The Former Steep Rock iron mine is host to numerous piles of mine waste and tailings impoundments of varying mineralogy and complexity. It is located approximately 6 km north-northwest of Atikokan, Ontario. The two tailings areas studied at the Former Steep Rock iron mine imparted separate and unique chemical signatures on both groundwater and surface water. The reason for the chemical difference lies within the mineralogy at each site, as the mineralogy of the tailings directly controls the chemistry of both groundwater and surface waters. Iron oxide rich tailings produced sulphate-rich groundwaters with near neutral pH; however, these levels sulphate dramatically decreased in adjacent surface water. Pyritic tailings produced acidic groundwaters and surface water elevated in sulphate, major cations, metals (Al, Fe and Mn). Key parameters are elevated in groundwater relative to downgradient surface water receptors.  This difference is a result of either precipitation of various mineral phases or dilution from groundwater.

Chris is currently working as Project Manager with True Grit Consulting Ltd. in Thunder Bay

For more details about this thesis contact Dr. Andrew Conly

The Bruce Formation is adiamictite succession located in the lower-most portion of the Paleoproterozoic Quirke Lake Group, of the Huronian Supergroup.  The Formation is exposed on the north shore of Lake Huron, and covers an area east of Sault Ste. Marie to east of Sudbury, Ontario, Canada.  This assemblage of rocks represents deposition on a passive margin after initial rifting and volcanism at approximately 2450 Ma (Fralick and Miall, 1989).  The passive margin succession is composed of three glaciogenic cycles beginning with outwash sandstones, which are overlain by glacial diamictites and capped by marine deposits.  The Bruce Formation is situated above the Mississagi Formation, which commonly shows evidence of extensive soft sediment deformation of its cross-stratified sandstones (Fig. A).  These are also more rarely intruded by clastic dykes (Fig. B), orientated perpendicular to bedding and filled with diamictite.  The upper contact with the Espanola Formation is sharp and conformable. The Espanola represents the oldest cap carbonate known in the worldwide geologic record and may be evidence of a snowball Earth event.  The Bruce Formation was studied in detail in an attempt to understand the ambient conditions that were present at the time of its deposition.  The study included measuring and describing 16 detailed sections in the field, plus petrological and geochemical analysis of samples collected from the field areas. 

Glaciogenic deposits can be either terrestrial or marine and marine deposits can be further divided into three lithofacies zones: 1) the grounding ice line zone, 2) the floating ice-shelf zone, and 3) the proximal iceberg zone.  Deposits in each of these environments have distinctive characteristics that, where present, can be used to identify the depositional setting.  Most outcrop areas in the sections studied consisted of massive diamictite that contained considerable quantities of sand and only scattered pebbles and cobbles.  The thickness of the assemblage of diamictites making up the Formation varied drastically from section to section,with three less than 10 meters thick and others hundreds of meters in thickness.  Within these massive diamictites are areas with more distinctive features.  Lenses and layers of moderately well-sorted sandstone are not uncommon.  In other portions of the section mud layers and mud wisps highlight layering in the diamictite, and at one location a fine-grained succession within the diamictite contained a dropstone (Fig. C).  If other dropstones exist in areas of the diamictite they are commonly impossible to recognize without layering to deform. However, where clay-rich layers and wisps are present in the diamictite they can be seen to bend under and be terminated by penetration of dropstones.  Layers of pebbles and cobbles in clast support were more rarely present (Fig. D).  These represent deflation lags produced by current activity removing the fine-grained material.  Rarest of all were flat bottomed and convex-up mounds of pebbles and cobbles in clast-support approximately one meter across, although a larger deposit of this type may also have been present in one section.  Similar features are produced in modern environments by uneven melting of icebergs causing flipping and dumping of melt-out debris on their surface.  In Pleistocene successions diamictite deposited near the grounding ice line commonly contains subaqueous outwash sand layers and lenses.  The diamictite deposited below floating ice shelves is generally massive but has features, such as mud-rich layers and sand-rich layers, which indicate current activity.  Dropstones and deflation lag layers can also develop in this zone. The proximal iceberg zone can also be dominated by massive diamictite, which has a lower clast concentration, and also contains dropstones.  The most conclusive evidence of the iceberg zone is the presence of mound shaped iceberg dumps, which are created when an iceberg overturns.  This implies that large segments of the glaciogenic succession were deposited under floating ice with open water present in the basin. The open water is necessary to develop current activity.  Although this data does not negate the development of a snowball earth at some point during this glacial period it does not support it.

A unit of mafic rock inDevonTownship, south ofThunder Bay, was mapped by Tanton (1931) and was termed Rove Formation Basalts.  Geul (1970) mapped this unit as aLogandiabase sill.  The primary objective of this study was to characterize the unit and test whether it is of intrusive or volcanic origin.  This was achieved by mapping the unit at a scale of 1:20 000, and through petrographic and geochemical analysis.

The unit is exposed on a plateau 7 km long and 0.8 to 1.0 km wide.  The unit is 4 to 6 m thick and is in apparent conformable contact with the underlying shales of the Paleoproterozoic Rove Formation, where a pronounced chilled margin consists of variolitic material up to 20 cm thick.  The flow-top also exhibits a variolitic texture ~15 cm thick.  The presence of ropy flow top and amygdules as well as quench textures, support a volcanic origin. 

Major element chemistry reveals a tholeiitic, intermediate composition with samples plotting in the basaltic andesite to andesite fields as well as in the basaltic trachy-andesite to trachy-andesite fields on a TAS diagram.  The unit typically has an intergranular texture consisting of randomly oriented plagioclase laths with interstitial chlorite, an alteration product of primary augite.  Most samples contain minor serpentine (after olivine), opaque minerals, secondary quartz, oxides, pyrite and calcite.  Amygdules are present in most samples and are infilled with some combination of calcite, quartz, chlorite and pyrite. Lower flow contacts and flow-tops are typically glassy with abundant spherulites that sometimes coalesce into bands.

Rare-earth element geochemistry shows the unit to be relatively enriched in both HREEs and LREEs, similar to the ultramafic sills of the Nipigon Embayment as well as the Riverdale Sill (Hollings et al., 2007, 2009).  A primitive mantle-normalized REE plot shows that the volcanic unit  is characteristic of an Ocean-Island Basalt, but with a negative Nb anomaly, most likely the result of lower crustal contamination.  This evidence is further supported by an ∊_Nd(t=1100Ma) of -3.48, which also suggests contamination of the unit by a lower crustal source.  The trace element characteristics of the volcanic unit suggest an origin in Keweenawan time as they are geochemically similar to volcanic units of the MCR (Hollings et al., 2007) rather than Paleoproterozoic volcanic units of the Gunflint Formation.

Field, petrographical and geochemical analysis suggests that the unit is of volcanic origin with evidence towards emplacement during Keweenawan Midcontinent rifting.  Thus, we are proposing that the unit be renamed the Devon Volcanics.

Rob is currently working on his MSc thesis at Lakehead University

For more information about this thesis contact Dr Pete Hollings

The Riverdale Sill is located within the southern city limits ofThunder Bay. Although the sill consists mainly of gabbronorite, olivine gabbro can be found in a number of localities. The intrusive contact between the sill and the Paleoproterozoic Rove Shale is sharp and the chilled margins are only a few centimetres thick. The sill is exposed over an area approximately 6 km long and 2 km wide but the true thickness is unknown because the upper contact is not visible.

In comparison to other Midcontinent Rift-related intrusions, the Riverdale Sill is geochemically similar to ultramafic intrusions such as Hele and Disraeli (Hollings et al. 2007). Although it is found south ofThunder Bayit most closely resemble the Jackfish Sill of the Nipigon Embayment rather than the Logan and Nipigon Sills which surround it.

The Riverdale Sill crops out in a quarry on West Riverdale Road where it has an exposed thickness of 10 m.  Detailed sampling was carried out every metre up through the sill to investigate geochemical variations within it.  There is no geochemical evidence for fractionation within the sill which is supported by the absence of cumulate textures.

On a primitive mantle-normalised plot, a number of samples of the Riverdale Sill broadly resemble Ocean Island Basalts. However, some samples within the sill have negative niobium anomalies though geochemical evidence for contamination of the sill is localized to within less than 1m of the contact with Rove Shale. Therefore, this contamination is best interpreted to be the result of crustal contamination at depth. The less-contaminated samples are typically found towards the center of the sill. The geochemistry of the center of the sill varies slightly from that near the sill margins. Samples of gabbronorite taken adjacent to a shale xenolith within the sill do not display a negative Nb anomaly.  The lack of this anomaly, combined with the lack of contamination above the contacts in the sill at the quarry, supports a model in which contamination is occurring at depth rather than during emplacement.

Geochemical variations within the sill can be interpreted as the result of two pulses of magma, with the first more-contaminated pulse intruded by the second, less-contaminated magma shortly after the emplacement within the shale. The less-contaminated magma may have pushed the contaminated magma to the edges of the sill, leaving a less-contaminated core.

Pink granophyric features in some of theLogan sills, particularly in the Navilus sill, just west ofThunder Bay, were attributed by Blackadar (1956) to in-situ assimilation of granitic material.  Petrographic and geochemical studies have been performed on both the Navilus and Terry Fox sills, with a more modern approach, in order to re-evaluate Blackadar's hypothesis.

Two unique zones consistently appear around the xenoliths found in the Navilus sill: a zone of quartzo-feldspathic intergrowths, or "granophyre", directly adjacent to the xenoliths, followed by a zone of discreet pyroxene grains on the interface between normal diabase magma and the granophyric zone.  Similar granophyric formations are found interstitial to plagioclase and pyroxene grains, along with closely associated iron-oxides, both of which appear to have formed during the latest stage of crystallization due to the immiscibility of a silica-rich and an iron-rich liquid which exsolved from the magma.  The similarity between the granophyre observed around the xenoliths, and the late-stage "groundmass" granophyre indicates that the former was also formed due to liquid immiscibility.  Introduction of silicate-rich xenoliths to the already silica-saturated, quartz-tholeiitic magma has been proposed as the cause for the premature exsolution of silica and iron-rich liquids from the magma.

Spherules have been observed in close proximity to the xenoliths and granophyric zones, with carbonate nuclei and chlorite rims.  Due to the high melting temperature of carbonate minerals, it is unlikely that these were derived from a melt, and were more likely formed as carbonate xenoliths from the overlying Gunflint Formation recrystallized and interacted with the magma to produce spherical chlorite rims.

REE diagrams for both the Navilus and Terry Fox sills indicate that geochemical variations between the diabase with inclusions (such as xenoliths and spherules) and the normal diabase have been caused by late stage fractionation during crystallization.

Variable enrichment of LILs as seen in the Spider diagrams for both sills may indicate that in-situ assimilation has taken place, though variable depletion of HFSEs may indicate that these patterns also represent the effects of fractionation.

The basal contact of the Terry Fox sill with Rove shale (SM011) displays REE and Spider diagram patterns that differ from the normal diabase in that sill, which may indicate that in-situ assimilation has taken place, though a more detailed analysis is required to fully understand the role of assimilation in these sills.

Plotting the samples of normal diabase from both sillson Gd/Yb vs. La/Sm and TiO2 vs. Mg# discrimination diagrams has grouped the Navilus and Terry Fox sills with the Nipigon sills, contrary to their previous designation as Logan sills.

The Bird River Sill is an approximately 600 metres thick, layered ultramafic and mafic intrusion that is intermittently exposed over a strike length of approximately 20 kilometres in southeastern Manitoba, Canada.  Continental arc and intra-arc, rift-related magmatism occurred from 2.75-2.73 Ga and resulted in the intrusion of the Bird River Sill into the Rice Lake Group of the Archean Bird River Greenstone Belt (Sanborn-Barrie et al., 2001).  Initial interest in the mineral potential of the Bird River Belt resulted from the discovery in 1917 of nickel and copper sulphides in ultramafic rocks within the northern limb of the sill.  Economic interest in the sill has continued to the present with the main objective of this study being to determine if there any minerlogical indicators for nickel-bearing sulphide within drill core provided by North American Palladium Ltd. in the summer of 2005.

Petrology, X-ray diffraction (XRD) and scanning electron microscopy (SEM) shows that regional metamorphism in the Bird River area induced weak to strong alteration within certain ultramafic rocks.  Major alteration products include uralitization of pyroxene and serpentinization of olivine within peridotite intervals.  Clinochlore also commonly replaces ferromagnesium pyroxene and olivine in ultramafic.  Mineralized intervals from North American Palladium's 2005 drill holes showed increased abundances of actinolite and clinochlore.  Along with this increased alteration, the minor amount of remnant olivine crystals present in mineralized samples display a slightly rounded habit.  This contrasts with unmineralized, less altered intervals within the Bird River Sill.  These unmineralized intervals show slightly elongated and more abundant remnant olivine crystals.  Alteration between mineralized and unmineralized intervals also shows differences in the modal abundance of actinolite and clinochlore where there is decrease inabundance of both phases unmineralized sections.

The purpose of this study was to provide biogeochemical data for a remote sensing companion study.  Rock, soil, and foliar samples were collected from an area covering two contrasting rock types - metavolcanic rocks and metasedimentary rocks.  The study area was located in the south east portion of Quetico Provincial Park, Ontario.  The foliar samples collected were Abiesbalsamea (L.) Mill, Acer spicatum Lam., Betula papyrifera Marsh., and Thuja occidentialis L..  The whole rock composition of rocks and soils were determined using X-ray fluorescence.  Mineralogy of soils was determined using X-ray diffraction techniques.  Foliar nutrient compositions were determined using Inductively Coupled Plasma Spectrophotometry.  Levels of foliar nutrients appear to be controlled by an array of factors.  Trends are more evident for foliar nutrient levels growing on the relatively homogeneous metavolcanic rocks than on the more chemically complex metasedimentary rocks.  Possible effects of nutrient inhibition and pH inhibition appear on some trends.

The Otjikoto project in Namibia is an orogenic gold deposit situated in the province of Otjozondjupa, approximately 300 km north of the capital city of Windhoek.  Research for this thesis was carried out through the microstructural analysis of thin sections (obtained from Auryx Gold) that were collected from drill core.  The microstructures produced by deformation exhibited in the minerals of this deposit provide information about the relative timing of metamorphism, deformation, quartz veins and gold mineralization of the Otjikoto project.

The metapelitic Okonguarri Formation, host to the Otjikoto gold mineralization, contains evidence for peak metamorphism at the temperatures and pressures of the sillimanite zone of the amphibolite facies.  Grain-size reduction of feldspar indicates that mylonitization also occurred at amphibolite facies temperatures.  The formation also exhibits heterogeneous ductile deformation, specifically associated with the competent amphibole and garnet porphyroblasts, which occurred during synchronous metamorphism and ductile deformation.  The mineralized quartz veins are synorogenic as evidenced by both brittle and ductile deformation under at least greenschist facies metamorphism.  In particular, boudins of coarse-grained quartz (interpreted to be boundinaged quartz veins) indicate the mutual overprinting of brittle and ductile deformation which is characteristic of a shear-zone-hosted gold deposit.

Based on evidence for the synchronous metamorphism, brittle deformation and ductile deformation, and the synorogenic mineralized quartz veins, a shear-zone-hosted gold deposit model should be considered for the Otjikoto project.  

A genetic model for the localization of uranium mineralization related to the Proterozoic rocks of the Thunder Bay District was proposed by Franklin (1978).  This model was investigated in detailed examination of a breccia-type uranium occurrence referred to as the Innes Lake Radioactive Breccia.  The occurrence is situated in the Good Morning Lake fault which transects a late Archean quartz monzonite.

Observations are:

1. STRUCTURAL - The Good Morning Lake Fault strikes 330°.  It is characteristic of the regional early Keweenawan faulting and fracture systems proposed by McIlwaine et al (1974).  Detailed structural analysis indicates that this fault zone pre-dates late Keweenawan fractures which strike 60°.  These tensional fractures host the lead-zine-barite veins which are also found within the district (Franklin and Mitchell, 1977).
2. VEIN SYSTEM- The fault zone comprises fine to coarse grained, altered wallrock and siliceous vein fragments within a very fine-grained hematitic groundmass.  Fragments indicate multiple stages of vein formation including: injection of siliceous fluids, crystallization, and subsequent brecciation.  Common vein structures include comb-structure, and miarolitic cavities.  Tourmaline formed at an early stage in vein development along with milky quartz.  A cherty breccia and a hematitic breccia are late stage events which are post-dated by uranium-bearing fluorapatite mineralization.
3. MINERALIZATION - Detailed ground radiometric surveys indicates high uranium: thorium ratios.  Autoradiographs have delineated radioactive concentrations within hematite-enriched fractures within the hematitic breccia.  These uranium-bearing fractures crosscut this breccia, thereby suggesting that uranium introduction was a late stage event.  Anomalously high P₂O₅ values (greater than 3%) and x-ray analysis of the mineralization suggest that the uranium mineralization is mineralogically associated with phosphate within the apatite species.
4. ALTERATION - Alteration zones are pervasive in the quartz monzonite wallrock which envelopes the breccia and consist of sericitization, chloritization, and hematitization.  The alteration is associated with the early stage tourmaline mineralization.  Geochemical analyses for uranium in the wallrock suggest that the metal is not derived from the alteration zones.

The anomalous P₂O₅ values associated with the uranium mineralization stage suggest that local apatite-bearing uraniferous Archean pegmatites are the probable source rocks as proposed by Franklin (1978).  The role which the nearby Archean/Helikian unconformity at the base of the Sibley Group played with regard to this mineralized fracture is unclear but Franklin (1970) has suggested that other types of vein mineralization within the district are the result of precipitation from circulating groundwaters along the unconformity.

Gilbert J. Kahara - 1992

Recent studies have shown that remanent magnetization can be affected by tectonic deformation.  It can be reoriented by the effects of plastic strain.  Its magnitude may change also.  This project was undertaken to test the behaviour of remanence rotation and to determine whether it behaves as a passive line or a material line.  Two magnetic minerals, magnetite and hematite were suspended in silicone-putty.  The two rock analogues were individually given an isothermal remanent magnetization (IRM) and deformed by simple shear.  The results show that the IRM in each mineral rotates as a rigid line, although the IRM in hematite tends to behave as a passive line.  These results are perhaps explained by a microscopic examination of both magnetite and hematite, which showed that hematite was plate-like and magnetite was equidimensional.  IRM rotation was accompanied by a decrease in intensity due to grain-scale scattering of remanence directions.