The Thunder Bay Amethyst Mine Panorama boasts one of the largest occurrences of amethyst in the world with two distinct generations of veining.  These two generations of veins display vastly different colours, with the first generation veins being colourless and the second generation displaying a purple colour.  It is hypothesized within this thesis that the second-generation veins bleached the first generation veins during their deposition.

A series of heating experiments were conducted to determine how amethyst colour changed with respect to heat and time.  Amethyst samples used for experimentation were collected from the main fault and cut into 15 by 9mm slabs.  These samples were examined using a photospectrometer before and after each heating interval.  The results were then graphed by examining the absorbance of light against energy of light; spectral peaks representing colour centers known to cause amethysts purple colour were then fitted.

Samples were heated at temperatures of 350°C, 300°C and 250°C using a tube furnace attached to a digital temperature interface until colour was complete lost.  Samples heated at 350°C and 300°C became bleached quickly at periods of 1 and 3 hours respectively.  Extended heating of samples at 250°C resulted in no colour loss after a time period of 622 hours.  Peak fitted photospectropic  scans were then examined after each subsequent heating period and compared to the scans before colour loss occurred.  These results decreasing Fe⁴⁺ colour centers when samples lost colour and no change in colour centers when colour loss did not occur.

The stability of colour within amethyst at temperatures lower than 260°C can be attributed to a lack of energy required to overcome the activation energy barrier.  It has therefore been determined that the deposition of second-generation veins likely did not cause bleaching of the first generation veins.

This pegmatite occurrence is part of the Georgia Lake Rare-Element Pegmatite Field of the Quetico Subprovince, NW Ontario, and is related to Stype, peraluminous Georgia Lake granites. The Georgia Lake pegmatite field is approximately 32 by 105 km wide, and is hosted entirely within the clastic metasedimentary rock of the Quetico Subprovince.  There have been 38 rare element occurrences discovered, including 10 spodumene-bearing occurrences, with approximately 11.7 million tons averaging 1.14% lithium oxide.  The 2670 +/- 2 Ma Glacier Lake Batholith extends greater than 100 km NE into the Quetico Subprovince, and has been interpreted to be the result of partial melting, creating the associated S-type granites of the Georgia Lake pegmatite field.

The Rock Tech Li pegmatite occurrence fits into the classification of albite-spodumene-type pegmatite. The associated dykes and veinlets are not heavily fractionated or diverse from the pegmatite body.  The aplite veins represent a fine- grained assemblage of the Rock Tech Li pegmatite with no exotic mineralogy.  The veins emplaced and expanded pre-existing fractures.

The Sharpsand River IOCG prospect is located within the southern Algoma district, of the western Abitibi terrane, in the Archean Superior province.  This study integrates field mapping, petrography and x-ray diffraction analysis to determine; mineralogy, the controls on mineralization, the paragenesis of the prospect and to constrain an appropriate deposit model for the Sharpsand River prospect.  It has had previous exploration work completed in 1962 consisting of trenching, magnetometer surveys and 297 m of diamond drilling.  Assay results from the trenches and diamond drill holes averaged 1.18% Cu throughout, and a maximum value of 5.40%.

Five lithologies were identified within the study area, consisting of Algoma monzogranite, Keweenawan diabase intrusives, quartz veins, silicified breccia and quartz/diabase breccia.  The Algoma monzogranite is the host rock in the study area and is comprised of weakly foliated, coarse- to medium-grained plagioclase, microcline, quartz and minor biotite.  The Keweenawan diabase dikes consist of 5 to 50 m vertical dikes intruding the monzogranite at a northwest-southeast trend, and are related to the Mackenzie dike swarm.  The dikes are comprised of fine-grained, massive plagioclase, pyroxene and finely disseminated magnetite.  After the intrusion of the Keweenawan dikes, the area underwent regional greenschist metamorphism, altering pyroxenes to clincochlore, forming selectively pervasive sericite alteration and causing recrystallization of primary quartz and magnetite.  The quartz veins occur in a northeast-southwest trending fault zone through the topographic low in the middle of the study area.  Silicification of the fault zone occurred penecontemporaneously to faulting.  The quartz veins consist of coarse-grained, euhedral quartz with minor clinochlore and chalcopyrite, with common open filling textures.  The silicified breccia unit represents the area between the intersections of diabase dikes and the barren quartz vein, characterized by 60-90% quartz by modal composition, with strongly altered diabase fragments and shear textures.  The quartz/diabase breccia occurs at the intersections of the diabase dikes and quartz veins, and is comprised of equal proportion of vein fill, dominated by quartz, and angular diabase clasts.  This unit hosts the strongest chalcopyrite and hematite mineralization.  The chalcopyrite and hematite mineralization was precipitated by late stage hydrothermal fluids, which intruded the fractured quartz veins and through oxidation of primary magnetite in the Keweenawan dikes, concentrated the mineralization in the quartz/diabase breccia unit.  Controls on the mineralization have been determined to be the presence of magnetite bearing diabase dikes, the northeast-southwest trending fault zone, silicification of the fault zone and the hydrothermal fluids to concentrate the mineralization.

The IOCG deposit model in the broadest sense is applicable to the Sharpsand River prospect.  The prospect fits the IOCG deposit model due to: (1) presence of copper and trace gold, (2) hydrothermal ore styles and strong structural controls, (3) abundant magnetite and hematite and (4) no clear spatial associations with igneous intrusions.  To constrain a specific IOCG deposit subtype, more research should be conducted through geochemical analysis to determine (1) the presence of LREE enrichment and low S sulphides, (2) the range in depth of formation of the prospect and (3) the Fe/Ti ratios of the Fe oxides.  Further exploration work would also be required to determine if the copper and gold are present in economic quantities.

The Hindon prospect is located on two leucocratic to mesocratic gabbro sills located 185 km north of Toronto Ontario. The sill has been interpreted as having evolved in the central gneiss belt during the Grenville orogeny. The Hindon property has historically been described as a folded gabbro sill, this is hard to reconcile due to an obvious lack of metamorphic texture. Since copper sulfides were discovered on the property in the 1950’s various work has been performed with in the property. Assays have shown a mix of promising copper results as well as possible PGE mineralization. Little is known about the structure and genesis of the gabbro; however, the two zones of the property show distinctly similar characteristics and therefore most likely share the same genesis. Copper mineralization is abundant but disseminated throughout the property. It is likely that the historically accepted mode of genesis for the gabbro with in the Hindon property is inaccurate, it is very likely that the gabbro intrusion occurred after the Grenville Orogeny. 

The Dickenson-Campbell diorite (DCD) is a lithological unit that is exposed at surface on and around the Red Lake Gold Mines (RLGM) near the town of Red Lake, Ontario.  The DCD has had an uncertain past with geologists using a variety of naming schemes for these rocks since their initial description in the 1940’s.  The goal of this thesis was to properly classify the DCD using modern geochemical methods combined with mapping and petrography.  Mapping was undertaken on all exposed DCD within Balmertown where structure and lithology were noted in detail.  Samples of the outcrop, as well as near-surface intersections of drill core were taken for geochemistry and petrography.  Analysis of the data that was obtained showed that the DCD is not an intermediate intrusive lithology.  Petrographic analysis revealed an abundance of glass and / or very fine-grained silica and carbonate mineralogy.  Not only was the very fine grain size an indicator of petrogenesis but the resemblance to the regional and underground basalts also helped refute the diorite theory.  Major and trace element geochemistry showed that all DCD outcrop and drill core samples were tholeiitic basalts and basaltic-andesites, with MORB-like signatures.  Mapping of the area provided an idea as to the stratigraphic relationship between the pillowed basalts and the DCD exposed at surface on the mine site.  Only one unit had well preserved pillows these showed evidence of south-western topping direction (towards the DCD).  The presence of narrow shear zones and conjugate fractures led to the conclusion that there has been an effect of pure shear on these rocks, likely due to regional scale deformation.  Samples taken from various areas in the Balmertown area revealed that there is a variation in the degree of alteration affecting the DCD.  The alteration is the most extreme near the base of the unit, where it is in contact with the underlying basalts.  The black ilmenitic flecks, commonly used as an identifier for the DCD, are the coarsest and most obvious where carbonatization and silicification of the rocks is the strongest.  This has led to the conclusion that the DCD is a rock type that is contiguous with the underlying Balmar assemblage basalts.

Neepawa Island, located within the Sioux Lookout greenstone belt of the Western Wabigoon subprovince has been an area of several historical gold occurrences over the past century.  In this study, structural controls of gold mineralization are assessed with an emphasis on microstructural analysis.  The study area on west Neepawa Island is situated at the southern edge of the central volcanic belt, approximately 12km southeast of Sioux Lookout, Ontario near the center of Minnitaki Lake.  Locally, the study area hosts intermediate pyroclastic and mafic volcanic flow units displaying brittle and ductile deformation, pervasive hydrothermal alteration, and metamorphism to the greenschist facies.  Microstructural analysis concluded that gold mineralization is related to non-coaxial deformation of north-south striking, steeply dipping vein set 1, the oldest vein set at the study area.  Gold is concentrate where deformation is greatest in the quartz-carbonate vein and adjacent pyritic halo, approximately parallel to the regional foliation.  Gold mineralization is hosted in microstructures such as subgrain ribbons and microfractures in the quartz veins, as well as microfractures and pressure shadows associated with pyrite.  These brittle and ductile microstructures were produced from competency contrasts during deformation between the mesothermal quartz-carbonate veins, metavolcanic host rock, and syn-deformational pyrite.  Gold-hosting microstructures may be controlled by deformation caused by the sinistral-reverse displacement related to the regional Ruby Island Fault system.

St. Andrew Goldfield’s Holloway mine is located along the dextral transpressional steeply south dipping, east to west striking Porcupine Destor Deformation zone. Heterogeneous brittle-ductile deformation characterizes the structural environments that host economical gold mineralization within the Smoke Deep ore zone.  Gold mineralization is associated with three different microstructural settings all of which accompany pyrite mineralization.  Favorable depositional sites include synkinematic veins, rheological boundaries and felsic lithologies.  These settings occur locally within medium-grained to coarse-grained spherulitic felsic lithologies that create competency contrast with the neighbouring southern and northern schistose units.  The ore units are interpreted as hypabyssal intrusions of albitite composition, with associated aplite pods. Constituent phenocrysts of the albitites retained their relict shape evident of competency contrast between itself and neighbouring volcanic lithologies.  During deformation the formation of microfractures in competent pyrite porphyroblasts aided in the development of low-pressure structural localities conducive to the accumulation of gold from auriferous-carbonate-rich metamorphic fluids.  The neighboring schistose units effectively envelope the ore lithologies and are characterized as mylonitized mafic volcanics and metasediments.  Metamorphic temperatures within the zone reached lower amphibolite facies conditions indicated by amphibolite textures including kink banding of feldspars, specifically of albite, and the development of subgrains from relict albite and potassium feldspar phenocrysts.

A lamproitic igneous occurrence was recently discovered by a prospector working in the area to the north of Marathon, Ontario.  It occurs near a large number of features related to the 1.1 Ga Midcontinent Rift such as the Coldwell Complex and the Trans-Superior Tectonic Zone, but no radiometric dating has been completed on this particular unit of rock.

At outcrop level, the unit appears as a collection of metre-scale mafic sills within granitic country rock.  These sills appear on all sides of a large lake, marking the lake as the likely location of the main body of the lamproitic rock.

The rock is composed of a variety of minerals, including forsteritic olivine, diopside pyroxene, sanidine feldspar, and a variety of spinels. Later periods of magmatism contributed secondary apatite and phlogopite.  At the same time, the volatile-rich fluids produced by the magma created a variety of alterations, such as serpentine, chlorite, and carbonate, and heavily disrupted the primary minerals in the rock.

This rock retains a classification as a paralamproite, with a mineral assemblage that cannot fulfill the defined composition of lamproite due to geochemical differences between definition and observed samples.

Deformation in the Animikie Group near Thunder Bay is characterized by intense, localized fold-and-thrust belt deformation within units that are otherwise relatively undeformed and flat-lying.  This deformation is interpreted to be the result of regional stress during Proterozoic tectonism.  Stereographic analyses of structural measurements and outcrop observations are used to determine beta-axes (mean fold axes) for fold populations, as well as to determine structural relationships within the region.  Two main fold populations are observable in the data.  The primary population exhibits a north-south trending beta-axis, indicating east-west compressive stress.  The secondary population exhibits an east-west trending beta-axis, indicating either north-south compressive stress or the presence of lateral ramps.  Slickenlines are also observed to trend north-south and east-west, depending on outcrop location.  East-west trending slickenlines tend to be in areas of more intense folding, indicating they may be older than the north-south trending slickenlines.   Older slickenlines may have been destroyed when fault surfaces were reactivated in areas of less intense folding replaced by the slickenlines associated with the most recent deformation.  Additional observations include the presence of fold-hinge breccia associated with non-cylindrical folding, which may indicate lateral ramp formation, as well as the presence of a possible cleavage duplex structure, which may indicate repetitive east-verging thrusting.
These observations suggest that the deformation of the Animikie Group began with regional east-west compression resulting in the development of an east-verging thrust belt.  Stresses associated with this thrust belt are interpreted to have resulted in fault-bend folding on frontal and lateral ramps in the region.  Most of these folds are included in the population with north-south trending axes, although lateral ramps on this thrust sheet likely resulted in the development of folds with east-west trending axes, as well as non-cylindrical folds and fold-hinge breccia.  East-west trending slickenlines on thrust faults were also developed during this compressive deformation.  Subsequently, north-south compression may have overprinted this deformation, developing folds with east-west trending axes and north-south trending slickenlines on fault surfaces, though not in areas of intense folding (indicated by preservation of east-west trending slickenlines).  Finally, north-south directed extensional deformation deformed the area, resulting in normal faulting and the reactivation of fault surfaces in areas not intensely folded.  This caused the development of north-south trending slickenlines on new and reactivated fault surfaces.  A specific tectonic history for the Animikie Group is suggested based on these observations and interpretations.  It is proposed here that primary east-verging thrusting was associated with the Trans-Hudson orogeny in the Paleoproterozoic.  Following this, there may or may not have been a secondary compressional phase due to the Yavapai-Mazatzal orogenies during the early to middle Proterozoic; the effects of these orogenies remain unclear.  Deformation likely culminated in the late Proterozoic with north-south extension related to the Mid-Continent Rift.