The Quetico metasedimentary subprovince and the volcanic-plutonic Shebandowan belt to the south meet along an east-west steeply dipping boundary that is believed to have been affected by dextral transpressional deformation.   It is also parallel to a steep metamorphic gradient from greenschist facies rocks to the north.

Macroscopic petrofabrics are difficult to observe along the belt to the west of Thunder Bay but magnetic susceptibility fabrics (low-field) are quite consistent.  These define a gently plunging extensional fabric parallel to the belt boundary.  Within the Kashabowie area, general field observations of subhorizontal stretching (and intersection) lineations, and cleavage directions are in agreement with magnetic susceptibility axis directions.  Mineral separation reveals that all samples have multiple sources of magnetic susceptibility, dominated by metamorphic phyllosilicates.  Consequently it is not possible to simply quantitatively relate the magnetic fabrics to strain magnitudes although the magnetic fabrics accurately monitor significant kinematic directions.  Analyses of strain of low-grade detrital quartz grains, magnetic fabrics and general field observations recognize flattened oblate fabrics.  Moreover oblique, subhorizontal lineations favour a transpressive kinematic model with compression normal to the belt boundary.  The obliquity between mineral and magnetic lineations seem to indicate dextral transpressive deformation.

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Paleomagnetic studies indicate the Meguma terrane's final emplacement occurred between the Mid-Devonian and Early Permian.  Lithostratigraphic units near the boundary of the terrane were investigated in order to provide constraints on the timing of this compressional event.

North of the Cobequid-Chedabucto Fault (Guysborough Basin), volcanic flows, pyroclastics and related sediments are overlain by gravelly to sandy braided fluvial and lacustrine lithofacies.  East-southeast paleocurrents and variable (non-Meguma) clast lithologies are typical of these units.  South of the Cobequid-Chedabucto Fault (St. Mary's Basin), coarse cobble - rich to sandy braided fluvial lithofacies are dominant.  Paleocurrents indicate flow to the north and clast lithologies are representative of the Meguma terrane.

Post Acadian (Late Devonian) basement fragmentation and associated volcanism modified the area noth of the Cobequid-Chedabucto Fault.  Basement block rotation, east end down, initiated Latest Devonian through Mid-Carboniferous sedimentation in a transtensile tectonic environment.  There is no lithostratigraphic evidence to suggest the presence of the Meguma terrane immediately south of the Guysborough Basin during this time interval.  However, the Meguma terrane was supplying sediment to the St. Mary's Basin by the Early Carboniferous.  Collison and wrench faulting probably initiated formation of this basin in a transtensile tectonic environment.  Subsequent dextral displacement along the Cobequid-Chedabucto Fault and transpressive tectonic conditions resulted in the removal of slices of both the St. Mary's and Guysborough Basins as these two distinct assemblages were juxtaposed.

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Accessory rare mineralization has been investigated in seven lithologies in intrusive Centres I and III of the Coldwell alkaline complex.  All units contain minerals that are enriched in a suite of granitophile elements, which typically include Nb, REE, Y, Th, U and Zr.  Mineral abundances, composition, and mode of occurrence differ between units.

Centre III is characterized by crystallization of subhedral-to-euhedral chevkinite, pyrochlore and monazite from late-stage melts or residual pore fluids in the more-evolved quartz and ferro-edenite syenites.  These minerals are invariably altered to fluorocarbonate or recrystallized by later F^- and CO₃^2- - bearing deuteric fluids.  The Centre I, ferroaugite syenite minerals exhibit similar morphological and replacement of plagioclase and amphibole by K-feldspar, zircon, fluorocarbonate, Nb-rutile (?), allanite, and rare chevkinite.  Fe-rich fluids under oxidizing conditions are believed to have precipitated Fe³⁺ - bearing fluorocarbonate in which one third of the (REE^.)F layers are replaced by Fe³⁺ layers. 

Most Centre I rare earth minerals are enriched in the HREE relative to those from centre III, in particular pyrochlore, fluorocarbonate, allanite in the eastern contact pegmatites and the quartz syenite dykes.  Compositional data for adjacent syntaxial intergrown domains of bastnaesite, synchysite, and parasite indicate that HREE-enrichment may, in part, be influenced by the Ca content of the species. 

The highest contents of Ce (4193 ppm), Zr (1613 ppm), Y (650 ppm), Th (223 ppm) and U (428 ppm) were found in the quartz syenite dykes intruding the Craddock Cove syenite and Port Munroe megaxenolith.  The emplacement of the quartz syenite dykes and the introduction of the metasomatizing fluids of the Craddock Cove syenite may be temporally related to the differentiation of residual fluids in the apical zone of the Centre I magma chamber.  Complexing of F^- and CO₃^2- with rare metals may have permitted their concentration, transportation and precipitation in structurally favourable settings.  The megaxenoliths have been susceptible to brittle fracturing and should be considered primary targets for further exploration.  The Craddock Cove syenites, although intruded by the dykes, may have been hot during dyke emplacement and therefore not as prone to brittle fracturing.

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Calcite Portland-cement aggregate samples were deformed triaxially at 25E with confining pressures of 200 Mpa.  The samples were deformed under experimental approximations of pure shear (dry and wet experimental conditions), transpressional shear and simple shear.   The pore fluid pressure during the wet pure shear test was less than 195 MPa.  Extensive grain rotation accompanied by twinning of the calcite grains occurred.

Optical analyses of calcite crystallographic fabrics have been used to infer the orientation of the maximum principal compressive stress (F₁).  Stress orientations in the deformed specimens agree well with the externally imposed stresses.  A new method has been successfully used to determine the F₁ orientation.  The method used contouring of the lamellae index associated with the compression direction determined from Turner's Dynamic analysis method.

In pure shear, preferred dimensional orientation (PDO) of the calcite grains are produced more efficiently in the presence of a pore fluid pressure.  In dry specimens, transpressional shear is more effective in producing a PDO in the calcite grain than either pure shear or simple shear.  Grain shape fabrics do not conform to the symmetry of the bulk deformation when extensive rotation of calcite grains is involved.  Mean grain alignment is perpendicular to the shortening in pure shear, initially inclined and later parallel to the shear zone wall in transpressional shear, and inclined to the shear zone wall in simple shear.  The mean orientation of the grain-alignment fabrics is, therefore, a reliable kinematic indicator under the conditions investigated.  Transpressional shear and dry pure shear exhibit higher lamellae indices than either wet pure shear or simple shear. 

Strain analysis of calcite grains by Robin's method (1977), the linearization method (Yu and Zheng, 1984) and Harmonic mean method (Lisle, 1977) yields overestimates of the experimental bulk strain in wet pure shear.  These methods fail to take into account interparticle motions that occur in the presence of a high pore fluid pressure.

The triaxial deformation of the Ancaster oolitic limestone was performed with a confining pressure of 200 Mpa, a natural strain rate of 10^-5/s and at a temperature of 135EC.  The samples were deformed under dry and wet experimental conditions.  The pore fluid pressure, during the wet test, was less than 60% of the confining pressure.   

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Anisotropy of magnetic susceptibility (AMS) has become a widely accepted method of fabric analysis in rocks, especially those which have been deformed tectonically.  The use of anisotropy of complex magnetic susceptibility (ACMS) is a new potential method of fabric analysis in which the imaginary, or out of phase A.C. component of an induction coil used for the measurement of magnetic susceptibility is used to delineate rock fabric.  Complex magnetic susceptibility is a function of electrical conductivity, thus making it potentially useful in the analysis of highly conductive sulphide-rich rocks, some of which are not suitable for AMS analysis.

A supracrustal sequence of rocks near Manitouwadge, Ontario consists of metavolcanic rocks, including pillow lavas, banded iron formation, amphibolite, and a quartzofeldspathic hornblende-biotite gneiss.  This rock has been given the name bladed gneiss to reflect the blade-like appearance of its mafic components.  Results of a detailed geological investigation of the entire supracrustal sequence suggests that the apparent fragmental appearance of the gneiss, and to a lesser degree the other rock types, is not a primary feature, but rather, the product of deformation.  The rocks were initially part of a layered sequence which became variably fragmented.  The blades are in part the result of the transposition of layers and the variations in blade morphology are attributable to the response of the layers to strain during folding.  Individual layers deform by the development of cuspate-lobate folds, buckle folds, and boudinage.  The extent of fragmentation during deformation is controlled by competency contrasts between adjacent layers, absolute and relative layer thickness, and layer orientation with respect to principal finite strain directions. 

Planar and linear structural elements in the metasedimentary and metavolcanic rocks suggest a deformational history which includes two episodes of folding accompanied by medium grade metamorphism and recrystallization.  Similarities in lithology and structural elements between the rocks of the study area and those of the nearby Manitouwadge synform suggest that parent rock assemblages were closely related and that structures present in both locations developed contemporaneously in response to regional tectonic activity.  "Mobilist" tectonic models for the development of the Superior Province entail northward directed subduction and accretion, and are popular with many workers.  The recumbent nature of F₁ folds, the shallow plunging hinge lines of F₂ folds, and their coaxial relationship may be related to low angle thrust faults and nappe structures which would be likely consequences in the proposed subduction model.

Many workers have attempted to map subprovince boundaries.  In the region of the present study, the boundary between the Wawa and Quetico Subprovinces is traditionally placed a few miles north of Manitouwadge.  If this is correct, the rocks studied form part of the Wawa Subprovince.  Results of this investigation suggest that, on the basis of lithology and structure, such a placement of the boundary is inappropriate.  It appears more appropriate to suggest that the terrain discussed in this thesis, as well as the rocks of the Manitouwadge synform, is best considered to form a zone of transition between the two subprovinces.

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The comparison of three mapped successions in northern Ontario to glacial deltas reviewed in the literature results in the definition of four end-member depositional environments for glacial deltaic sedimentation.  Similar processes of sedimentation occur within two main glacial delta types, distal-fed, and ice-contact.  Distal-fed deltas divide into nonglacial and ice-influenced.  The other two end member types defined are subglacial and supraglacial ice-contact deltas.

Fine-grained laminated beds sedimented by interflows and overflows, as well as diamict and subaqueous outwash deposits underlie the glacial deltaic sequences.  The prodelta region consists of multiple reverse-graded beds, massive units, and laminated sediments deposited from interflows and overflows, and minor rippled units indicating intermittent underflows.  Within the delta front underflows deposited rippled and graded units, and occasionally planar cross-stratified units were sedimented by grainflows.  The delta plain contains trough cross-stratified sands and gravels which infill multiple distributary channels.  Dropstone deposition was restricted to the prodelta and delta front regions of ice-influenced distal-fed deltas, and ice-contact deltas.

Distributary mouth bars, large scale cyclic sedimentation, subaqueous outwash systems overlain by a glacial deltaic sequence, multiple processes of sedimentation within the delta front, and reworking of glaciogenic deposits have not previously been documented in glacial deltaic systems.   These deposits and processes, as well as the inability to define the strandline position indicated glacial deltaic systems are complex.

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The Quetico subprovince is a northeast-southwest striking linear belt of migmatites, gneisses, and metasedimentary rocks.  These Archean rocks form part of the southern Superior Province.  This study involves an examination of variations in metamorphic grade along cross-strike transects in an area north of Thunder Bay, Ontario.

The rocks of the Quetico subprovince include metasedimentary rocks with well preserved primary structures, knotted schists, gneisses, migmatites, and anatectic granitic rocks.  Metamorphic porphyroblasts include muscovite, biotite, garnet, staurolite, cordierite, andalusite, and sillimanite.  Chemical analyses of garnets, geothermobarometry, and mineral assemblage data were used to determine variations in metamorphic grade in transects across the subprovince.

Mineral assemblages characteristic of low to high grade metamorphism are exposed along an across-strike transect.  Metamorphic grade rises gradually from low grade (521°C) to high grade (714°C) northwards along Highway 527.  North of the peak conditions, the grade drops off sharply.  Garnet-biotite geothermometry confirms this pattern.  Maximum pressure reached in the study area is approximately 5 kbar.  

The model proposed to account for the distribution of metamorphic assemblages and minerals involves transpression of the Quetico accretionary prism between the Wabigoon volcanic cratonic margin to the north and the docking Wawa volcanic complex to the south.  Buckling and folding of the sedimentary rocks was accompanied by thrusting.  Erosion has exposed high grade migmatitic and anatectic rocks within the Quetico fold belt which developed as a result of thermal relaxation of depressed isotherms.  The boundaries between metavolcanic and metasedimentary terranes are structurally complex.  Boundaries may be best described as geometrically complex zones up to several kilometres in extent in which various rock types representative of the adjacent terranes have been folded, faulted, and intruded.

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The Seine Group metasedimentary rocks are situated between two converging major dextral transcurrrent faults, the Quetico Fault to the north and the Seine River Fault to the south.  To the west lies the Bad Vermilion Intrusive Complex (B.V.I.C).  The Seine Group shows one major period of deformation resulting in major F₁ folds.  Regional metamorphism of chlorite to biotite zone greenschist facies was synkinematic with the deformation.  Later minor deformation include localized crenulation cleavage and faults and shear zones.

Strain analysis of deformed conglomerates indicates 50-67% shortening in a north-south direction.  The B.V.I.C. has behaved rigidly during the deformation and produced a strain shadow in which only 18-42% shortening has occurred, deflected to a WNW-ESE direction.

The schistosity has an average trend of 252.3/85.7°NW, and the average trend of the stretching lineations is 063.4/43.4°.  However in the strain shadow of the B.V.I.C. the strikes are deflected to the NNE.

The AMS fabric in the Seine Group is controlled by paramagnetic chlorite and biotite.  The AMS foliation has an average orientation of 251.6/81.4°NW.  The AMS lineation has a peak trend of 059.7/41.7°.  The AMS ellipsoids are mostly oblate, with the least anisotropic fabric located in the strain shadow.  The AMS fabrics are deflected in the strain shadow of the B.V.I.C. in the same sense as the schistosity.

The anisotropy of isothermal remanent magnetization (ASIRM) of each sample was determined, using a saturating field of 500 mT, and then repeated at 800 mT.  The ASIRM fabric in the Seine Group is controlled by the ferromagnetic minerals magnetite and pyrrhotite.  The ASIRM lineation has a peak trend of 060.3/33.3°.  These fabrics are deflected in the same sense as the schistosity in the strain shadow of the B.V.I.C.

Although the three steep planar fabrics measured are similar in orientation, they are offset in plan view.  The angle between the schistosity and the AMS foliation is 4.4°.  The angle between the AMS and ASIRM foliation is 4.2°.  The schistosity, defined by deformed quartz and feldspar, is the oldest fabric.  The AMS fabric is younger, as the chlorite and biotite formed during metamorphism.  The magnetite and pyrrhotite which define the ASIRM formed later still, and thus represent the youngest fabric.

The successive offsets between the three fabrics is consistent with a dextral transpressional strain history operating throughout the fabric development.  The strain history had components of simple shear and non-coaxial shortening.  The initial shortening probably took place in a SE-NW direction.

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The metasedimentary rocks along the traverse reveal low to high grade metamorphism from chlorite schist near Atikokan, through biotite schist to migmatites in the west within the centre of the Quetico Belt.  Continuing toward the ESE, near Huronian Lake, the metamorphic grade decreases symmetrically but with somewhat less steep gradients to Kahabowie.  The metamorphism was syn- to late-tectonic.

Only one pervasive tectonic fabric was observed in the interior of the belt, with NE-SW striking S₁ foliations (mean direction:  256/85°NW, n=121) and extension lineations L₁ plunging shallowly to the NE (mean direction:  70-20°, n=52).  In migmatite and pegmatite zones foliation was often less steep.  It was probably deflected due to the intrusion of pegmatite or granitoid bodies.

Minerals contributing to ferromagnetic properties are mostly monoclinic ferromagnetic pyrrhotite within the belt with some magnetite in medium grade amphibolite - rich outcrops in metavolcanics of Shebandowan Belt.

Anistropy of magnetic susceptibility fabric (AMS) is mainly controlled by paramagnetic biotite or chlorite and subordinate ferromagnetic pyrrhotite in metasediments of the Quetico Belt.  In some outcrops of mafic metavolcanics near Kashabowie, the high magnetite content controls bulk susceptibility more than its anisotropy.  Variations in AMS fabric are largely due to variations in relative composition of magnetite, pyrrhotite and paramagnetic sheet silicates, not due to changes in strain along the traverse.

AMS foliations and lineations within the belt and on its south-east margin are generally coaxial with tectonic fabric, with AMS foliation less steep (dip of 70°) in the interior of the belt.  However a slight (2-5°) anticlockwise offset of the mean AMS foliation from S₁ can be postulated in the centre of the belt and at the southern margin.  When fabric data is studied separately for each sample, such offsets are not significant.  In the Atikokan area, AMS fabric is partly of sedimentary origin.  The offset of mean AMS lineations with respect to L₁ was confirmed for the Kashabowie - Huronian Lake area (also reported by Borradaile and Spark, 1990) but it is not prominent in the centre of the belt.

Anisotropy of remanence based on acquisition of anhysteretic remanence (AARM) is controlled by preferred crystallographic orientation of pyrrhotite in metasediments and partly by preferred dimensional orientation of magnetite in metavolcanics.  It is substantially higher than AMS fabric (mean P' of order 3 to 5).  AARM foliation is usually oriented closer to the tectonic fabric than AMS foliation; it is vertical at the margins and less steep in the centre of the Belt.  AARM lineations usually plunge more gently than tectonic and AMS lineations in the centre of the Belt and at the southern margin in the Kashabowie - Huronian Lake area.  At the northern margin, AARM fabric is highly oblate, so that fabric lineations are difficult to define. 

At the belt margins, a slight anticlockwise offset of AARM foliations with respect to the tectonic fabric exists, when fabrics for individual samples are examined.  However, the relative orientation of tectonic and magnetic fabric (AMS and AARM) are not a region - wide consistent kinematic indicator of dextral transpression.

Correlation studies between magnetic susceptibility and ARM intensity indicate that a monotonic correlation between ARM and MS exists only in the Calm Lake - Perch Lake area, in which pyrrhotite controls ARM.  In other areas a higher content of magnetite increases magnetic susceptibility in several samples, but not ARM.

Both magnetic fabric (AMS and ARM) are usually oblate in low grade metasedimentary rock (at the Belt margins), but in metavolcanic rocks magnetite can produce prolate ARM, but in metavolcanic rocks magnetite can produce prolate ARM, whereas ARS is oblate.  In the interior of the Belt, 50% of samples have prolate AARM, but most of them are pyrrhotite-bearing.

The AARM fabric is believed to have arisen by the growth of ferromagnetic grains (at least in case of pyrrhotite) in the later stages of transpressive penetrative deformation with a dominant dextral shear component of deformation along an ENE - SWS, vertical plane.  The preferred orientation of pyrrhotite grains was probably controlled by the older biotite - chlorite matrix fabric.  This would explain the lack of a more significant deflection of the youngest ARM fabric from the oldest tectonic fabric.  However, the accuracy of determinations of ARM axes (at least 5-10°) limits the validity of these conclusions.

Characteristics directions of magnetic remanence obtained during thermal or AF step-wise demagnetization form a weakly developed girdle along the basal plane of ARM anisotropy.  Therefore natural remanent magnetization is probably entirely of chemical origin and controlled mostly by high anisotropy of pyrrhotite and its preferred crystallographic orientation.  The orientation of NRM toward basal plane of ARM is believed to be mostly an effect of deflection from the true Earth's magnetic field direction due to anisotropy of pyrrhotite (P' of values of 3-5, Fuller, 1963), and not the effect of grain rotation.  Stress control of post - metamorphic remagnetization of  primary ChRM is also a possibility.  Therefore, it is suggested that NRM was acquired in the same late stage of deformation as AARM, when sizes of individual ferromagnetic grains were suitable to carry a stable remanence.  Any primary magnetization acquired at the time of rock formation was not preserved.

The model of different ages of development of paramagnetic and ferromagnetic fabric is consistent with the dextral transpression model of the deformation for both margins and the fabric of the Quetico Belt.  The latest ferromagnetic sub-fabric formed along the shear plane when the paramagnetic matrix was already oriented subparallel to this plane and mimetically controlled the orientation of crystallization of ferromagnetic phase.  The ferromagnetic fabric is not therefore useful as a kinematic indicator of shear component in those areas.

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