A reconnaissance of five silver-bearing veins between Schreiber, Ontario and Marathon, Ontario indicate that the Pb-Zn-Ag veins in this area are genetically related.  The three veins of this type that were studied (the Deadhorse Creek North, Deadhorse Creek South, and Morley High Grade veins) have very similar mineralogies with freibergite as the Ag-bearing phase.   A general paragenetic sequence was noted, from early massive sphalerite ± pyrite to later massive galena + sphalerite ± chalcopyrite ± freibergite.

Fluid inclusion studies on these three veins indicate low to moderate temperatures of formation (approximately 160-355 degrees Celsius), low salinites, and some form of NaCl-KCl-MgCl₂-H₂O fluid compositions.

The veins are not, as previously suggested, related to intrusion of the Coldwell Alkaline Complex since one vein cuts the thermal aureole of the Complex and another is over 60 km away from it.  The veins may, however, be rift related with much of the data presented here lending support to this hypothesis.

The other two veins studied are of indeterminate origin.  They are not directly genetically to the Pb-Zn-Ag veins since they have much different mineralogies.  The Mogatherium vein contains a complex Cu-Pb-Bi-Te-Ag-S ore mineral assemblage, while only pyrite was found in the Gold Range samples analyzed.

Fluid inclusion analysis yielded poor results for these veins and thus their mode of formation is still a point of conjecture.  They may be related to the intrusion of the Terrace Bay Batholith, with which the veins are spatially associated.

The diagenetic history of a Carboniferous limestone sheet (Ardness Formation) present in the Cumberland Basin, Nova Scotia, was studied.

The diagenetic environments that altered the limestones of the study area were:  1) Near-Surface Processes  2) Vadose Processes, which only affected Knoydart Brook oolitic shoals  3) Freshwater Phreatic Processes  4) Deep Burial Processes  5) Hydrothermal Processes.

Petrographic evidence suggested the following sequence of diagenetic events:  1) bioturbation as a form of biological diagenesis in Knoydart Brook but not in Northumberland Shore,  2) microboring and the consequent micritization of bioclasts forming micrite envelopes,  3) early compaction,  4) very early freshwater-phreatic cements around echinoderm plates in the form of syntaxial overgrowth cement, and around ooids in the form of drusy cement,  5) grain-to-grain pressure solution,  6) blocky cement as well as void filling calcite cement.

Other processes which were pervasive throughout the sections are  7) neomorphism,  8) stylolite formation,  9) pyrite and hydrocarbon overprints.

The cements in the study area were mostly Mn-enriched and are likely to have precipitated from Mn-rich fluids that were related to hydrothermal vein systems.  Mn content in some ooids is higher than nearby cement indicating that the ooids were formed from Mn-rich seawater.  The hydrothermal processes were most affective near the basin margin of the shallow Windsorian area, a continental setting similar to the present day Persian Gulf.  In this case a hydrothermal vein system was operative near the continental transform faults of the Cumberland Basin during an early stage of block movement.  Hydrothermal fluids which were generated by convection within the basin rose along the permeable zones and fractures of the basin margin faults and carried Mn and other base metals towards the surface.

Ductility contrasts between individual clasts and matrix and the affects of a single, non-coaxial, pure shear deformation has resulted in the heterogeneous and non-passive strain features observed on a two dimensional outcrop surface of the Seine Conglomerate in northwestern Ontario.

Two strain analysis techniques yielded different stain values for each clast lithology thus reflecting the relative competencies.

The bulk strain of the conglomerate outcrop is partitioned between the ductile matrix and a rigid framework of the more competent clasts.  The finite strain ratios of metavolcanic clast may represent the state of strain of the matrix due to the passive manner in which the two components have deformed.  The bulk strain of 72.5% shortening is intermediate between the value calculated for the metavolcanic clasts and the granitoid clasts.

Values of strain calculated for the porphyritic igneous clasts are close to the estimated bulk strain ratio for the entire outcrop.  Thus the popphyritic clasts are a small scale analogy of the conglomerate: porphyritic clasts have a rigid phenocryst versus ductile groundmass phase similarily, the conglomerate has a rigid clast versus a ductile matrix phase.

A previously unidentified Cu-Pb-Bi-S mineral was found to be aikinite, a member of the aikinite-bismuthinite homologous series of sulphosalts, through the use of x-ray diffraction and precession analysis.  A noted compositional disparity from that of ideal aikinite was discerned.  Previous workers have attributed such compositional deviations to either limited solid solution or to disordered intergrowth of end members of the series.  An examination of % metals vs % sulphur has shown that both solid solution and disordered intergrowth mechanisms occur in the sample under study.

Three samples of Ag-Hg bearing material were analysed through the use of X-ray diffraction and elemental analysis in order to discern any structural variation from the face-centered cubic silver structure that might arise due to the mercury content.  The small size of the Big Harry vein specimen precluded any work being done on it.  The other two samples from Chile and British Columbia, previously identified as arquerite, were determined to be native lead and mercurian silver respectively.

The Quetico subprovince; which consists of metasedimentary rocks, gneisses, and migmatites, is a east-to-west trending linear belt in the Superior Province of the Canadian Shield.  This subprovince has been subjected to extensive periods of metamorphism and deformation throughout its evolution.  Hosted within this subprovince are a number of igneous intrusions that are granitic to quartz monzonitic in composition, and show little evidence of a complex geological history.  Emplacement of these plutons have resulted in the development of contact metamorphic aureoles in the regionally metamorphosed host country rock.  The objective of this study was to find evidence of such an aureole in the host rock, and to describe the mineralogical and textural features that are commonly developed in this type of aureole.

The study area under consideration is located northwest of Thunder Bay, Ontario.  In this area, a late-stage pluton, the Barnum Lake pluton is hosted in metagreywackes.  A series of samples were taken and studied for evidence of contact metamorphic overprinting.  These studies revealed features characteristic of contact metamorphic aureoles, such as the presence of hornfelsic texture and the growth of second generations of minerals such as biotite.  Mineral assemblages found in the host rock, were consistent with those described in the literature as typical of contact metamorphic aureoles.

Oriented samples were also taken directly from the Barnum Lake pluton, and were the object of anisotropy of magnetic susceptibility studies.  AMS studies revealed that the pluton was emplaced, and that the emplacement of the pluton was responsible for the contact metamorphic features observable in the host rocks of the Quetico subprovince.

No abstract provided.

Paleomagnetism and magnetic fabrics were determined for 2903 samples of the Akamas ophiolite, for comparison with the Troodos ophiolite, both located on the island of Cyprus.  The relationship between the ophiolites is inferred from the anisotropy of magnetic susceptibility (AMS), natural remnant magnetism (NRM) combined with low temperature demagnetization (LTD) and thermal demagnetization (TD), and paleopole studies.

From these data, it is determined that the ophiolites are of similar origin but produced at different times and locations.  Akamas is a Triassic slow spreading center from a rifted continental margin and Troodos is a Cretaceous slow spreading center from a suprasubduction zone.  The magnetic fabric from both Akamas and Troodos is that of an S-fabric, with a slightly continuity into the L-fabric field.  The AMS data for both ophiolites dips east-south-east, with two distinct regions of foliation, one steep and one shallow.  Principle component analysis determined two distinct magnetic polarities, both exhibiting a mild tectonic smearing.  The paleopole for these data points is determined to be 73 N, 95 W and 75 N, 85 E in a normal field and 27 S, 45 E and 10 S, 20 E in a reversed field.  The mean declination and inclination for these data is 159/-62 and 210/-47 in a normal field and 159/62 and 210/47 in a reversed field (a₉₅ = 10.6).  These data are plotted in the apparent polar wander path for Cyprus determined by Borradaile and Gauthier (in prep.).  It is concluded that the difference in magnetic polarity seen in the PCA analysis of the NRM (LTD, TD) results represent a reversal of the Earth's magnetic field.  This reversal is confirmed by magnetostratigraphy comparisons with Upper Triassic data.  The paleopole data also indicates a ~120° anticlockwise rotation of the Akamas ophiolite and the Mamonia terrain, prior to the documented 90° anticlockwise rotation of Cyprus.

Perovskite-type compounds in the series tausonite-lueshite, (SrTiO₃-NaNbO₃), were synthesized by solid-state reaction and analyzed using X-ray powder diffractometry.  The structures of several intermediate compositions were determined using the Rietveld refinement method.  In the compositional range 0≤ x ≤0.2, the series consists of an undistorted cubic structure in the space group Pm3m, with cell dimensions ranging from a≈3.905-3.916....  At the composition of x=0.9, a combination of the orthorhombic spaces groups Pbma and Pbnm is believed to occur (a ≈ 5.558, b ≈ 15.625, c ≈ 5.519 ...).  In the compositional range 0.95≤ x ≤1.00, the structure is orthorhombic and belongs to the space group Pbma.  In the series (SrTiO₃-NaNbO₃), the degree of structural distortion increases with x as a result of Na substituting into the A-site for Sr, and Nb substituting into the B-site for Ti.

The agate deposit at the TBAM is located 1 km northeast of Thunder Bay, Ontario in ferrodolomite of the Gunflint Formation.  The age of the agate deposit is delimited by the age of The Gunflint Formation and the age of the Logan sills which crown the Gunflint sediments to the west of the deposit.  The agate shows a consistent sequence of mineralization from nucleation against the host-host: dark amorphous silica (opal-A?), light amorphous silica (opal-CT?), translucent chalcedony, a-quartz, and vug-filling graphitic carbon.  The deposition of the agate appears to be related to pervasive, early silicification of the Gunflint and other Lake Superior-type iron formations.  Siliceous solutions from thermal springs located near the centre of the depositional basin were expelled to the margins by compaction.  At the site of agate deposition, the solutions encountered CO₂ from decaying organic matter.  The presence of CO₂ and organic material would create a pocket of decreased pH and temperature.  δ¹³C valves for vug-filling graphitic carbon show it is organic in origin.  Geochemical modeling demonstrates that the sequence of mineralization observed at the TBAM will precipitate from a solution in equilibrium with dolomite and atmospheric CO₂ as it experiences a decline in pH and temperature.

The carbonate sequence located in the upper most portion of the Paleoproterozoic Gunflint Formation was studied in detail, in an attempt to understand the ambient conditions that were present at the time of deposition and cementation.  The study included analyses of shore proximal sediments and structures using geochemical instrumentation, as well as qualitative interpretations of depositional environments based upon in-depth microscopic observations.  The carbonate sequence itself was located on the border between the sediments of the Gunflint Formation and the siliciclastic Rove Formation.  Moving up through the Gunflint Formation, through the carbonate and eventually into the Rove Formation one encounters major changes in the depositional environments in the surrounding area.  Indications of these major changes are drawn from the broad differences in compositions of the units.

Whole and partial rock geochemistries were acquired via the ICP-AES at Lakehead University (LUIL), as well as from the ICP-MS at the Ontario Geologic Survey, located in Sudbury.  Quantitative SEM analyses and qualitative SEM elemental mapping were conducted; as well the samples were subject to combustion reactions to determine H₂O and CO₂ content of samples via the LUIL.  Also, a vast amount of information was gained using a high-power Olympus petrographic microscope digital imaging system via the Lakehead University Geology Department.

Although the carbonate sequence throughout the area was discontinuous, those outcrops sampled contained similar units in comparable order and could be correlated.  The majority of the outcrops sampled contained strata that placed them in a shore proximal environment that may have been sub-aerially exposed at some point in the Paleoproterozoic.  These features included a stromatolitic layer with an adjacent scoured fine carbonate sand, as well as upper and lower coarse carbonate sands.  Analyses of the units indicated that they are composed mainly of Fe-rich chlorite grains bounded in a calcite cement.  As well, some layers contained abundant dissolution and silica replacement.  Abundant V enrichment was associated with the Fe-rich chlorites throughout the shore proximal sediments.

As a comparison, outcrops located at a stratigraphically lower level in the carbonate sequence were sampled.  These samples represented more off-shore sediments deposited in the submarine environment at the time.  Analyses of these sediments indicated a much different composition to the more shore proximal sediments.  Not only did the samples not contain any of the shore proximal features, they were composed almost entirely of ankerite.  The submarine sediments also contain rare, highly silicified stromatolite fragments, as well as pressure solution features, such as styloites characteristic of the deep burial environment.

The fact that the shore proximal sediments contain cements that do not reflect the chemistry of the ocean during the Paleoproterozoic suggests that the calcitic cements were more reflective of the meteoric environment.  The large V enrichments also suggested the presence of a redox boundary, as well as suggesting an oxic atmosphere.  REE curves for the ankeritic marine precipitates show Ce anomalies that reflect an anoxic ocean, whereas those of the meteoric calcite cements reflect an oxic atmosphere, further reinforcing conclusions from other geochemical data.