a). These lineaments trend approximately
northward and correspond to a decrease of the verocal gradient. As such they
appear similar, geophysically, to the Tabbemor Fault traces discussed eariier.
There are no corresponding topographie features on the surface. but this area is
covered by Athabasca Group sandstones and is in a wide zone of swamp and
general low relief. Both these features would combine to mask any expression of
basement brecciation and glacial erosion seen at the other locations. The Rabbit
Lake Fault does not show up on the map but the larger Moffatt Lake Fault dearly
shows up as a lineament along the northern edge of the Harrison massif, and continues west where it has apparent sinistral displacement.
Unfortunately such good geophysicai data are not available for the Compulsion
Bay area and therefore no similar interpretation can be made for that area.
5.2 Field Mnpping
Detailed field mapping was camed out during the coune of summer seasons in
1996 and 1997. Because of poor inland exposure the mapping was almost
exclusively along the shoreline of Wollaston Lake. Two areas, Hidden Bay and
Compulsion Bay (Fig. 2.4), were chosen as they were reasonably accessible by
boat and previous mepping had shown outcrop adjacent to welldefined TFZ
splays. The ernphasis of mapping was to wlled as much structurai data as
possible, espeaally adjacent to the TFZ splays. The mpping and correlation of
lithological units was not attempted, but descriptions of lithology were still
recorded at al1 locations and these generally agreed Ath the earlier reports of
Wallis (1 971 ), Lewry et al. (1 981 ), and Sibbald (1 983).
The orientation of rock fabrics was recorded wherever seen almg with a
description of the fabric type, Le. cornpositional layering or the prefened
orientation of minerais. Orientations of pegmatitic and leucograniüc intrusions,
and quartz veins were recorded as it was apparent from prelirninary observations
and previous reports that several generations of intrusive events had taken
place. Brittle features such as joints and micro faults were noted as well as the
sense and amount of displacement where evident. The results of the data
collection in the Hidden Bay and Compulsion Bay areas are shown in figures 2.7
to 2.13.
5.2.1 Hidden Bay area On the basis of the vertical gradient map interpretation, the area has been
divided into two domains (Fig. 2.7). The division is based on those outcrops that
lie within. or adjacent to, the PISZ, and those that do not. The second domain
was modified to include data from a small group of islands within Hidden Bay and
at the southern point of the bay. The reason for this modification has to do with
the dominant lithology at these locations and will be discussed in more detail
later. The two dornains will be discussed separately as their structural elements
show a marked difference in orientation and presurnably history.
Flgun 2.7. A) Form surha map of the HMdan Bay arma. Tha
devalopmant of S1 1s Intwpmted as k l n g a widaspmad event
assoclatad wlth early Hudsonlan datomatlon. Sa 18 mlatad to post-
colllslonal daformation In the THO. and k mtrlcted to Tabkrnor-
relakd hult zones. The exwptlon Is calc-slllcak and marbk unlts
exposed on Islands within Hidden Baym 8, 1s dominantly defined by
the transposition of S1 on to the D, dafomratlon plane, but at
H mlneml fabrlc thd overprlnb 8,. Tha solld llnw that deflne the
boundarles of the PIS2 also deflna the l lmb of data Included ln
domaln II. The orkntatlon and genamtion of fabrlca has been
extmpolated to amas wham thmm Is Insufflclant exposum, uslng
the modal for davelopment of S1 and Sa hbrlcs. 6) Inset showing
cartoon Illustmtlon of foilatlon orlentatlons In the PI=. The shear
zone contalns motless folds and boudins pamllel to the Sa
follatlon. ln hlgh stmin areas the follastlon may be norlentated to IIe
parallel to the shear zone. or a new shear cbavage may be
developed.
Dornain 1: outside the PIS2
Foliation readings outside the PIS2 am consistent about an average strike of
06P (Fig. 2.8a). The dip varies from moderately- to steepiy-dipping to the
southeast (counting peak of 5 3 O ) . The foliation is typically defined by fine.
millimetre-de, altemating bands and blebs of quartz and feldspar, with more
mafic segregations in which biotite flakes show a strong prefened orientation.
Typically the foliation is not observed in relationship to any other fabric. and
forrns massive, monotonous outcrops of gneiss. This indicates that the previously
existing sedirnentary layering has been obscured by development of the gneissic
foliation. In locations where quarute outcrops north of Hidden Bay the original
protolith contained little or no mafic component. Here occasional oxidized seams
and mica flakes define a discontinuous foliation.
Fold data collected outside the PIS2 show that folding in the dornain is consistent
w'th one phase of deformation that produced the previously mentioned foliation
(Fig. 2.9b). The fold axes fit well on a great cirde, the pole to which is coincident
with the pole to the average of the foliation readings. This agrees with the field
observations that fofded veins and dykes are tightly folded and often rwtless. with the foliation Ming planar to the folds. The fact that the fdd axes are not
co-linear shows that the dykesîfoliation were not CO-pîanar prior to deformation.
This may be due to an earlier unrecognised deformation event, pobsbiy the early
thermally-controlled doming of the basementcover contact (Lewry and Sibbaid,
1980). Alternatively the dykes may have been intnided into the rnetasedirnentary
rocks discordant to the foliation.
Although not as consistent, the axiai plane data also have a counting peak
coincident with the average foliation reading. A plot of the axiai trace data shows
that the average stnke of the folds is 067O. again consistent with the foliation and
fold axes data.
Flgure 2.8. Contoumd stemogmphlcal pmJactlons of .tructuml
data fmm the Hlddm Bay ama. Thesa and al1 prowadlng
stereonets am lower hamisphan, equal-rma, .trmogmphlcal
proJectlons. Whan stemoneîs are contourad It 1s dom udng Gausslan countlng method wham th. axp.ckd count for a random
dlstrlbutlon, E-m. Contoum am d m ovwy 20 abovm the
expected count. A C = Domaln 1. A) pohs to gnolulc (bllaüon; 8)
poles to dykes; C) polas to velna; DQ - Domaln II. D) polos to
gnelsslc follllon; E) polas to d m ; F) polos to velni.
Figure 2.9. Stereographical projections of fold data from the
Hidden Bay area. A) al1 fold data from Hidden Bay area; 8) fold data
from Domain I-outside P.I.S.Z. Shown for reference is a stereonet
of foliation data from Domain 1. (as figure 8a). Data suggest that
folds are compatible with formation during the development of the
gneissic foliation (S,); C) fold data from Domain II-inside P.I.S.Z.
Shown for reference is a stereonet of foliation data from Domain II.
(as figure 8d). Data suggest that folds are compatible with
formation during the transposition of the gneissic foliation (S,)
ont0 the plane of flattening to produce (S,), inside the P.I.S.2.
Fold Axes N
/ I
\
Axial Planes N
Axial Traces N
Foliation b) Domain 1 - Outside P.I.S.Z.
Foliation N
T *= FOI^ Axes = Axial Planes
Axial Axial Traces
Domain II - lnside P.I.S.Z. Axial Planes
N
Axial Traces LI
Granitic and leucogranitic intrusives are cornmon in this domain. There appear to
be at lest two separate generations of intnisives. The first generation appean
as pale pink quartr and feldspar veins and dykes which Vary in thickness from
1cm-50cm. The intnisives crosscut the foliation at a low angle and generally
show evidence of gentle folding and/or boudinage. The plane of flattening
appears to be the plane of the foliation. although the data suggest that the dyke
orientation is more variable than the foliation (Fig. 2.8b). Mafic minerals are
generally absent but occasional tourmaline crystalline aggregates were seen
intergrown with quartz.
The second generation of intrusives crosscut the foliation at a high angle, in
contrast to the eariier generation. and where the two are seen together the later
generation crosscuts the eadier one. They range in thickness from 2cm-2m and
are rectilinear. These later intrusives are similar in composition to the first, k i n g
cornposed al most entirely of quark and feldspar. Rare. large, biotite books ocair
in the second-generation intnisives but these are the exception. The biotites
show no preferred orientation and no foliation is developed. Hematite is a
ubiquitous accessory minerai in late fractures and dong deavage planes in the
feldspars.
The two generations of intrusives can be distinguished on the basis of colour, the
second generation being a more vivid deep pink or red. Another distinguishing
characteristic of the second generation of pegmatitic intnisives is the angular
nature of the wall contacts. Dyke (sensu lato) walls show sharp, planar contacts
with the sunounûing rocks (Plate 2.1) with no indication that melt rnatenal
migrated from the irnmediate surroundings. Dykes also exhibit sharp changes of
direction, suggesting they were intruded into brittle fractures. Rafts of country
rock can be cleariy made out in several dykes. These rafts can easily be
correlated to sections of the adjacent wall rock, suggesting that the dykes did not
under go significant lateral movernent across them dunng emplacement. There is
a strong preferred orientation to these dykes, tightly dustered around a strike of
Plah 2.1. Secondqomraüon pogmitlk dyka, nonh shom of Pow
rlgM of the plctun. This dyk. shom wvml of ai. dlagnostlc Laturw of socondganwatlon Int~shms. Flrstîy, nnd the sharp
contact ktween th. dykm and th. adjacent roda. Al80 note the
angular natum of the bloda of country mck whlch have spalkd ,
frorn the dyke wall during intrusion. Secondly, the dyke Is
u n a M e d by deformation, and no follatkn k developod withln lt. Flnally, the dyka trends appmxlmately northward, am do many
other dykes of thk genemtlon. Thk partlcular dykm k wldar than the avemga, it 1 Om*. For scak th. wmpau la lOcm long.
350-005" and verücally ôipping (Fig. 2.8b). The lad< of significant offset suggests
that the second generation of intrusives were emplaced during an extensionai
event, perpendiwlar to the dyke orientation.
Quartz veins appear to follow the same broad trends as the pegmatite intrusives.
bath mineralogically and stnictuially (Fig. 2.û~). Examples intemediate between
dykes and quartz veins exist. with quartz-feldspar margins and a pure quartz
core. Actinolite laths up to Smm long were observed in a series of quartz veins at
locality 18081 (Fig. 2.7). The orientation of quartz veins is sirnilar to the dykes
with the second generation of veins trending 330-000" and vertically dipping.
Domain n: lnside the PlSZ
Foliation readings within the PIS2 are far less consistent in orientation than those
outside (Fig. 2.8d). 60th strike and dip Vary by about 60-70 degrees, but as a
general rule the foliation is steeper and closer to NE-trending than the foliation in
domain 1. This is reflected in the counting peak for the foliation within the PIS2
which is 048/7S0. The nature of the foliation is sirnilar to that in dornain 1. It is
typicaily defined by compositional variations consisting of aiternating bands of
qua* and feldspar, with nanower more mfic bands of quartz+feldspa»biotite
smphibole. There is more evidence of boudinage in the foliation in the PIS2
than outside, and grah flattening and elongation is cornmon. Outcrop-scale folds
within the foliation, which are rare in the foliation outside the PISZ, are also more
abundant.
At location 21071 (Fig. 2.7) on the eastern shore of Parker Island, a gneissic
foliation striking 020" is seen to tnincate a foliation. of what appears to be the
same generation, striking 360" (Plate 2.2). If these two foliations are of the same
generation then their discordant relationship can be explained by asyrnmetric
foliation boudinage (Lacassin. 1988) of this competent layering. The initial break
in the foliation may have evolved into a 'C' type shear plane with sinistral shear
displacement. This would explain the cuirent geometry of the foliation and the
Plate 2.2. Devalopment of asymmetrlt follatlon boudlnage at
location 21071, south east ahor, of Parker Island. The follitton to
the far Ieft of the photograph, trrndlng 020°, truncatm the folillon
In the centra, tmndlng 36Um. 60th kllatlons am defined by gnelulc
layering In quarkdch gnmki.. and quublt.. th.1 pmdomlnate
on Parker Island. The mxplinmtlon g h n for thmlr cunrnt discordant mlationshlp b t h 1 thoy have bwn dkloorkd along a
plane whlch nins pamllel to ai@ fdMlon on the kCI, but cub acroms foliatlon to the flght This dlrlocitlon occumd during Iarge~cale
foliatlon boudlnaga of the compooltlonal Iaymring. Seo text for more cornpleb descrlptlon of the structure.
orientation of the break between the blodrs, which is approxirnately parallel to the
plane defined by the PISZ. Generally on the Parker ldand outaops the main
foliation is north to NE-trendhg and subvertical. Two locallies (21 021 and 22021 ;
Fig. 2.7) show a well defined stretching lineation on the main foliation plane. and
in elongated quartz dasts. These lineations plunge 39" towards 232'. in a
foliation 21 7/76".
Still on Parker Island at outcrop 21041 (Fig. 2.7) a dudile fault with the
orientation l95/85" offsets the foliation sinistrally with an unknown displacement
(Plate 2.3). Adjacent to the fault the foliation is rotated around until it lies paraflel.
It appean as though at least sorne of the offset dong this fault was achieved by
foliation-parallel slip. Eight more small-scale faults with similar orientation and
style of ductile sinistral offset were obsewed in or adjacent to the PISZ. A mixture
of quartz and feldspar has intruded five of these faults.
Folding is cornmon in the rocks exposed on Pafker Island, such as on the srnall
islands of the northeast point, where the foliation and dykes are folded into üght
to isoclinal folds with fold hinges that plunge moderately NNE-SSW. The data for
domain II show that the folds lie on a plane of flattening which is coinadent with
the counting peak for foliation readings within the PISZ, Le. 0 W 5 O (Fig. 2.9~).
Axial plane readings within the PIS2 are consistent with the average foliation
plane, and axial traces show a maximum trend of 048'. This suggests that the
folds are examples of SI isodinaîly folded ont0 the 0 2 plane of flattening, with the
limbs being transposed ont0 S2. It is possible that these folds represent FI folds
transposed ont0 the 0 2 plane of flattening. and this explanation should not be
discounted.
Abundant boudinage of the foliation-parallel leucogranitic dykes and resistant
bands in the gneissic foliation suggests that flattening onto the plane of the
foliation has been extensive in dornain II (Plate 2.4). 'Chocolate tablet boudinage'
structures seen in some locations indicate that extension occurred in two
Plate 2.3. SrnaIl-k ductltlk huit with nljawnt m n g slnlstml
dmg, location 21041. souanist ahom of Parker kbnd. Tho f.uM plane .Mk# 185., dlpplng 115. to tha south. Thk Ir slmllar to the lnfernd orknbtion of the PIS& and the 8Inl.tril .bar fibric m n In the Compuklon Bay ama (seu section Sm2.2). On the rlght-hand
side of the huit a slngk prk puarbrlch kymr, appmxlmibly 6cm wide, has boon tlattonod parrlkl to th. f.uk plan.. T hm tnincation of adjacent layon In tha gnablc folktlon auggmb t h e 1 hast
soma of the dkplacement on thk hua was achleved by Iayer
pamllel slip. Compau k 1 Ocm long.
Plate 2.4. Ext.nshm boudlnage of pogmatltlc materlal wlthln well-
follated, finegralned blotltequarh gneiss, locatlon 25021. Thls
location Is north d the Hidden Bay arma In one of the additlonal
mapplng amas. î t k loatmd wlthln a strong topogmphlc Ilneament,
trendlng 02S0, thmugh Greenaway Island on Wollaston Lake. The M follatlon strlkas 220°, whlch Is about the average for domaln II of
the Hldden Bay ama. Tho boudlnagmd material may d t h r k part
of an eariy 'in-mlk18 mdtsegmgatlon or a Iater Intrushm dyke. In the
cantm of the phatogmph small hocllnal, motleu fold withln a
section of pm#mdto Indlcib. th. ûmnsposltlon of the aarliw
follatlon onto the cumnt Watbnlng' follatlon. Hmmer In shot Ir
3Ocm long.
directions TighUy folded quartz veining at IocaOons 13021 -13061 and 29061 - 29091 show i~odinal folâing with wavelengths of 2-1 Ocm. about a well developed
axial planar fabric. The folding shows approximately equal amounts of 'S'- and
'2'-folds, suggesting that there was no strong wmponent of shear parallel to the
foliation during deformation. Dyke and vein orientations (Fig. 2.80 and f) show
that both types of intrusives have strongly dustered orientations parallel to the
foliation.
5.2.2 Compulsion ûay a m As vertical gradient suwey data were not available for the Compulsion Bay area
no similar means of subdividing the data into structural domains was available.
Because of this the domains were distinguished by the occurrence of a visible
shear cleavage. Despite the recognition of this new fabric it has not been
possible to define a continuws zone of shear like that in the Hidden Bay area.
Thus for this study the areas displaying the shear deavage are treated as
isolated regions in an otherwise unaffected dornain (Fig. 2.1 0).
Domain 1: amas umffected by sheai developmnt As with the Hidden Bay data, the main foliation is defined by compositional
layenng on a millimetre to centirnetre d e . In more micaceous horizons the
mica flakes (predominantly biotite) have a strong prefened planar orientation that
gives nse to strong schistosity. Much of the mapping included areas of basernent
gneiss outcrop and at these locations the foliation is poorly developed. Where
present, it is defined by the preferred planar orientation of discrete biotite flakes
that make up 2-10 percent of the rock. There is considerable variation in the
strike of the foliation but it is consistently steeply NW- or N-dipping. The counting
peak for foliation readings in the regions unaffeaed &y sheai is 253/76O (Fig.
2.1 1 a).
The granitic intrusives are similar to second generation of dykes in domain 1 of
the Hidden Bay area. The dykes are leucogranitic, with occasional rnafic
Flgun 2.10. Loatlan map of tha Compublon Bay mpplng a m .
BIack d d r Indiatm th. Ioaüons af outcmpm dlsplaylng shou
fabrlcs, and thmforr Intludd In domaln lZ (mae tmxt for explination). Tha solid linos mpmaont the Imation of TFZ huit splays, and dashed llna IndIcabs the pmbabk posltlon of a major TFZ huit spiiy bmwd on mignotic flald p.tbms and llmttod
mapping.
Figure 2.11. Stwwgmphlul pto).dlom of 8 ~ c t u r i l d d i from th.
Compulsion Bay 8ri.o. A C - Domaln 1. A) pd.o to gnokdc
foliation; 6) pohs to dykw; C) pok. to wlrm; O+ - Domaln II. 0)
poks to grniulc tollatlon; E) polos to dyk.8; F) polos to vmlns.
Domain I Domain II
Veins
rninerals, planar with sharp wails, and unfdded. Hematite is an important
accessory mineral as is magnetite at certain locations. Zircon has been noted in
thin section as well as several other unidentifid acçessory phases. A few of the
dykes show shear of the foliation adjacent to the dyke margins. consistent Ath
sinistral shear, but the majority show no evidence of deformation. Even in those
dykes where there is evidenœ of shear adjacent to the margins the dyke rock is
unsheared, and composeci of 1 -2cm feldspar crystals in a coarse-grained mat rix.
Typicai dyke width is 2-15cm. Several dykes show a transition to quartz-
dorninated or even monomineralic quartz veins. The dykes are dustered about a
peak orientation of 350/83O (Fig. 2.1 1 b). The number of quartz vein readings is
small but severai of the veins follow a similar trend.
Dornain II: areas showlng development of shear featuies
As mentioned above the diagnostic feature of sites induded in this subset is the
presence of a shear deavage or parallel joints. Reagnition of these features is
based on severai criteria. First, the shear planes and joints have a very
consistent orientation. They are tightiy dustered about an average of 014/86".
Second, shear deavage development is associateci with strong deflecüon or drag
of the foliation with a wnsistently sinidrai sense. Third, both the shear deavage
and joints show patchy to continuous r d hernatite coating the surface of the
planes, which may be in part siiicified. Quartz fiII in open planes, or dilations on
inegular planes, is cornmon and mineral growth steps and slickenlines suggest
sub-horizontal sinistral movernent. Locally joints and deavage planes have an
associated, pink aiteration halo 1-5mm either sida of the plane that is
preferentiall y eroded on weat hered or glaaated surfaces
The counting peak for the main foliation is 229ff8O although, as in domain ïï in
the Hidden Bay area, the range in foliation orientation is larger than in dornain 1
(Fig. 2.1 1 d). The foliation is more obvious at locations displaying the shear fabric,
especially where exposure is of basement gneiss. In contrast to basement gneiss
outcrops elsewhere that show scattered biotite flakes, these outcrops have semi-
wntinuous seam of biotite, appmximately Imm thidc Quartz grains are
severely flattened into ribbons of quartz aggregates parallel to the foliation. The
sheared foliation is displayed in location 520201 (Fig. 2.1 2, Plate 2.5), where the
shear deavage is also well developed. Hem the shear planes are approximately
5mrn apart. discontinuous and easily identifiable with the naked eye. In thin
section the rock shows strong ribboning of quartz aggregates and strong
alignment of biotite flakes parailel to the foliation. Adjacent to shear planes the
quartz and feldspr show drastic grain-size reduction. A new generation of
biotites has grown along the shear plane, or the existing mineral grains have
been reon'ented parailel to the shear plane. These biotites have undergone
pervasive chloritization (see sedion 5.2.3). From visual inspection alone (Plate
2.5) it appean as though this new shear deavage is in fact a classical S-C fabric.
Although the similarity is striking the author is reluctant to use this terrninology.
The reason for this-~eluctanœ is that although the gniessic layering resembles
the 'S or flattening plane it is not a new fabnc developed simultaneously with the
'C' or shear plane, as shown by Berth& et al. (1979). Lister and Snoke (1984)
argue that the 'S and 'C fabric elements need not be developed simultaneously
although they still infer fabric development dunng the same deformation episode,
which is contrary to the mode1 argued for the development of the tabric shown
here. In addition the s d e of fabric development is larger than that typically
associated with S-Gtype fabrics (Lister and Snoke, 1984; Blenkinsop and
Treloar, 1995). in which are C planes are sepaiated by prn or mm.
Deformation associated with small-sale ductile faulting is restricted to rocks
immediately adjacent to faults. A foliation swing of 34 degrees over 2m was
recorded adjacent to a small ductile fault, orientated 013î74°, at location 490701
(Fig. 2.10). Similar deflections of the foliation were recorded adjacent to faults at
locations 580301 and 61 0201 (Fig. 2.1 0). Both of these locations show granite
pegmatites intruding the fault planes. Shearing of the pegmatite is only seen at
the rnargins of the intrusives at location 580301.
Figure 2.12. D.trlkd tkld m.p of l d l o n 52û201. Tho location h
an outcrop of Archan b.#mmt ginlu (part of th8 Johnson Rlvw
adjacent TF2 f.uh sply. Dnormmtlon k c h . m k r b d by
Inbiislffatkn of th. gri.k.lc folktlon and dovmkpmont of a
cleavagm planas by qrinMc mît rnmîmrlml h r kd to many cloi.ly-
s p a d narrow gmnltlc dyk.8 whlch pmmlkl the mhur dlrrctlon. Sem figure 10 for location.
Plate 2.5. Closely-spaced shear cleavage in Archean gneiss of the
Johnson River Inlier, location 520201, west of Compulsion Bay.
Note the extreme development of a flattening foliation, defined by
elongate quartz 'ribbons' and biotite seams. This is in contrast to
the poorly-developed foliation elsewhere in Archean basement
rocks. The shear cleavage, striking 00g3 and dipping 86O west, is
patchy but where present it has rotated the foliation with
consistent sinistral sense. The photograph is 2Ocm from top to
bottom.
Folds are uncornmon in the Compulsion Bay area, espedally in the granite
gneisses which f o n the Johnson River Inlier. Fold orientation data is shown in
figure 2.1 3.
The dykes within domain II are bimodd in orientation. One group of dykes is
sirnilar in al1 charaderistics to the dykes from the dornain unaffected by the shear
foliation. trending 335-360" (Fig. 2.1 le). The second set of dykes is parallel to
the shear fabric. Le. trending 010425°, and shows lots of examples of sinistral
shear in the wall rock adjacent to the dyke (Plate 2.6). At two outcrops the dykes
themselves are sheared, with minor biotite flakes afigned parallel to the dyke
walls, but only at the edges of the dyke. The cores of the dykes remain
undeforrned.
As with other locations the qua- veins appear to rnirror the orientation and style
of the quartz-feldspar dykes. They are composed of two populations, one
intruded into shear planes and showing strong deformation. the other trending
330-350" and undeforrned (Fig. 2.1 le).
5.2.3 Srnall-scale Reactivation Fmtures common to both Hldden Bay and Compulsion Bay
Reactivation of ductile fault features. filled by intrusive material, is not comrnon
but where it occurs it follows a consistent pattern. 60th dykes and veins show
eari y ductile shearing of coane-grai ned quartz and feldspar. Biotites show
occasional kink bands. Deformation is associated with biotite alteration and/or
replacement. This style of dyke deformation is well displayed at location 520201
(Fig. 2.10). Here 2-3cm thick dykes deariy intnide shear deavage planes with a
separation of 50cm or less. Thin section anaiysis of the dykes shows a
discontinuous zone on both margins of the dyke about 2mm wide. Within this
zone quartz and feldspar grains have been sheared out into elongated
aggregates that display a drastically reduced grain size as cornpared to the rest
of the dyke (Plate 2.7). Seams of heavily altered biotite are aligned parallel to the
Compulsion Bay ama. All th. fold data wi. calkcbd h m domaln ïï amas. Shown for nnirnœ am pdœ and planos for both th.
avamge follatlon phnm and the avmg. 8h.u cloawgo plane (u FIg. 11d). Nd . t h l both the told .x.r and th. otld plan- Ik
somewhem betwun th. avmg. follmtlon plam and the shear
plana suggosüng thit thmy h m undorgona -Ion tomrûs th.
shear plan. r mrmsult d hlgh -ln In th. rock.
Plate 2.6. Gmnlk dyke 1ntnid.d lnto the ah- claavage, location
520201, samm u platm 2.5. f h m gmnlk-pogmatItIc dyke 1s hfnt
(dashed whwhlk Ilma show thm dg-), but k deflnd by the Iack of follatlon devdopment, and darkmr plnk colour with hemltte
stalnlng. Folldon planes In th. gnak. am ahumd out wlth . obvlous slnlstml dmg but th. dyk. ahom no dgna of dudlo
defonnatlon. The da* lmguhr llm ninnlng dom the centre af the
dyke (whlte amw) k hctum pkm t h l devmloped durlng b M e
reactivatlon of th. 8h.u niMc. Duk patchms on the gnelss a n
Ilchen growth. T hm dykm k 8ppmxim.kly 3cm wldm.
Plate 2.7. Photomlcrogmph of tha maigln of a dykm Intruded lnto
the rhaar cleavaga, from locatlon 520201. Thlr c l r r l y shom the localkation of shaaring withln tha dyka. Tha corn (uppmnast and
to the right) Is composed of coanegmlrnd quark and hldapar
gralns whlch am i.latlvely unddonnd. Tha only aitomtlon k wmak
the d g e of the dyka shom oxtnma anln si20 mludlon of qua-
and feldspar ln nsponse to shearlng. The shearing is accompanld by the Introduction of ahoargamlkl ah- of blotlb
(swn as bright layem due to hlgh blmfrîngenœ). Thosa h m b n n alkmd to a mMum of chlorlb, wrlclte (llllt.3) and mlnorapldok.
shear plane. These are now replaced by what appean to be a Cnegrained
phyllosilicate aggregate, induding chlorite, sencite and minor epidote.
Quartz veins contain rafts of highly-strained, undulose quartz in a fi negrained
recrystallized quartz matrix, with strong flow banding (Plate 2.8). The margins of
the intrusives are more heavily deformed than the cores. Later deformation
consists of brinle fractures that crosscut both quartz and feldspar grains.
Hematite staining is assoaated with many of these late fradures. It is not
uncornmon for the fractures to be filled by a new generation of quartz. At location
18081 (Fig. 2.7) severai parailel quartz veins show extensive brittle deformation.
The fractures crosscut and offset actinolite needles in the vein. The fractures are
filled by a cornplex assemblage that indudes euhedraJ zoisite (Fe-poor epidote).
surrounded by a halo of fine-grained carbonate and then by seriate.
Many of the intrusives are reactivated as brittle faults with well identifiabie
slickenline lineations. One example of a granitic dyke reactivated as a b r d a t e d
fault zone was seen at location 560501 (Fig. 2.10). The core of the dyke now
consists of subangular fragments of quartz and feldspar in a silicified hematite
mat ri x.
Small-scale brittle fault planes are common in both field areas. They are typically
reactivated joints or. in the Compulsion Bay area, deavage planes. Minerai
growth steps ailow the determination of movement sense where present.
Minerakation on the fault surfaces is typically quartz and hematite although
chlorite, epidote and unidentified day minerais are also present on some
surfaces. The faults are more common in the Archean basement gneiss than in
the overlying ~phebian gneiss.
Plate 2.8. Photomlcmgraph of qua- from vdn Intnidad lnto fault
plane. The eadlest oh8ervabk ovent k charactorhed by the
crystalllzllon of coamegmln.d q u e In the veln. Subsequont
ductilo deformatlon resulted ln the mcrystalllzatlon of much of thls
and the dawlopmant df low bandlng wlthln the quark. Wlthln thls flnerqmlnad, mcrystallkad quark tham am romnant 8mb' of the
origlnal quartz whlch hava a chamcterlstlc undulma texture due to
the straln asaoclatmd with m.ctlvaüon. Later roactlvatlon causd
brittlo fmcturlng that crosa~cutm both ganemtlons of quark gmwth.
6. Interpretation of Data
6.1 Ductik ûefomiation Assoclateâ with the Tmns-Hudson Orogen
In agreement with previous studies of the Hidden Bay and Compulsion Bay areas
two foliations have been recognized. The first foliation (SI) in areas unaffected by
shearing is reasonably consistent in its trend of 067-247' in the Hidden Bay area,
and 063-243" in the Compulsion Bay area (Figs. 2.8a and 2.1 1 a). The dominant
southeasteily dip direction in Hidden Bay is consistent with the area ocaipgng
the southeastem flank of major structural dome, cored by Archean gneisses of
the Harrison and McClean massifs (Figs. 2.4 and 2.6). Likewise the northwesterly
dip direction in the Compulsion Bay area rnay be the result of its position on the
northwest flank of the Johnson River Inlier, another Archean a r e to a major
structural dome (Fig. 2.4). Alternatively. the change in dip direction has been
attributed to a division of the Wollaston Domain into a western segment where
dips are to the southeast. and an eastem segment where dipû are to the
northwest (Annesley pers. comm., 1998). A dominandy low aerornagnetic field to
the West and a dorninantly high aeromagnetic field to the east distinguish the two
segments. The lineament separating the two segments passes just south of the
Hidden Bay area. There is some evidenœ supporting this later hypothesis as
readings from northwest of the smaller Trout Nanows granite (Fig. 2.4) indicate a southeastward dip, contrary to what would be expected of this location if the SI
foliation dip were controlled by position relative to the basement domes.
Folding in these structural domains is consistent with flattening ont0 the plane of
the SI foliation, typified by tightly folded pegmatic segregatians. As noted earlier.
the lack of CO-axially within the fold axes suggests that the foliation was not co-
planar and may indicate a prior deformation episode not distinguished here. The
limited amount of data shown in the paper rneans that little importance can be
placed on this distribution, and the proceeding arguments on the nature of
deformation within the TF2 are not affected by the earlier deformations. The
folded dykes are not evident in the ~orn6ulsion Bay data because the host
lithology is dorninantly basement gneiss that did not Contain many early m î t
segregations. The limited fold axes data suggest that there was little rotation of the axes to towards parallelism. indicating that there was not a strong
constrictional strain (Fig. 2.9b).
Unlike the results of previous studies, it is dear from the data here that the
second foliation (S4 is not a universai overprinting fabric, but is restricted to
narrow belts that trend between 010-020". The most easily definable of these is
the PIS2 although it is dear from the Compulsion Bay data that such a shear zone, or zones, must exist in that area as well. These shear zones offset the
lithology and Sc foliation consistent sinistral sense. As with the SI foliation.
the orientation of the S2 foliation in Hidden Bay is comparable with that in
Compulsion Bay, being 048ffS0SE and 229/78*NW respectively (Figs. 2.8d and
2.1 id). Thlsauggests that shear zones in the Hidden Bay and Compulsion Bay
areas underwent a similar degree of shean'ng and sinistral rotation of the local
plane of flattening.
The only exceptions to S2 being confined to the linear belts or shear zones are
found on severai srnqll idands in Hidden Bay (Fig. 2.7). The dominant lithology at these locations is cabsilicate rich arkoses and dirty marbles. These lithologies
are considered to be the m s t ductile within the mapping area. It is not surprising
then that these rocks should take on the characteristics of the D2 deformation,
whereas other lithologies outside the shear zones do not.
The fact that S2 is generally not seen in relation to SI suggests that S2 is developed by transposing the eailier gneissic fabric onto the 0 2 plane of
flatteni ng . The transposition was accompanied by intensification of the g neissic
foliation, tight folding and boudinage. This is well displayed at location 25021
(Plate 2.4). Folding of the transposed SI foliation about F 2 folds was noted on the
outcrop scafe but no regionai scale folds have been identified. The fold data from
the PIS2 show that fold axes are flattened ont0 a plane parallel to Si (Fig. 2.9~).
This may be a combination of neMy fomed F2 folds, and FI fol& rotated to lie on
the 0 2 plane of flattening.
Results from the Compulsion Bay area show that a third deformational fabric. in
the form of a shear deavage, is present in areas where S2 is weII developd. The
fact that &and the shear fabric occur at the same localif es and that SZ occurs in
belts parallel to the shear fabnc suggest that the two were developed during the
same deformation episode. As discussed above Sz develops paralel to the 0 2
plane of flattening, whereas the shear foliation is developed parallel to the
component of simple shear within the shear zone. Location 520201 (Fig. 2.10)
displays the best-developed strain features as a result of the D2 deformation.
What is noticeable at this location is that the S2 foliation is strongly sheared out
adjacent to the deavage (Plates 2.5 and 2.6). This effect is seen on a larger
scale at location 540101 (Fig. 2.10) where the foliation deflection is in the order
of 25 degrees over 20m adjacent to r d oxide-stained joint planes that are
interpreted as being part of the shear deavage. Fold data from Compulsion Bay
also show the effect of the sinistral sheanng (Fig. 2.13). Fold axes and axial
planes lie somewhere between the plane defined by & average and the plane of
shearing. Thus the fol& are assumed to have developed on the D2 plane of
flattening, but in zones of high strain the plane of flattening has rotated towards
the shear plane.
This shear fabnc has been recognized at several locations in the Compulsion
Bay area but not the Hidden Bay area One explanation may be that the host
lithology controls the occurrence of the shear deavage, and that it was not
developed in the more ductile rocks of the Hidden Bay assemblage. On Parker
Island the more northeily strike of the foliation. existence of foliation boudinage,
and mineral stretching lineations point to high strain accommodation in the rock.
An alternative explanation is that the deavage may have developed at both
locations but outcrops in the Hidden Bay area are not preserved. The occurrence
of the shear planes causes the rock to possess a fielity, even in the
mechanically resistant granitic gneisses where it is be$t dispiayed. In less
resistant rock this fissility could result in a dramatic increase in amount of surface
erosion, espeaaily by recent glacial activity. As noted, the PlSZ is characterird
by very poor outcrop along its length, and it defines the shoreline on much of its
western rnargin. Another possible reason is that the shear deavage was not
recognized as a separate fabric and grouped Ath the other joints. Reanalysis of
the joint data from the Hidden Bay area shows that severai of the joints
orientated paraltel to the shear plane do show the characteristic red oxide-
staining seen on shear joints in Compulsion Bay. Several others have slickenside
lineations. which are also characteristic of shear planes in the Compulsion Bay
area.
The previously defined Tabbemor Fault lineaments, typically N-trending, do show
weak reorientation of the foliation, consistent with sinistral shear, but this is
normally confined to a few meters either dde of the overprinting brittle fault
planes. They also appear to have a restricted laterai extent, suggesting that they
die out or rnerge into the main shear structures, trending 020". The mst
plausible explanation of these structures is that they are 'Riedel-like' in origin,
seperated by an angle of approximately 20 degrees from the main TF2 structures
(Fig. 2.7).
The intrusion of pegrnatites and quartz into srnall-scale faults and shear zones
appears to be a widespread feature of structures associated with the D2 event.
The trend of dykes within the Compulsion Bay area and their structural
characteristics suggest that many of them are intruded into D2 deformation
structures, but the lack of strong deformation or Row structures within most dykes
suggests that they were emplaced after the bulk of deformation. The lack of
deformation and foliation development is a feature they share with the second
generation of pegmatite dykes in domain 1 of Hidden Bay. They are also
superficially similar in mineralogy, and trend. Because of these observations, the
intrusion of second-generaüon dykes is tentaüvely attributed to the same event
as the intrusion of pegmatites and quartz veins into the D2 fault features.
Intrusion occuned in response to an approwimately east-west tensional event.
after 0 2 , that caused the formation of new tension garhes in the unsheared
areas. These filled with melt material ascending from below. In those areas affected by Dz shearing the shear deavage and parailel joints provide a pre-
existing weakness plane that is utilized as a conduit for magrna ascent.
Subsequent reactivation of the 0 2 structures caused deformation at the margins
of severai dykes, but for the most part ductile deformation appeared to have
ended before the intrusion of the pegmatites.
On a larger scale, late-Hudsonian porphyritic granites such as the Kidd Lake
granite, Horton Island granite and smaller granitic bodies identified by Wallis
(1 971), Chadwick (1966; 1967) and Sibbald (1983) occur throughout the
Wollaston Lake area. These are described as deep pink, unfofiated, homogenous
granites. Despite this last statement Wailis (1 971) noted that some of the srnaller
intrusions "...grade through foliated granite porüons into pegmatized, pink. meta-
arkose." It was also noted that the Kidd Lake granite is foliated irnmediately
adjacent to the Kidd Lake Fault. The lack of a foliation to the cores of the
intrusions suggests that they were intnrded after 0 2 deformation. The
devalopment of a foliation at the margins of dykes and smaller intrusives and
adjacent to faults indicates there was localized reactivation of structures dunng or
after intrusion. It would appear that the location of lager granite bodies was
controlled by pre-existing or active structures such as the Kidd Lake Fault. Thus
both mineralogidly and stnicturally the larger granitic intrusives are very sirnilar
to the small-scale intrusive dykes noted in this study. Wallis made the same
genetic link between the Hudsonian granitic bodies and late, rectilinear
pegmatites in Hidden Bay (P3 generation of Wallis, 1971. p. 39).
As noted earlier, the most recent radiogenic data from these granitic bodies
suggest that they were intruded circa. 181 5Ma (Annesley et al.. 1997; Madore
and Annesley, 1998) dunng the peak of Hudsonian thermal metamrphism. This
means that deformation associated with the Oz event ocairred before 181 5Ma.
Subsequent ductile deformation of the intrusives is likely linked to late
transpressionai sheaiing during retrogressive rnetamorphism, as noted by the
alteration of biotites associated with the deformation event.
6.2 Brittle Reactivation of Hudsonian Features
The reactivation of joint and shear planes as brittle faults is a cornmon
occurrence in both areas. Orientation data were analyzed to see if the faults were
caused by a single recognizable event or due to localized stress buildups with no
widespread coherency. The orientations of the fault planes and slickenline
lineations were entered into a data file dong with the movement sense. This file
was entered into the BRUTE3 fault-slip data inversion program (Hardcastle and
Hills, 1991). BRUTE3 caiculates the best-fit stress tensor for the recorded fault
data. The vaiues of cohesion. C. the coefficient of friction, p. and the fluid
pressure, Pw. were. assigned as 0, 0.4. and 0.5 respectively, using values
suggested by Hardcastle and Hills (1991). Where two or more subsets of
unrelated faults exist they maybe subâivided using the accornpanying SELECT
prog ram.
Modeling of the Wollaston Lake data is shown in figures 2.14 and 2.15. Figure
2.1 4b shows that of the 64 faults recarded in the Hidden Bay data set. 38 (59%)
are compatible with a single stress tensor. Another 15 (23%) are compatible with
a separate stress tensor (Fig. 2.14~). The Compulsion Bay data show that 50 of
62 faults (81%) fit a single stress tensor (Fig. 2.15b). As a test of the method's
reliability the values of p and PRU~ were varied from 0.1 to 0.8 to see if it would
significantly alter the orientation of the resultant stress tensor. The results
showed that neither the values of p nor Ptl"~ had a significant effed on the
orientation of the stress tensor or the inclusion of individual faults into a
genetically-related subset.
Flgun 2.14. S ~ m p h l c a l p m ~ o n s of britth hult data h m
the Hldden Bay ami; A) stemogmm showlng the orlentalon of al1
brittle faub Includd In the maln data set. The small dots
repmrnt thetrund and plunga ofth. Ilneatlons on thehult planes.
The IlnaatJons may lia sIlgMly off the plane definhg the fault, due
to mors asaoclated with field mmsummants, but If th. llnutlon Is more than 10. out d the hult plain both the f.uk and the Ilinatlon
were culled h m the data ad; B) poIm to M i t pknas Included In
sub set 1, and thm orknhtlon of thm dafinoâ paleodmss bnror.
Prlnclpal st- ut- am 0, -1 S61ûOa, a, = O6Wû(r, a, - 2W4'; C)
poles to huit planes Included In sub sut 2, and the orlentatlon of
the defïned paleo+tmss tonsor. Prlnclpal strass axes am a,
=142Mm, a, - 276148., a# =034/24@.
a) All Fault data N
b) Sub Set 1 N
c) Sub Set 2
Sinistral fault plane Sinistral fault plane lineation Dextral fault plane
= Dextral fault plane lineation
Flgure 2.15. Skrmgmphlcal pmJectIonr of brlttk huit data h m the Compuldon Bay ana; A) sbmognm showlng the orlentitlon
, of al1 brittle h u b lncluded in th. maln data set. nia data Ir
dbplayed as In figum Ils; 6) polos to fruit pknm included In sub set 1, and the orkntatlon of the d.flnod pako-stmss bnsor.
a) All Fault data N
b) Sub Set 1 N
Sinistral fault plane Sinistral fault plane Dextral fault plane
lineation
Dextral fault plane lineation
The results of the fault-Jip data inversions are significant. The similanty between
the first subset from the Hidden Bay data and the Compulsion Bay data strongly
suggest that these two paleostress tensors are part of a widespread basement
reactivation event that affected the Wollaston Lake area sometime after the
intrusion of the granite pegmatites, i.8. 1815Ma. No definitive age can be
assigned to this tectonic event but it is possible that it is related to the Dm or D H ~
events of Annedey et al. (1997). Altematively this tedonk event may linked to
widespread Hudsonian fault reactivation that accompanied the main phase of uranium minerakation in the Athabasca Basin 'unconformity-type' deposits
(1 400-1 500Ma; Saskatchewan Geologicai Survey, 1994). The possibility of a link
between small-scale reactivated faults and uranium mineralization is enhanced
by the similar nature of fault plane mineralogy and alteration associated with
many deposits. The typical hematite and quartz mineralization that forms on fault
surfaces is similar to the outer alteration haloes sunounding uranium deposits
(Komninou and Sverjensky, 1996; Wilson and Kyser, 1987; Kotzet et el., 1992).
Alsol the orientation of the stress tensor is compatible with reverse movement on the northeast-trending thnist faults such as the Rabbi Lake thrust and the Collins
Bay thnist, hosts to severai large deposits (Fig. 2.6). Seismic pumping (Sibson et
al., 1975; Sibson. 1990) due to tedonic reactivation is a very effective fluid
circulation mechanism to concentrate the uranium in the absence of an eievated
heat source.
There is no obvious geologicai event to account for the second stress tensor in
the Hidden Bay area. It may be related to one of the late Hudsonian events. to
the uranium mineraking event, or even to tectonic effects associated with the
intrusion of the Mackenzie dyke swarm at circa 1265Ma.
7. Discussion
The eailiest recognized gneissic fabnc in the Wollaston Lake ama is SI, which is
seen in the unsheared areas of the Wollaston domain. Its average trend of 070-
250' is not compatible with the average trend of the aeromagnetic anomaiies in
the area, which is approximately 045-225'. Thus the current trend of the orogenic
belt, which is parallet to the regional magnetic anomalies. is not due to
deformation associated with the formation of SI alone. The S2 foliation, trending
048-228O, could account for the current trend of the aeromagnetic anomalies but
data anaiysis suggests that S2 is confined to north-northeast-trending belts of
restricted areai extent. The S2 shear fabnc, which trends approximately 01 SO, is
certainly not compatible w-th the bulk trend of the orogen. This suggests that the
shear fabric is restrided to a few high strain zones, or the magnetic anornaly patterns would have an orientation doser to that of the shear fabric. The
conclusion frorn this research is that the current bulk trend of the orogenic belt is
due to a combination of the Sr foliation and pooily-defined shear zones where
the SI foliation is transposed on S2 and then sheared out dong the S2 shear
plane. The poor exposure in these shear zones probably led to lack of
recognition of this by eailier workers. In order to amunt for the regionai
geometry of the Wollaston domain, there would need to be a large number of
previously unmapped TF2 fault spîays. This is considered a reasonable
possibility as there is very little structurai modification assoaated with the shear
zones, except in the highest strain zones. On top of this much of the ductile
deformation is obscured by later brittle faulting and glacial erosion. Topograpghic
lineaments and sinistrai offsets of the magnetic anomaly patterns are seen
throughout the ~ol laston domain. This geometry of TFZ fault zones would give
the Wollaston belt a 'staircase' profile on aerornagnetic maps. Such an effect can
be seen on the outline of the McClean massif (Fig. 2.6a).
East of the Wollaston Lake area the Wollaston Domain rotates around to be f-
trending across Manitoba and into Hudson Bay. To the west the dornain trend
continues to rotate counter-dockwise until it straightens out, trending 025O
parallel to the NFSZ, at a longitude of 104O30' (Stauffer and Lemy, 1993). The
longitudinal limits of this change in trend are approximately the Iimits to which
splays of the TFZ are seen (Fig. 2.1). As noted earlier. the eastem contact
between the NHZ and the Wathaman-Chipewyan bathdith is an intrusive contact
whereas the western and southem margins are in fault contact, dong the NFSZ.
Thus a scenario is required whereby the western segment of the NHZ - Wathaman-Chipewyan batholith contact is activated as a dedral fault, but the
eastern segment stays undefomied. Given the immediate proximity of the TFZ to
the terminus of the NFSZ and the western 'big bend' it is reasonable to speculate
that they may be linked.
The timing of movement along the NFSZ is constrained between 1857Ma and
1 760Ma. most ductile s h8ating havïng taken place before 1 785iUla (Fedorowich
et al.. 1995). Timing of ductile movement on the TF2 is constrained between
1848+6/-5Ma and 1737i2Ma (Elliott. 1995). with results of the cunent study
suggesting that the bulk of ductile mwement occuned before 1815Ma. Thus the
two faults could have been adve synchronously as ductile features between
1848Ma and 181 5Ma. This would be somewhere between the regionai DI and 0 2
eve nts.
The geometry and mavernent sense of the faults would result in the
southwestward escape of the bulk of the Glennie dornain. La Ronge domain.
Rottenstone dornain and Wathaman-Chipewyan. This scenario is the one
favored by Hajnal et al. (1996) where the NFSZ is one of several shear zones
that facilitate the escape of the western internal domains. Ejection of these
domains would result in a void space at the NFSZ - TFZ junction. Such a void
could be dosed by severe north- or northwestward compression of the juncticn
and anticlockwise rotation of the western segments of the Wollaston domain.
Rottenstone domain and Wathaman-Chipewyan batholith (Fig . 2.1 6). The
northern segment of the TFZ, from the Glennie domain noithward, is redundant
in this simple 'wedge escape' mode1 but may aa as a transpressional structure to
Figure 2.16. IndwpmWüvo cartoon mhowlng th. avolutlon of the
THO. A) Posltkn of th. mmln trcdonlc domalm e r 0, dmfonnatlon
domain h u aIr#dy doc id ta th. southam m q l n af thm H m m m Craton, and thrtth. Smk Cnton Is k lng ovwthrust by oœanlc uc tomnes of tha Gknnk. Hinson Wtr and Flln Flon domalna. 8) Posllon of th. nuln t.ctonlc domalns d b r 4 defomatlon In the
Wollaston Lake a m . clma. 1800Ma. Ex'tmnsln cni.trl I m M d o n usoclatmd wtth th. Gdlklon of th. Suparior Cmton k 8up.rcd.d
aid escape and orodinal rotation of the western intemal domains. Intensive
folding with north-trending axid surfaces at the teMnus of the Erch Rapids
Strait Belt (BRSB, Schwerdtner and Hirsekom, 1995) (Fig. 2.17) and in the
Numabin Complex (Le- et al., 1990) indicates that the TFZ in that area is
indeed assoaated with strong compression across the fault. As the fault splays
bifurcate northward it appears that the compressional component of deformation
decreases as tight north-trending fol& are not reported in the Wollaston domain.
But the strong boudinage assodated with the PIS2 suggests that even well into
the northern hinterland of the THO the TFZ is a transpressional structure.
Throughout the THO the TF2 has been recognized as a sinistral fault system.
Within the western Wollaston domain there are several fault splays with north- or
northwesterl y strike and sinistral offset. These faults have b e n previousl y
classified as Tabbernor-related because of their similar characteristics, but the
aeromagnetic lineaments suggest that they do not link with the main trace of the
Tabbernor Fault in the Glennie domain (Fig. 2.17). Most of the faults appear to
die out where they intersec( the NFSZ or its easterly extensions, the Parker and
Reilly Lake shear zones (Lafrance and Varga. 1996) (Fig. 2.17). This supports
the idea that the TFZ and northeast-trending shear zones such as the NFSZ and
the BRSB were active synchronously during regionai post-collisionai deformation.
Figure 2.17. Compllation map of a sekct.d ama of northam
Saskatchewan showlng the nlatlonshlp k t w w n aemmagnetlc
Ilneamenb that d n l m the tram of the T.FZ and major
lithotectonlc boundarles. Nd6 the apparent dlsappearance of
many of the aeromagnetlc Ilneaments (dashed Ilnes) 8s they
InteMct major .tnictuml h l u m much as the N.F.SX or RL.S2.
Abbnviatlons:- R.D. - Rotbnstorn domaln; M.L.B. Mackan Lake
Belt; N.F.82. = Nodk Falls Shear Zone; P.L.SZ. = Parker Lake
, Shear Zone; R L S Z - Rellly Lake Shear Zone; T.FZ. = Tabkrnor
Fauk Zone; 6.RS.B. - Blrch Raplds StralgM 8.k W.L. - Wollaston
Lake; R.L. - Rolndeer M e . Box- 1ndlcate:- 1. = Hldden Bay arma; 2.- Compulrlon Bay ama; N-EA = aeromagnetlc test ama.
Aeromagnatic Ilneamenta mi, traceâ from 1:63,36û scale map
sheets publlrhd by Saskatchewan Geologlcal Survay. The
domaln boundarks m m Saskatchewan Geologlcal S u m y (1994).
Posltlons of the N.F.SZ., P.L.S.2.. and R.LS.2. h m Staufhr and
Lewry (1 993). Poslon of the B.R.S.B. (dam gn,y)from Lewry et a$.
(1990) and Schwmrdtner and Hlrsekorn (1995).
I
1
Kisseynew '
8. Importance of the TF2 to Uranium Exploration As noted previously, the Wollaston domain beneath Athabasca Group
sandstones is a highly productive area of highgrade uranium minerditation.
Most of these deposits are of the 'unconfomiity-type', which are fault-controlled at
or near the unconformity contact. Although none of the wrrently known deposits
have been directly linked to the TFZ it is becoming dear that shear zones such
as the PIS2 may have a direct link to the location of mineralization.
Given that the major deformation a - a t with the TF2 trends 010-020'. and
not 350-000° as previoud y defi ned by discontinuous topographic lineaments
such as the Dragon Lake lineament, it can be seen that several deposits have
strong Tabbernor-like characteristics. Deposits such as the Sue (Mattheus et al.,
1997), Midwest Lake (Ayres et al.. 1983), and Dawn Lake (Clarke and Fogwill.
1986) ail are aligned on trends that are much doser to the 010-020' trend than
the regionai trends of 067O for Sl. or 048O for S. The McClean Lake deposits
trend approximately east-west and are not aligned parallei to the Tabbernor
trend. The limits of minerakation are, however, contained within a 10Wm+
corridor that trends 021 (Wallis et al., 1 983b, p. 1 07). which is again much doser
to the Tabbernor trend than to the regionai trend. Also conductive horizons
defined during exploration show a pattern that can be reasonably explained by
rotation into a sinistral shear zone passing through this location, dong a trend of
approxirnately 020° (Wallis et al.. 1983a. p. 60)
Better structurai evidence for TF2 control on mineralization cornes from the
Rabbit Lake Pit where the highest grade ore is contained in a microgranite-
breccia zone (Heine, 1986). The microgranite is dyke-like and '..appears to have
been emplaced along an old fracture zone, and was itself subsequently broken
up by continued movement along this break." (Heine. 1986, p. 139) The microgranite is rnineralogically very similar to circa. 181 5Ma granites described
earlier, and is only 2km from Hudsonian granites of similar affinity (Madore and
Annesley. 1992; Annesley et al.. 1996b). The trend of the intrusion is
approximately 0200 though the central part of the pit. Also, within the pit the
hanging wall rocks have b e n folded into a series of major antidines and a
syncline. w*th axial traces variable but northeily trending. The fold axes plunge
about 6 degrees to the north (Heine. 1986). Both the brecciated microgranite and
the folds are features identifiable as having an ongin related to the Tabbemor
Fault in this report.
South of the Rabbit Lake pit. dong a trend of 020° are the Raven and Horseshoe
deposits (Figs. 2.6 and 2.7). At a drill camp. west of Horseshoe Lake. is an
example of a well-developed S2 'straight* gneissic foliation. trending 0 1 5".
abuîting what is interpreted as SI& trending 063O. An inegular body of
pegmatite obscures the contact between the two. This relationship. as with the
sirnilar discordant foliation relationship on Parker Island, can be explained by
foliation boudinage. Nearby the SI foliation is folded into an outcrop-sde open
fold. Developed within the fold is a very weak shape fabric defined by the
orientation of mafic grains. This fabric is axial pianar to the foldi ng in the gneissic
foliation. The shape fabnc trends 050° and is steepiy dipping either side of
vertical. Intersection lineations defining the fold axis pîunge 56O towards 024".
This is interpreted to be the only example of S2 developed axial pîanar to a fold in
SI seen during mapping. Again, these structures are typicai of those developed
within sinistral shear zones such as the PISZ.
On a quartzite ridge midway between the Rabbit Lake and RavenlHorseshoe
deposits (Fig. 2.6) SI stnkes consistently between 050-060". At one outcrop the
foliation trend changes abruptly to 208O. in an area of strong brecciation. This
location is exactly along strike between the Rabbit Lake and Horseshoe Lake
locations. If this 015020° trend is continued southward it would pass dose to the
Kidd Lake granite, and a northward extension would pass through the
topographie low defined by Collins Creek. lt is noticeable that the Collins Bay
Thrust, a regionaîly important rninerdized structural feature, changes trend from
060" to approximately 030° at a point where it intersects the northward extension
of this zone (Sibbaid, 1983) (Fig. 2.6). Thus it appears as though there is strong
evidence for a shear zone developed west of Hidden Bay and that passes
through several important uranium dep~sits. The detailed verücal gradient map
does not show any evidence of sinistrai shear but the area is one of generai low
gradient and structural features are hard to distinguish.
A model for TFZ fault-control on mineralization would rely on ductile deformation
to estabiish the fault splays as preexisting weaknesses in the rock. This is
achieved by the development of closely spaced planar fabnc Ath low shear
strength, i.e. the shear deavage, and associated mineraiogical changes that
weaken the rocks around the fauits. These fault zones will then preferentially
reactivate during brittle deformation assoaated with the mineralizing event. The
fault would allow deep circulation of fluids within the basement rocks, causing
reduction of the fluid by interaction with graphitic gneiss horizons. These ffuids
then migrate up to the unconfomity contad where they interact with a uranium-
bearing oxidized fluid and cause the precipitation of uranium mineralization
(Kotzer and Kyser, 1993, 1995; Komninou and Sverjensky, 1996). The rnost
likely site for mineraiization would be at the intersection of TF2 fault spiays and
other faufts such as the Rabbit Lake thrust and Collins Bay thrust.
This is a preliminary analysis, without detailed structural mapping and dating at
any of the mineraiized locations, but in light of this observed structural similarity it
is suggested that more comprehensive follow-up work be undertaken to see if the
lin k between the TFZ and uranium mineralization can be substantiated.
9. Conclusions The TFZ in the Wollaston Lake area is defined by disaete transposition of Sl ont0 a NE-trending, steeply dpping & plane. Transposition is generally confined
to continuous zones trending approximately OIS0. Folding and boudinage
suggests that the transposition was accompanied by reorientation of preexisting
structures ont0 the S2 plane of fiattening. In the zones of highest strain a new
shear fabric is developed paralfel to the trend of the shear zones. The shear
fabric is developed as either a spaced deavage or joints and shows consistent
sinistral offset of the SIISI foliations dong fi. Small-scale sinistral faults with
ductile drag parallel the shear zones.
Intrusion of granitic or pegmatiüc melts was controlled by the occurrence of TF2
structures that acted as conduits for magma ascent. The age of intrusion is circa.
181 5Ma, late in the main phase of regional D2 metamorphism and deformation.
The melts were emplaced as dyke-structures that were weakly deformed dunng
subsequent retrogressive metarnorphisrn and shearing. Later readivation of the
faults caused a brittle overprinting of the eailier deformation. Intensive fluid
circulation associated with reacti-vation caused quartz predpitation and
widespread oxidation of the basernent rocks, concentrated dong the Tabbernor
features. This britüe deformation event may be synchronous with the formation of
economically important uranium deposits, and on a regionai scale the
mineralization may have been controlled by the occurrence of TFZ shear zones.
Link: The Role of Proterozoic Fault Detonnation in Controliing Phanerozoic Fault Reactivation All evidence presented in chapter 2 shows that the deformation assoa'ated with
the TFZ dunng the Proterozoic era had a fundamentai effect on the properties of
the fault rocks. It has been show that the deformation caused the transposition
of SI onto the S2 foliation plane, and folding and boudinage in the Wollaston Lake area. This would have an effect on the rheology of the rock, espeaally in regard
to the development of a strength anisotropy. Also, the development of the shear
cieavage would drasücaliy reduce the shear strength of the rock within the shear
zones. The development of mylonites in the Neilson Lake area would have had a
sirnilar effect on the fault rocks at that locality. All of this is overprinted by briNe-
ductile and bnttle fault fabrics developed dun'ng the waning stages of the THO. In
the Wollaston Lake area this manifests itself as lodized shearing of the granitic
and pegmatitic intnisivei;'and development of mineraiized briffle faults and
micro-faults. Intense fluid circulation dunng this hime led to hematization,
chloritization, illitization, and siliafication. Mfferent minerals have conflicüng
effects on rock strength but the resultant minerai assemblage is weaker than the
pre-aiteration assemblage (Wintsch el el., 1995).
As well as the change in the rock properties of the exposed rock, consideration
should be given to the rocks at mid-trustai levefs, and deeper. In any mode1 of
crustal-scale. strike-slip fault development the rocks at greater depth are hotter
and at greater pressure than those at surfaœ. In the Wollaston Lake area the
rocks currently at surface are indicated to have been at a depth of 15-23km
(denved from the estimate of 4-6kbars of Annesley et al., 1997. and a cnrstai
density of 2700 kg m'3, suitable for granitic rocks) and a temperature of 725-
775°C (Annesley et al., 1997) during MH~. At this depth the dominant quanz-
feldspar mineraiogy would have responded in a ductile manner to applied forces,
assuming a moderate main rate. The same is true of the fault rocks that
currently occupy that crustal position. Thus the low strength of any fault zone is
dominantly due tu the rocks at midcnistal depths, and not to those that currently
o m p y the top several kilometres of the cnist.
Deep crustal deformalion. induding structures going fight through to the upper
mantle (Nemeth and Hajnal, 1996), make the fault even more susceptible to
reactivation. The debate as to whether the TFZ is tnrly a through-going cnistai
structure, or terminates on a low-angle detachment thrust in the midcrust (Lucas
et al., 1993), is unresolved but it has a significant bearing on the reactivation
potentiai of the TFZ.
Chapter 3
Evidence for Orogeny-driven Phanerozoic Reactivations of the Tabbernor Fault Zone, Saskatchewan, Canada J. R. Davies. Dept. of Earth and Planetary Sciences. MiIl University. 3450
University Street. Montrad, QC, H3A 2A7, CANADA.
Abstract
P hanerozoic reactivation of the Tabbernor Fault in Saskatchewan has occurred
during at least two separate episodes. A strong tectonic episode related to the
Late Devonian Antler orogeny caused fault reactivation and syn-sedimentary
fault control on the depositional patterns of the Wwdbend and Winterburn
Groups within the Williston Basin. Saskatchewan. Fault movement also
breca'ated previously depoôited Ordovician and Silurian strata. Further north the
fault reactivation caused rembilization of U and Pb in the m p r uranium
deposits of the Athabasca Basin. A second reactivation episode related to
Cordilleran orogenic adivity during the midGretaœous Period had a similar
effect on depositionai patterns and U-minerakation. Minor tectonic episodes
may also have caused localized reactivation of fault drudures during the Eady
Permian Period and Late Triassic-Eariy Jurassic Penods.
1. Introduction The central western portion of the Canadian Shield. comprising the exposed
shield in Saskatchewan and Manitoba as well as the southern continuation
buned beneath the Western Canadian Basin (Fig. 3.1), is traditionally thought of
as a stable tectonic Mock which responds uniformly to extemal stresses at the
shield margin. The Canadian Shield acaimulated during several orogenic events
in eail y- and middle-Proterozoic times. Reactivated and reworked Archean
crustal blocks such as the Superior Province and the Heame Province (Fig. 3.2)
are therefore separated by jwenile orogenic belts containing major fault systems
that acted as ancestral weaknesses to control locaiized reactivation of the
Canadian Shield during Phanerozoic tectonic events. Reactivation of the
Proterozoic Canadian Shield in central Canada is contrary to traditionai t houg hts
on continental accretion which treat the craton as a stabie block unaffected by
marginal processes. The objective of this paper is to diswss the evidence for
reactivation of the Tabbernor Fault zone and adjacent structures in the
Phanerozoic eon. Evidence is set forth for discret9 intra-cratonic adjustments in
response to changes in the tectonic regime at the cratonic margin. These
adjustments control depositionai patterns in the acaimulating Phanerozoic rocks
as well as reworking preexisting uranium deposits in the PaleoHelikian
Athabasca Basin.
Flgum 3.1. Phainmoolc mlomonb of th@ w#tnn North Anmlcan
continent. MJor .tructuml akmrint. show am th- whlch hmm had a rrw contrd on ..dhiwntitkn durlng th. Phinwosolc a i . Th. llgM gmy pa(bm ls th. cumnt llmlt of outcrop (or
rock. in wmtmm Canada. Tho duk gmy m m k tha llmlt of âoop
basln sedlmontuy rodu In th. Al- and Wlllkton b l n s . Tha
black patbrn Indlcrit.. tha Ilmit af L.b Davonkn. Laduc
Fornilion mf buIldup.. Ako shown am th. appr0xlrn.b. llmlb of the Antlar-age orog.nlc front, and the Cordllkmn-agm ormgenIo front. Adapted from Wright etal. (1994); 8wlb.r et dm (lm); Hayes
et al. (1 894); &voy and Mouqoy (1 985).
Flgure 3.2. Tdonlc domalns of th. mrtem Cinadlan buement. Modlfied from Ross et d. (1SW). E x p o ~ d sub4lvlslons of the - mns-Hudson Orogan (shadeâ) h m Clow# (1897). Duhed box Indlcates Inset flgum 3.4.
2- Reactivation Reactivation is defined as qhe accommodation of geologically separaMe
displacement events (intervals >1 Ma) dong pre-existi ng structures" (Hddswrth
et al., 1997). Traditionai approaches to the study of crustal structures have
concentrated on the kinematics and history assoa-ated with the structures'
formation, typically during orogenic events and cnistal accumulation. e.g.
Ramsay and Graham (1970). or Stauffer and Lewry (1993). More recently
researchers have begun to address the significance of reactivation on pre-
existing structures assoQated with postsrogenic deformation (Butler et al.. 1997,
and references thenin). The reactivation may have the same sense of
displacernent as e a h events, kinernatic reactivation, or a different sense,
geometric readvation. The recognition of separate episodes of reactivation
along major intra-continental shear zones has lad to the rethinking of cratonic
blocks reacting uniformly to external forces and changes in the intemal stresses.
Studies on structures such as the Archean Thabatirnbi-Murchison Linearnent, S.
Africa (Good and De Wit, 1997). and ltacaiunas Belt, Brazil (Pinheiro and
Holdsworth, 1997) have shown that reacüvation of cnistal-scale shear zones can
occur over large time intentais. with different reactivation geornetries. presumably
relecting changes in the regionai stress field. Eariy ductile mylonitic fault tabrics
have been shown to control the occurrence of later britüe-ductile and brittle
fabrics that are dated by radiometric studies of the mineralogy in the fault zone.
Other methods for recognizing reactivation include stratigraphic control on syn-
tectonic 'pull-apart' basins (Pinheiro and Holdsworth, 1 997); changes in the
distribution and nature of deformation within faults and I or shear zones (Imber et
al., 1997; Hanmer, 1997); and focused plutonic activity in shear zones (Hanmer,
1997; D'Lemos et al., 1997). In al1 studies the long-ten weakening of the shear
zones by a variety of kinematic and mineralogical processes is fundamental to
t heir role as reactivated structures.
3. Reactivations in Western Canada Although the role of basement structures has long been considered to have been
important in controlling sedirnentary fades in western Canada (Rutherford.
1954). little condusive evidence has been found to link the two elements. Recent
work in the Western Canadian Sedirnentary Basin (Fig. 3.1) has been driven by
the economic i rnpohce of basement structures in controlling the build-up of
Late Devonian-age carbonate reefs in central Ai berta (Greggs and Greggs. 1 989;
Savoy and Mountjoy, 1995; Edwards and Brown, 1996). In assessing the
question of basement involvement in the control of Upper Devonian reef chain
distribution, such as the Rimbey-Meadowbrook and Bashaw-Duhamel (Leduc
Formation) reef chains (Fig. 3.1). Edwards and Brown (1996) conduded that low
angle thnists emanating from the basernent may offset the basement cover
contact. These offsets produced subtie changes in relief in the overl ying
sedimentary cover. These low-relief topographic highs are considered to have
been sufficient to locally control the developrnent of Leduc Formation reef
complexes. Although local mntrol by basement fault structures was found to
affect the position of overlying reef complexes no dominant basement controls
were found on the regional-scaie distriMion of Leduc carbonate reefs.
Basement structures may have dso pîayed an important role in the distribution of
linear sandbodies in the Western Canada Sedirnentary Basin dunng the
Cretaceous Penod. Recent studies in the Alberta Basin (Bergman and Waiker,
1996; Enckson and Bergman, 1997) and Peaœ River Arch area (Bergman and
Walker, 1996; Chen and Bergman, 1997) (Fig. 3.1) suggest that the distribution
of Cretaceous sandbodies is controlled by a complex combination of syn-
depositional tectonism, eustatic sea-level change and change in sedi ment
supply. In a similar study, Collom (1997) suggests that reactivation of basernent
fault structures in the Peace River Arch area (Fig. 3.1). during the Upper
Cretaceous Penod. affected deposition of Dunvegan-Cardium Formations (-97-
87k2.5Ma1). He proposes a link between basement reactivation and teirane
accretion or subduction dong the western margin of the North American craton.
Chen and Bergman- (1997) ai= suggest a link between reactivation of the
basement and tectonism on the western margin of the craton, but imply that the
controlling mechanism was a change in the direction of regional compression.
3.1 Regional Stmtigraphy
The western Canadian continental margin was a passive margin where
carbonates and dastics f o r w in miogeodinal seas throughout most of the
Paleozoic era (McCrossan and Glaister. 1964). From eaily Givetian time
(-380118Ma) onward, significant build up of increasingly deeper-water facies
sediments occurred in the Western Canadian Sedimentary Basin (Oldale and
Munday, 1994; Switzer et al., 1994). During deposition of the Woodbend Group
megacycie (374370k15Ma) (Savoy and Mountjoy, 1995) in centrai Alberta the
steady deposition of the Cooking Lake Formation platform carbonates gave way
to the Duvernay Formation artoxic Mack shaies. This was accompanied by rapid
rise in sea level (Johnson et al., 1985; Savoy and Mountjoy. 1995). Subsidence
was synchronous with Antier-age orogenesis involving arecontinent collision
(Burchfield and Royden, 1991 ; Smith et al, 1993; Savoy and Mountjoy, 1995 and
references therein), -and Leduc Formation reef cornplex growth (Dwernay
Formation is equivaîent in age to the middle Leduc Formation) (Fig. 3.1). This
adds credibility to the idea of a basement-reactivation control on reef distribution
in a tectonicaily active setting.
As with the Late Devonian-Early Carboniferous intetval, the Late Jurassic-Eariy
Tertiary stratigraphic sequence in the Western Canadian Sedimentary Basin
staits with an abrupt change from miogeoclinal or platformal deposits to
increasingly deep-water faaes. black shales, limestones and thin sandstones
(Fermor and Moffat, 1992; Poulton et al., 1994). A westedy derived source is
t AI1 &tes quoicd in thc papcr arc umvcrtcd ban ihc pcriod or agc quotcd in lhc source Lo bc concordant with the DNAG gcdogic tirne d e (Palma, 1983)
identified for Oxfordian-Tithonian (1 63-1 50k15Ma) siitstones and sandstones,
interbedded with marine shaies of th8 Femie Formation and basai Nikanassin
Formation, indicating orogenic uplift to the west (Poulton. 1984; Stott, 1984;
Fermor and Moffat, 1992). This is succeeded by shallow marine sandstones of
the Kootenay Group (1 56-1 44SMa), indicating sedirnentation kept place with
rapid cnistal subsidence (Beaumont, 1 981 ). This unconfomity-bound package of
Fernie Formation and Kootnay Group (and equivaients) forms Cyde 1 of Lecke
and Smith (1992), and first dastic wedge of Stott (1984). A second cyde of
sedimentation (Cyde 2 of Leckie and Smith, 1992; second dastic wedge of Stott.
1 984) followed trends broadly similar to the fint although there was less deep
water facies sedimentation than that associated with the onset of the first
'megacycle'. Cyde 2 is typified in central Alberta by a basai chert in the Cadornin
Formation (120-1 18SMa) which is overiain by the Manville Group (120-
1 08BMa), composed of sandstones, interbedded siltstones and occasional
shales (Hayes et al., 1994). and lower Colorado Group (1 04-94MMa) induding
interbedded shales and sandstones (Leckie et al.. 1994; Reinson et al.. 1994).
The unconformity that separates the first and second rnegacydes appears to
represent significant isostatic adjustment of the craton (Stott, 1984; F e m r and
Moffat, 1992). A third rnegacycle, unconfoltnity-bound like the first two, extends
frorn early Campanian (84i4.5Ma) to early Paleoœne times. or even younger
(<66Ma) (Fermor and Moffat. 1 992).
Leckie and Smith (1992) divide the sedimentary succession into 5 cydes, and
Stockmal et al. (1 992) into 6 dastic wedges, but the pnnaple of cydic deposition
controiled by tectonic processes associated with Cordilleran-age orogenesis is
evident in each study. Studies of syn-depositionai wntrols on Cretaœous
sandbodies diswssed above (Bergman and Walker, 1996; Enckson and
Bergman, 1997; Chen and Bergman, 1997; Collom. 1997) ocair broadly within
the time frame of cycle 2 of Leckie and Smith (1 992).
3.2 Driving Mechanlsms for Toctonlc üafomutlon The m s t widely acœpted geodynamic mode1 for the production of a foreland
basin, with assodated sedirnentary facies changes, is one of elastic (or visco- elastic) flexunng or downflexing of the continental lithosphere (Beaumont. 1981 ;
Quinlan and Beaumont, 1984; Cant and Stockmal, 1989; Stockmal et al, 1992;
Fermor and Moffat, 1992) in response to loading of the fithosphere by
overthnisting of accreted terranes. Modeling shows that, in addition to the
foreland basin, the tectonic loading produces a peripheiai bulge ahead of the
foredeep (Fig. 3.3a). 60th of these elements will migrate cratonward as terrane
accretion continues. As terrane accretion ceases the penpheral bulge migrates
back towards the foredeep, and the basin deepens because of relaxation of the
bending stresses in the overth~st plate (Quinlan and Beaumont. 1984) (Fig.
3.3b). This may be counteracted by basin iebound as the tectonic load is
rernoved (Stockmal et al., 1992), produang an unwnformity surface across the
entire basin (Fig. 3.3~) . H is a combination of the above effects that best explains
the unconformity-bound dastic wedges seen in many foredeep basins.
The work described above parüaily resolves the question of how marginal
orogenic events affect the North American craton, espetiaily the link between
tectonism and sedimentary cycles. It is now widely accepted that tectonic
processes linked to convergence at the craton margin control megacycles of
inboard deposition, such as the Late Devonian megacycles (Savoy and
Mountjoy. 1995) or Cretaceous megacyles (Stott, 1984; Leckie and Smith, 1992).
In contrast, the mechanisms that link these marginal tectonic processes to syn-
sedimentary basement tedonism and localized sedimentary control are still
poorly understood.
Other mechanisms cited as being important in controlling sedimentary basin
developrnent. and which rnay also play a role in basement reactivation indude: 1)
tilting of continentai interiors by dynamicaf effects of subduction (Mitrovica et al..
1989); 2) depression of the continental cnist above subduction zones (Gurnis,
Figure 3.3. Constraints on the development of a classical foreland
basin. A) Development of a foredeep due to loading of the cratonic
rnargin by the allochthonous terranes, and infilling of the foredeep
by sediments; B) thermal relaxation of bending stresses within the
continental plate causes additional subsidence of the foredeep
and migration of the peripheral bulge back towards the orogen; C)
syn- and post-orogenic erosion of the thrust sheets causes
widespread rebound of the craton, most apparent close to the
orogenic front. Adapted from Quinlan and Beaumont (1984),
Stockmal et al. (1 992).
Orogen 1 - Peripheral Bulge
C ----- - -
\
Basin rebound - Epeirogenic uplifl
Allochthonous terranes
Deep water sediments
Shallow water molasse sediments
Additional basin fiIl
1993). (the latter two~rnodels are similar in effect and rely on the rate and angle
of the subducüng plate); 3) mantle dynamics and dramatic downwelling beneath
continental lithosphere (Pysklywec and Mitrovica, 1997); 4) mantle convection
and assembly of supercontinents (Kominz and Bond. 1991); 5) syndepositional.
fault-controlled, local basin development (ünk et al., 1993); 6) waxing and
waning compressive in-plane stresses transmitted throug h the foreland
lit hosphere, reactivating pre-existing fault stmctures (Dorobek et al., 1 990).
4. The Tabbernor Fault Zone
4.1 Introduction
The Tabbernor Fault zone (Tm) is a cim. 4 500km. N-trending, topographid
and geophysical lineament in eastem Saskatchewan (Elliott and Giroux, 1996)
(Figs. 3.1 and 3.2). lt is defined as a fault system through Archean and
Proterozoic rocks from north of the 60°N parallel, to the contact with
Phanerozoic-age cover rodo southeast of La Ronge. From there it extends
southward at least as far as 4g0N latitude, as a purely topographicsil Iinearnent
defined by dry creek valleys, river channels, and soi1 color variations (Elliott and
Giroux, 1996). Geologicaily it is an important structurai element of the Trans-
Hudson Orogen (THO) (Fig. 3.4) and is believed to have formed in association
wit h late orogenic effects of the THO (Lewry, 1 981 ; Elliott. 1 995) . -
The THO is one of a nurnber of known Proterozoic orogens (Fig. 3.2). the final
collision of which led to th8 formation of Laurentia. The orogen can be broken
down into four distinct zones (Hoffman. 1988; Lemy and Collerson. 1990;
Clowes, 1997) dependent upon the rock type. radiometric age. and style of
deformation within. In northern Saskatchewan and Manitoba the cor6 of the
orogenic belt is composed of an m a t e telescoped collage of 1.9-1.8Ga juvenile
terranes, termed the Reindeer Zone (Le- et al., 1990) (Fig. 3.4). The Reindeer
Zone is bounded on either side by vanously reworked Archean cnistal blocks. To
the southeast it is bounded by the Churchill-Superior Boundary Zone, and to the
northwest by the Noithwestern Hinteriand Zone. Separating the Reindeer Zone
from the Northwestern Hinterland Zone is the Andean-type Wathaman Batholith.
This was intruded at the junction of the subducting juvenile crust and the Archean
continental cnrst at circa. 1.855Ga (Meyer et a.. 1992). The Northwestern
Hinterland Zone is composed of Archean basement rocks overîain by early to
middle Aphebian rift (Delaney, 1995) and platformal sediments which have been
affected by Hudsonian thermotectonism. Early (pre-1.85Ga) deformation (Dl),
possibly assoaated with arc-continent collision, was followed by the main phase
Figure 3.4. Slrnp1M.d geologlcal rnap of expowd THO and bounda y nglons. Llhotectonlc zonas am sub-dlvlded lnto domalns mg. Flin Flon, Kissoynm etc. Abbmvlatlons: C.S.B.Z. = C hurchlll - Sup.rior Boundary Zone; T.FZ. - Tabkrnor Fauk Zone;
. N.F.SX. = Nwdh Falk Shew Zone; B.R.S.B. - Blrch Raplds Stmlght 8eIt; 8.82. - Stanley Shew Zone; P.L.82. - Parker Lake Shaar Zone; S.TZ - Snowblrd T.ctonIc Zone. Red dab mark locations dkcusseâ In the bxt; 1 - Wollaston Lake; 2 - Neilson Lake; 3 = Llmestona Polnt Lake. Mappd Is adapbd dbr Lamy et al. (1990); llthokctonlc dlvklons a8 of Clowms (1 997).
of deformation (Da). a 1.83-1.8ûGa nappe-fofmïng event dunng continent-
continent collision (Bickford et al., 1990). This is in dose agreement Ath stuclies
by Annesley et al. (1996a) and Madore et al. (1996) in the Wollaston Domain
(Figs. 3.2 and 3.4) which indicate a 1.84Ga MI rnetamorphic event, followed by
peak metamorphism and plutonism. M2, at 1.82-1.81 Ga. The later studies also
report a third retrograde mtamorphic event. &, at -1 -80-1.775Ga.
4.2 ûeformational Chancter and Geometry
The TFZ is one of several large-scale shear zones and linear belts which help to
subdivide the THO into tectonic domains (Fig. 3.4). What is unusuai about the
TFZ is that it is oblique to the main fabric trend in the orogen. Between the
Glennie Domain and the Hanson Lake Block the TF2 is a domain boundary. but
in other places. such as the Wollaston Domain. the fault deflects and offsets
fabncs within a single domain. It is well documented that the fault offsets earlier
Hudsonian structures in both the centrai Neilson Lake area (Elliott. 1994a) and
further north in the Wollaston Lake area (Wallis, 1971; Davies. 1996). with
consistently sinistral offset (Fig. 3.4).
The character of the TF2 changes along its length. Between the Glennie Domain
and Hanson Lake Block the eailiest rnovernent is characterized by sinistral
ductile shear and development of an eady mylonitic fabric. Mineral lineations
within this mylonitic fabric change across the fault. They are moderately to
steeply S-plunging in the east, changing to moderately N-plunging in the west.
These two distinct dornains are separated by a brittle to semi-brittle fault trace
with subhorizontal slickenside lineations that overprint earlier ductile fabrics
(Elliott, 1994a).
As the fault progresses northward its rnorphology changes from a single or
severai anastomosing splay(s) with restricted longitudinal extent, to a bifurcating
array of discrete fault splays and topographical lineaments which extend from
102OW to 105OW. This is a width of approximately 170km. The change in style of
the fault coincides with the transition from where the fault -pantes the Glennie
Domain from the Hanson Lake Biock and Kisseynew Domain. to where it
penetrates into the La Ronge Domn and extends northward to the Wollaston
Domain (Fig. 3.4).
As in the Glennie Domain, brittle deformation overptints earlier ductile
deformation, but brittle deformation is the dominant style in bath the Hidden Bay
and Compulsion Bay areas of Wollaston Lake (Fig. 3.5b). Mapping as pait of this
study, and previous dudies. wggest that major fault splays in the Wollaston
Lake area are approxirnately 2-5km apart. Minor structures are less continuous
and therefore harder to map. but rnay be separated by distances of as little as
1 km. This means that TFZ structures are very impoitant to the geology of the
Wollaston Lake area, and more generaîly throughout the Wollaston Domain.
Brittle deformation is characterized by quartrcMorite mineral fibres defining a
subhorizontal lineation and sinistral movement sense on small-sde fault planes.
Elsewhere the fault splays are topographie lows, where intense brecdation is
amrnpanied by hematite staining.
The most notaMe difference between the TF2 in the WoHaston Lake area and its
counterpart in the Neilson Lake area is the la& of mylonitic fabrics developed in
the former. Ductile deformation there is restricted to rotation of earlier Hudsonian
fabrics, and isolated development of a weak shear fabric. Another significant
difference between the TFZ in the two study areas is the intrusion of post-
D2,s harp-walled granitic, leucogranitic and pegmatitic i nt~sions into the trace of
the fault. and adjacent faults, in the Wollaston Domain (Heine, 1985; Davies. in
press a). No dates have been determined for the age of these intrusions in the
TFZ.
Flgum 3.5. A) Slmplllhd gdog la l map of tha Athabasca Basln and adJaœnt bvwmont domilna, modl(l.d dtmr Snkitchwan
showing th. Ilthotdmnlc domrln boundrrk.. Amam of mapplng ,
by the author irm Indlwbâ by bluk box#. 0ash.d Ilnos show TF2 splays Indlatod by g.ophy.lc.1 llnmmo& ind by bodrock mapplng whom I1rnlt.d oxpaaun allam. Both m.p. rhow tha locatlon of mJor umnlum d.pos)b and mlna s)b. dkcussod In the text.
4.3 Geophyslcal Chafact@firtlcr Seismic imaging of the TFZ. as part of the LITHOPROBE Trans-Hudson Orogen
Transed, has reveaîed the TFZ to be a mde verticai zone of iow reflectanœ
(Hajnal et al., 1992; Lucas et ai., 1993) (Fig. 3.6). Strong reflectors teminate at
the TFZ through much of the trustai profile. Its verticai extent is undear. Lucas et
al. (1 993) interpreted the TFZ to teminate on a shallowly dipping lower crustal
reflector, and therefore not a throughgoing cnistd structure. The migrated
seismic profile is incondusive, and though reflectors correlate on both sides of
the fault, they are not continuous with the same reflectance nght across the fault
zone.
However, Nemeth and Hajnal (1996) suggest that velocity anisotmpy in the
upper-lithospheric mantle can be attributed to reorientation of the mantle fabric
by the TFZ and adjacent Needle Falls Shear Zone (NFSZ). This would suggest
that the TFZ does penetrate through the m h o boundary, making the TF2 a
throug h-going crustai structure.
Magneticafly the TF2 is well defined by a corridor of N-trending magnetic
anomalies that diverge from the regionai NE-trending foliation (Jones and
Craven, 1990). The southern extrapoîation of the m. south of the Canada-
United States border, is defined by the boundary between moderate- to highly-
magnetic rock to the east and weakly magnetic rocks to the west (Green et a., 1 985).
The gravity anomaly associated with the TFZ is not highly conspicuous. If the
previously defined magnetic lineament is supetimposed on the gravity map. the
TFZ can be seen as a steep gradient in the Bouguer gravity anomaly field (see
Jones and Craven, 1990, Fig. 6; Green et al., 1985, Fig. 5), corresponding to
juxtaposed domains with different cnistai properties. This observation is
supported by magnetoteliuric data collected across the TFZ. near the shield
margin (Ferguson et al., 1996). These show conductive rocks in the mid to lower
Flgure 3.6. Interpmtatlon of the Interna1 geometry of the THO.
A)Geologlcal cross-sect lon showlng p r lnc lpa l
tectonostmtlgmphlc unlta of the Tmns-Hudson Orogen ( h m HaJaal et al., 1882). The section Is constmlrid by THOT mflactlon
, profila 9. B) Innt of the mlgmtmd aeismlc profile. The wdlon Is
from O to 12 wconds (TWT), and rquatms to a dmpth of approxlmatoly 36km. The TF2 is charackrized by a zona of low reflecbhnco. Nok that although reflecton In the lomr cru.1 appear to tnincate the TFZ, they ara not contlnuous acrou the fault with the same Mectance.
crust. below the Hanson Lake Bock. terminating a! a position irnmediately below
the TFZ. and having no equivaîent to the west of the fault. This also suggests
that the TF2 separates domains with dffering characteristics at a austal scaie.
4.4 Offset
Magnitude of offset across the TFZ varies with location but the sense is
consistently sinistral.. Offset of a north-east dosing fold hinge, across a single
Tabbernor splay in the Neilson Lake area, was documented to be 2km sinistrally
(Elliott, 1 994a). Frorn this it was argued that the offset across the main fault trace
was greater than 2km. Further north, in the Wollaston Lake area, offsets across
individual fault splays have been suggested to be 400rn-3000m+ (Wdlis. 1971 ;
Davies, 1996). bas& on field mapping augmented by aeromagnetic
interpretations. In addition to the well defined geologicel and topographiml fault
traces the author has doairnented nurnerous, northedy-trending, srnall-scale
fault features Ath 10's of cm's sinistral displacement. and condudes that total
displacement summed across Tabbemor-related structures is significantiy
greater than that recoided on the main spiays aione. Metamorphic isograds mapped by Sibbald (1978) and Wilcox (1991) in the Neilson Lake\ Pelican
Narrows area suggest sinidrai displacernent across the entire fauH of 6-8km.
although these isograds are argued to be mntrolled by lithology (Elliott, 1994a)
and do not reflect true displacement.
Despite its size, character and evident regional significance, the importance of
the TF2 has been downplayed by severai recent authors (Lewry et al., 1990;
Tran et al.. 1996; Maxeiner. 1996) due to the Jack of significant offset of lithologies.
4.5 Absolut. Ag88 ot Movmmt Deformation assoa*ated 4th the formaüon of the myionitic strain zone in the
Neilson Lake area is constrained. by aoss-cutüng relationships, between
1848+6/-5Ma and 1737I2Ma (Elliott, 1995) (Fig. 3.7). Constraints on mvement
along the TFZ in the Wollaston Domain suggest that the fault zone initiated after
DI that is synchronous with Ml rnetamorphism, dated at 1840-1850Ma by
Annesley et ai. (1996a). A lower limit on âucüfe defoimation is suggested by the
intrusion of undeformed granitic and pegmatitic dykes into the trace of the Tm.
These i ntnisives are tentative1 y conelated to adjacent granitic bodies. intruded at
circa. 181 5Ma (Annedey et al., 1997; Madore and Annesley, 1998). Brittle
deformation in both locations overprints ductile fabrics and is therefore younger
(Fig. 3.7).
Flgun 3.7. Aga constralnts on ductlle ddonnllon wlthln the
Tabbernor FauIt Zona In the Neilson and Wollaston Lako amas. Tha aga constralnts In the Nailson Lako ami mm from th. Nalkon Laka
pluton and i cross.cutting pogmatlt. (Elllott, 1985); aga
constmlnts In the Wollaston Lake ana are bawd on the dlsruptlon
of D, hbrla, dabd at 1.05-1.840. (Annadey et& 18H, 1897), and
.an assumad aga of 1815Ma for und.formd pogmrtld, dykn Intruded lnto the TFZ (se. text for explandon).
5. Phanerozoic History of the TF2
5.1 Previous Woik
Little evidence has been collected to show the Phanerozoic history of the TFZ.
Byers (1962) reported that topographic linearnents in the shield could be traced
southward into Silurian strata. In addition to this. work by Giroux (unpubîished
M.Sc. thesis) shows that lineaments in airphoto and satellite images extend
500+km south of the sedimentary cover contact. Examination of two drill cores
intersecting the trace of the TFZ showed that there are anomalous breccias in
the Upper Ordoviaan and Silurian strata (Haidl. 1988). Further examination of
the cores by Kent Wilcox (unpublished MSc. thesis) and Elliott (1995)
demonstrated that the breccias were tectonic in origin. If these observations are
to be believed then the wnstraint on Phanerozoic reactivation of the TFZ is that it
was active after lithification of lower Silurian carbonates. A study of an outlier of
deformed Ordoviaan limestones at Limestone Point Lake (Fig. 3.4) by Elliott
(1 99413, 1996a) wnduded, in agreement with the previous observations, that
deformation took place after lithification and dolomitization. The outlier lies above
one of a series of parailel, N-trending basement linearnents defined by the
truncation of regionai magnetic anomalies (Elliott, 1996a). It was suggested that
these basement linearnents may be related to the TFZ. The traang of
topographic lineaments of the TF2 into Silurian strata by Byers (1962) may
further constrain the upper limit on the timing of deformation. Alternatives to this
last observation are that the lineament could have resulted from a solution collapse breccia forming in the Silurian strata above the fault, or that there were.
in fact, severai pulses of reactivation of the TFZ during the Phanerozoic eon. and
that movement could have occurred both before and after Sifurian carbonate
deposition.
5.2 Fission Tmck Analyrh
Fission track andysis of rodes from two transeds orthogonal to the trace of the
fault i ndicates that t here has been rneasurable Phanerozoic displacement across
the TFZ. The Neilson Lake transect (Fig. 3.8) shows that apatite from samples
east of the fault yield younger fission track dates than samples to the west and
within the fault. The younger samples indicate a slightly deeper. hotter pre-ugift
crustal level. The explanation for this is that there has been east-side up vertical
movement across the fault. The diffetence in the ages of samples suggests that
there was between 250-400m of vertical displacernent (pers. comm. B. Kohn).
The constraint on the timing of rnovement is that it was after the date given by
the youngest sample, i.e. 316k15Ma. The exact age of movement is not known
but companson to other studies in the Canadian Shield indicate that it is definitely
late Phanerozoic (pers. cornm. B. Kohn).
The second transect was taken across the eastem shore of Wollaston Lake (Fig.
3.9). The 15km long transect crosses several defined and probable TFZ fault
splays. The results of the analysi$ were surprising in that there was no
identifiaMe rnovement on many of the fault spiays. The rnost signifiant sample is
3701 1. This sample is the most easteriy in the transed and yields an age much
younger than samples immediately to the west, samples 1 1021 and 1 1 Oïl. A
prominent N-trending topographic lineament. passing through the locality known
as Trout Nanows separates these samples fmm sample 3701 1. This lineament is
the probable location of a Phanerozoic fault splay. As m'th the Neilson Lake area
the recording of younger ages from samples east of the fault indicates that rocks
to the east were exhumed from a deeper level. Apparently the other fault splays
were either not reactivated or the movement is not resolvable using this rnethod.
Flgure 3.8. L d o m and mlb fblon.brdr ag# of umpk. callectod dong Nmlkon Wu b.nwct. Linas n-nt ml1
ddnad TFZ huit rplays (ml#) and mlnor or probibk TF2 fiun
Flgum 3.9. Location and .prtlt. fbkn4ack .g.. d .rnpk.
colloctoâ dong Hlddmn Bay trinaoc& Wolk.ton Idm. Llnos rapraaont ml1 ddnoâ TF2 h l t .play. (h.ivy d88h.d) and mlnor or probabk TF2 hum 8pl.y. (fim dniud). Nob th. sIgnMt.ntiy youngr aga d t h umpk furlh..t .wt (37011), In th. location
which codod from a dœpor prm-upllftdmpth than mckm to th. dm
The posltion of th. huit accmrnmodatlng dHhrrnflal upltft mua II. betwemn thla a m p k and sunpk. 11021\11071 on k h k y Paninsula. It k Ilbly Lat It runs dong thm topogmphlo low that
definma thm Tmut Numm. Tha umnooumly old aga of tha samplm
27021 is d w to tha high chlorlna In th. aprtld., Incm~Ing thm
5.3 Williston W n oiporl tkn Phanerozoic sedimentation in southern and central Saskatchewan started in the
Cambrian Period ad continued through until the Terüary Pedod. Structure maps and isopach maps, for ail the major inteivais are awered in Moasop and Shetson
(1 994). Like the foreland basin of Alberta the Williston Basin in Saskatchewan
shows changes in stratigraphy and depositional rates that reflect the role of
orogenesis on the basin (Kent and Christopher, 1 994).
An isopach map for the Late Devonian Woodbend (374-370115Ma) and
Winterbum (370-36211 1 Ma) Groups (Fig. 3.10) show that sedimentary thickness
in the Williston Basin exceeds 200m in parts of southern Saskatchewan for these
groups. The map also shows that the deposition is irregular. with areas
undergoing differentiai sedirnentation. lllustrating this, the 200m isopach for the
combined Woodbend and Winterbum age sedirnents shows a marked change in
trend, from roug hly east-west to north-south, approximatel y coincident with the
103OW line of longitude. The Winteibum zero edge (limit of deposition of the
group) is strongly aligned dong a similar noithedy-trend. The Jgnificance of this
abrupt change in trend is that 1 lies dong strike of the TF& as it disappears
beneath the Phanerozoic cover 350km due north (Fig. 3.1 0). It is also coinadent
with the rerote sensing lineament that is interpreted to be the extension of the
TFZ to the south (Elliott and Giroux, 1996). There is a second lineer trend in the
200m isopach at approximately 102W. which may also be rnatched by a similar
trend in the Winterbum zero edge. The significance of this second linear trend is
discussed later. The distribution of the isopachs shows that deposition was
greater to the West of both lineaments than it was to the east. This is compatible
with the fission track analysis suggesting east-side up rnovement dunng the late
Phanerozoic eon.
The sarne linear trends are obsenred in the isopach m p for the Ctetaceous
middle Upper Manville Group (-1 13-108MMa) (Fig. 3.1 la). While most of the
southeastern part of Saskatchewan was submerged beneath shailow seas or
Flgum 3.10. hop.ch mmp of th. Woodknd (374470Ma)- Winterbum (370462Ma) and oquM.nt groupa of th0 Uppw
depositlonal adgo of tha group.. Tho dots mpfmsont contiol mlk;
O miles
1 00
54' / zero edge
I /
I ,Lineuvents offecting
I I isopach
Figure 3.11. A) Isopach map (in metru) of Cmtaceous Upper
Manvllle Gmup (and equlvalents) In Saskatchmwan (adapted alter Hayes et a&., 1994). 6) PaIeog.ogmphlanl ncon8trudlon of
Ctetaceous mlddte Upper Manvlllm Gmup (and equlvalenb)
~ ~ g m p h y In Saskatchewan ( a d a m dbr SmHh. 1994). Shadlng
denotes: da& gmy = fluvlal sysbms; llgM giry = progrrdlng
deltalc; patternad = amas sufbrlng woslon dufing Upper Manvllle
t lm . Also shown Is the known trace of the Tabbernor fault In the
exporeâ shkld to cornpan agmlnat the pakogeogmphy and
Isopach brnd Ilnes; the dasheâ Ilnos mpresant the bopach
Ilneaments tmced h m figure 3.10.
forrned deltaic systems, certain locations were emergent highlands (Kg. 3.1 1b).
These highlands follow the east-west trend of the Punnichy Arch. in centrai
Saskatchewan, and the southem end of the Birdtail-Waskada Axis in Manitoba
and southeastem Saskatchewan (compare Fig. 3.1 wi-th Figs. 3.1 la and b). 60th
these structurai features have been suggested to be tectonically contmlled and
reactivated periodically dunng the evolution of the Williston basin (Kent and
Christopher, 1994; Poulton et al., 1994). The eastern edge of the highlands
coincident with the Punnichy Arch teminates at 103OW, the same longitude as
the Late Devonian isopach lineament. The western limit of the highlands forrned
by the Birdtail-Waskada Axis teminates at -1 02OW. again coincident with a Late
Devonian isopach lineament (Fig. 3.1 1 b). Unlike those eailier lineaments, the
Manville Group highlands do not show the same sense of verticai displacement.
The termination of the eroded highland at 103°W, indicatesdeposition to the east
of the lineament, whereas the lineament at 102OW shows deposition to the west.
This suggests that the TF2 spîay at 103W aitered from being an east-side up
fault in the Late Devonian Period to a west-side up fault during the Early
Cretaceous Period.
The second lineament at -1 02W parallels the trace of the Setting Lake Fault
zone in the subsurface (te& the Thompson Boundary Fault in its subsurface
extension by Baird et al., 1992). The northern extension of this fault in the
exposed basement rocks is the eastern boundary of the Reindeer Zone,
separating the Kisseynew Domain to the east from the reworked Archean rocks
of the Thompson Belt to the west (compare figures 3.1 0 and 3.1 1 with figures 3.2
and 3.4 showing the basement tectonic domains). As such it is a major Iitho-
tectonic boundary between the Churchill-Supenor Boundary Zone and the Reindeer Zone.
5.4 Geochionology and Isotope Syrtomaüca trom Umnlum ûeposlt Mineralogy
Reactivation of basernent structures has affected the uranium deposits of the
Athabasca Basin and sunounding districts. Beck (1970) suggested that
reactivated fault movements were linked to anomalously young radiometric dates
from deposits on the northem shore of Lake Athabasca. PuMished within that
paper were K-Ar radiogenic dates of 467f28Ma and 486255Ma, taken from an
ultramylonite at Cluff Lake (Fig. 3.5) having a protolith denved from both
basernent granite and Athabasca sandstone. Also puMished were two U-Pb agas
f rom pitch blende in Athabasca sandstones at Stewart Island (Fig . 3.5) yielding
dates of 41 8Ma and 448Ma (no errors given).
The deposits are of two broad types. The C n t are the econornically significant
'unconformity-type' deposits, such as Collins Bay '6' zone and Key Lake (Fig.
3.5). These are fault-controlled and lie at or near the unconfomity between
Wollaston Domain basernent rocks and overlying PaJeoHelikian sandstones of
the Athabasca Basin (Tremblay, 1982; Cameron. 1983; SibbaU and Petnik,
1985; Evans, 1986). Disaissi*on on the formation of wch 'unconfomity-type'
deposits can be found in Komninou and Sverjensky (1 996). and Fayek and Kyser
(1 997).
The second type, l e s econornically signifiant but more nurnerous, are the
'fracture-type' deposits. They are al1 basement hosted, in faults and fractures t hat
may or may not be part of large-scale fault systerns (Beck, 1969). The largest
concentration of 'fracture-type' deposits is found on the north shore of Lake
Athabasca, north of the Athabasca Basin (Fig. 3.5). The term 'fracture-type' has
been used here to clarify the more confusing 'simple mineraiogy' and 'cornplex
mi neralog y' classification of Beck (1 969), and 'cornplex vein-type' of Kotzer and
Kyser (1993). It denotes only that the mineralization is hosted by once-open
fractures in the basement and makes no inference regarding source or
composition of the mineralization.
Many fracture-type deposits are thougM to have fomied during late-Hudsonian
tectonic events at 1750Ma. whereas the unconforrnity-type deposits give U-Pb
ages for prirnary minerakation that indicate formation around 1400-1500Ma
(Saskatchewan Geologicel Survey, 1994). S o m deposits rnay show elements of
both types of minerakation. but the host seming is not important to the ensuing
arguments.
Numerous radiometric data have been extracted from various minerals
associated with both 'unconformity-type' and Yracture-type' deposits. These
typically make use of the U-Pb or Pb-Pb systems in the main ore mineral. U02.
This occurs either as a cubic crystalline form, uraninite, or as a sooty black,
massive variety, pitchbiende, which is charaderistic of lower temperatures
(Tc250°C: Fryer and Taylor, 1987). More recently, stabie isotope evidence has
been used to show that fracture-controlled kaolinites around the McArthur River
deposit formed from rock interacting with a fluid equivaient to modern meteoric
waters, and that this was controfled by readivated faults (Kotzer and Kyser,
1995).
A summary of radiometric data, giving Phanerozoic ages. from Udeposits in and
adjacent to the Athabasca basin is show in Table 3.1. This shows that there is
li mited concordance of dates between different radiogenic dating methods.
Despite this some cornparisons can be drami between radiogenic age data from
the various deposits and systerns. Ali the chernical U-Pb ages for stage two and
three uraninites. pitchblendes, coffinites and Ca-U hydrates as reported by Fayek
and Kyser (1 997) are significantly younger than earlier (as established by growth
relationships) stage one uraninites and pitchblendes. There is some correlation
between stage-3 uraninite ages, as three of the analyses overlap within analytical
error at approximately 370Ma and a fourth is slightly out at 403Ma. Two ages
from McClean Lake (Sue zone) overlap between 125-1 32Ma.
Table 3.1. Cornplfation of Phanerozolc mdloganlc aga data derlved
from U-Pb dllna mathodo on unnlum mlnemllzatlon. The locations of tha dapoolta clkd In the tut a n k found In Flgum 5.
Rehmnces: a - Cummlng and Rlmalk, 1878; b - Fayak and Kysar,
1897; c - Hoave et dm, 1885; d - Cummlng and Krstlo, 1992; O - Andrade, 19119; f - Budsgurd of#& ISû4; g -PhIllppa et& 1883; h - Phllippe and Lancol* 18û8; I - HOmdorf et al., 1885; J - Trockl et
alm, 1984; k - R u z ~ c , ~ ~ 1986. .
Prim. and sec. pitch. from Rabbit Cake Coffinite from McCiean Lake
Primary pitchbiende from Rabbit Lake Stage 3 uraninite from Midwest Lake Late pitchblende from McArthur River
Uraninite from Eagle Point Primary pitchblerde from Midwest Lake
Coffinite from Midwest Lake Primary pitchblerde frun Midwest Lake
Prirnary uraninite from Cigar Lake Stage 3 uraninite from Eagie Point
Prim. uran. and @ch, f r m Cigar Lake W. R., mineralized zones from Key Lake W. R., mineralized zones from Key Cake Primary uran. and pitch. from Cigar Cake W. R., mineralized zones fiom Key Lake
Pitchblende from Rav- Stage 3 uraninïîe from McArthur River
Ca-U hydrate fm Eagle Poirit Secondary pitchblenôe from Rabbit Lake
Primary uraninite fiom Key Lake Secondary pitchblende from Rabbit Lake
Coffinite from Eagle Pois Late pitchblende f rom McArthur River
Stage 3 uraninile from Cigar Lake Sec. uran. and pitch. from Cigar Lake Stage 3 uraninite from McClean Lake
Prim. pitch. and CM. from Midwest Lake Primary pitchblende frun Key Lake
Stage 3 uraninite from McClean lake Ca-U hydrate from Key Lake
Late pitchblende frorn McArthur River Ca-U hydrate from McArthur River
Sec. pitch. and coff. from Midwest Lake Ca-U hydrate from McClean Lake
~bbreviations: Ref. - Reference; prim. - pn'mary; sec. - s a m d bitch. - piîchblende; eoff. - &inil& Na - w o r nd availabte.
Coricordia L. 1. Chernical Age Comadia L. 1. Chemical Age Corwxndia U. 1. Concordia C. 1. Goricordia L. 1. Chemical Age Corwrndia L. 1. Corwxndia L. !. Chernical Age Concardia L. 1. Concordia L. 1. Concordia L. 1. Coricordia L. 1. Concordia L. 1. Concordia U. 1. Chemical Age Chernical Age Concordia U. 1. Concordia L. I- Concordia U. I. Chemical Age Concordia U. 1. Chemical Age Concordia L. 1. Chemical Age Coricordia L. 1. Concordia L. 1. Chemical Age Chemical Age Concordia L. 1. Chemical Age Concordia L. 1. Chemical Age
Summary description of andyzad matorid based on mare cornplet@ descriptions given by the author in the referenced paper.
'~ethod of dating either UPb chernical age or UPb concordia mahod (U. 1. = Upper Intercept; L. 1. = Lower Intercept).
'Given in Ma.
Concordia method lower intercepts frorn six samples of eaily minerakation give
ages between 322i38Ma and 340hk. These are interpreted as indicatin9 there
was a major episode of minera1 remobikation affecting the 8ady U-
mineralization. Another lower intercept from Midwest Lake gives an age of
12W17Ma. This is -compatible with the U-Pb chernical ages from stage 3
uraninites at McClean Lake.
Of the 'unconformity-type* deposits listed in the table, many are dong or near to
northerly-trending fault features which are interpreted to be splays of the TFZ.
For instance the Collins Bay 'B* zone deposit o m n in a segment of northeast-
trending, southeast-dipping reverse fault. Mineralkation is concentrated where
the thrust deviates from its northeastedy trend to a northerly trend. This is
coincident with a weak north-trending aeromgnetic lineament considered to be
the geophysicai expression of a TFZ fault splay.
The Key Lake deposit consists of two tabular ore bodies on the same thnist fault
separated by a distance of approximately 1 km (Dyck and Boyle. 1980; Tremblay,
1982; de Cade, 1986). 60th orebodies are cut by several north-northwest
trending faults that are considered to be part of the Tabbernor Fault grouping, as
they have the same orientation as faults seen at the nearby Janice Lake copper
showing (Fig. 3.6). These have been rnapped by severai authors as being
connected to the TFZ (Scott. 1973; Delaney et al., 1995; this study). In at least
one instance at Key Lake, the Tabbernor lineament coincides with a dilution of
the mineralization. De Carie (1986) noted that repetitive movement on north-
nort hwest trending faults has '. . . brecciated, remobilized and, l ocall y, displaced
the deposits". indicating fault movement post-dates ore deposition.
Other deposits such as those at Rabbit Lake and Eagle Point show no evidence
of Tabbernor Fault splays cross-cutting them, but are w'thin 1 km of minor
Tabbernor Fault splays (Heine, 1986; Ruzicka 1986; this study). A few such as
the Midwest Lake and McClean Lake deposits (Aryes et al.. 1983; Wallis et al..
1983) are not dose to identified Tabbernor spiays. Despite this it is reasonable to assume that with the high density of aeromagnetic lineaments and minor
Tabbemor-related faults in the basement. as rnapped on the shore of Wollaston
Lake to the east. the reactivation of the TF2 would result in a general fluid
circulation event throughout the basement.
5.5 Field Evldence of Qhanerozoic Reactivation of t h TFZ
Field evidenœ for Phaneroroic reactivation is poor. Whilst mapping over two field
seasons in the Wollaston Lake area produced ample evidence for the brittle
reactivation of Tabbemor-related structures, none of t hese c m be confident1 y
assigned to the Phanerozoic eon. Early Hudsonian age deformation. which is
characterized by discrete ductile sheanng, but no rnyionite development. is
overprinted by hematization, brecciation and horizontal quartz - chlorite growth
fibres on slickensided joint planes. Brirle fault features are widely distributed in
the basement rocks exposed in the Wollaston Lake area, but become more
densely distributed around TFZ fault spiays. Poor exposure and lad< of good
rnarker horizons predudes assignrnent of the relative displacements to the
ductile or brittie phases of deformation. Individuai brittle rnovement planes show offsets between 4 c m - S m . Work on the nature of britlle faulting in the
Wollaston Lake area suggests that the rnajority of these feahires are not
Phanerozoic (Davies. in press a). They were formed during a widespread
basement reactivation. possibly in the middle Proterozoic eon synchronous with
the early stages of U-minerakation.
The cleaily defined trace of a mafic dyke on the aeromagnetic field map of the
area (Kornik, 1983) shows no offset across any of the major Tabbernor Fault
splays. The dyke is assumed to belong to the Mackenzie dyke swarm, dated at
1267eMa (Cumming and Krstic. 1992, and references therein). Thus JI
significant horizontal displacernent on the fault splays in the area, within aeromagnetic field map resolution (300m line spaang), ended before dyke
emplacement and well before any Phanerozoic reactivation.
6.1 Timing of Phanerozoic Basement Reactîvatîons Tectonic reactivation of basement structures in the western Canadian Shield is
an idea that has gained much aîtention in recent tirnes. Because of the inherent
weakness of fault rocks and change in cnistal properties that commonly oaxin across large-scale cn~stai faults. they will preferentially accommodate intraplate
stresses (Heller et al.. 1993). The TFZ in the exposed shield. and presumably
under the Williston Basin, shows many properties that would rnake it a favorable
locus for tectonic reactivation. Therefore it should corne as no surprise that the
TFZ should show ample evidenœ of reactivation during the Phanerozoic eon.
Fission track data from transects across the fault show that there was
rneasurable vertical movement across the fault in two locations, with east-side up
movement sense. The timing of movernent is canstrained to be l e s than the
date given by the youngest rocks, i.e. 316î15Ma for the Neilson Lake transect
and 338I14Ma for the Wollaston Lake transect.
Fault reactivation also manifests itself as dilution and brecciation of uranium
mineralization at the Key Lake deposit. The constraint on the timing of fault
reactivation here is oniy that it be younger than the mineralization. This is loosely
dated at - 1 400I50Ma
Brecciation of the Ordovician and Silunan carbonates in drillcores intersecüng the
trace of the TF2 show that tectonic movement must have occurred after
lithification of the strata. The age of lithification is not known but it is estimated
that the strata were lain down at -438st12Ma.
Assuming that fault control on depositional patterns in the Williston Basin was
syn-sedimentary, then the best evidence for the timing of TFZ reactivation cornes
from the Upper Devonian Woodbend (374-37Oi15Ma) and Winterburn (370-
362i11 Ma) Group. with the Winteikim Group being the more strongly affected.
The Eariy Cretaceous upper Manville (113-108f4Ma) Group also shows
evidence of fault activity during deposition. The Setüng Lake Fault was aiso active during both these periods. As with the Tabbernor Fault it is a structure that
can be reasonably expected to readivate preferentially during a major tectonic
episode. Evidence for such reacüvations is given by Bezys (1 996).
U-Pb data (Table 3.1) show that concordia method lower intercept ages from
eariier stages of minerakation (-320-340Ma) are consistently younger than the
U-Pb chernical ages from late stage mineraiization (-370Ma). The reason for this
is probably due to amtinued remobilization of both U and Pb by interaction with
oxidizing groundwaten.
A possible expianation for why older generations of uraninite and pitchblende are
more susceptible to Pb-loss than younger minerakation lies in the valence of the
uranium ions. The ideal formule of U02 is based on the assumption that ail the
uranium is in the ub onjdation state. In nature this is rarely the case, especiaily in
the unconfonnity deposits, and the m'nerai is always somewhat oxidized, with the
conversion of U& in part to U~ (Fryer and Taylor. 1 987). This can conf nue up to
a poorl y defined limit (Frondel. 1 958) without modification of the crystal structure.
but beyond this the minerai will start to bewme anisotropic. The change in the
valence state of the uranium is cornpensated for by the entrance of oxygen into
vacant positions in the crystal lattiœ. lt is believed that this structural modification
will aid the migration of lead. and maybe uranium. out of the mineral. *
The early formed uraninites are comrnonly identified optically by their botryoidal
texture. lighter colour and high-reflectance (Cumming and Krstic. 1992: Cari et
a 1992; Phillipe et al., 1993; Fayek and Kyser, 1997) which indicates a high
degree of crystallinity. Later, dtered, generations of uraninite that forrn as rims
and fracture fillings to the earlier minerai. are darker, less refleclive. These
pro babl y result from oxidation of earlier formed urani nite and concomitant
breakdown of the crystd latüce. The latest, stage3 mineralization identified by
Fayek and Kyser (1997). appean to be extremely pristine and is characterized
by low to moderate Pb contents. Their condusion was that this represents either
the introduction of new ore, or the cornpiete recrystallization of previoudy
deposited ore. The fonner explanation is favored hem.
The earlier rnineralization is interpreted to have precipitated at the rnixing front of
an oxidizing basinal fluid and a reduung basement fluid (Kotzer and Kyser.
1995). Interaction between these eariier generations of mineralization and
extre me1 y oxidized fiuids t hat characterized basin fluid incursions du ring the
Phanerozoic eon would lead to extensive uranium oxidation, 4 t h associated U
and Pb remobilization. This in turn would lead to relative Pb-loss out of the
mineral and enoneously young agec for lower intercepts from eadier
mineralization.
The latest stage of mineraiization. i.e. rnineraiization foming after -500Ma bop..
precipitated in equilibrium with these oxidized fluids and wu ld not suffer the
same level of oxidation as the earlier ores. Therefore they suffer less from U and
Pb remobilization. This is reflected in their high reflectivity. lad< of alteration
features and more concordant ages.
Thus the goal of this discussion is to show that in attempting to estirnate the
timing of U-remobilization. and by association fault reactivation, the data from the
late mineralization gives better indication of timing than data from the eaiiier
mineralization. Wlh this in mind it is evident that U-Pb ages for late
rnineralization are in strong agreement Ath the ages of fault reactivation
indicated by the control on depositional patterns in the Williston Basin, i.e. 370Ma
and -1 20Ma.
These two dates ernphasized in the discussion of stage03 mineraiization take on
greater significance when wmbined with the data from Pb/Pb analysis of sulfide
and sulfate minerais from the Key Lake. McArthur River and Eagle Point depodits (Kotzer and Kyser, 1993) (Fig. 3.1 2). These minerals are intimately assodated with U-minerdiration and their = p b P ~ b and m 7 ~ b p ~ b ratios suggest a
highly uranogenic source (Cumming et al.. 1984; Kotzer and Kyser, 1990) i.0. the
altered U-mineras.
Using the secondary isochron equations of Cumming et al. (1 984), Kotzer and
Kyser (1993) showed that Pb ratios in the late-formed sulfides and sulfates are
compatible with uranogenic Pb evdving in a dosed system (i.e. the U-bearing
minerals) until disniption of the system and incorporation of the radiogenic Pb
into the sulfides and .sulfates. The samples give ages of 369Ma (Key Lake. Fig.
3.1 2a) and 1 30Ma (McArthur River and Eagle Point. Fig. 3.1 2b) which represent
the time at which the system was disnipted and S-bearing mineras were
precipitated. These show good agreement with the U-Pb ages from the late
mineralization and dates from depositionai data in the Williston Basin. The Late
Devonian data show an especiaily strong correlation.
The possibility exists that there were more than the two reacüvation events
discussed so far. For example, there are several deposits for which the concordia
lower intercepts from prirnary mineralization give ages of 232-41 Ma to 30MMa
(TaMe 3.1). In addition, two concordia upper intercepts from late rnineraiization
give ages of 21 0fGMa and 275f25Ma (Table 3.1 ). Whether these data represent
real episodes of rembilization of the ore. or are simply due to more recent
continuai diffusion of Pb out of the U-minerals is unclear.
The lack of supporting U-Pb chernical ages from late U-minerais. or Pb-Pb ages
from late sulfides and sulfates. suggests these ages are not as significant as the
other data. However, Chipley and Kyser (1996) published ages of haiite
recrystallization from the Middle Devonian Prairie evaporite Formation in
southern Saskatchewan. The ages published, 371 Ma, 284Ma. 214Ma and
<35Ma. are in excellent agreement with the concordia upper intercepts for late-
mti- In aultld. and su- minmin of vuylng -18 from t h m Ath.b..a Bwin (tom u\d K m 1993). Symbd8 mpi#.nt Pb ritk. dobrmlnoâ in gmkm 1C#n P m dopomlb .t
Key Lakm U om d.poilb (md# Wangk.), pyrb and niw#.i tm in
undstori.. and fmcturr 1 K.y Wt., YokLhur Rlm. and Eagk Point (opan cirok.), mngiaitm in a b r d undatanom pmximil do Kay Wro U or, doposb (0p.n aquai..). 8CIcmy3(rrmom gmwth
cunn shown for i.hmnca (6btry and Krifmm, 1O75). a)
Socoriduy kodiron plot comprklng Pb müa m m gakna 1
Key Lmko. Aga cmlculatod umlng wconQy kochron oqudons
(a.g., Cummlng ot al., WW), murnlng an mg. af 1400 Ma lbr th.
mdloganlc Pb aoum. b) mndmry bochron plot comprklng Pb
ratIo8 h m pyrlt., rnammlt., and 8ngk.b .t b y kk. (1- kCt)
and from h.cturm-fmW cubk Wrl(, .t McMhur Rlvor and Eagia
Point. Aga calcuiatd using wtondwy koohmn oquitlons (~mgm~
Cummlng at d.. 1@64), mumlng th. aga d t h m mdlogmnlc Pb
soum wu 800 Ma, rimilu to thm aga of ~ u m c o n t r o l i o â
comnlb formitkn In th. m i n (HOhndorf of al., 1-1.
Key Lake
slope =O. 1 004 MSWD = 9.5 Age = 369Ma
McArthur River + Eagle Point
slope = 0.0724 MSWD = 41.6 Age = 130Ma
stage minerdiration. This would suggest that there is additional evidence for
repeated basernent reacüvation through much of Saskatchewan du ring the
Phanerozoic eon. Chipley and Kyser (1 996) suggested that halite
recrystallization was related to tectonic events in the cordillera to the west.
Summarizing al1 the data presented it is possible to present a tima frame for TFZ
reactivation during the Phanerozoic eon. This started with a stmng episode of
fault movement at 370Ma that controfled sedimentation in the Williston Basin and
remobilized U and Pb from deposits in the Athaôasca Basin. This event can dso
be used to explain the anornalous breccias observed in Ordoviaan and Silurian
rocks. This event cannot, however, explain the fission track data which show that
there was vertical movement on the fault after -325Ma. This vertical movement is
probably related to the episode of Eaily Cretaceous fault reactivation that is
poorly constrained somewhere around 1 10-1 20Ma. Alternatively the vertical
movement can be attributed to one of the minor basement reactivation events
that may have occurred at circa. 280Ma and 21 0Ma.
6.2 Cause and Mechanisms of Reactivation
As noted earlier rnany authors have proposed links between a variety of tectonic
and stratigraphie features in the western sedirnentary basin and orogenic activity
on the western margin of the North American continent. Cornparison with the
best estimates on the timing of Cordilleran tectonics shows that there is an
excellent correlation between basernent reactivation and major collisional
episodes on the western cratonic margin. Earliest orogenic activity is suggested
to have begun in the Middle to Late Devonian Period with the Antler Orogen (see
references given earlier). Successive sequences of terrane accretion resulted in
the Late Permian (258-245&24Ma) Sonoma Orogen, Jurassic (208- 1 4421 8Ma)
Nevadan Orogen (Windley. 1995). Early Cretaceous (1 19-1 O5I9Ma) Columbian
Orogen (Pavlis. 1 989; Sprinkel, 1992). and Late Cretaceous (97.522.5Ma)
Laramide-Sevier Orogen (Windley, 1995). These events are in excellent
agreement with al1 the ages given for reactivation for the TFZ.
Discussion of the nature of the mechanisms connecting marginal tectonic events
to reactivation of th8 Tabbemor Fault and other basement ieatures is at best
speculative. The main reason for linking the tm, processes is the strong
correlation in the timing of the episodes. This suggests that the rnechanism(s)
that link orogenic ad-vity to basement reactivation must transmit the stresses
needed to initiate reactivation extremeiy rapidly, geologically speakhg. The
mechanism of lithospheric flextufing discussed at the beginning of this paper
would certain1 y have an eff ect on the stresses within the conti nentai lithosphere.
Helier et al.. (1993) discuss the cause of tectonic reactivation in the Rocky
Mountain region, related to Cordilleran orogenic activity. They condude that
reactivation of pte-existing basement structures can be brougM about by W e s t changes in intraplate stress fields. Far-field processes such as plate-margin
orogenesis, or local effects, such as intraplate loading and flexure can bring
about these changes in intraplate stress magnitudes andlor orientations.
Pavlis (1989) suggested that the Cdumbian Orogen on the noithwestern margin
of the North American continental margin was characterlzed by a cornplex
arrangement of extensional and contractionai tectonism associated with the
th rusting of the Wrangdlian composite terrane beneath previously accreted
terranes. Extensional tectonics at this time may explain why the TFZ reactivated
as a west-side up fault dunng Mannville Group deposition, as opposed to east-
side up movement during the dorninantly contractional Ant!er Orogen.
Other mechanisms cited at the beginning of the paper, such as supercontinent
assembly by mantle convection and tilting of continental interiors by dynamitai
effects of subduction, could aiso bring about changes intraplate stresses, but it
would be difficult to link them to the timing of orogenic activity.
7. Conclusions The Tabbernor Fault is a long-lived fault zone that has undergone repeated
reactivation duri ng the Phanerozoic eon. The most signifiant reaaivation events
probably occurred in the Late Oevonian (-370hk) and Early Cretaœous
(-120Ma) Periods. aithough there may have been severai other reactivation
episodes. The readivation of the fault dong rnost of its length led to significant
controi on depositioncil patterns in the Williston Basin, and remobilizationl
preapitation of uranium-bearing minerais in high-grade deposits of the
Athabasca Basin. Apatite-fission track analyses of rocks froni the exposed
basement in northem Saskatchewan show that there was differential uplift across
the TFZ dunng the Phanerozoic eon, with vertical. east-side up, movement and
an unknown component of horizontal movement. The ultimate cause of fault
reactivation was linked to orogenic activity at the western continental margin. which was synchronous with reactivation. There is supporting evidence that the
reactivation of the TFZ was part of a larger scaie reactivation of the western
continental basement structures, due to the differentiai accommodation of strain
within the lithosphere.
Chapter 4
Summary and Conclusions
General Conclusions As a result of wrk camed out during th8 cornpletion of this project severai new
discoveries have been made on the history of the Tabbernor Fault zone. These
are listed below in point form:
1) The earliest movement along the TFZ in the Wollaston Lake area is
characterized by the tranposition of the regional SI fabric ont0 an upnght
NE-trending plane of flattening, produang Sn. This transposition is typified
by tightly folded and boudinaged pegmatite segregations within an
intensified gneissic foliation. The limits of this tranposition are defined by
NNE-trending sinidrd shear zones such as the Parker Island shear zone.
2) In high strain zones the newly developed s2 fabric is modified by a near
vertical, NNE-striking, sinistrai shear deavage. As a result of modification.
the foliation and associated fold structures are rotated away from the
regional 0 2 plane of flattening towards the shear plano.
3) The fault and assodated parallel structures controlled the intrusion of a
granitic or pegmatitic melt phase during a break in deformation. This
intrusive event ocarrred after the bulk of sinistral sheanng that affected
the adjacent rocks. Mineralogical and structural similarities between the
intrusive phase in the TFZ and a regional phase of Hudsonian granitic
intrusions dated at -1815Ma suggest that the Tabbernor Fault was active
prior to 181 5Ma.
4) Given the assurnptions made above the most likely explmation for origin
of the TFZ is as a strike-slip fault that accomrnodated sinistral rnovement
during post-collisional escape of the 'Sask' craton beneath the Reindeer
Zone. riming of this post-cdlisional event is indicated to be synchmnous
with peak metamorphism at arca. 181 5-1 830Ma.
5) Subsequent renewal of ductile shearing caused localized reactivation of
TFZ structures and rninor development of shear fabrics with the intrusives.
This was related to late orogenic adjustrnents of the THO dunng Dm and
D H ~ tectonomorphic events.
6 ) The TFZ rnay have a strong role in wntrolling the location of major
uranium deposits in the Athabasca Basin. Not only rnay the fault act as a
fluid conduit. ailowing deep circulation of the ore-forming fluids, but
structural evidence from identified deposits suggests that they are situated
within ductile, Tabbernor-related, structures.
7 ) Readivaüon of TFZ structures oaxrrred over much of the fault's length
during the Phanerozoic Eon. Evidenœ from as far afield as the Williston
Basin and the Athabasca Basin ail wggest that the TFZ was active during
the Antier Orogeny and the Laramide-Sevier Orogeny. Reactivation
caused differentiai upiift of basement rocks, depositional control of active
sedimentation, and extensive uranium mobilization.
Contributions to Knowiedge This study is the first investigation focusing solely on the TF2 within the
Wollaston Domain. As a result of work published here the probable age of the
eariiest ductile movernent within the fault has b e n narrowed to a window of
1815-1848Ma. This indicates that fault movernent was refated to major orogenic
events, rather than minor pst-orogenic adjustments as suggested by some
worken. lt is also the first wrk to compile geologic data coming from the known
geographic and temporal extent of the TFZ. From this it is possible to present an
intermittent history of the fault over >1 S a .
This is the first puMished study to identify a possible link between the TFZ and
uranium mineralization. This link, if substantiated, rnay be of extrerne importance
in the future exploration for 'unconformity-type' uranium deposits in the eastem
Athabasca Basin. A test of this hypothesis would be to try and ide~tify outcrop-
scale fault features that are sirnilar to those seen within TFZ spiays mapped on
the shore of Wollaston Lake.
To the south, the link between the FZ, sedirnentary patterns, and structures
within the Williston Basin has the potentiaî to control the economic occurrence of
hydrocarbon piays. One oil and gas field. the Minton field. has already been
located immediately above the TFZ.
The idea of intracratonic stability is put into further question by the knowledge
that the TFZ has had a very long, repeated history of reactivation. This is despite
being oblique to the active plate margins during the THO and far removed frorn
any active plate margin subsequently.
References and Bibliography Andrade, N., 1989: The Eagle Point uranium deposits, northern Saskatchewan.
Canada. In: Uranium resources and geology of North America.
International ~ tomic Energy Agency Technical Document. 500, p. 455-
490.
Annesley, 1. R., Madore, C., and Shi, R., 1996a: U-Pb geochronology and
thermotectonic history of the Wollaston Domain in the Wollaston Lake area,
Hearne Province, Saskatchewan. In: GAC-MAC program with abstracts, v.
21, p. A4.
Annesley, 1. R., Madore, C., Shi, R., and Krogh, T. E., 1996b: U-Pb
geochronology and thermotectonic history of the Wollaston Domain in the
Wollaston Lake area. Hearne Province, Saskatchewan. Poster
presentation at GAC-MAC annual meeting in Winnipeg, p. PlS.
Annesley, 1. R., Madore, C., Shi, R., and Krogh. T. E., 1997: U-Pb geochronology
of thermotectonic events in the Wollaston Lake area, Wollaston Domain: A
summary of 1994-1 996 results. In: Sumrnary of Investigations 1997, Sask
Geol. Surv., Sask Energy Mines, Mis. Rep. 97-4, p. 162-173.
Ansdell, K., Lucas, S., Connors, K., and Stem, R., 1995: Kisseynew
metasedi mentary gneiss belt , Trans-Hudson orogen (Canada): Back-arc
origin and collisional inversion. Geology, v. 23, p. 1039-1043.
Ayres, D.E., Wray, E. M., Farstad, J., and Ibrahim, H., 1983: Geology of the
Midwest uranium deposit. h: Cameron, E. M., (ed.) Uranium Exploration in
the Athabasca Basi n, Saskatchewan, Canada. Geological Survey of
Canada, Paper 82-1 1 , p. 33-40.
Baadsgaard, H., Curnming, G. L.. and Worûen. J. M., 1984: U-Pb geochronology
of minerals from the Midwest uranium deposit, northern Saskatchewan.
Canadian Journal of Earth Sciences, v. 21, p. 642-648.
Baird, J. D., Nelson, K. D., Waiten, J., Hauck, M., and Brown, L. D., 1992: Deep
structure of the Proterozoic Trans-Hudson Orogen beneath the Williston
Basin: Results from recent COCORP seismic reflection profiling. h: AGU
1992 spring meeting, Eos, Transactions, American Geophysicaî Union. v.
73, n. 14, suppl.. p. 321.
Beaumont, C.. 1981: Foreland bans. The Geophysical Journal of the Royal
Astronomical Society, v. 65, p. 291-329.
Beck, L. S., 1969: Uranium deposits of the Athabasca region, Saskatchewan.
Sask. Dep. Miner. Resour., Aep. 126, pp. 140.
Beck, 1. S., 1970: Genesis of uranium in the Athabasca region and its
significanœ in exploration. CIM transactions, v. 73, p59-69.
Bergman, K. M. and Walker, R. (3.. 1996: Basement control of linear Cretaceous
sandbodies in the Western Canada Sedimentary Basin (VVCSB): Progress
report. In: Ross, G. M. (comp.), 1995 Alberta Basement Transects
woikshop, LITHOPROBE Rep. #SI. p. 198.
Berthe, D-. Choukroune, P., and Jegouzo. P., 1979: Orthogneiss, mylonite and
non-coaxial deformation of granites: the example of the Armorican Shear
Zone. Journal of Structural Geology, v. 1, n. 1, p. 31 -42.
Bezys, R. K., 1 996: Sub-Paleozoic structure along Manitoba's northeast flank of
the Williston Basin: exploration implications for the mining and petroleurn
industries. In: GAC-MAC program with abstracts. v. 2 1 , p. Ag.
Bickford, M. E., Collerson, K. O.. Lewry, J. F., Van Schmus, W. R., and
Chiarenzelli, J. R., 1990: Proterozoic collisional tectonisrn in the Trans-
Hudson Orogen, Saskatchewan. Geology, v. 18, p. 14-1 8.
Bleeker, W., 199û: New structurai-metamorphic constraints on Early Proterozoic
oblique collision dong the Thompson Nickel Belt, Manitoba, Canada. In:
Lewry, J. F. and Stauffer, M. R., (eds.), The Early Proterozoic Trans-
Hudson Orogen of North America, Geological Association of Canada,
Special Paper 37, p. 57-73.
Blenkinsop, T. G. and Treloar. P. J., 1995: Geometry, classification and
kinematics of the S-C and S-C' fabrics in the Mushandike area, Zimbabwe.
Journal of Structural Geology, v. 17, n. 3, p. 397-408.
Burchfield, B. C. and Royden, L. H., 1991 : Antier orogeny: A Meditenanean-type a orogeny. Geology, v. 19, p. 66-69.
Budding, A. J. and Kirkland, S. J. T., 1956: The geology and mineral deposits of
the Hanson Lake area. Sask Miner. Resour., Rep. 30 .42~ .
Butler, R. W. H., Holdsworth, R. E., and Uoyd, G. E., 1997: The role of
reactivation in continental deformation. Journal of the Geologicai Society,
London, v. 154, n. 1, p. 69-71.
Byen, A. R., 1962: Major faults in the western part of the Canadian Shield
special reference to Canada. In: Stevenson, J. S., (ed.), The tectonics of
the Canadian Shield, Royal Society of Canada, p. 40-59.
Cameron, E. M. (editor), 1983: Uranium Exploration in Athabasca Basin,
Saskatchewan, Canada. Geological Survey of Canada. Paper 82- 1 1 , pp3l O.
Cant, D. J. and Stockmal, O. S., 1989: Stratigraphy of the Alberta foreland basin:
an interpretation in terms of Cordifieran tectonics. Canadian Journal of
Earth Sciences, v. 26, p. 1 964-1 975.
Cari, C., von Pechmann, E., Horndorf, A., and Ruhnnann, G., 1992: Mineralogy
and U/Pb, and S m d geochronology of the Key Lake uranium deposit,
Athabasca Basin, Saskatchewan, Canada. Canadian Journal of Earth
Sciences, v. 29, p. 879-895.
Chadwick. B., 1966: The geology of the Nekweaga Bay area (west half),
Saskatchewan. Sask., Dep. Miner. Resour.. Rep. 109.
Chadwick, B., 1967: The geology of the Morell Lake area (west half),
Saskatchewan. Sask., Dep. Miner. Resour., Rep. 116.
1
Chandler, F. W., 1978: Geology of part of the Wollaston Lake fold belt, north
Wollaston Lake, Saskatchewan. Can. Geol. Surv., Bull. 277.
Chen, D. and Bergman, K. M.. 1997: High-resolution stratigraphie analysh of
Cretaceous formations in the Peace River Arch area of the Western
Canadian Sedimentary Basin: Depositional processes and possi ble
controlling mechanism. h: Ross, O. M. (comp.), 1997 Alberta Basement
Transects workshop, LiTHOPROBE Report 159. p. 129-1 62.
Chipley, D. and Kyser, T. K., 1996: Ages, Sr and Pb isotopic compositions of halites from the Middle Devonian Prairie Formation evapontes in
Saskatchewan. In: GAC-MAC program *Nith abstracts, v. 21 , p. A1 7.
Clarke. P. J. and Fogwill, W. 0.. 1986: Geology of the Dam Lake uranium
deposits. northern Saskatchewan. In: Evans, E. L, (ad.). Uranium deposits
of Canada. CIM Spec. Vol. 33, p. 184-192.
Clowes, R. M.. (ed.), 1997: LITHOPROBE Pham V Proposal - Evolution of a Continent Revealed. Published by the LITHOPROBE secretariat. The
University of British Columbia, Vancouver, B.C., pp. 292.
Cumming, G. 1. and Fümsaite, J., 1979: lsotopic suidies of lead-depleted
pitchblende, sewndary radioactive minerais, and sulphides frorn the
Rabbit Lake uranium deposit, Saskatchewan. Canadian Journal of Earth
Sciences, v. 16, p. 1702-1 71 5.
Cumming, G. L. and Krstic, O., 1992: The age of unconformity-related
minerakation in the Athabasca Basin, northern Saskatchewan. Canadian
Journai of Earth Sciences, v. 29, p. 1623-1 639.
Cumming, G. L.. Krstic, D., and Wilson. J, 1987: Age of the Athabasca Group.
Northern Alberta. In: GAC-MAC prograrn with abstracts. v. 12, p. A35
Cumming, G. L., Krstic, D., Worden. J.. and Baadsgaard, H.. 1984: lsotopic
composition of lead in gaienas and Ni-arsnides of the Midwes: deposit.
northern Saskatchewan. Canadian Journai of Earth wences, v. 21, p.
649-656.
D'Lemos, R. S., Schofield, D. 1.. Holdswonh, R. E., and King, T. R., 1997: Deep
crustal and local rheologicai controls on thc sitting and reactivation of fault
and shear zones, northeastern Newfoündland. Journal of the Geological
Society, London, v. 1 54. p. 1 1 7-1 21 .
Davies, J. R., 1996: PostdlisionaJ tedonics assoaateâ with the Tabbernor
Fault system, Wollaston Lake area: Preliminary report. In: Summary of
Investigations 1996. Sask. Geol. Surv.. Sask. Energy Mines, Misc. Rep.
96-4, p. 1 27- 1 29.
Davies, J. R.. in press a: Structural Investigation of the Tabbernor Fault Zone,
Wollaston Lake: Implications for Regional Deformation Assoaated with
Post-collisional Tectonics in the Trans-Hudson Orogen
Davies, J. R., in press b: Evidence for Orogeny-driven Phanerozoic Fieactivations
of the Tabbernor Fault Zone, Saskatchewan, Canada.
De Carie, A. L., 1986: Geology of the Key lake deposits: In: Evans. E. L. (ed.), Uranium deposits of Canada. CIM Spec. Vol. 33, p. 1 70-1 77.
/
Delaney, G. O., 1995: Som perspectives on the stratigraphy and metallogeny of
the eastern margin of the Wollaston Domain. In: Hajnal, Z. and Lemy. J. F.
(eds.) Trans-Hudson Orogen Transed meeting, LITHOPROBE Report No.
48, p. 87-1 01.
Delaney, G. D., Maxeiner, M. L., Rawsthorne, M. L., Reid, J., Hartlaub, R., and
Schwann. P., 1 995: Geological setting of sedirnent-hosted copper
rnineralization in the Janice Lake area, Wollaston Domain. In: Summary of
Investigations 1995, Sask. Geol. Surv., Sask. Energy Mines, Misc. Rep.
95-4, p. 30-48.
Corobek, S. L., Reid. S. K., and Elrick, M., 1990: Timing and scale of foreland
response to episodic Antler convergence events, Devonian-Mississippian
stratigraphy of Montana and Idaho: effects of horizontal and vertical
loading. GSA abstracts with prograrns, v. 22, n. 7, p. 283.
Dyck, W. and Boyle, R. W.. 1980: Radioactive disequilibrium in suificial materials
from uraniferous environments in northern Saskatchewan. CIM bulletin,
June, p. 77-83.
Edwards, J. E. and Brown. R. J., 1996: A geophysid perspective on the
question of basement involvement with the distribution of Upper Devonian
carbonates in centrai Alberta. In: Ross, G. M. (cornp.), 1995 Alberta
Basement Transeds workshop. LITHOPROBE Report #SI. p. 133-1 97.
Elliott, C. G., 1 994a: Structural relationships across the Tabbemor Fault. Nielson
Lake area, Trans-Hudson Orogen, Saskatchewan. In: Current Research
1 994-C: Geological Su rvey of Canada. p. 1 1 3- 1 20.
Elliotî, C. 0.. 1994b: Stiuctural mapping of the Paleozoic outlier at Limestone
Point Lake (NTS 63N-2). In: Manitoba Energy Mines, Report of Activities 1 994, p. 1 44-1 47.
Elliott, C. G., 1995: The Tabbernor Fault and Proterozoic and Phanerozoic
Movernents in Saskatchewan and Manitoba. In: Hajnal. Z. and Lewry. J. F.
(eds.) Trans-Hudson Orogen Transect meeting. LITHOPROBE Report No.
48, p. 148-1 55.
Elliott, C. Gal 1996a: Phanerozoic deformation in the ustable" craton, Manitoba,
Canada. Geology, v. 10, p. 909-91 2.
Elliott, C. G., 1996b: The Tabbemor fault in four dimensions. In: Hajnal, 2. and
Lewry, J. F. (eds.) Trans-Hudson Orogen Transea meeting,
LITHOPROBE Report #S. p. 5-9.
Elliott, C. G. and Gimux, O. L.. 1996: Readvated faults in the Western Interior
Basin, Saskatchewan and Manitoba. In: GAC-MAC program with abstracts.
v. 21, p. A25.
Erickson. P. 1. and Bergman, K. M., 1997: Influence of basement movements on
the location of Cretaœous linear Cardium sandbodies in the Western
Canada Sedimentary Basin (WCSB). In: Ross, G. M. (comp.), 1997
Alberta Basement Transects workshop, LITHOPROBE Report #59, p.
1 15-1 28.
Evans. E. L. (ed.), 1986: Uranium deposits of Canada. CIM Spec. Vol. 33, pp.
324.
Fayak, M. and Kyser, T. K., 1997: Characterization of multiple fluid-flow events
and rare-earth-dernent mobility associated with formation of unoonforrnity-
type uranium deposits in the Athabasca Basin. Saskatchewan. Canadian
Mineralogist, v. 35, p. 627-658.
Fedorowich, J., Stauffer, M., Le-, J., & Kerrich, R., 1995: The age of the
Needle Falls ~hea r Zone. In: Hajnai, 2. and Lewry, J. F. (eds.) Trans-
Hudson Orogen Transect meeting. LITHOPROBE Report #M. p. 1 02-1 03.
Ferguson, 1. J., Stevens. K. M., Cassells, J. P., Wu, X., Shiozaki, 1.. and Jones.
A. G., 1996: THOT MT studies: eastern segment. In: Hajnal, Z. and Lewry.
J. F. (eds.) Trans-Hudson Orogen Transect meeting, LITHOPROBE
Report #55, p. 10-25.
Fermor, P. R. and Moffat, I. W., 1992: Tectonics and structure of the Western
Canada Foreland Basin. In: Macqueen, R. W. and Leckie, D. L., (eds.),
Foreland Basins and Fold BeIts. Arnerican Association of Petroleum
Geologists. Memoir 55, p. 90-1 06.
Frondel, C., 1958: Systematic rnineraiogy of uranium and thorium. United States
Geological Survey Bulletin, n. 1064, pp. 400.
Fryer, B. J. and Taylor: R. P., 1987: Rare-earth element distributions in
uraninites: implications for ore genesis. Chernical Geology, v. 63. p. 101-
108.
Gerhard, L. C.. Anderson, S. B., and Lefever, J. A.. 1987: Structural history of the
Nesson Antidine, North Dakota. In: Longman. M. W. (ed.). Williston Basin
- anatomy of a cratonic oil province, Denver, Colorado, Rocky Mountain
Association of Geologists, p. 337-353.
Good, N. and De Wit, M. J., 1997: The Thabazimbi-Murchison Linearnent of the
Kaapvaai Craton. South Africa: 2700Ma of episodic reactivation. Journal of
the Geological Society. London, v. 154, n. 1, p. 93-97.
Green, A. G., Hajnal. 2.. and Weber, W., 1985: An evolutionary mode1 of the
western Churchill Province and western margin of the Superior Province in
Canada and the north-central United States. Tectonophysio, v. 116, p.
281 -322.
Greggs, R. G. and Greggs, D. H., 1989: Fault-block tectonism in the Devonian
subsurface, western Canada basin, Journal of Petroleum Geology. v. 12,
p. 377-404.
Gurnis, M., 1 993: Depressed continental hypsmetry behind oceanic trenches: A
due to subduction controls on sea-level change. Geology. v. 21. p. 29-32.
Haidl, F. M., 1988: Uthology and stratigraphy of Lowr Paleozoic strata: New
information from cores in the Cumberland Lake area, east-central
Saskatchewan. In: Summary of Investigations 1 988, Sask. Geol . Sunr .. Sask. Energy Mines, Misc. Aep. 88-4, p. 202-210.
Hajnal, Z., White, O., Green, A., Lucas, S., Lewry, J., Bezdan, S.. Ashton, K.,
Thomas, M., and Clowes, R., 1992: Crustal architecture of the Trans-
Hudson Orogen. In: Program and abstrads. Fifth International Symposium
on Seismic Reflection Probing of the Continents and their Margins. Banff.
Al berta. Canada, p. 86.
Hajnal. Z., Lucas, S., White, D., Lewry, J., Bezdan, S., Stauffer, M. R.. and
Thomas, M. O., 1996: Seismic reflection images of high-angle faults and
linked detachments in the Trans-Hudson Orogen. Tectonics. v. 15, n. 2. p.
427-439.
Hanmer, S., 1997: Shear zone reacüvation at granulite facies: the importance of
plutons in the localization of viscous flow. Journal of the Geological
Society, London, v. 154, n. 1. p. 1 1 1-1 16.
Hardcastle, K. C. and Hills, L. S. 1991 : BRUTE3 and SELECT: QUICKBASIC 4
programs for determination of stress tensor configurations and separation
of heterogeneous populations of fault-slip data. Cornputers and
Geosciences, v. 17, p. 23-43.
Hayes, B. J. R., Chnstopher, J. E., Rosenthal, L., Los. G., McKercher, B.,
Minken, D., Tremblay, Y. M., and Fennell, J.. 1994: Cretaceous Mannville
Group of the Western Canada Sedimentary Basin. In: Mossop. G and
Shetsen, 1. (comp.), Geological Atlas of the Western Canada Sedimentary
Basin, Calgary. Canadian Society of Petroleum Geologists and Alberta
Research Counal, p. 31 7-334.
Heaman, L. M., Ashton, K. E.. & Lemy. J. F.. 1995: U-Pb geochrondogy of the
Peiican Window: Preliminary Results. In: Hajnal. Z. and Lewry, J. F. (eds.) Trans-Hudson Orogen Transect meeting, LITHOPROBE Report #48, p.
1 43-1 47.
Heine, T. H., 1986: The geology of the Rabbit Lake uranium deposit,
Saskatchewan. In: Evans, E. L., (ed.), Uranium deposits of Canada, CIM
Spec. Vol. 33, p. 134-143.
Heller, P. L.,
Cause
region
1006.
Hickman, S.,
Beekman, F., Angevine, C. L., and Cloetingh, S. A. P. L., 1993:
of tectonic reactivation and subtle uplifts in the Rocky Mountain
and its effect on the stratigraphie record. Geology, v. 21, p. 1003-
Sibson. R., and Bruhn. R.. 1995: Introduction to speciai section: d Mechanical involvernent of fiuids in faulting. Journal of Geophysid
Research. v. 100, n. 87, p. 12,831-12,840.
Hoeve, J. and Sibbaid. T. I. 1.. 1978: On the genesis of Rabbit Lake and other
unconformity-type uranium deposits in northem Saskatchewan, Canada.
Economic Geology, v. 73, p. 1450-1 473.
Hoeve, J., Cumming, G. L., Baadsgaard, H., and Morton, R. D., 1985:
Geochronology of uranium metallogenesis in Saskatchewan. h: Sibbald,
T. 1. 1. and Petnik, W. (eds.), Geology of Uranium Deposits, CIM Spec.
Vol. 32, p.255.
Hoffman, P. F., 1988: United plates of America, the birth of a maton: Early
Proterozoic assembly and growth of Laurentia. Annuai Review of Earth and
Planetary Science, v. 16, p. 543-603.
Holdsworth, R. E., Butler, C. A., and Roberts, A. M., 1997: The recognition of
reactivation during continental deformation. Journal of the Geological
Society, London, v. 154, n. 1, p. 73-78.
Horndorf, A., Lenz, H., von Pechmann, E., Voutsidis, V., and Wendt, l., 1985:
Radiometnc age determinations on samples of Key Lake uranium
deposits. h: Sibbald, T. 1. 1. and Petruk, W. (eds.), Geology of Uranium
Deposits, CIM Spec. Vol. 32, p.48-53.
Imber, J., Holdsworth. R. E.. Butler, C. A., and Uoyd, G. E., 1997: Fault-zone
weakening processes along the reactivated Outer Hebrides Fault Zone,
Scotland. Journal of the Geological Society, London, v. 154, n. 1. p. 105-
109.
Johnson, J. O., Klapper, G., and Sandberg, C. A.. 1985: Oevonian eustatic
fluctuations in Euramerka: OSA Bulletin, v. 96, p. 567-587.
Jones, A. G. and Craven, 3. A., 1990: The North American Centrai Plains
conductivity anomaly and its carrelation with gravity, magnetic, seismic,
and heat flow data in Saskatchewan, Canada. Physics of the Earlh and
Planetary Interiors, v. 60, p. 169-1 94.
Kent, D. M. and ~hns to~her , J. E., 1994: Geological history of the Williston Basin
and Sweetgrass Arch. ln: Mossop, G and Shetsen, 1. (cornp.), Geological
Atlas of the Western Canada Sedimentary Basin, Calgary. Canadian
Society of Petroleum Geologists and Alberta Research Counal, p. 421-
429.
Kominz, M. A. and Bond, G. C., 1991 : Unusually large subsidence and sea-level
events dunng rniddle Paleozoic time : New evidence supporting mantle
convection models for super continent assembly. Geology, v. 19, p. 56-60.
Komninou, A. and Sverjensky, D. A., 1996: Geochemical modeling of the
formation of an unwnformity-type uranium deposit. Economic Geology. v.
9 1 , ~590-606.
Korni k, L. J., 1983: Vertical magnetic gradiometer survey and interpretation,
NEAAAEA Athabasca test area. In: Carneron, E. M., (ed.) Uranium
Exploration in the Athabasca Basin, Saskatchewan, Canada. Geological
Survey of Canada, Paper 82-1 1, p. 147-1 50.
Kotzer, T. G. and Kyser, T. K., 1990: The use of stable and radiogenic isotopes
in the identification of fluids and processes with unamformity-type uranium
deposits. In: Modern Exploration Techniques, Sask. Geol. Soc. Spec. Pub.
10, p. 115-131.
Kotzer, T. O. and Kyser, T. K., 1993: 0, U, and Pb isotopic and chernical
variations in uraninite: Implications for determining the temporal and fluid
history of ancient terrains. Arnerican Mineralogist, v. 78, p. 1262-1 274.
Kotzer, T. G. and Kyser, T. K.. 1995: Petrogenesis of the Proterozoic Athabasca
Basin, northern Saskatchewan, Canada, and its relation to diagenesis,
hydrothennal uranium rnineralization and paleohydrogeology. Chernical
Geology, v. 120, p. 45-89.
Kotzer, T. G., Kyser, 1. K., and Irving, E., 1992: Paleomagnetism and the
evolution of fluids in the Proterozoic Athabasca Basin, northern
Saskatchewan, Canada. Canadian Journal of EaRh Sciences, v. 29, p.
1474-1 491.
Lacassin, Ral 1988: Large-scale foliation boudinage in gneisses. Journal of
Structural Geology, v. 10, n. 6, p. 643-647.
Lafrance, B. and Varga. M., 1996: Structural studies of the Parker Lake shear
zone and the Reilly Lake shear zone, Reindeer Lake. In: Summary of
Investigations 1996, Sask. Geol. Suw., Sask. Energy Mines, Misc. Rep.
96-4, p. 1 1 9-1 24.
Leckie. O. and Smith, O., 1992: Regional setting, evolution, and depositional
cycles of the Western Canada foreland basin. h: Macqueen. R. W. and
Leckie, D. L., (eds.), Foreland Basins and Fold Belts, American
Association of Petroleum Geologists, Memoir 55. p. 9-30.
Leckie, D. A., Bhattacharya, J. P., Bloch, J.. Gilboy. C. F., and Norns, B.. 1994:
Cretaceous ColoradolAlberta Group of the Western Canada Sedimentary
Basin. In: Mossop, G and Shetsen, 1. (cornp.), Geological Atlas of the
Western Canada Sedimentary Basin, Calgary. Canadian Society of
Petroleum Geologists and Alberta Research Counal, p. 335-352.
Lewry, J. F., 1981 : Lower Proterozoic arc-microcontinent collisional tectonics in
the western Churchill Province. Nature, v. 294, p.69-72.
Lewry, J. F. and Collerson, K. D., 1990: The Trans-Hudson Orogen: extent,
subdivision, and problems. In: Lewry, J. F. and Stauffer, M. R., (eds.), The
Eaily Proterozoic Trans-Hudson Orogen of North America. Geologicai
Association of Canada, Speaal Paper 37. p. 1-1 4.
Lewry. J. F. and SibbaJd, T. 1. l . , 1980: Thermotectonic evolution of the Churchill
Province in noithem Saskatchewan. Tectonophysics, v. 68, p. 45-82.
Lewry, J. F. and Stauffer, M. R., 1990: The Early Proterozoic Trans-Hudson
Orogen of North Arnerica. Geologicai Assoaation of Canada. Special
Paper 37, pp. 505.
Lewry, J. F., MacDonald, R., and Stauffer, M. R., 1989: The development of
highly strained rocks in the Pelican Window during high-grade
metarnorphism and anatexis. In: Surnmary of Investigations 1989, Sask.
Geol. Suw., Sask. Energy Mines, Misc. Rep. 89-4, p. 58-65.
Lewry, J. F., Thomas, D. J., MacDonald, A. and Chiarenzelli, J., 1990: Structural
Relations in Accreted Tenanes of the Trans-Hudson Orogen,
Saskatchewan: Telescoping in a Collisionai Regime? h: Lewry, J. F. and
Stauffer, M. R., (eds.), The Early Proterozoic Trans-Hudson Orogen of
North America, Geological Association of Canada, Special Paper 37, p. 75-
94.
Lewry, J. F.. Thomas, D. J., Rees, C. J.. and Roberts, K.. 1981 : Geology of an
area around Compulsion Bay, Wollaston Lake. Sask. Miner. Resour., Rep.
205. ,
Link, P. K., Wilson, E., and Preacher, J. M., 1993: W e l s for hybrid loaded and
fault-bounded Antler Yoreland basin" in Idaho. GSA abstracts with
programs, v. 25, n. 5, p. 173-174.
Lister, G. S. and Snoke, A. W., 1984: S-C mylonites, Journal of Structurai
Geoiogy, v. 6, n. 6, p. 617-638.
Lucas, S. B., Green, A. G., Hajnai, 2.. White, 0. J.. Lewry, J. F., Ashton. K. E.,
Weber. W., and Clowes, R. M., 1993: Deep seismic profile of a Proterozoic
collision zone: Surprises at depth. Nature, v. 363, p. 339-342.
Macqueen, A. W. and Leckie. D. L., (eds.), 1992: Foreland Basins and Fold
Belts. Amencan Assoaation of Petroleum Geologists, Memoir 55, pp. 460.
Madore, C. and Annesiey, 1. R., 1992: Petrography and geochembtry of eaily
Proterozoic calealkaline granites in the Rabbit Lake area Saskatchewan.
ln: GAC-MAC program with abstracts, v. 17, p. A72.
Madore, C. and Annesley, 1. R., 1993: Metamrphic pressure-temperature
conditions of the basai Aphebian Wollaston Group, Hearne Province,
northem Saskatchewan. In: GAC-MAC program Ath abstracts, v. 18. p.
A65.
Madore, C. and Annesley, 1. R., 1996: Petrography and geochemistry of the
granodiorites of the Sandy Islands gabbro cornplex, Wollaston Domain,
Saskatckewan. In: GAC-MAC program with abstracts, v. 21 , p. A6 1 .
Madore, C. and Annesley, I. R., 1998: Petrography, geochernistry and tectonic
significance of the Horton Island granite, Wollaston Dornain, Saskatchewan. In: GAG-MAC program with abstracts, v. 23, p. A1 1 5.
Madore, C., Annesley, 1. R., and Shi, R., 1996: Regional metamorphism in the
Wollaston Lake area, Wollaston Domain, Heame province, Saskatchewan.
In: GAC-MAC program with abstracts, v. 21, p. A61.
Matthews. R., Koch, R., and Leppin. M.. 1997: Advances in intergrated
exploration for unconformity uranium deposits in western Canada. ln:
Gubins, A. G. . (ed.), Proceedings of Exploration 97: Fourth Decennial
International Conference on Mineral Exploration, p. 993-1 024.
Maxeiner, R. O., 1996: Bedrock geology of the Henry Lake area (parts of NTS
64D-6 and -1 1). northem La Ronge Domain. ln: Sumrnary of Investigations
1996. Sask. Geol. Surv., Sask. Energy Mines, Misc. Rep. 96-4, p. 51 -65.
McCroçsan, R. O. and Glastier, R. P., 1964: Geologicel history of western
Canada: Calgary, Alberta, Alberta Society of Petroleurn Geologists. pp.
232.
Meyer, M. T., Bickford, M. E., and Lewry, J. F., 1992: The Wathaman batholith: a
short-lived Earîy Proterozoic continental arc in the Trans-Hudson orogenic
belt, Canada Geological Society of Arnerica Bulletin, v. 104, p. 1073-1 085.
Mitrovica, J. X., Beaumont, C., and Jarvis, O. T., 1989: Tilting of continental
interiors by the dynarnic effects of subduction. Tectonics. v. 8, n. 5. p.
1 079- 1 094.
Money, P. L., 1968: The Wollaston Lake fold belt system. Saskatchewan-
Manitoba. Canadian Journal of Eaith Sciences, v. 5. p. 1489-1 504.
0 Mossop, G. D. and Shetsen. 1. (cornp.), 1994: Geological atlas of the Western
Canada Sedimentary Basin. Calgary, Canadian Society of Petroleurn
Geologists and Alberta Research Counul, pp. 51 0.
Nelson, K. D., Baird, O. J., Waiters, J. J., Hauck, M., Brown, L. D., Oliver, J. E.,
Ahern, J. L., Hajnal, Z., Jones, A. G.. and Sloss, L. L., 1993: Trans-Hudson
orogen and Williston basin in Montana and North Dakota: New COCORP
deep profifing results. Geology, v. 21, p. 447.450.
Nemeth, B. and Hajnal, 2.. 1996: Structure of the lithospheric mantle beneath the
Trans-Hudson Orogen, Saskatchewan. In: Hajnal, Z. and Lewry, J. F.
(eds.) Trans-Hudson Orogen Transect meeting, LITHOPROBE Report t55,
p. 190-1 96.
Oidale, H. S. and Munday, R. J., 1994: Devonian Beaverhill Lake Group of the
Western Canada Sedimentary Basin. In: Mosop, G and Shetsen, 1.
(cornp.), Geological Atlas of the Western Canada çedimentary Basin, Calgary. Canadian Society of Petroleurn Geologists and AlbeRa Research
Council, p. 1 49-1 63.
Palmer. A. R.. 1983: The decade of North Amencan geology 1983 geologic tirne
scale. Geology, v. 1 1, p. 35-39.
Pavlis, T. L.. 1989: Middle Cretaceous orogenisis in the northern Cordillera; a
Meditenanean anaiog of collision-related extensional tedonia. Geology,
v. 17, p. 947-950.
Philippe, S. and Lancelot. J., 1988: U-Pb geochronological investigation of the
Cigar Lake U ore deposit, Saskatchewan. Chernical Geofogy, v. 70. p.
135.
Philippe, S., Lancelot, J. R., Clauer, N.. and Pacquet, A., 1993: Formation and
evolution of the Cigar Lake uranium deposit based on U-Pb and K-Ar
isotope systematics. Canadian Journal of Earth Sciences, v. 30, p. 720-
730.
Pinheiro, Fi. V. L. and Holdsworth, R. E., 1997: Reactivation of Archean stnke-
slip fault systerns. Arnazon region. Brazil. Journal of the Geological
Society. London. v. 154. n. 1, p. 99-1 03.
Poulton, T. P., 1984: The Jurassic of the Canadian western Interior, from 49ON
latitude to Beaufort Sea. In: Stott, D. F. and Glass. O. J.. (eds.), The
Mesozoic of middle North Arnerica. Canadian Society of Petroleum
Geologists, Memoir 9, p. 15-41.
Poulton, T. P., Christopher, J. E., Hayes, B. J. R, Losert. J.. Tiflemoie, J., and
Gilchrist, R. D.. 1994: Jurassic and lowermost Cretaceous Strata of the
Western Canada Sedimentary Basin. In: Mossop, G and Shetsen, 1.
(camps.), Geological Atlas of the Western Canada Sedimentary Basi n ,
Calgary. Canadian Society of Petroleum Geologists and Alberta Research
Cou ncil, p. 297-31 6.
PysWywec, R. N. and Mitrovica, J. X., 1997: The Role of mantle dynamia in the
Devonian to Carôoniferous subsidence of western Canada- In: Ross, G.
M. (comp.), 1997 Alberta Basement Transects workshop, LiTHOPROBE
Report #59, p. 81 -90.
Quinlan. G. M. and Beaumont, C., 1984: Appalachian thrusting, lithospheric
flexture, and the Paleozoic stratigraphy of the eastern interior of North
America. Canadian Journal of Earîh Sciences, v. 21. p. 973-996.
Rarnaekers. P., 1983: Geoiogy of the Athabasca Group, NENIAEA Athabasca
Test Area. h: Carneron, E. M.. (ed.) Uranium Exploration in Athabasca
Basin, Saskatchewan, Canada. Geological Survey of Canada, Paper 82-
1 1, p. 15-25.
Ramsay, J. G. and Graham, R. Hel 1970: Strain variation in shear belts.
Canadian Journal of Earth Sciences, v. 7, p. 786-813.
Ray, G. E., 1 978: Reconnaissance geology: Wollaston Lake (west) area (part of
NTS area 64L). h: Summary of l nvestigations 1 978, Saskatchewan
Geological Survey, Sask. Miner. Resour., Misc. Rep. 78-10. p. 25-34.
Ray. G. E.. 1979: Reconnaissance bedrock geology, Wollaston Lake east (part of
NTS area 64L). h: Summary of Investigations 1979. Saskatchewan
Geological Survey, Sask Miner. Resour., Misc. Rep. 79-10, p. 19-28.
Reinson. O. E.. Warters, W. J., Cox. J.. and Pnce, P. R.. 1994: Cretaceous
Viking ~omiation of the Western Canada Sedimentary Basin. h: Mossop,
G and Shetsen, I. (comps.), Geological Atlas of the Westem Canada
Sedimentary Basin, Calgary. Canadian Society of Petroleum Geologists
and Alberta Research Counal, p. 353-363.
Ross, G. M., Broome, J., and Miles, W., 1994: Potential fields and basement
structure - Western Canada Sedimentary Basin. h: Mossop, G and
Shetsen, 1. (comps.). Geological Atlas of the Westem Canada
Sedimentary Basin, Calgary. Canadian Society of Petroleum Geoiogists
and Alberta Research Counal, p. 41 -47.
Rutherford, R. L., 1954: Structurai interpretation of loci of petroliferous parts of
Devonian reefs in Edmonton area, Alberta, Canada. In: Clark, L. M., (ed.),
Western Canadian Sedirnentary Basin. Ralph Leslie Rutherford memonal
volume, Arnerican Assoaation of Petroleurn Geologists, p. 204-203.
Ruzicka, V., 1986: Uranium deposits in the Rabbit Lake-Collins Bay area,
Saskatchewan; In: Evans. E. L. (ad.). Uranium deposits of Canada, CIM
Spec. Vol. 33, p. 144-1 54.
Saskatchewan Geological Sutvey, 1994: Geology and Minerai Resources of
Saskatchewan. Sask. Energy Mines, Misc. Rep. 94-6, pp. 99.
Savoy, L. E. and Mountjoy, E. W., 1995: Cratonic-margin and Antler-age foreland
basin strata (Middle Devonian to lower Carboniferous) of the southern
Canadian Rocky Mountains and adjacent plains. In: St ratigrap hic evolution
of foreland basins. SEPM Spec. Pub. 52, p. 21 3-231.
Schwerdtner. W. M. and Hirsekorn. D, 1995: Structural analys& of the
Rottendone gneissea in the Birch Rapids StraigM Belt (BRSB) of northem
Saskatchewan: prelirninary results of 1994 field work. In: Hajnal. 2. and
Lewry, J. F. (eds.) Trans-Hudson Orogen Transect meeting. LITHOPROBE
Report #48, p. 1 1 1 -1 21.
Scott, B. P.. 1973: The geology of the Pendleton Lake area (west half),
Saskatchewan. Sask Miner. Resour., Rep. 154, pp. 58.
Sibson, R. H., 1990: Conditions of fault-valve behavior. ln: Knipe, R. J. and
Rutter, E. H. (eds.), Deformation Mechanism, Rheology and Tectonics.
Geological Society Spec. Pub. 54. p. 15-28.
Sibson, R. H., Moore, J., and Rankin. A. H., 1975: Seismic pumping - a
hydrothermal flua transpoii mechanism. Journal Geol. Soc. London. v.
1 31, p. 653-659.
Sibbald, T. 1. 1.. 1978: Geology of the Sandy Narrows (East) area, Saskatchewan
(NTS area 63M-3E). Sask. G d . Sun.. Sask Miner. Resour., Rep. 170.
Sibbaid, T. 1. 1.. 1979: NEAllAEA test area: basernent geology. ln: Summary of
Investigations 1979. Sask. Geol. Surv., Sask. Miner. Resour.. Misc. Rep.
79- 1 O, p. 77-85.
Sibbald, T. I . 1.. 1983: Geology of the Crystailine Basement. NENIAEA
Athabasca Test Area. h: Cameron. E. M. (ed.) Uranium Exploration in
Athabasca Basin, Saskatchewan, Canada, Geological Survey of Canada,
Paper 82-1 1, p. 1-1 4.
Sibbald. T. I . 1. and Petruk, W. (eds.), 1985: Geology of uranium deposits. CIM
Spec. Vol. 32. pp. 264.
Smith, D. G., 1994: Paleogeographic evolution of the Western Canadian
Foreland Basin. In: Mossop. G and Shetsen. l. (cornpilem). Geologicai
Atlas of the Western Canada Sedimentary Basin. Calgary. Canadian
Society of Petroleum Geologists and Alberta Research Counul, p. 277-
296.
Smith, M. T., Dickenson, W. R., and Gehrels, G. E., 1993: Contractional nature of
Devonian-Mississippian Antler tectonisrn along the North American
continental rnargin. Geology. v. 21, p. 21-24.
Sprinkel, O. A., 1992: Stratigraphie reinterpretation of a synorogenic unit of late
Early Cretaceous age. Sevier orogenic Wt, central Utah. GSA abstracts
with programs, v. 24, n.6, p. 63.
Stacey, J. and Kramers. J., 1975: Approximation of terrestrial lead isotopic
evolution by a two-stage model. Earth and Planetary Science Letten, v.
26, p. 207-221.
Stauffer, M. R. and Lewry. J. F.. 1993: Regionai setting and kinematic features of
the Needle Falls Shear Zone, Trans-Hudson Orogen. Canadian Journai of
Earth Sciences, v. 30. p. 1338-1 354.
Stockmal, G. S., Cant, D. J.. and Bell, J. S., 1992: Relationship of the
stratigraphy of the Western Canada Foreland Basin to Cordilleran
tectonics: lnsights from geodynamic rodels. In: Macqueen, R. W. and
Leckie, D. L., (eds.), Foreland Basins and Fold Belts. American
Association of Petroleum Geologists, Memoir 55, p. 107-1 24.
Stott , D. Fes 1984: Cretaceous sequences of the foothills of the Canadian Rocky
Mountains. ln: Stot?, O. F. and Glass, D. J., (eds.), The Mesozoic of middle
North Amerka. Canadian Sodety of Petroleum Geologists, Mernoir 9, p.
85- 1 07.
Suryam, J. V.. 1984: Seismic investigations on the perimeter of the Athabasca
Basin in northern Saskatchewan. (Wollaston Lake - Black Lake areas)
NTS 64L (part) and 74P (part). Sask. Geol. Surv., Sask. Energy Mines.
Rep. 21 68.38~.
Switzer, S. B.. Holland, W. G., Christie. D. S.. Graf, G. C., Hedinger. A. S..
McAuley, R. 3.. Wiezbicki, R. A. & Packard, J. J., 1994. Devonian
Woodbend-Winterburn strata of t ha Western Canada Sedimentary Basin.
In: Mossop, G and Shetsen, 1. (comps.). Geological Atlas of the Western
Canada Sedimentary Basin. Calgary. Canadian Society of Petroleum
Geologists and Alberta Research Council. p. 165-202.
Symons, 0. T. A-. 1991 : Paieomagnetism of the Proterozoic Wathaman batholith
and the suturing of the Trans-Hudson orogen in Saskatchewan. Canadian
Journal of Earth Sciences. v. 28. p. 1931 -1 938.
Symons. D. T. A-, 1994: Proterozoic rotation of the Peter Lake domain in the
Tram-Hudson orogen of Saskatchewan, Canada, deduced from
paleomagnetism. Precambnan Research, v. 69. p. 1 1-24.
Thomas, M. W., 1983: Compilation bedrock geology. Wollaston Lake. NTS area
64L. Sask. Geol. Surv., Sask. Energy Mines, Rep. 211, 1:250 000 scaie
map with marginal notes.
Tran, H. T., Lemy. J. F., and Ashton, K. E.. 1996: The geology of the Medicine
Rapids - Grassy Namws area. In: Summary of Investigations 1 996, Sask.
Geol. Suw., Sask Energy Mines, Misc. Rep. 96-4, p. 43-50.
Tremblay, L. P., 1982: Geology of the uranium deposits related to the sub
Athabasca unconformity, Saskatchewan, Geologid Suwey of Canada.
paper 81 -20.
Trocki, L. K.. Curtis. D. B., Gancarz, A. J., and Banar, J. C., 1984: Ages of major
uranium mineralization and lead loss in the Key Lake uranium deposit.
northern Saskatchewan, Canada. Economic Geofogy, v. 79, p. 1378-1 386.
Wallis. R. H., 1971: The geology of the Hidden Bay area, Saskatchewan. Sask.
Dep. Miner. Resour., Rep. 137,75p.
M Wallis. R. H., Saracoglu, N., Bmmmer. J .J., and Golightly, J. P.. 1983a:
Discovery of the McClean Uranium Deposits. In: Cameron, E. M. (ed.)
Uranium Exploration in Athabasca Basin, Saskatchewan, Canada,
Geological Survey of Canada, Paper 82-1 1, p. 51 -70.
Wallis, R. H.. Saracoglu, N., Bnirnmer, J .J., and Golightly, J. P., 1983b: Geology
of the W l e a n Uranium Deposits. In: Cameron, E. M. (ed.) Uranium
Exploration in Athabasca Basin, Saskatchewan, Canada, Geological
Survey of Canada. Paper 82-1 1, p. 71 -1 10.
Wilcox, K. H., 1991 : Geological relationships in the Wood Lake area, Tabbernor
Fault zone, Saskatchewan. In: Summary of Investigations 1991, Sask.
Geol. Surv., Sask. Energy Mines, Misc. Rep. 91-4, p. 135-1 43.
Wilson, M. R. and Kyser, T. K., 1987: Stable isotope geochemistry of alteration
associated with the Key Lake Uranium deposit. Canada. Economic
Geology, v. 82. p. 1540-1 557.
Windley, B. F., 1995: Evolving Continents (3rd ed.). John Wiley and Sons Ltd.
(London), pp. 526.
Wintsch, R. P., Christofferson, R., and Kronenburg, A. K., 1995: Fluid-rock
reaction weakening of fault zones. Journal of Geophysical Research. v.
100. n. 87, p. 13,021 -13,032.
Wright. G. N., McMechan, M. E., and Potter, O. E. G., 1994: :"wcture and
architecture of the Western Canada Sedimentary Basin. In: Mossop, G
and Shetsen, 1. (comps.), Geologid Atlas of the Western Canada
Sedirnentary Basin. Calgary. Canadian Society of Petroleurn Geologists
and Alber(a Research Council, p. 25-44).
