Scott J. Mooney HBSc thesis abstract

Thesis Title: 
Geochemistry of Mica From Some Australian Lamproites and Some MARID-Suite Xenoliths, Bultfontein, South Africa
Scott J.

Phlogopite mineral separates from five samples of lamproite, three MARID suite rocks, and a sample of metasomatized lherzolite were studied with respect to major and trace elements as determined by instrumental neutron activation analysis.

High K/Cs ratios and similar K/Ba and Rb/Cs ratios were found in lamproitic samples whereas lower K/Cs and more variable ratios were found in MARID suite micas.  The elements Rb, K, Mn, and Co were similar but Sc, Cr, Cs, and Ba were significantly different for phlogopites from these two rock suites.  Most noteworthy are Cs and Ba, the former being less abundant in lamproites due to its large ionic radius and volatile nature, which is believed to be indicative of source differences between these rocks and those of MARID suite composition.  Any possible relationship must be complex in order to account for variations in geochemical nature found with respect to phlogopite mineral separates.

In addition, amphibole and clinopyroxene mineral separates were prepared from the MARID suite samples.  These were analysed for REE by radiochemical neutron activation analysis using the oxalate precipitation method.  Instumental neutron activation analysis data was used in the determination of chemical yield for this experiment.

Similar REE distribution patterns were produced to those determined by Kramers et al. (1983).  The clinopyroxenes contain a much higher absolute abundance of the REE and define a much wider range of REE enrichment than was obtained by Kramers et al. (1983).  Two liquids of different REE content but with similar elemental ratios are thought to have generated the MARID suite composition.  This is believed to have occurred by open system crystallization with loss of a fugitive phase from an intital melt approximating kimberlite composition (Kramers et al., 1983).

David M. Gauthier HBSc thesis abstract

Thesis Title: 
Magmatic flow from magnetic fabrics in the Sheeted dike complex, Troodos ophiolite, Cyprus
David M.

Orientation distributions of crystals were determined for 291 samples of the Sheeted Dike Complex of the Troodos ophiolite, located on the island of Cyprus.  These were inferred from anisotropy of magnetic susceptibility (AMS), anisotropy of anhysteretic remanent magnetism (AARM), and natural remanent magnetism (NRM).  From these data the dispersion of magmatic flow fabrics with a mild tectonic overprint were recognized.

The study area (~60km2) is located near the Arakapas Fault Belt (AFB), a fossil transform fault in the Western Limassol Forest Complex, which was responsible for the tectonic overprint.

The predominantly magmatic AMS fabrics combine normal, inverse, and tectonic components, making the interpretation of magmatic flow ambiguous.  NRM vectors, both before and after low-temperature demagnetization (LTD), generally trend north, and show an anticlockwise tectonic offset progressively with distance from the AFB.  AARM fabrics do define magmatic flow in the dikes, which in all sub-areas was steeply up and to the southwest.  This indicates that the magma chamber that fed these dikes must have been located somewhere to the north (present co-ordinates) of the study area.  These results imply localized magma chambers, thereby supporting the slow-spreading origin of the Troodos crust.

John McBride HBSc thesis abstract

Thesis Title: 
Investigation of the Magnetite Olivine Coarse Grained Gabbro Units of the Eastern Gabbro, Marathon, Ontario

The investigation of the Magnetite-Olivine Gabbro unit within the Eastern Gabbro of the Coldwell Alkaline Complex was carried out in order to determine whether the Magnetite-Olivine Gabbro unit was petrogenetically related to the EG.  Petrographic analysis of the mineral phases and textures of the newly defined magnetite-olivine coarse grained gabbro was undertaken to determine if it is a subunit of the Easter Gabbro or petrogenetically a separate unit similar to other gabbro units in the area, such as the Geordie Lake Intrusion or the Two Duck Lake Intrusion.  Petrographicly the Magnetite-Olivine Gabrro is a distinct unit showing an increases grain size, magnetite banding, plagioclase alignment and mineral components which are not seen in the Eastern Gabbro such as biotite, apatite and chalcopyrite.  Using SEM-EDX, both the Eastern Gabbro and the Magenetite-Oliving Gabbro were analyzed revealing that all major components were compositionally similar suggesting the same parent magma.  Relative to the other gabbroic intrusions into the Eastern Gabbro the Magnetite-Olivine Gabbro shows little to no correlation to that of the Geordie Lake Intrusion however, it is similar in some respects to that of the Two Duck Lake Intrusion, but is more evolved.  In reference to mineralization in the Magnetite-Olivine Gabbro there was no visible PGM, however, there was an increase in chalcopyrite.

David Gauthier MSc thesis abstract

Thesis Title: 
Magnetic Fabrics from Sheeted Dikes Reveal Regional Magma Flow Patterns, and the Spacing and Dimensions of Ophiolite Magma-Chambers, Troodos Ophiolite, Cyprus

Orientation-distributions of crystals were determined for 1289 specimens of the Sheet Dike Complex of the Troodos ophiolite, located on the island of Cyprus.  These were inferred from anisotropy of magnetic susceptibility (AMS).  From these data the dispersion of magmatic flow fabrics with a mild tectonic overprint were recognized.

The study area (~400km2) is located to the east of Mt. Olympus, and adjacent to a fossil transform fault (STTFZ) that was responsible for shearing of dikes and a change in their orientation from predominantly north-south to east-west as the fault is approached.

The predominantly magmatic AMS fabrics blend a flow-aligned paramagnetic component from mafic silicates with a ferromagnetic component from titanomagnetites.  The inclination of magma-flow axes varies from near vertical to near horizontal throughout the area with predominantly steep magma flow regions separated from regions with predominantly shallow magma-flow.  Fast Fourier Transform (FFT) analysis of steep-flow region spacing shows that the magma chambers that fed the dikes were point-source with minimal along-axis extent, and very short lived.  FFT wavelength calculations suggest that they may have been spaced approximately every 4km along the ridge, and every 100,000 to 250,000 years in time.  These results imply localized magma chambers, thereby supporting the slow-spreading origin of the Troodos crust, and refine models for slow-spreading ridge processes to include a point-source magma delivery system between magma reservoirs and the sheeted dike complex.

Keith David Peden HBSc thesis abstract

Thesis Title: 
The Metamorphic Character of the Boundary Between the Quetico and Shebandowan Structural Subprovinces, Shabaqua, Ontario
Keith David

In this study, a traverse is taken across the boundary between the Quetico gneiss belt and the Shebandowan - Wawa volcano-plutonic belt as established by previous workers.  The detailed mapping was carried out at Shabaqua, Ontario, approximately 55 kilometers west of the City of Thunder Bay.

Three different rock types are recognized at the outcrop scale.  They are:  1/  conglomerates,  2/  metapelites and interbedded arenites, and 3/  biotite schists.

Towards the south end of the map area is a polymict conglomerate with clasts up to 25 centimeters in length.  The matrix is a coarse lithic greywacke.

A metasediemntary sequence of metapelites with minor interbedded arenites occupies the central portion of the map area.  The metapelites are fine grained, dark grey foliated rocks.  The arenite are light coloured and display relict sedimentary textures.

The biotite schists, in the northern end of the map area, are foliated, porphyroblastic rocks.  Sedimentary textures are not observed.

Microscopically, seven mineral assemblages are identified, defining three metamorphic facies.  In the conglomerate and part of the metapelites, lower greenschist facies is represented by the assemblage; quartz-plagioclase-chlorite.  The upper greenschistfacies is outlined within the metapelites by the diagnostic mineral assemblages of; quartz-plagioclase-biotite and quartz-plagioclase-biotite-garnet.  Four assemblages define the lower amphibolite facies in the metapelites and biotite schists.  They are:  quartz-biotite-cordierite, quartz-biotite-cordierite-garnet, quartz-biotite-muscovite-garnet, and quartz-biotite-muscovite-staurolite.

Based on textural and mineralogical work, the metamorphism across the boundary appears to be gradational and continuous.  The boundary is not a discrete line but rather, a transition zone.

Mike Maric MSc thesis abstract

Thesis Title: 
Sedimentology and Sequence Stratigraphy of the Paleoproterozoic Rove and Virginia Formations, Southwest Superior Province

The Paleoproterozoic Rove and Virginia Formations are lithostratigraphically and chronostratigraphically correlative units which comprise the upper sedimentary strata in the Animikie basin.  They sharply overlie an intensely altered zone within the upper Gunflint and Biwabik iron formations that was subaerially exposed by compressional forces during the Penokean Orogeny.  Dating of volcaniclastic zircons from the upper Gunflint yielded a pre-Penokean age of 1878 Ma.  Tuffaceous layers very near the base of the Rove and Virginia Formations provided U-Pb zircon ages of approximately 1835 Ma placing commencement of sedimentation into the newly resubmerged basin during the final stages of Penokean igneous activity.

This study involved examination of 3200 m of drill core from eleven continuously drilled holes and one twiced drilled hole extending over 424 km from south of Duluth to south of Thunder Bay.  Observation of the lithofacies present and their stratigraphic relationships provided insight into the depositional environment as well as the tectonic regime operating at the time.

The basal Rove and Virginia Formations were deposited as transgression progressed across the depressed basinal area.  They consist of black, carbonaceous shale with thin interbeds of siltstone, very-fine grained sandstone and friable green tuffaceous layers, possibly contributed by volcanic activity within the Penokean terrain.  From approximately 5 m above the base, siltstone and sandstone layers gradually diminish in frequency upward, until the succession is almost completely dominated by approximately 100 to 150 m of fissile black shale.  Microscopic examination of thin sections of this unit revealed the presence of very thin shale laminae and other laminae composed of angular silt grains or microlayers consisting of carbon.  This sediment - starved, condensed sequence developed with increasing water depth, and with anoxic conditions probably caused by high organic loading in the bottom sediments.  A siltstone and very-fine grained sandstone-rich unit traceable across the basin occurs midway through the shale-dominated succession.  This coarser unit thickens near both the northern and southern margins of the basin.  Above it another coarser-grained interval within the shale-dominated succession is observed in the southern third of the basin, probably representing sediment contributed by Penokean sources to the south.  A gradational transition between the shale and an overlying sandstone-shale unit occurs over 80 m in the north, thinning to the south.  The upper sandstone-shale unit varies in thickness, with a maximum of 350 m, and consists of over one hundred individual coarsening upwards parasequences.  The individual packages are composed of graded, commonly massive, fine-grained sandstones separated by shale layers millimeters to centimeters thick.  Shale units separating the parasequences are decimeters to one or two meters in thickness.  The sandstone-shale assemblage fines to the south.  Approximately 500 m above the base of the section the uppermost unit is dominated by lenticular bedding of fine-grained sandstones in the black shale, with both current and wave ripples present.  The entire succession represents the transition from a sediment-starved basin, with exceedingly slow deposition rates, to active deltaic progradation with sediment probably derived from the Trans-Hudson orogenic zone to the north.

Steven Therrien's HBSc Thesis Abstract

Thesis Title: 
Mineralogy and Geochemistry of Possible Iron Formation at The Red Lake Mine, Ontario

The Red Lake Mine, located approximately 560 km northwest of Thunder Bay, Ontario, contains three possible iron formation units that reside in the metamorphosed, Archean tholeiitic volcano-sedimentary Balmer assemblage within the Red Lake greenstone belt part of the Uchi Subprovince of the Superior Province.  These three units were investigated to determine if the units are indeed iron formation.  

Forty-three samples were collected in total from 16, 21 and 46 levels of the Red Lake mine's Balmer Complex.  Forty-three thin sections and whole-rock geochemical analysis were used to define the mineralogical and geochemical characteristics of all three units.  X-ray diffraction was used in conjunction with petrography to confirm mineralogy.

Samples consist of sulphide-rich and sulphide-poor bands macroscopically and microscopically.  Sulphide-rich bands consist of mainly pyrite and pyrrhotite while sulphide-poor bands mainly consist of quartz, muscovite and chlorite.  All three units display slight positive Eu anomalies and fractionated LREE<HREE profiles indicative of hydrothermal input and characteristic of ancient Archean iron formations.  All three lithologies contain a large proportion of detrital material with 16 and 21 level containing the highest proportion and 46 the lowest.  46 level has the highest proportion of metalliferous material of all three lithologies.

It was determined that 16 and 21 level samples did not meet the criteria to be called iron formation, but rather these levels correspond to metalliferous sediments.  On the other hand, 46 level samples correspond to sulphide facies Algoma-type iron formation that have been diluted by detrital sediment.  Geochemical data from the surrounding area suggests that the major source of detritus is calc-alkaline in origin with some mixing with an unidentified additional source lithology (ASL) enriched in Th and HFSE elements.