The Thunder Bay Amethyst Mine is composed of vein and breccia mineralization, containing amethyst, colourless quartz, prasiolite and citrine.  The mine occurs in a strike-slip fault situated within a Archean batholitic intrusion of granodiorite.

During the present study fluid inclusions in amethyst indicated temperatures on the order 60 to 90°C during vein deposition.  Eutectic temperatures in fluid inclusions suggest the solution composition consisted of a CaCl₂ + NaCl system.  Salinity of the solution decreases in the direction of vein growth from 22.9 to 15.3 equiv. wt.% NaCl.  The presents of Na in the system may assist in the production of hole and electron colour centers by allowing for a charge compensation in the substitution of Fe³⁺ for Si⁴⁺ in the crystal lattice of quartz.  Variations in salinity in the direction of growth may reflect changes in amethystine colour density.

 Eh-pH conditions, calculated on the basis of paragenetic sequence within Cu-sulfide inclusions, suggest a reducing thrend during deposition.

Sulfur isotopic composition of pyrite in amethyst (delta³⁴S = -0.6 to -0.4) was compared to the sulfur isotopic composition of lead-zinc-barite veins in the Dorion area (delta³⁴ S = -0.1).  The similarity in isotopic signature suggest that both types of deposit have similar origin.

The paleo-declination and inclination measurements of the natural remanent magnetism of oriented samples taken along cores of glacial and post-glacial lacustrine sediments represent the magnetic conditions prevalent at the time of deposition.  As such, graphs plotting the change in declination and inclination with depth are records of the secular variations in the earth's magnetic field.  Similarities in the oscillations of these values noted for cores within the Goderich basin, as well as the Great Lakes system, mark layers of comparable ages.  Other paleomagnetic parameters, such as magnetic intensity (J), magnetic susceptibility (K), and Q-ratio (J/K) are also useful for time-parallel correlation and as stratigraphic markers, albeit to a lesser extent.

Sixteen cores of Late Quaternary lacustrine sediments from Lake Superior were collecting during the summer of 1983.  Paleomagnetic ages for post-glacial to glacial-varve contacts were determined by correlating with the paleomagnetic 'type' logs of Creer and Tucholka, 1982.  This provided insight into the rate of glacial retreat and also the post-glacial sedimentologic history of Lake Superior.

The rate of glacial retreat appears to have been uneven over time but generally followed a northeast direction.  Glacial varve deposition ended about 8700 years BP in the southeastern part of the lake and about 8000 years BP in the Nipigon Bay region.  Rates of sedimentation varied greatly throughout the lake but generally were related to the various lake phases of Lake Superior during post-glacial time.

The Coldwell alkaline complex was intruded into rocks of the Schreiber-White River belt, during the Neohelikian Subera.  The complex was emplaced in three distinct magmatic episodes, magmatic centers were displaced to the west with time.  Block Faulting has disturbed the geometry of the major rock units in the western and central regions of the complex. 

Syenitic rocks in the vicinity of Craddock Cove were formed by albitization of a monzonitic parent.  A basaltic xenolith, several square kilometers in area, was block faulted into the syenite.  Fracturing of the xenolith during its emplacement allowed contact metasomatism of the basalt.

Lamprophyre dykes associated with Center II magmatism, intrude the syenite.  These dykes show evidence that they formed as a result of magma maxing at depth.  Intrusion of the syenite by these dykes and petrographic features of the syenite, indicate it to be a Center I rock type.

The geology of the Thunder Bay area exhibits a sequence of flat-lying Proterozoic Aphebian sedimentary rocks essentially free from tectonic deformation.  These unconformably overly the Archean metamorphic rocks.

Within the Proterozoic sequence lies a pronounced, thin, stratiform lapilli tuff.  The tuff comprises crystal fragments, pumice fragments as well as accretionary lapilli and lapilli of other origins.

There has been a strong post-depositional compaction.  This was recognized from shape (strain) analysis of the accretionary lapilli and from the shape and orientation of the magnetic susceptibility ellipsoid.  A preliminary paleomagnetic investigation indicates a paleolatitude of the time of sedimentation (or diagenesis) of about 66°.

Detailed study of the sequence has indicated that it is characterized by intimately interbanded pyroclastic and epiclastic facies rock units.  The predominantly felsic (rhyolitic) to intermediate compositions of most of the rock units within the sequence indicate that, assuming a single source of rock material, that rock material was derived from an active volcano.  Primary depositional structures indicate that the sequence was deposited in a subaqueous environment of the flank of that volcano.

The presence of planar laminated and bedded ash flow tuffs, a planar laminated base surge deposit and an adjacently overlying coarse, felsic volcanic breccia indicate that the sequence was deposited as a result of intermittent periods of volcanism which probably varied from effusive to explosive in nature.  The presence of interbedded turbidite sediments and a graded, probably channelized conglomerate unit supports the intermittent nature of the volcanic activity.  Considered collectively, these facies indicate that the depositional environment of the sequence was analogous to a submarine fan environment.

The pyroclastic facies within the sequence have been compared to other similar deposits.  The planar laminated base surge deposit and overlying volcanic breccia have been interpreted to have been deposited simultaneously as two distinct facies of a single pyroclastic flow.  This interpretation is supported by the physical characteristics of the two units and grain size and composition analyses which were done on representative samples from these and all other pyroclastic units within the sequence.

The area is underlain by Archean sedimentary and volcanic successions and forms part of the Shebandowan-Wawa volcano-plutonic belt.  In the area the rocks have been subjected to three distinctive episodes of deformation.  Two phases of folding were followed by development of kink bands and a crenulation cleavage.  The first folding consisted of tight, recumbent folds with east-west trending axial traces.  The second phase of folding consisted of smaller, more open folds with northeast trending, steeply dipping axial traces.  The later kink bands formed only in rocks possessing a strong planar anisotropy.

The most abundant rock type present in the study area are greywackes.  These greywackes exhibit features characteristic of turbidites.  Framework minerals of these rocks consist primarily of felsic volcanic rock fragments.

The presence of coarse pyroclastic rocks interbedded with these sedimentary rocks is the result of contribution of detritus from multiple sources.

The metasedimentary unit at Little Dog Lake consists of schists and gneisses.  These rocks formed a layered regionally metamorphosed sequence with minor folds and late intrusions.

Parts of the metasedimentary unit are composed of angular to sub-angular clasts set in a medium grained matrix.  The clasts show a strong preferred orientation which parallels the structural foliation.

Chemical analyses show the clasts and matrix to be quite similar.  Geochemical data indicates the rocks to be pelitic in compositon.

Assemblages characteristic of the amphibolite facies were found.  These rocks constitute a medium to high pressure facies.  Field evidence suggests the granitic gneiss to be the oldest unit.  The dioritic intrusion which bounds the southern extent of the metasedimentary unit is relatively unmetamorphosed.  Petrographic data indicates this to be the last event to occur.

Well exposed, glacially polished iron formation outcrops near the town of Mellen, Wisconsin.  There, units form a portion o the western Gogebic iron range which strikes east-west through the area.  Iron formation exposure of this calibre is unusual in the Lake-Superior region and provides an opportunity to investigate physical and chemical sedimentary controls on accumulation of this type of sediment.

A 40 x 40 m section of iron formation composed of trough cross-stratified chert grainstones and parallel laminated slaty iron formation was mapped in detail.  The sequence is composed of three distinct stratigraphic units.  The first comprises 12 m of parallel laminated slaty iron formation with small chert lenses appearing at the bottom of the section.  The second is a 15 m thick succession of large trough cross-stratified grainstone lenses, some extending laterally 10-15 m.  The third unit lies immediately above the grainstone succession and is composed of 8 m of slaty iron formation.  Paleocurrent data is dominantly unidirectional from the north.

Slaty iron formation is dominated by parallel laminated beds 2-5 mm in thickness.  In regions where slaty iron formation coexists with small grainstone lenses the characteristic parallel lamination gives rise to wavy bedding.  Ripple lamination is present in the lowest stratigraphic unit.  Many beds are both physically and chemically graded.  Variations in the distribution of Al, Mn, Fe and Mg are seen within individual beds and throughout the entire span of the section.  Mineralogically, the dominant phases are hematite, magnetite and chert with minor amounts of greenalite, apatite and manganese oxide.  A few of the largest magnetite grains possess cores composed of ilmenite.

The trough cross-stratified chert grainstone lenses are composed of rounded chert and hematite grains ranging in size from 0.1 to 2 mm.  Many chert grains are coated with hematite, suggesting rolling by bottom currents through iron-rich muds.  The matrix is dominantly chert & calcite with traces of stilpnomelane.  Lenses range from 2 to 40 cm thick and may extend laterally 0.70 to 15 m.  The smallest grainstone lenses appear at the base of the section within slaty iron formation.  The largest lenses are found in the succession of trough cross-stratified grainstones.  Rip-ups of slaty iron formation, 1-3 cm in length, are common at the base of the largest lenses (30 cm thick, 8-11 m wide) at the top of the succession.

The section is characterized by a coarsening then fining upwards sequence in which muddy shelf deposits pass through ripple laminated fine sand into a succession of cross-stratified dunes, then back into muddy shelf deposits.  Both offshore bar complexes and tidally influenced, storm enhanced shelf deposits possess sedimentary structures similar to those described.  The thin ripple lamination in slaty iron formation in the lowermost slaty unit may represent sands moved by storm produced currents.  The dominantly unidirectional paleocurrent pattern is also indicative of storm enhanced currents.  Slumping is suggested throughout the sequence by the presence of extensive convolute bedded slaty iron formation.

A Middle Devonian carbonate-hosted lead-zinc-flourite occurrence was studied in northern Saskatchewan.  Drill core was obtained from Canadian Occidental Petroleum Limited, Minerals Division.  Because fluid inclusion temperatures of about 100°C were obtained, it is likely that these temperatures could only be achieved by pore fluids originating from a large basin outside the study area.  Fluids transporting lead and zinc likely used the Cambro-Ordovician sandstone as an aquifer.  The reason for precipitation of the sulphides specifically in the grey argillaceous bed of the Smoothstone River Formation is obscure.  It was found that mineralization from the study area has many similarities to that found in most deposits located in the Mississippi Valley area of the United States.