The Kenbridge deposit is a nickel-copper deposit hosted in a pyroxenite intrusion.  The country rock consists of pillowed mafic lavas, while the deposit consists of several gabbroic intrusions followed by a later pyroxenite intrusion, which hosts the mineralization.  The edges of the Kenbridge deposit have been altered to a talc schist.  This was originally believed to have been caused by a shear zone.  However, petrographic observations show that the transition between the pyroxenite to the talc schist is very gradual.  Therefore, it seems more likely the talc schist was created by metamorphic fluid and is an alteration product of the talc schist.  The idea of a metamorphic fluid is supported by the analysis of the variable nickel : copper ratio seen in the deposit.  The secondary ore minerals, which for the most part include chalcopyrite, showed a strong correlation with quartz.  The quartz is a secondary mineral which was brought into the system; therefore, it was concluded that the same method that brought the quartz into the system was also responsible for remobilizing the chalcopyrite.  The possibility that the system could have been altered by a metamorphic fluid is supported through SEM analysis and the creation of theoretical equilibrium reactions for the mineral assemblage using SupCRT92.  The SEM analysis was used to determine the chemical composition of the clinopyroxenes and amphiboles in the deposit.  It was established that metamorphic talc, tremolite and diopside were being created.  These minerals were used in the theoretical equilibrium reactions, and it was determined that first appearance of each of the three minerals represent its own pressure-temperature boundary.  More importantly, these reactions can occur at relatively low pressure and temperature ranges meaning that it is possible for thee reactions to have occurred in the Kenbridge deposit.

The Mackenzie Granite is a large granitic intrusion consisting of medium to coarse grained, pink to green granite composed primarily of oligoclase, microcline and quartz.  It is located within the Shebandowan-Wawa greenstone belt of the Superior Province where it is hosted by mafic to felsic volcanic country rocks and an amphibolite rock which may be contact metamorphic or later in origin.  The intrusion appears to be unconformably overlain to the south by Gunflint formation sediments.  The granite contains sparce xenolithic enclaves and is cut by a number of late stage dikes and later joints dikes and veins.

Detailed mapping and sampling of the granite, its immediate host rock, enclaves and dikes have been undertaken to ascertain the structure and internal fabric of the intrusion; the detailed petrology of granitic intrusive rocks, their enclaves and the possible source of such enclaves.

The instrusion contains felsci and mafic xenoliths which are representative of the contact metamorphic country rocks.  A single enclave sample of a chlorite litharenite containing oolitic fragments may represent a fragment of a Proterozoic paleosoil horizon.

The granite appears to have been intruded during the Archean Kenoran orogeny.  Structural data suggests that subsequent deformation and alteration of some areas of the granite, intrusion of later dikes and the origin of mineralized veins occurred during the Proterozoic.  Petrological evidence indicates that chloritic altearion of the granite may be genetically related to the formation of the mineralized veins.

This study investigates the environmental impact of pyritic waste dumps and associated catchment ponds at the southern portion of the Steep Rock mine site, an abandoned iron mine north of Atikokan, Ontario. The primary concern of these piles is the oxidation of pyrite and the production of acid rock drainage (ARD). In this study, only the top one meter of waste rock piles was sampled; thus the redox front was not transected and only materials within the oxidizing zone were studied.

The dominant mineral phases present in the waste rock piles are quartz, goethite and hematite. The presence of goethite and hematite stems partially from oxidation of pyrite to these iron oxides, although the majority of these minerals were present in the original mine wastes. The flow of contaminated groundwater produces precipitates in the waste rock materials and lake sediments. The primary product is gypsum; however, jarosite is also produced, although in lower abundances. Acid rock drainage contaminated water ultimately flows from the waste rock piles into adjacent catchment ponds via groundwater flow or surface runoff. These ponds consequently have serious water quality concerns, characterized by pH as low as 2.5, sulphate concentrations as high as 2000 mg/L and high concentrations of metals such as iron, calcium, magnesium, manganese, aluminum, nickel and zinc. In some areas, carbonate minerals are able to partially buffer the low pH.

The former mine pits at the Steep Rock site have flooded since mining operations ceased, and the lake levels continue to rise. The rising water level will ultimately flood the study area and result in the pit lakes merging, and this combined lake will eventually reach the former lake level. The presents a unique situation of a pit lake with a littoral zone, and in this case the littoral zone will consist of pyritic waste rock materials. This interaction of shallow, oxygenated water with the waste rock materials presents long term concerns about the potential for continued production of acid rock drainage, and the resultant water quality of the combined lake. 

For more details about this thesis contact Dr. Andrew Conly

The area of investigation is located in the Wabigoon subprovince of the Canadian Superior Province in Northwestern Ontario.

The rocks in the study area consist largely of graywackes of intermediate composition.

Turbiditic sedimentary features reflect a submarine fan environment.

The structure of the metasedimentary rocks is critically examined.

A well developed cleavage is present in the steeply dipping bedding planes of the sedimentary units.  The cleavage is shown to be axial planar to the dominant, sideways closing folds in the area.  Reversals in structural facing directions indicate that the cleavage developed in previously deformed rocks.  

A third deformation event produced locally occurring kink bands by shortening parallel to the bedding and the well developed cleavage in the rocks.

The Hamlin Lake area is located approximately 120km southwest of Thunder Bay, Ontario, in the Shebandowan Greenstone Belt of the Wawa Subprovince in the Superior Province.  The area has been explored for its copper and gold mineralization for more than 50 years, but has only recently been treated as an iron-oxide copper gold (IOCG) occurrence.  The aim of this study was to characterize the alteration at the occurrence through space and time, and to relate this paragenesis to the formation of mineralization.

Localized field mapping and re-logging of drill core established several relationships between styles of alteration.  Rocks were examined in hand specimen and thin section, and minerals were examined with scanning electron microscope (SEM) to identify mineral assemblages and associations.  Consistent variations in space could not be mapped, so textural relationships were used to relate the timing between six styles of alteration and the local brecciation that hosts the potential ore.  These are: (1) sodic, (2) early potassic, (3) calcic(-iron), (4) late potassic, (5) carbonate, and (6) silicic.

Sodic alteration is largely composed of albitisation, and is occasionally conserved in fragments of the breccia.  The early potassic stage of alteration consists of biotite and magnetite in the matrix of the breccia, which is cross-cut by epidote and sphene from the calcic(-iron) stage.  Sodium cobaltinitrite staining was used to identify potassium feldspar alteration associated with mineralization of the late potassic stage.  The mineralization in this stage is represented by the assemblage chalcopyrite + pyrite + magnetite.  This first stage of mineralization was succeeded by carbonate precipitation, and finally by a second stage of mineralization associated with a vuggy quartz breccia.

The two phases of mineralization are primarily different in that stage I mineralization is associated with potassic alteration and iron-oxide mineralization, whereas stage II mineralization is associated with quartz and has a general lack of massive iron-oxide.  The alteration leading up to the first stage of mineralization, and the stage I mineralization itself are consistent with the general alteration patterns observed in other magnetite-group IOCG deposits worldwide.  The onset of carbonate alteration, followed by vuggy quartz with moderate- to high-sulfidation assemblages of stage II mineralization, is more typical of an epithermal environment.

Thermodynamic parameters of the mineralizing fluids were ascertained by the use of fluid inclusions.  Fluid inclusions from the vuggy quartz associated with stage II mineralization were analyzed and suggest a low-salinity fluid with a temperature in the approximate range of 200° to 250°C responsible for mineralization.

Stable oxygen isotopes from chlorite, magnetite and sulphur isotopes from sulphides were measured to establish the source of the fluids responsible for the formation of the deposit.  Oxygen from the magnetite of early mineralizing assemblages has a narrow range of values for δ¹⁸O_water from +8.9€ to +10.9€.  These are indicative of a deep-seated metamorphic or magmatic source for early fluids.  Oxygen from chlorite associated with the later stages of mineralization have a wider range of δ¹⁸O_water values (+0.4€ to +5.9€), which may suggest that meteoric or other crustally derived fluids played a role in stage II mineralization.  δD values were measured on the chlorite as well; however, these may have been reset by later metasomatic events.  Sulphur isotope values from mineralization were measured (δ³⁴S -6.9€ to +1.8€), and indicated that an exotic sulphur source probably played a role in mineralization.  

The most common dyke rocks in the Coldwell Alkaline complex are lamprophyres associated with Centre 2 magmatic activity.  Samples of analcite tinguaites, sannaities and ocellar lamprophyres were analysed by Neutron Activation Analysis.

Distribution patterns of rare earth, incompatible and transition elements define a comagmatic series from parental mafic ocellar lamprophyres to evolved analcite tinguaites.  A proposed petrogenetic scheme involves 86 percent batch fractionation of mafic magma in deep seated "plumbing" systems to produce the felsic rocks.

The Kama Hill Formation of the Sibley Group has been sampled in detail at Albert Lake, Kama Hill and Stewart Lake.  Depositional microtextures such as interbedding of reworked and undisturbed laminae, soft-sediment deformation and clay galls suggest tidal flat sedimentation.  However, crossbeds, flaser bedding and substantial current ripple marks are not observed - thus, convincing evidence of tidal activity in not documented.

Salt casts, authigenic microcline, thomsonite and mixed-layer clay minerals point to a warm, semi-arid climate and a high pH, saline depositional and post-depositional environment.  Such a climate is consistent with paleo-equatorial position of the Sibley depositional site as preposed by Robertson (1973).

The purpose of this study was to estimate the relative accumulation rates of different sediment types within the Lumby Lake and Finlayson Lake Greenstone Belts.  Platinum group element (PGE) geochemistry (specifically iridium values), major and trace element geochemistry, cosmic element abundances, and a constant influx of extraterrestrial material for the Earth were used in calculations to determine the sedimentation rate.  Sedimentation rates calculated represent minimum values due to a probable decrease in cosmic influx rates through time.  Ascertaining the relative sediment accumulation rates for various lithologies, especially of certain chemical sedimentary units not presently forming represents an important advance in our understanding of Mesoarchean depositional systems.

Different types of iron oxides occur in the oceanic rocks, found in the ophiolites of Cyprus, at different stages of alteration at varying depths and distances from the fossil spreading axes.  The distinct Curie temperatures and susceptibilities are identified by tests done on the Curie Balance and the susceptibility-temperature apparatus, respectively.

Cyprus provides a perfectly exposed ophiolite and various parts to study the ocean floor structure of part of the Cretaceous Neotethys Sea.  The ocean floor structure is generally as follows: a harzburgite and lherzolite mantle at its core, an overlying, discontinuous gabbroic complex, succeeded by a large sheeted dike complex topped by pillowed volcanics and a sedimentary succession.  The Troodos ophiolite is thought to have had three fossil spreading axes that were of intermediate spreading rate, around 50 to 150mm/year.

From Troodos there were six mantle sequence rocks and eight sheeted dike complex rocks used in the Curie balance.  Nine of the Troodos mantle rocks and ten from the sheeted dike complex were used for the low temperature (77K to 300K) susceptibility variations with temperature experiments.  The high temperature (300K to 900K) susceptibility variations with temperature experiments involved five Troodos mantle specimens and five sheeted dike complex specimens.  From Akamas eight samples were used in the Curie balance, ten in the low temperature susceptibility experiments and five used in the high temperature susceptibility variations with temperature tests.

It is concluded that the sheeted dike complex underwent more alteration than the mantle sequence rocks of Troodos and Akamas.  The Akamas ophiolite mantle sequence shows more oxides to indicate more alteration when compared to the Troodos mantle sequence rocks.  In the mantle sequence, magnetite is the most common with a Curie temperature of 582°C in the Curie balance and a range of 855K (582°C) to 885K (612°C) in the susceptibility versus temperature apparatus.  TM60 is found in both the Troodos and Akamas mantle sequence rocks, but more frequently in the Akamas specimens.

In the sheeted dikes, TM60 was found to be fairly constant in the high temperature susceptibility experiments.  The unblocking temperature for titanomagnetite, TM60 was established to be in the range of 410K to 440K.  The unblocking temperatures for magnetite were between 850K (577°C) and 890K (617°C).  The more often a specimen was heated, the more pronounced the presence of the magnetite became.  Specimens would start out with three to five transitions and after one or two more heating treatments all transitions were removed except the Tc for magnetite.  The Tc would also decrease in temperature by small increments after each heating.  Two samples from the sheeted dike complex in Troodos ophiolite was heated and one from the Akamas mantle sequence.

The Rossport Formation stratotype, located on Channel Island near Rossport, Ontario, may be subdivided into eight distinct lithostratigraphic units.  The lower six units, which belong to the Lower Member of the formation, consist primarily of dolomite, sandy dolomite, and arenite.  The Central Member is composed of cryptalgal and banded chert-carbonate, and the Upper Member consists of crudely banded dolomite.  The red colouring of the carbonates is due to a diagenetic hematization process.

The Rossport Formation, at Channel Island, appears to be representative of a Neohelikian shallow shelf sea environment which became shallower and more restricted as deposition progressed.