The Yava lead deposit at Salmon River, Nova Scotia, is a sandstone-hosted lead deposit situated in fluviatile clastic sediments, of late Carboniferous age. Ore reserves are estimated to be 5.6 million tonness at 5.3% Pb. During a 2 ¹/₂ year underground production operation (1979-1981), 388,000 tons were extracted.

The host rocks consist of cyclical fining-upward sequences of conglomerate, sandstone and shale, deposited in an upper meandering river environment. These rocks are grey-green in colour and contain abundant coaly matter.

The dominant sulphide is galena, occurring as concordant and discordant bands, clouds and disseminations. Pyrite and sphalerite are present, in association with galena, in minor amounts. These sulphides occur as a cement, infilling pore spaces in the clastic lithologies. The mineralisation is confined to the basal 15 m of the sandstones, above an unconformable contact with Windsor Group shales (Visean) and late Pre-Cambrian/early Cambrian basement rocks. Three ore zones have been outlined at Yava, and these are spatially related to palaeo-depressions in the basement landscape. In the West Zone, the ore horizon, which is up to 8 m thick, occurs in footwall contact with the Windsor unconformity.

Correlation of lead grade distribution, host rock stratigraphy and palaeotopographic features in 135 surface drill cores for the West Zone, in combination with underground mapping and channel sampling in the upper part of the same zone indicates the following features.

Regional pre-requisites to base metal concentration at Yava are: a porous sandstone host rock is a reduced state, an impervious footwall lithology, underlying basement of granitic composition, and an unconformity at the base of the mineralised sequence marking a period of emergence and sub-aerial weathering.]

Controls to ore localisation in descending order of importance are: negative topographic features in the pre-tectonic footwall relief, internal stratigraphic configuration and compositional variations within the clastic package, and the extent of sandstone diagenesis.

It is proposed that depressions in the buried Windsor landscape acted as basinal traps where metal-bearing solutions (derived from saline groundwater) pooled, while the porous organic-rich clastic host rocks provided the necessary conditions for fluid flow and sulphide precipitation.

Detailed petrological and geochemical studies in the Goldenville Formation of the Lower Paleozoic Meguma Group metasediments near Yarmouth, Nova Scotia, indicate that this sequence was affected by regional metamorphism ( 415 Ma, c.f. Reynolds et al., 1978) under conditions of low pressure ( 3kb) and low grade (400-470^oC). Biotite formation occurred by a reaction involving muscovite and ankerite. In the system SiO₂-Al₂O₃ MgO-K₂O-CaO-H₂O-CO₂, the reactant and product components of reaction may be represented as follows:

This reaction terminated when the dolomite-component was entirely consumed.

The regionally metamorphosed sediments were subsequently intruded by the Wedgeport pluton ( 310 Ma; Keppie, J. D., pers. comm., 1983). This resulted in the development of a localized contact aureole with mineral assemblages characteristic of the hornblende-hornfels facies (c.f. Turner, 1981). The physical conditions of contact metamorphism were as follows:

PH2O = 1000 - 3000 bars

T = 550 - 700^oC

The effects of a hydrothermal event ( 300 Ma (??), Reynolds et al., 1981) associated with the late stages of granite intrusion, are present within the metasediments. Chalcopyrite-pyrite-sphalerite-cassiterite mineralization has been localized within pre-existing, NE-SW trending shear zones within the metamorphosed Goldenville Formation lithologies. These zones display extensive alteration "halos" where chemically and optically distinctive secondary chlorites, biotites and garnets have been recrystallized from the pre-existing biotite zone assemblages. Secondary biotites, enriched in Mn and F, have formed along the margins of chalcopyrite-pyrrhotite-pyrite-arsenopyrite-sphalerite-cassiterite bearing quartz-calcite veinlets within the metasediments.

Late-stage NNE-SSW trending, strike-slip faulting and shearing offset portions of the mineralized Wedgeport pluton. The mica-argon age of 258 Ma (c.f. Reynolds et al., 1981) may, at least in part, record this late deformational event.

Olivine diabase and lamprophyre dykes some of which are Triassic in age, intruded the Wedgeport pluton commonly along northeast southwest trending faults and the Goldenville Formation metasediments along pre-existing shear zones.

Supervisor:G. Muecke

Halifax Inlet is one of a series of estuaries along the Atlantic coast of Nova Scotia that have experienced post-glacial transgression. The following lithofacies are the result of unmixing of poorly sorted submarine and subaerial deposits: (i) pebble/boulder lag deposits, (ii) sands, and (iii) muds.

The study area is situated in the outer harbour, where the predominant sediment type is mud. Two subfacies are distinguished within the muddy facies: (i) bioturbated muds and (ii) muds containing sandy laminae. The occurrence of the latter subfacies corresponds to periods of exceptional storms in Halifax. The individual sandy laminae were deposited as a result of storms with a recurrence interval of 25 to 75 years.

To delineate the effects of storms on local sedimentation, suspended sediment concentrations were monitored from January to June, 1982, a sediment dynamics experiment was carried out in March 1982 and sediment traps were deployed. These data demonstrate: (i) sediment on sand substrates is locally resuspended by waves during winter wind storms; (ii) in shallow water, water turbidity may decrease rapidly, with water movement away from McNab`s Island; (iii) near-bottom and/or mid-depth intrusions of turbid water are present in the outer harbour following storms.

Sediment dispersal patterns are complex. Transport of sediments is from several directions with temporal variability on time scales from seconds to tens of years.

Supervisor:D.J.W. Piper

The Middle River area of the southern Cape Breton Highlands is underlain by a sequence of interlayered metasedimentary and metavolcanic rocks. The Middle River unit, in the south, consists of two distinct east-west belts. Low- to medium-grade schists and phyllites with thin metabasite sheets form the "underlying" southern belt while high-grade paragneisses form the "overlying" central belt. The Egypt Highland unit, composed of foliated granitic rocks grading into a less deformed granite, makes up a third belt in the northern part of the area.

Four phases of deformation are recognized. The first is associated with a poorly preserved enclosed schistosity found only in the central belt. The second is represented by the principal fabric of the rocks of the Middle River and Egypt Highland units and by east- and west-plunging folds possibly related to the "stacking" of the belts along the shear zones. The third and fourth phases are represented by north-trending small- and large-scale folds respectively. A southward and upward movement of the complex along a northeast-southwest mylonite zone and parallel north-south faults produced the observed structural configuration of the Middle River complex.

The grade of metamorphism increases rapidly northward in the southern belt from the biotite zone to the staurolite-kyanite zone. Peak metamorphic conditions reach the kyanite zone in the central belt during D1 but were subsequently overprinted by garnet zone conditions during D2. Calculated temperatures from calcite-dolomite and garnet-biotite geothermometers cluster between 500'C and 600'C and reflect these overprinting conditions. 40Ar/39Ar ages of 377+9 Ma for biotite and 386+9 Ma for coexisting hornblende from a metabasite sheet in the central belt apparently ascribe the cooling of the sequence during uplift following D2 to the Middle Devonian Acadian orogeny.

The study area is enclosed by Mississippian sedimentary rocks to the west, a granodiorite of uncertain age to the east, a Devonian monzogranite to the northeast, and deformed volcanic and volcaniclastic rocks to the southeast.

Supervisor:B. Jamieson

Detailed study of large sympatric populations and fossil assemblages of the highly variable species Elphidium excavatum (Terquem) collected from 20 widely spaced locations indicates that a variety of morphotypes of Elphidium can be linked to one another in a number of interlocking intergradational series. Ten morphotypes are recognized and groups as formae (ecophenotypes) of Elphidium excavatum (Terquem); these morphotypes were previously considered as 22 independent taxa by various authors.

To test the hypothesis that these ecophenotypes are distinct morphologically, the ten ecophenotypes were separated into groups based on differences in external morphology; 15 of the characters by which the groups are distinguished were measured and or scored on 721 individuals (11-163 per forma). Discriminant and classification functions were calculated from these character measurements using SPSS computer program DISCRIMINANT. To illustrate the derivation of these functions, two examples (2 groups and 2 variables; 3 groups and variables), were calculated and explained step by step using the MINITAB interactive statistical package.

Fifteen analyses, using either one sample or split sample approaches, and simultaneous or stepwise analytic methods, classify 84-90% of the specimens into the subjectively defined formae to which they were assigned. Either morphotype (forma) or location was treated as the dependent variable. The analyses showed that there is not strong relationship between formae and geographic location, thus strengthening the subjective conclusion that these are ecophenotypes and not subspecies.

Although all of these formae belong to the same species, it is suggested that the distinction among them should be retained because of their potential as a valuable interpretive tool in paleo-ecological and biostratigraphic studies of Holocene and Pleistocene sediments.

Supervisor: F. Medioli

Cassiterite and base metal sulphides have recently been discovered in Yarmouth County, southwestern Nova Scotia, in an area of folded and metamorphosed Cambro-Ordovician turbidites of the Meguma Group intruded by the monzogranitic Wedgeport pluton.

Several kinds of tin mineralization occur:

1. rare detrital cassiterite grains in a pelitic "microscour".
2. stratiform sulphide-cassiterite replacement bodies in calcareous layers.
3. sulphide-cassiterite veinlets in metasediments with restricted chlorite alteration.

Cassiterite occurs in several habits:

1. equant - in detrital, stratiform replacement bodies and veins.
2. prismatic - in stratiform replacement bodies.
3. acicular - in veins.
4. botryoidal - in stratiform replacement bodies (rare) and veins.

Geochemical analysis of drill core show that most background values in the metasediments and pluton are low compared to lithologies in the Cornish tin district and specialized ore-bearing granitoids. The sulphide-cassiterite veinlets exhibit a mineralogical and therefore geochemical variation with distance from the pluton: from Mo and W within 2 km of the pluton, to Sn about 3 to 4 km distant, to Pb and Zn about 4 to 7 km distant.

Supervisor: M. Zentilli

The Gays River lead-zinc deposit consists of stratiform bodies and discordant fault controlled vein systems within a Mississippian dolomitic reef that overlies unconformably a Cambro-Ordovician metasedimentary basement and is overlain by Mississippian evaporites.

Detailed underground mapping and laboratory studies suggest 3 main states of evolution: 1) pre-ore evaporite deposition, pervasive reef dolomitization and growth of marcasite, 2) precipitation of ore sphalerite, galena, chalcopyrite and calcite, and 3) post-ore deposition of calcite, fluorite, barite, marcasite, pyrite and selenite. Fluid inclusions homogenize at the following temperatures: sphalerite, 215^oC; ore-stage calcite, 172^oC; post-ore calcite, 142^oC; fluorite, 143^oC, and barite, 137^oC. Salinity of the hydrothermal fluids was approximately 20.4 equivalent weight percent NaCl during deposition of post-ore calcite and fluorite.

Gypsum and anhydrite in the overlying evaporites and barite within the ore, are enriched in heavy sulfur ( 34S +13.1 to +16.5o/oo); ore-stage sphalerite, galena and chalcopyrite show a limited spread of 34S (+8.0 to +13.65o/oo); whereas post-ore marcasite and pyrite give widely scattered light

34S values (-9.7 to -4.6o/oo). The similarities of the 34S values of gypsum, anhydrite and barite with that of Mississippian seawater confirm this as the dominant sulfur source for the sulfates. The heavy sulfur of the ore-stage sulfide minerals is either directly contributed from seawater or from a solution of equilibrium with evaporites. A biogenic source is preferred for the sulfur in post-ore marcasite and pyrite. Mineralized carbonates are significantly depleted in the heavier isotopes of carbon and oxygen with respect to the unmineralized equivalents. Preliminary lead isotope data for galena suggest that the source of the lead is in the Cambro-Ordovician metasedimentary basement.

The present evidence eliminates the possibility that the lead-zinc ores are an early low-temperature diagenetic cement of the dolomitic reef as previously envisaged. Contact relationships and remarkable similarities between the stratiform and vein ores suggest that the discordant veins acted as feeders for the epigenetic conformable mineralization. A model involving deeply circulating brines released during gypsum dehydration best explains the metal leaching, transportation and subsequent deposition of lead and zinc ores as replacements and open-space fillings within the dolomitic reef.

Supervisor: M. Zentilli

The 1.9-km-thick sequences intersected by the IRDP 1978 drill hole at Reydarfjordur, eastern Iceland, is correlated with the westward dipping exposed volcanic succession on the basis of extensive field mapping and paleomagnetic studies. The base of the landward extension of sea floor magnetic anomaly 5 (epoch 9) and other exposed marker formations can also be identified in the core. Field observations, including vertically discontinuous dykes, the lack of lava-feeder relationships, and the measured K-Ar age difference between dykes and surrounding lavas suggest that, contrary to previous interpretations, dykes of the Breiddalur dyke swarm were intruded by lateral injection from the south. These dykes are considerably younger than, and thus could not have fed, the exposed lava succession in the vicinity of the drill site.

The lowest 450 m of the core may represent lavas related to activity in the Reydarfjordur volcanic center 13.5 km to the east. It is proposed that about 10.3 Ma the Reydarfjordur volcanic center ceased to be active and volcanic activity shifted about 20 km to the west, where the Breiddalur and Thingmuli volcanic centers later developed. The above field observations allow a model for the upper crustal construction of eastern Iceland to be proposed. The model assumes that the lava succession of eastern Iceland was formed in at least three successive volcanic zones that resulted from frequent shifting of the location of greatest volcanism.

Contrary to what is generally assumed, no systematic decrease in magnetic intensity with depth was observed for a 0.9 km thick vertical lava section in Holmatindur, about 13.5 km east of the drill site. This suggests that previous generalizations based on regional studies may have little predictive value when applied to certain specific areas.

Supervisor: M. Zentilli

Two hundred and fifty grab samples from the continental margin off Nova Scotia were examined for total (live+dead) foraminiferal content. One hundred and twenty species were recognised, seventy five of which occur with an abundance greater than 3% in any one sample. Q-Mode factor analysis of the raw abundance data (total population) determined 8 shelf and 4 slope factor assemblages, accounting for 87.5% and 77% of the original raw data respectively. Comparison of the live data with the factor assemblages enabled the detection of anomalous assemblages which are un-representative in respect to present day environments.

In the north east of the study area (around Misaine, Canso and Banquereau) an exclusively agglutinated assemblage dominated by Adercotryma glomerata occupies both banks and basins. In the LaHave and Emerald Basins of the central shelf, a predominantly calcareous assemblage occurs with maximum amounts of Globobulimina auriculata and Nonionellina labradorica. Transitional between these two shelf assemblages is an agglutinating assemblage dominated by Saccammina antlantica. Consistently present along the shelf edge is a Trifarina angulosa assemblage. Present in Chedabucto and Gaberous bays and in a few samples near Sable Island is an agglutinating Eggerella advena assemblage. A relict and in some areas a transport affected assemblage is recognised in the south western approaches to Emerald Basin on the Scotian Gulf; this is dominated by Elphidium escavatum. Occupying the hard, rough bedrock, and sandy/gravelly areas of the inner shelf and outer bank regions is a Cibicides lobatulus assemblage.

Four assemblages lie seaward of the shelf break. An upper slope assemblage is dominated by Bulimina exilis, with a local variation dominated by Trifarina occidentalis. A lower slope assemblage is dominated by Uvigerina peregrina. Also present in slope regions is another Elphidium excavatum assemblage which is thought to be the down slope equivalent of the shelf assemblage.

The statistical relationship of these defined assemblages to various aspects of the marine environment (depth, temperature, salinity, percent gravel, sand and mud) were investigated through multiple regression techniques. This indicates that the present foraminiferal distribution patterns off Nova Scotia are mainly a response to the prevailing hydrography. The Adercotryma glomerata assemblage is influenced by the presence of cold, less than normal salinity waters of arctic, Labrador current origin. The central basin assemblage (G. auriculata) is related to warmer more saline waters of slope origin. The transition between these two bottom waters is marked by the Saccammina atlantica assemblage. The primary influence of the hydrography on assemblage distribution patterns on the shelf off Nova Scotia is probably related to calcium carbonate availability which is a function of temperature, salinity, and carbon dioxide content within each water type. Preferred substrate character is found to determine the occurrence of the Cibicides lobatulus assemblage.

Diversity trends within the study area were examined (S,H(s),x,E). Each index used produced similar patterns which indicate relationships to hydrography and environmental stability.

Implications of the present study for further work on Pleistocene to Recent climatic changes are discussed with reference to a piston core from Canso Basin. On the basis of this study the down core changes in foraminiferal populations indicate several distinct variations in temperature and salinity since the last glaciation; these variations are probably a result of the varying degree of influence that Labrador derived waters have had in this area and is in turn a function of changing ice volumes to the north.

Supervisor: F. Medioli

The Goose Cove copper deposit lies within the Goose Cove Schist of the St. Anthony Complex, northwestern Newfoundland. The initial theory of ore emplacement was epigenetic replacement of the greenschist host rocks (Stephenson, 1937). Field relations, petrography and geochemistry investigated in the course of this thesis indicate an opposing model of formation.

The ore consisting of pyrite, chalcopyrite, pyrrhotite and sphalerite is generally confined to the porphyroclastic metavolcanics and related to the main foliation (Sm).

The porphyroclastic metavolcanics are depleted of Cu, Ni and Zn with respect to their protoliths (the undeformed porphyritic pillow lavas of the Ireland Point Volcanics) suggesting a mobilization of the ore-forming elements in the pillow lavas and resulting reconcentration either prior to or synchronous with the Fm folding event.

Although the exact paleoenvironment of the primary pillow lavas cannot be defined, it is likely that the volcanics formed in a tectonically unstable oceanic setting (i.e.: mid-ocean ridge, ocean island or ocean floor). Syngenetic mineralization of the basaltic lavas may have occurred.

Supervisor:B. Jamieson

The effects of hydrothermal alteration and ore mineralization were studied in 34 basalt drill core samples from the Agrokipia Cretaceous seafloor hydrothermal system in Cyprus. Transmitted and reflected light microscope, X-ray diffraction and electron microprobe techniques were employed to determine the variation of secondary minerals and textures with depth. The depth intervals examined were the 24.00 m to 92.85 m interval in hole CY-2 and the 136.70 m to 406.85 m interval in hole CY-2A. These intervals represent the most altered sequences of the cores.

The four stable secondary mineral assemblages which occur in the samples studied are:

1. smectite + green chlorite + minor quartz + hematite in relatively fresh to partly altered basalt (in CY-2 samples and in CY-2A between 136.70 m and 150 m)
2. chlorite (green and brown) + smectite + pyrite + sphalerite + chalcopyrite in highly mineralized and partly to highly altered basalt (CY-2A 150 m to 170 m)
3. illite + quartz + sphene + pyrite + hematite in highly to pervasively mineralized and pervasively altered basalt (CY-2A 170 m to 300 m)
4. abundant green and brown chlorite + albite + epidote + minor pyrite + trace sphalerite in partly mineralized and highly to pervasively altered basalt (CY-2A 300 m to 406.85 m)

With the exception of the 30 m to 60 m interval, it appears that hole CY-2 did not penetrate any hydrothermally altered basalts while the 150 m to 300 m interval in hole CY-2A represents the most intense hydrothermal activity.

Microprobe analyses revealed the occurrence of Mn-rich chlorite and calcite with the highest Mn content in the chlorite of sample CY-2 92.85 and the calcite of sample CY-2A 153.25. The MnO values of the chlorites in hole CY-2A appear to increase with depth while those of calcite decrease with depth. In all cases, the vesicle chlorites contained higher levels of MnO than the matrix chlorites.

Supervisor:J. Hall

The Pictou Group of Northern Nova Scotia has to date received relatively little study. Several authors have studied these rocks in context with other groups in the area and as part of regional basinal studies.

This study looks at a small (310 m) section of Pictou Group rocks which are well exposed and easily accessible at Cape John, Nova Scotia. Detailed attention is paid to lithology, relative position in the sequence, fossils, relative thickness and paleocurrents.

Results of the study favour a meandering fluvial model of deposition of these rocks. Paleocurrent and mineralogical data suggest a source area to the north, south or east and provide finer resolution of the geomorphology of the depositional basin.

Variations from the classical meandering fluvial model are seen in the section and are discussed as to their implications regarding the environment and basin of deposition.

Supervisor: M. Gibling

In a study carried out at the Fifteen Mile Stream gold district, Halifax County, to document the distribution, character, and composition of gold in till around the former gold mines, 21 sample sets of A, B, and C horizon material were collected from the soil profile. Sampling was conducted at 10m intervals in till exposed by two trenches which are oriented perpendicular to the strike of both the veins and host strata.

Geochemical analyses for gold, silver, lead and arsenic were performed on samples of the B horizon and on 4 size fractions of the C horizon. Samples of the A horizon were analyzed for gold only.

The >2f fraction of the C horizon with a mean gold content of 217 ppb contains higher concentrations of gold than other size fractions and horizons analyzed.

The gold occurs as foliated flakes which are morphologically similar to gold particles from the tailings of the mine. That the gold is not far-travelled is evident from the lack of surface striations or other deformational features indicative of abrasive transport.

Microprobe analyses of gold from the till gave unexpected compositions which differed significantly from those of the presumed source. Gold from the till has an average composition of 69% copper, 10% gold, 9% zinc and 1% silver as compared with gold from the mine tailings which average 91% gold and 9% silver. This discrepancy in composition between the primary and secondary gold is thought to be due to a hydromorphic redistribution of gold in the till.

On the basis of correlation analysis performed on the geochemical results, and compositions determined using EMP analyses, gold, arsenic, copper, and zinc are considered the most important elements to be analyzed in pedogeochemical exploration for gold mineralization in rocks of the Meguma group.

Sediment-water interface samples from five small lakes in southwestern New Brunswick (Bonaparte Lake, Bocabec Lake, Gibson Lake, St. Patricks Lake and Big Pond [Deer Island]) were quantitatively examined for the presence of arcellaceans. Two major assemblages, with one assemblage (I), being subdivided into three sub-assemblages, were delineated; all assemblages were dominated by Difflugia oblonga. Reduced total and species numbers in the second, assemblage (II), of Bonaparte Lake may be a function of anoxic bottom conditions and/or acid rain pollution. Variations in most Assemblage I sub-assemblages are probably the result of chance colonization events. However, the presence of Difflugia bidens in Assemblage Ic seems to be an indicator of increased terrigenous input.

The surface information was also used to perform a first order interpretation of a core from Gibson Lake. Diversity and total numbers generally increased following transition from marine to freshwater conditions, with a decrease in total numbers in the upper part of the core, due to oxidation. Difflugia oblonga dominated all core assemblages except in the brackish freshwater transition zone, where Centropyxis aculeata dominated.

The results of this study provide further documentation of the value of arcellaceans as paleolimnoloical indicators of the benthic environment.

Supervisor: D. B. Scott

In 1982 field work was carried out in northwestern British Columbia for Noranda Exploration Company, Ltd. Here a sequence of porphyritic and vesicular volcanic flows containing interbedded gypsum was discovered. Finely disseminated sulphide was found within this gypsum. Whether economically important quantities of copper-bearing sulphides exist here is unknown at this time.

Microscopic study of thin sections, and X-Ray diffraction spectra, show the mineralogy to be representative of greenschist facies metamorphism. Sulphur isotope data: dS34 = +11.7 for gypsum and +11.3 for barite are interpreted as indicating a middle to late Permian age of these sulphates.

The Denali fault system is a dynamic fault zone active since Cretaceous-Jurassic time and presumed still active. This system is responsible for assembling the series of originally temporally and spatially separated units observed today in Mule Creek. The pulsing of this system through time has produced extensive brecciation and shearing over the whole study area.

Supervisor: G. C. Milligan

The generation of alkaline rocks is a complex process. The East Eifel volcanic field in West Germany represents the most alkalic rocks in the alkaline province of Central Europe and France. The area of particular interest, in this study, the Laacher Sea.

The rocks in this study include phonolites (including selbergites), tephritic phonolites, nephelinites and phonolitic tuffs. They have been divided into two major groups; mafic (M) and felsic (F) on the basis of petrographical, major and trace element geochemical and mineralogical analyses. Group M can be further subdivided into two subgroups: Group M-1 is composed of nephelinites and Group M-2 is composed of phonolites.

The samples from Group M and F are intricately related in space and are approximately the same age. These observations together with the experimental results indicate that all the groups are petrogenetically related.

Supervisor:

The Lawrencetown beach ridge plain is located approximately 25 kilometres northeast of Halifax, along the Eastern Shore of Nova Scotia. It consists of two beach ridge complexes, one sub-parallel and the other sub-perpendicular to the present coastline. The formation of beach ridges began approximately 700 years B.P. Their presence is the result of marine reworking of sediments derived from drumlins during transgression. Their configuration is related to a drumlin, now a submerged boulder retreat shoal located between Lawrencetown Head and Half Island Point. The process of beach ridge formation is discussed and put into the context of an evolutionary model, which is concerned with the development of coastal sedimentation along the Eastern Shore of Nova Scotia.

Supervisor:

The conglomerates of northern Cape George represent a tectonic block, thrusted from the north during the Carboniferous. Previous provenance studies of the Cape George alluvial fan sediments have not been done in great detail so that a probable source of the sediments had not be determined. During a provenance study of the Cape George sediments the following questions were asked, concerning the reliability of the southeasterly paleocurrent direction:

1. Has the Cape George thrust block received any rotation?
2. Are the strata of Cape George representative of only a part of an alluvial fan or is the entire fan contained in Cape George?
3. Have enough paleocurrent vectors been measured so that a reliable average paleocurrent direction can be determined?

During the Middle to Late Devonian, uplift in northern Nova Scotia and Cape Breton Island resulted in extensive unroofing and weathering of deeply buried metaquartzites and granites. During the Early Carboniferous extensive block faulting resulted in the formation of deep intermontane basins in which thick accumulations of sediment occurred. The coarse-grained, poorly sorted orthoconglomerates of northern Cape George were deposited by alluvial fans during the Early Carboniferous and accumulated to a thickness of greater than 1 km. Southward thrusting of the Cape George conglomerates, with minor amounts of rotation, occurred during the Carboniferous.

An analysis of structural and sedimentological data, together with a study of the clast lithologies in the conglomerates, suggests that the Cape George sediments were probably derived from a northerly source and that since the Early Carboniferous most of the original rocks in the source area have been eroded or buried.

Supervisor:P.E.Schenk

The Upper Ordovician (Ashgillian) to Middle Silurian (Wenlockian) graptolitic carbonates and cherts of the Cape Phillips Formation accumulated in the deep water basinal environment of the Hazen Trough. The coeval platform carbonates of the Allen Bay Formation to the east in a shelf environment. Nineteen stratigraphic sections were measured in order to obtain data on the lithological variation within this facies transitions, specifically within the Cape Phillips Formation. Integrated petrological and x-ray diffraction analyses of the samples collected indicates the presence of seven distinct lithofacies, six in the Cape Phillips and one in the Allen Bay Formation. These lithofacies are;

1. laminated limestone
2. calcareous mudstone
3. laminated argillaceous limestone
4. massive limestone and rudaceous graded limestone
5. chert
6. laminated dolomite
7. massive dolomite

The distribution of these lithofacies is strongly related to the paleogeography and water depth. The shallow water carbonate buildup of the Allen Bay Formation is composed of massive dolomite. The slope carbonates of the Cape Phillips Formation consist of laminated dolomite and laminated limestone with minor massive limestone and rudaceous graded limestone. The basin is dominated by calcareous mudstones and displays a significant development of chert.

To explain the distribution and origin of the lithofacies, a model is proposed whereby the carbonate grains and mud were produced on a shelf platform and carried basinward by wave - and tide - generated currents. Massive limestone and rudaceous graded limestone are the proximal deposits of gravity flows. Laminated limestone and laminated argillaceous limestone are the distal deposits of gravity flows. Calcareous mudstone and radiolarian chert were deposited from hemipelagic and pelagic suspensions and turbid layers. Replacement chert resulted from the silicification of carbonate. Dolomitization of the platform carbonate buildup and the adjacent upper slope succession created the massive dolomite and laminated dolomite lithofacies respectively. Dolomitization may have occurred in a schizohaline environment.

The dominance of calcareous mudstone in the upper Cape Phillips compared to laminated limestone, which is dominant in the lower Cape Phillips, suggests a deepening of the basin and a general transgression during the accumulation of the Cape Phillips Formation. It appears to have been deposited in relatively deep water, at least below wave base and generally above the carbonate compensation depth, between 100m and 5400m deep.

Supervisor: M. Gibling

The Lady Franklin Sand and Gravel is an informal term for a compositionally sand and/or gravel surficial sediment unit of the southeastern Baffin Shelf, delineated on the basis of grab samples and acoustic data by Praeg and MacLean (in preparation). The unit tends to occur above a bathymetric depth of about 200 m below which there is often surficial till of the Baffin Shelf Drift, and above which there is either (1) thin sand and gravel over thick tills, (2) thin sand and gravel over bedrock, or (3) an intermediate thickness cover for which it is uncertain whether there is thin sand and gravel over thin till, or solely thick sand and gravel. The Lady Franklin Bank area is an example of the latter case. In this area, the sand and gravel is overlain or grades into the silty/clayey sediments of the restricted Monumental Basin.

Twenty-five randomly distributed surficial van Veen grab samples are available from the unit in the Lady Franklin Bank area. These had undergone grain size analysis prior to inception of the thesis, and were subsequently submitted to detailed lithologic and textural analysis of three selected grain size intervals: gravel (-50 to -30), coarse sand -20 to 00), and fine sand, (20-30).

Grain size distributions indicate assemblages dominantly bimodal between gravel and fine sand, with silt/clay mode of variable importance. Grain size parameters across the study area indicate a general coarsening with increasing depths, except for two coarse grained medium depth samples off Loks Land. Hydraulic interpretation indicates currents of ~20 to 35 cm/s are required to mobilize the fine sand modes, values in the range of existing oceanographic currents.

Lithology of the three selected intervals of the sediments are dominated by crystalline siliclastic material and limestone, with minor uncertain brown siltstones and very minor quartz sandstones, largely reflecting the underlying Pre-Cambrian granites and gneisses and Ordovician limestones of the Lady Franklin Bank/Monumental Basin bedrock. Lithologic distributions of all three selected intervals are non-random, and similar, showing a relation to the bedrock adjacent to bathymetrically shallow areas, (< 150 m) and no relation to the bedrock over deeper areas.

Textural study of the three grain intervals delineates the presence of a distinct grain surface history comprised of an older, rounded, low relief surface, broken by a younger, angular high relief surface, which has been subsequently slightly modified by rounding. Entirely young surface grains are most common, followed by grain exhibiting both the old and new surfaces and entirely old surface grains. Scanning Electron Microprobe study of -20 to 00 quartz grains also recognizes the surface history, although it is confused by silica precipitation/solution features. Environmental discrimination indicates that the old surface is of the aeolian, subaqueous, and possibly source material environments, while the new surface is of the glacial environment. The new surface has been modified by rounding and surface forms of the subaqueous environment.

Roundness distributions for the new surface are non-random, and show a noticeable increase in roundness modification with increasing depth.

The evidence indicates a probable relative sea level low of 100 to < 150 m to produce the old surface, followed by ice advance (glaciation) to produce the new surface, and the observed lithologic distribution. The resulting till was modified and is probably till being modified by oceanographic bottom currents, which have decreasing strength to the west (decreasing depths), thus producing the existing grain size and roundness distributions.

Supervisors: Ron Boyd / M. Gibling

The Pembroke (also Glenbervie) prospect is a carbonate-hosted lead deposit located at 45^o17'05" North Latitude and 62^o56'15" West Longitude in Colchester County, Nova Scotia. The deposit is stratabound within the Macdonald Road Formation limestone of the Lower Carboniferous Windsor Group, a sequence of cyclic marine carbonates, evaporites and red-beds. Coarse-grained galena occurs in calcite veinlets as well as filling interskeletal and intraskeletal pores created by abundant fossil brachiopods.

Homogenization temperatures obtained from fluid inclusions in mineralized calcite indicate that the minimum temperature of crystallization was 214.8^oC.

Oxygen and carbon isotope data for mineralized calcite indicate mean values of +19.08SMOW and +1.38PDB respectively. Mineralization resulted in isotopic exchange, lowering the original 18O and 13C values of the host limestone.

The mineralizing event probably occurred during the Maritime Disturbance (Pennsylvanian) when high geothermal gradients accompanied the dewatering of evaporites, the resulting brines leaching the underlying Ordovician metasediments and transporting metals to favourable sites of deposition along the Horton-Windsor contact.