identifier: Scott, James L. <https://research.library.mun.ca/view/creator_az/Scott=3AJames_L=2E=3A=3A.html>   (1992) Mineralization in the Karmoy ophiolite, southwest Norway.  Masters thesis, Memorial University of Newfoundland.

abstract: The Karmoy ophiolite is a remnant of Early Ordovician oceanic crust which is thought to have formed in a supra-subduction zone environment, and undergone development in a back-arc basin before its final emplacement on the Baltic craton. The uppermost sections of this ophiolite are exposed in the study area; the rock types are gabbros. sheeted dykes, plagiogranites, and lesser amounts of pillow lavas, diorites, volcaniclastic sediments, and breccias. -- Contained within these rocks are two sulfide deposits, the Visnes massive l-c-Cu /.n sulfide deposit and the Feoy massive Fe-Cu-Ni-PGB sulfide deposit. While they arc spatially quite closely related, these deposits record two distinctly different periods of mineralization during the evolution of the ophiolite complex. -- The Visnes deposit formed as a result of sub-seafloor alteration of basaltic rocks of the Visnes High Level Complex. Rocks of this complex are altered to spilites on a regional scale. Geochemically, alteration of the sheeted dykes is defined by: a relative loss of K2O, CaO, MnO, A1O203, MgO, Cr, Ni, Cu, Zn, Pb and Sr; a relative gain of TiO2, Fe2O3, Na2O and Zr, and; variable changes in P2O5 and SiO2 relative to unaltered rocks from similar tectonic environments. -- More local zones of intense alteration and mineralization within the sheeted dykes are called "epidosite zones", and these represent flowthrough zones for highly corrosive, magma-influenced hydrothermal fluids. "Epidotites", or deuterically formed rocks composed of nearly 100% coarse crystalline epidote, are closely associated with such zones, and their presence suggests that the hydrothermal fluids responsible for formation of epidosite zones may well have had a direct magmatic water input. However, oxygen isotope evidence from epidotites and plagiogranites suggest that the magmatic fluids may ultimately have been derived from magma-chamber assimilation of seawater altered roof rocks. -- The Feoy deposit is a small, orthomagmatic Ni-sulfide body which appears to have very few known analogues elsewhere in the world. Petrogenetic modelling using Platinum Group Element (PGE) abundances and sulfur isotopes indicates that the sulfides precipitated from an already-depleted partial melt during its ascent from a mantle source. The deposit is predominantly a massive pyrrhotite/chalcopyrite deposit with minor pyrite and pentlandite. It is unique in its high concentrations of Platinum Group Minerals (PGM's); this is a reflection of the PGE-enriched nature of the residual sulfide fraction present in an already-depleted (previously melted) mantle parent. -- The co-magmatic silicate host rocks for the Feoy deposit are high-Mg basalt dykes, and these contain Ni-sulfides interstitial to silicate minerals. The host rocks can be petrogenetically modelled using PGE's, and as expected show PGE patterns indicative of formation from a second stage melt, or from partial melting of an already-depleted mantle. -- The Feoy deposit formed later than the Visnes deposit; rocks associated with the Visnes deposit are spilitized, and are dated al ca. 493ma (using Pb/Pb Zircon dating techniques); rocks associated with the Feoy deposit (high-Mg dykes. Type 2 plagiogranites and clinopyroxene-phyric intrusions in the Feoy area) are not spilitized, and are dated at ca. 470ma. -- All rocks in the study area are variably altered and deformed. It appears that such deformation post-dates formation of both sulfide deposits as well, since they have both been mobilized along shear zones. Also, volcaniclastic sediments of the Torvastad Group, which are compositionally and genetically related to late clinopyroxene-phyric intrusions in the area, and which represent a period of arc-basin formation following arc-volcanism, are themselves quite deformed and cut by shear zones. -- The occurrence of tourmaline-bearing breccias in the Feoy area is an intriguing addition lo the study of late deformation features. Breccia, containing rounded Ni-sulfide and tourmalinite fragments in a hydrothermal cement matrix, is found in the Feoy area. Textural, isotopic and chemical analysis of the breccia and tourmaline strongly suggests that it formed as a result of the forceful intrusion of a hydrous granitic body into the surrounding country rocks. This may well represent part of the nearby West Karmoy Igneous Complex, which is a large granitic pluton that intrudes all rocks of the Karmoy ophiolite. Indeed, shear zone formation in the study area may also be related to this late, post-emplacement event.


identifier: Muzuka, Alfred Nzibavuga Nyarubakula <https://research.library.mun.ca/view/creator_az/Muzuka=3AAlfred_Nzibavuga_Nyarubakula=3A=3A.html>   (1990) Late Pliocene-Quaternary history of the northwestern Indian Ocean: an organic geochemistry perspective.  Masters thesis, Memorial University of Newfoundland.

type: Thesis NonPeerReviewed

format: application/pdf application/pdf

abstract: The residue organic carbon (OC) content and stable isotopic compositions of OC and nitrogen for sediment samples from the Ocean Drilling Program (ODP) Leg 117, Sites 724 and 725, have been used to establish the history of the monsoon wind regime and its effect on coastal upwelling and primary productivity, in the northern Indian Ocean since the late Pliocene. Generally, residue OC content at Site 724 is greater than 2%; whereas at Site 725 it is less than 1%. Sediments deposited prior to the onset of the Pleistocene contain larger amounts of OC that have relatively depleted stable carbon and nitrogen isotope values. High primary productivity, reduced microbial activity as a result of the intrusion of highly saline waters from the Red Sea and the Persian Gulf, and/or enhanced preservation, produced these larger amounts of OC and relative depletion. -- The amount of organic matter preserved near the Pliocene-Pleistocene boundary is low due to decreased coastal upwelling, productivity and weak southwest monsoon winds. The lower amounts of organic matter preserved during the Pleistocene-Holocene period are generally associated with more positive stable nitrogen isotope values, owing to an intensification of the oxygen minimum zone and denitrification since the early Pleistocene. A correlation of the residue OC content with oxygen isotope stages, at Site 724, indicates slightly better preservation during interglacial periods due to increased coastal upwelling, primary productivity and/or preservation. Generally, stable nitrogen isotope compositions are relatively enriched at Site 725 than at Site 724. This may be attributed to the stable oxygen minimum zone and intense denitrification at shallower depths. A correlation of the OC isotope values with oxygen isotope stages indicates an enrichment in ¹³C during glacial periods. -- Based on stable isotope ratios, terrestrial input of organic matter into the Oman Margin is minimal owing to the lack of major rivers and low productivity in the source regions.


identifier: Seyed-Mahmoud, Behnam <https://research.library.mun.ca/view/creator_az/Seyed-Mahmoud=3ABehnam=3A=3A.html>   (1994) Wobble/nutation of a rotating ellipsoidal Earth with liquid outer core: implementation of a new set of equations describing dynamics of rotating fluids.  Masters thesis, Memorial University of Newfoundland.

abstract: In this thesis I implement a new set of scalar equations describing the free oscillations of rotating self-gravitating compressible fluids, to solve for the wobble and inertial modes of a rotating Earth with rigid mantle and liquid core. A Galerkin method is used to integrate these equations in the liquid core. It is shown that by using the divergence theorem it is possible to make use of the 'natural' boundary conditions to reduce the order of the derivatives from second to first in the Galerkin formulation of the governing equations. As a partial test of the reliability of our formulation, the eigenperiods of the Earth's Chandler wobble (CW), nearly diurnal free wobble (NDFW) and some of the other inertial modes are computed for the case of a compressible, but neutrally stratified, core and compared to those for the homogeneous incompressible core model.


identifier: Stander, Edward <https://research.library.mun.ca/view/creator_az/Stander=3AEdward=3A=3A.html>   (1984) The stratigraphy and structural geology of the Twillingate region.  Masters thesis, Memorial University of Newfoundland.

abstract: The Twillingate region is underlain by three lithologic units. The oldest of these is the Sleepy Cove Group, a one to two kilometer thick volcanic pile which exhibits ophiolitic affinities. To the west, and in thrust contact with this group is the Moretons Harbour Group, a massive, 8 to 9 kilometer thick volcanic pile which most likely developed in an island arc environment. The Twillingate Granite is intrusxve into both units and is thus the youngest unit in the region. -- The Twillingate Granite and its basaltic hosts were affected by four deformational episodes. The earliest of these events (D₁) produced two high temperature shear zones. Of these, the SHTI zone parallels the southern boundary of the study area and is characterized by recrystallized quartz grains enclosed in a recrystallized sodic plagioclase matrix. The BBB zone forms the contact between the Moretons Harbour Group and the Sleepy Cove Group, and is characterized by sheared and elongate pillow basalts and dykes. -- The D₂ deformation resulted in the development of open to tight upright folds in the basalt and a strong, localized L-S fabric in the granite body. Quartz microstructures and petrofabrics in the granite suggest that this deformation occurred at much lower temperatures than D₁. -- D₃ was also a low temperature deformation episode and was mainly responsible for developing broad, upright folds in the basalts of North and South Twillingate Island. This event does not appear to have affected the granite terrain to any great extent. -- The last event to affect the region (D₄), produced local kinks and faults in both the Twillingate Granite and the surrounding volcanic groups.


identifier: Evans, D. T. W. <https://research.library.mun.ca/view/creator_az/Evans=3AD=2E_T=2E_W=2E=3A=3A.html>   (1993) The Midas Pond gold prospect, Victoria Lake Group: geology, alternation and mineralization.  Masters thesis, Memorial University of Newfoundland.

abstract: The Midas Pond gold prospect, discovered by BP Canada Inc. in 1985, is located at the southwest end of the Cambro-Ordovician Tulks Hill volcanics, Victoria Lake Group. Host rocks include variably deformed, waterlain felsic and mafic pyroclastic rocks of island arc origin. -- Alteration and mineralization are confined to a 200 m wide, brittle, ductile-shear zone. This shear zone formed in response to regional D₁ deformation and the shear zone fabric parallels the regional S₁ foliation. D₂ deformation resulted in broad Z-shaped flexuring of the shear zone. -- Advanced argillic alteration and an extensive Fe-carbonate and pyrite halo surrounds the gold mineralization. Alteration assemblages include pyrophyllite, paragonite, quartz, plagioclase, chlorite, fluorite, Fe-carbonate and pyrite. -- The gold, which is intimately associated with pyrite, occurs in three structurally-controlled vein sets. These veins are confined to the contact between a highly deformed breccia termed the Banded Mafic unit and the structurally overlying, altered felsic tuffaceous rocks. The vein sets include: V₁ boudinaged veins developed parallel to the shear zone fabric (C-shear veins) , and V₂ and V₃ extensional fracture veins which are controlled by an S₂ fracture cleavage. V₁ veins are the earliest vein set and contain the lowest concentrations of gold. V₂ and V₃ veins appear to be concentrated within the hinges of the D₂ flexures and selected assays from these veins include 7.9 g/t Au over 0.9 m and 14.74 g/t Au over 1.15 m. -- The mineralizing fluids are interpreted to have been CO₃ ²⁻ and F⁻ rich, slightly acidic and v/ith a temperature range of 250 to 300°C. These fluids are interpreted to have originated through metamorphic dehydration and decarbonation of mixed island arc and continental crustal rocks. Gold precipitation resulted from the reaction of these fluids with the Fe-rich Banded Mafic unit. Pre-existing and simultaneously crystallizing pyrite served as nuclei for gold precipitation.


identifier: Mulrooney, Daniel Joseph <https://research.library.mun.ca/view/creator_az/Mulrooney=3ADaniel_Joseph=3A=3A.html>   (2004) Residence and partitioning of REE and selected trace elements in amphibolite-facies metabasites : an example from the St. Anthony complex, northern Newfoundland.  Masters thesis, Memorial University of Newfoundland.

abstract: Metabasites from the metamorphic sole of the Hare Bay Allochthon, northern Newfoundland, exhibit a narrow metamorphic field gradient from greenschist- through epidote-amphibolite to amphibolite-facies. The metamorphic facies are defined from the distribution of the following mineral assemblages (all with quartz and titanite): chlorite-epidote-plagioclase-Ca amphibole (greenschist), Ca amphibole-plagioclase-epidote (epidote amphibolite), and Ca amphibole-plagioclase (plagioclase amphibolite). The assemblage Ca amphibole-plagioclase-garnet-biotite-apatite (biotite amphibolite) equilibrated in a K₂O-enriched shear-zone. Representative samples from each metamorphic facies were were analyzed for rare earth elements (REE) and a suite of trace elements (Sc, V, Cr, Ni, Cu, Zn, Sr, Rb, Y, Zr, Nb) in bulk rocks and the major minerals Ca amphibole, plagioclase, epidote, titanite and garnet, by solution ICP-MS and laser-ablation microprobe (LAM)-ICP-MS respectively. Major-element concentrations of bulk rocks and minerals were determined by XRF and electron probe microanalysis (EPMA) respectively. -- On the basis of bulk-rock, major- and trace-element data and chondrite-normalized REE data, two suites of metabasites were distinguished: (i) gamet-absent greenschist and amphibolite characterized by relatively low SiO₂ and A1₂O₃ and Y+MREE-enrichment; and (ii) garnet-bearing amphibolite with relatively low FeOtotal + MgO, high P₂O₅ and Zr+LREE enrichment. The bulk P₂O₅ and LREE enrichment in garnet-bearing rocks is inferred to be sequestered in unanalysed fine-grained apatite. -- Ca amphibole, plagioclase, epidote, garnet and titanite exhibit systematic distributions of major- and most trace-elements, including REE in epidote amphibolite, plagioclase amphibolite and biotite amphibolite assemblages, indicating a close approach to equilibrium. However, variations in the distributions of a few trace elements (e.g., Rb and Nb between certain phases) suggest that equilibrium may not have been achieved for all elements at a thin-section scale. -- In garnet-absent amphibolites, LREE are partitioned in the sequence titanite>epidote>>Ca amphibole≥plagioclase, whereas HREE are partitioned in the sequence titanite>>CA amphibole>epidote>>plagioclase. For biotite amphibolites, LREE and HREE are partitioned in the sequence titanite>>Ca amphibole ≈ plagioclase>garnet and titanite≥garnet>>Ca amphibole>>plagioclase respectively. -- Controls on trace-element incorporation in individual phases, and hence on partitioning behaviour, were qualitatively evaluated in this study. Crystal structure exerts a major control on trace-element partitioning so that the distribution of elements that occupy non-analogous sites in the two minerals (e.g., Sr in the A site in plagioclase and the X site in garnet) is characterized by a quasi-'parabolic' curve in Onuma-type diagrams in which distribution coefficients are plotted against ionic radius. Such diagrams are useful for the qualitative extraction of site parameters such as site radius and elasticity in the two minerals. In the case of mineral pairs that partition a trace element on analogous sites in the two minerals (e.g., Ni in MVI sites in Ca amphibole-epidote pairs), information on site size and elasticity is masked by interference between the similar competing sites and the qualitative extraction of site parameters is more problematic. In addition to crystallographic controls, several major-element compositional controls on trace-element incorporation in Ca amphibole, plagioclase, epidote and garnet were recognized and evaluated. For example, REE and Y partitioning into Ca amphibole, garnet and plagioclase are influenced by the major-element occupancy of the M4, X and A sites of these three phases respectively; and abundances of several divalent first row transition metals (Zn, Cu, Ni, Co) are positively correlated with the content of octahedral A1 in M3 sites in epidote. -- Integration of mineral modes with trace-element mineral concentration data was carried out to determine mass balances for garnet-absent samples of similar bulk composition and the results were cross-checked against bulk-rock trace-element data. The results yield very good matches between the measured and reconstructed trace-element abundances in all cases, indicating that all the hosts for these elements had been analysed. They also illustrate the change in the relative importance of the four minerals, Ca amphibole, plagioclase, epidote and titanite, as carriers of the REE and analysed trace elements across the epidote-out isograd. In particular, they show that in most epidote-amphibolite, the trace-element enriched phases titanite and epidote, especially the former, are the dominant carriers of Y, Nb and all REE, accounting for approximately 90% and 65% of the LREE and HREE budgets respectively despite their low modal abundances, and that the ΣREE carried in plagioclase is negligible. However, where modal titanite and epidote are relatively less abundant (or where epidote is absent in plagioclase amphibolite), the relative capacities of these phases as trace-element or REE reservoirs are significantly diminished, Ca amphibole becomes the primary REE reservoir and ΣREE in plagioclase is increased. -- Major-element mineral compositions from representative epidote amphibolite and plagioclase amphibolite that straddle the epidote-out isograd were examined using the algebraic technique of singular value decomposition to quantitatively model the epidote-out reaction isograd. The following balanced reaction provides a realistic representation of the isograd, textures, and modal variations observed in natural samples throughout the study area: 1.00Ca amp₄₆ + 1.70PI₄₆ + 0.34Ep₄₆ + 1.77Ttn₄₆ = 1.07Ca amp₄₉ + 1.92Pl₄₉ + 1.80Ttn₄₉ where the superscripts 46 and 49 refer to compositions of minerals in samples below and above the epidote-out isograd respectively. -- The results of evaluating the redistribution of selected trace elements and REE across the epidote-out isograd using the model reaction are compatible with the uptake of LREE by Ca amphibole, and to a lesser extent plagioclase, due to an reduction in LREE abundance in titanite and the breakdown of epidote. These linked changes indicate that there are both crystal-chemical and mineral assemblage controls on REE and trace-element partitioning in these rocks. This study illustrates the significance of the minerals epidote and titanite as the principal carriers of REE in epidote-amphibolite-facies metabasites and the quantitative estimation of partition coefficients shows that Ca amphibole acts as an important carrier for REE above the epidote-out isograd.


identifier: Elfigih, Omar Bouzid <https://research.library.mun.ca/view/creator_az/Elfigih=3AOmar_Bouzid=3A=3A.html>   (1991) The sedimentology and reservoir characteristics of the Lower Acacus formation, NC2 concession, Hamada Basin, NW Libya.  Masters thesis, Memorial University of Newfoundland.

abstract: Analyses of core and wireline logs from twenty one (21) wells distributed inside and outside the study area demonstrate that the Lower Acacus Formation consists regionally (across the Hamada Basin) of at least fourteen progradational sandstone units (A1-A14) from south to north. Locally, in the study area, at least nine progradational sandstone units (A6-A14) exist. On the basis of a best-facies-fit approach the stratigraphic framework indicates deltaic packages change laterally northward, in a progradational fashion, from fluvial-channel sands to coastal-deltaic sands and silts and eventually to offshore-marine reworked sands and shales. The depositional patterns of some sandstone units in the Lower Acacus Formation are lobate. Sand axes in each unit are offset from those in the older units due to sediment loading and differential compaction within the delta complex. From core data and log responses the Lower Acacus sandstones are interpreted to been have deposited as deltaic lobes during shoreline progradation, where each lobe consists of two lithofacies; (1) a horizontal cross-laminated, clean sandstone or proximal delta front lithofacies which has the best reservoir quality, low clay content, and (2) a bioturbated silty-sandstone or distal delta front lithofacies (marginal), with poor reservoir quality and high clay content. -- Secondary porosity, found to be the dominant porosity type in the Lower Acacus Sandstones, was derived mainly from partial dissolution of carbonate cements, some detrital grains, and rock fragments. This porosity is characterized by oversized, elongate, corroded and irregular pore spaces. Primary pores are minor, but where present are small, concavo-convex and trianglular in thin-section cross-sectional shape and are usually associated with quartz-supported clean sandstones. -- Core plug porosity quantifies total porosity but does not distinguish micro-porosity from macroporosity (effective porosity), and shows an insignificant relationship with corresponding permeability values due to microporosity associated with clay-rich sandstones. Thin-section porosity on the other hand most significantly reflects corresponding permeability values and identifies meaningful correlation after the elimination of clay-rich sandstones. -- Oil-bearing sands with high reservoir quality are found to be closely related to sedimentary environmental facies. The best reservoir quality sandstone units are found in the proximal delta front facies at the top of deltaic lobes in wells which occur in the central and southern part of the study area. They are characterized by an average porosity of 20.3%, an average permeability 921 md., an average hydrocarbon saturation of 62% and a cutoff point of 48% for formation water saturation. The cumulative estimation (total hydrocarbon estimation) of hydrocarbons from multiple pay zones in the Lower Acacus Sandstones on a per well basis is 803 BOPD with 0.931 MMCFGPD, while the estimated oil-in-place for all structures producing from the Lower Acacus Sandstones in the study area is calculated to be about 190.12 MMSTBOIP and 117.19 MMMSCFGIP. -- Information from wells in the study area, with specific reference to GR log shapes, and integrated with sand isopach maps has resulted in paleogeographic maps which illustrate the depositional history of the Lower Acacus Formation and provides the basis for future exploration prospects.


identifier: Chow, Nancy <https://research.library.mun.ca/view/creator_az/Chow=3ANancy=3A=3A.html>   (1985) Sedimentology and diagenesis of middle and upper Cambrian platform carbonates and siliciclastics, Port au Port Peninsula, Western Newfoundland.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract: The Port au Port Group is an outer shelf, peritidal carbonate and siliciclastic platform deposit composed of six lithofacies: (1) parted limestone; (2) grey and variegated shale; (3) ooid calcarenite; (4) carbonate laminite; (5) stromatolite and thrombolite mound; and (6) mixed glauconitic sandstone and oolite. Ooid calcarenites, carbonate laminites, and variegated shales together were deposited as a series of carbonate sand shoals in which the shallow-subtidal and intertidal zones were each regimes of in situ ooid formation and accumulation. Parted limestones and grey shales were deposited on muddy tidal flats leeward of the carbonate shoals. Both muddy tidal flats and carbonate sand shoals were sites of stromatolite and thrombolite mound growth. Siliciclastic sands and silts represent eolian deposits and reworking of nearshore siliciclastics. -- The lithofacies occur in two types of meter-scale assemblages: (1) predictable meter-scale, shallowing-upward cycles of parted limestone and shale deposited in the muddy tidal flats, which were largely controlled by variable rates of sedimentation; and (2) unpredictable meter-scale assemblages of ooid calcarenite and carbonate laminite, which resulted from the sporadic but frequent migration of the carbonate shoals. These two assemblages together form Grand Cycles that reflect the complex interplay of sea-level eustasy and regional variations in sedimentation and environmental conditions. These Grand Cycles are distinct from western North American cycles because they are composed almost entirely of peritidal sediments; thinness of the cycles; and restricted areal occurrence. These differences may reflect narrower shelf widths; lower rates of sedimentation; and lower amplitudes of relative sea-level rise on the northeastern margin of the North American craton compared to the western margin. -- Concentric ooids in intertidal brown oolites were originally bimineralic; aragonitic laminae are now blocky calcite and laminae of fibrous and micritic Mg calcite have altered to calcite with well-preserved fabrics. Radial ooids in subtidal grey oolite were Mg calcite only and underwent progressive alteration during burial to give rise to a variety of cortical fabrics, ranging from radial to blocky calcite. The facies-specific nature of ooid mineralogy and morphology suggests that local environmental conditions strongly influenced ooid formation, particularly turbulence and sea floor topography. -- The spectrum of calcite cements, mudstones and dolomites represents a protracted history of diagenesis, which includes: (1) synsedimentary peritidal lithification, erosion and dolomitization; (2) possible shallow-burial meteoric lithification and alteration of metastable carbonates; (3) deep-burial lithification and dolomitization; and (4) cementation and dedolomitization related to uplift. Peritidal lithification and dolomitization, along with minor shallow-burial lithification, determined the final appearance of the rocks; deeper burial and re-exposure events resulted in only a diffuse overprinting of all lithofacies.


identifier: Kilfoil, Gerald Joseph <https://research.library.mun.ca/view/creator_az/Kilfoil=3AGerald_Joseph=3A=3A.html>   (1988) An integrated gravity, magnetic and seismic interpretation of the Carboniferous Bay St. George Subbasin, western Newfoundland.  Masters thesis, Memorial University of Newfoundland.

abstract: Gravity, magnetic and reflection seismic data were compiled and interpreted to determine the basement and internal structure in the Carboniferous Bay St. George Subbasin of Western Newfoundland. Gravity data, compiled from portions of several datasets for onshore regions, were complemented by those from a recent underwater gravimetry survey of St. George's Bay. Magnetic data from published aeromagnetic maps, a private aeromagnetic survey and a sea magnetometer survey were integrated into a single data set by application of corrections and offsets to bring each to a similar datum. Reflection seismic data of 1971 and 1973 vintage cover an area of the outer St. George's Bay. -- The geophysical interpretation strongly supports the hypothesis of a subbasin opened by northeast-directed right-lateral wrench tectonics. In addition, less prominent structural features are discussed in the text and a basement structure map is produced. Evidence in support of structure within the sedimentary section is also discussed. -- Sedimentation in the early history of the subbasin was controlled by vertical displacements along the northeast directed strike-slip faulting of the Cabot Fault system that initiated the basin opening during Famenian time. The Long Range Fault, which borders the subbasin to the southeast, is readily identified from the contoured datasets by its strong geophysical signature. A fault identified as trending northeast along the southeast St. George's Bay coastline exhibits a similar but less prominent geophysical character. The latter fault bounded the early subbasin on its northwest margin during deposition of the Anguille Group. -- North-northeast oriented faults, which are associated with vertical displacement of Lower Paleozoic rocks on the Port au Port Peninsula, are extrapolated offshore on the basis of a series of magnetic highs whose maxima define an east-west trend south of the peninsula's southern coastline. -- Basement picks on the reflection profiles delimit the offshore subbasin as a half-graben dipping monoclinally to the southeast and interrupted locally by strike-slip faults. Gentle gravity gradients to the southeast attest to the agreement of datasets and enable depth mapping in the inner reaches of the bay. Results of the present interpretation show the subbasin as transected by several east-west dextral strike slip faults spaced on the order of 10 km, and laterally displacing features resulting from the earlier faulting by distances of the order of 5 km. Vertical displacements along these faults is minimal with the single exception of a fault at 5365N (UTM km) where a northward throw of greater than 2.0 km has been identified from offsets in the basement seismic reflector. Timing of secondary faulting is uncertain, but is considered to largely postdate deposition of the Missippian-aged Codroy Group, with possibilities of initiation as early as the Mississippian/Pennsylvanian time boundary. -- Gravity and magnetic data profiles, selected where best constrained by the seismic interpretation and geology, were modelled using available physical parameters and developed modelling techniques to obtain estimates of depth to basement, configurations of major lithologic units and the extent of large evaporite structures within the Carboniferous strata.


identifier: Tuach, John <https://research.library.mun.ca/view/creator_az/Tuach=3AJohn=3A=3A.html>   (1987) The Ackley high-silica magmatic/metallogenic system and associated post-tectonic granites, southeast Newfoundland.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract: The Ackley Granite Suite occupies 2,415 km² in southeastern Newfoundland, and intruded across the boundary between the Avalon and Gander tectonostratigraphic terranes. An Rb-Sr whole rock age of 355 ± 9 Ma is younger than ⁴⁰Ar/³⁹Ar ages around 370 ± 5 Ma. Two calc-alkaline granodiorite-granite plutons to the west and northeast of the Ackley Granite Suite provided an Rb-Sr whole rock age of 427 ± 12 Ma, in agreement with an ⁴⁰Ar/³⁹Ar biotite age of 410 ± 4 Ma. -- Much of the Ackley Granite Suite exhibits geochemical signatures of A-type granites, and a muscovite-bearing phase occurs in the north. Geochemical enrichment/depletion trends culminate at significant, endocontact, spatially separate, aplite-pegmatite Mo deposits at Recontre Lake, and quartz-topaz-Sn greisen deposits at Sage Pond. Hydrothermal muscovites from the deposits provide almost identical ⁴⁰Ar/³⁹Ar ages, indistinguishable from ⁴⁰Ar/³⁹Ar ages of biotite in granites. The granites and the mineralized areas have high-temperature, magmatic, oxygen isotope signatures, with minor evidence for high-temperature meteoric hydrothermal activity at the prospects, and evidence for low temperature subsolidus exchange with meteoric fluids through much of the Ackley Granite Suite. The data confirm previous interpretations that large areas of the Ackley Granite Suite were rapidly cooled, and together with fluid inclusion data, provide evidence for the contemporaneity of magmatic and mineralizing processes. -- The southern Ackley Granite Suite is the frozen equivalent of high-silica, chemically zoned, magma chambers responsible for the formation of large ash flows. Convective fractionation may have operated to produce the observed chemical zonations. An emplacement model based on available geophysical data indicates stoping of large (20 km x 10 km) blocks from the upper to middle crust in response to regional crustal extension and lower crustal melting. -- The H₂O content and the degree of trace element enrichment in the magma appear to have been important controls on mineralization. The Mo deposits formed from fluids evolved from a relatively H₂O-rich magma while Sn mineralization formed from F-rich fluids evolved from a more specialized, relatively anhydrous magma. A genetic trend from Mo-mineralization to Sn-mineralization during development of the high-silica upper magma layer is suggested. -- Keywords: Ackley Granite Suite; granite; high-silica; post-tectonic; tin; molybdenum; chemical zonation; metallogenesis; isotopes; geochemistry; pluton emplacement.


identifier: Jin, You-Huang <https://research.library.mun.ca/view/creator_az/Jin=3AYou-Huang=3A=3A.html>   (1991) Vertically integrated models of bottom mixed layer growth in the ocean.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract: A new vertically integrated model is developed for the growth of bottom mixed layers. Unlike the usual slab models this model retains the vertical variation of mean speed with height, which appears as a parameter in the energy balance. The mixed layer growth problem is solved analytically for a horizontal flat bottom and numerically for a sloping flat bottom. A relaxation problem, the decay of motion in the bottom mixed layer after the geostrophic flow in the interior ceases, is also solved analytically and numerically. Finally solutions including thermal wind effects on bottom mixed layer growth are obtained for both a horizontal flat bottom and a sloping flat bottom. -- For the horizontal flat bottom case, an algebraic formula for mixed layer thickness is obtained for arbitrary values of the Brunt-Vaisala frequency and Coriolis parameter. The results show that the vertical variation of speed must be taken into account when the ratio of the Brunt-Vaisala frequency to the Coriolis parameter is less than or of order unity, and that the formula is consistent with that obtained by Weatherly and Martin (1978). Formulae for dependence of friction velocity and veering angle on stratification are also obtained. -- For a sloping bottom at the initial stage of bottom boundary layer growth the vertically integrated model produces results very similar to those obtained by Weatherly and Martin (1978) using the Mellor and Yamada Level II turbulent closure model. The main effect of bottom slope is to produce upwelling or downwelling within the bottom boundary layer. After the initial period of boundary layer development the vertically integrated buoyancy force can grow to reach a balance with the vertically integrated driving pressure gradient so that the Ekman transport is extinguished and the layer becomes arrested. The length of the initial period greatly depends on the sign of bottom slope. -- The effects of thermal wind are shown to be important. For a horizontal flat bottom if the vertical shear in the interior is positive the mixed layer grows indefinitely. If the vertical shear is negative the thickness reaches a constant value or decreases with time. For a sloping flat bottom the thermal wind is important when the isopycnal slope is comparable to or much greater than the bottom slope. The results are in agreement with the observations made by Weatherly and Van Leer (1977) on the western Florida Continental Shelf.


identifier: Desrochers, Andre <https://research.library.mun.ca/view/creator_az/Desrochers=3AAndre=3A=3A.html>   (1985) The Lower and Middle Ordovician platform carbonates of the Minigan Islands, Quebec: stratigraphy, sedimentology, paleokarst and limestone diagenesis.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract: An undeformed sequence of Lower and Middle Ordovician shallow-water carbonates is exposed on the Mingan Islands located along the Quebec North Shore of the Gulf of St. Lawrence. This sequence comprises dolostones of the Romaine Formation and limestones of the Mingan Formation. The late Canadian to earliest Whiterockian Romaine Formation is subdivided into three formal members: Sauvage Member, Sainte-Genevieve Member and Grande Ile Member. The Chazyan Mingan Formation is subdivided into four formal members: Corbeau Member, Perroquet Member, Fantome Member and Grande Pointe Member. -- The Romaine Formation represents a shallowing-upward sequence comprising a thin basal assemblage of trangressive sandstones, a middle assemblage of subtidal carbonates and an upper assemblage of cyclic peritidal carbonates. Romaine sediments were pervasively dolomitized in shallow subsurface environments (possibly in mixing zones) before the end of post-Romaine karst erosion. -- The Mingan Formation is a complex environmental mosaic of peritidal and subtidal limestones with a basal trangressive sandstone overlain by tidal flat siliciclastics. Sedimentation changed abruptly with deposition of peritidal and subtidal limestones prior to a period of subaerial exposure resulting in the formation of a karst surface with substantial relief. Resubmergence of this irregular rocky coastline with scattered beachrocks, resulted in a complex facies mosiac with sand shoals forming in underlying paleokarst depressions as tidal deltas 1-10 km wide. -- Three superimposed calcarenite cycles are present in the Mingan sand shoal complex. These sand shoals were periodically exposed and subject to karstification in response to minor fluctuations in sea level. The amount of sea level fall was minor and deeper inter-shoal areas were not affected by subaerial exposure but were sites of more restricted deposition. -- Mingan reef limestones are of three types: biostromes, bioherms which grew in tranquil settings, and bioherm complexes which grew under more turbulent conditions. Reef organisms include lithistid sponges, bryozoans, tabulate corals and solenoporacean algae which occur in a variety of different biotic assemblages. These builders are in part inherited from older bioherms and in part newly involved taxa. Mingan bioherms are typically small mound-shaped structures composed of abundant skeletons and rich in lime mud. Stromatoporoids are conspicuously absent as builders in the Mingan bioherms in contrast to the classic Chazy reefs of Vermont and New York. -- Three different types of paleokarst surfaces are present in the Mingan sequence: 1) an extensive karst plain, represented by the post-Romaine unconformity; 2) an irregular karst, represented by the intra-Mingan paleokarst and 3) local karst surfaces capping calcarenite cycles. -- Alteration of the Mingan limestones resulted from three distinct phases of diagenesis: marine, near-surface and deep burial; near-surface is the most important, especially beneath subaerial exposure surfaces. Vadose cement is not present in spite of extensive evidence of subaerial exposure. Crystal debris, similar to "vadose silt" and formed by the internal erosion of contemporaneous phreatic cements, was subsequently deposited as geopetal internal sediment.


identifier: Malpas, John Graham <https://research.library.mun.ca/view/creator_az/Malpas=3AJohn_Graham=3A=3A.html>   (1976) The petrology and petrogenesis of the Bay of Islands Ophiolite Suite, Western Newfoundland.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract: The Bay of Islands Complex, situated on the west coast of Newfoundland, forms the upper slice assemblage of a number of allochthonous slices that were emplaced on platformal carbonate rocks of the ancient North American continental margin during the lower Middle Ordovician. The Complex consists of a complete ophiolite sequence disposed in four main massifs and believed to represent obducted portions of oceanic lithosphere. During early stages of displacement from the oceanic environment, a basal dynamothermal aureole was developed and remains part of the Complex. Temperatures of metamorphism in this aureole suggest that the ophiolitic rocks were just formed and still hot when displaced. This, together with other evidence, suggests their production in a marginal basin or in the environs of a ridge, subduction zone, transform triple point. -- Petrological, mineralogical and chemical data show that the Complex may be divided into a lower series of ultramafic tectonites representing mantle material, and a higher series of cumulate and extrusive rocks capped by clastic sediments which may be correlated with oceanic crust. -- Examination of the tectonite series reveals a lower spinel lherzolite member overlain by harzburgites. Both rock types are cut by numerous deformed and undeformed olivine-pyroxene veins. These veins represent early crystallisation products from a picritic tholeiite magma derived at 18 kb and 1100°C by ~ 23% partial melting of a spinel lherzolite to leave a harzburgite residuum. The remainder of the magma crystallised as different cumulate and extrusive rocks under crustal conditions. -- The petrogenetic model derived from the mineralogy and chemistry implies a rising diapiric body beneath an accreting centre and allows for the production of tholeiitic, transitional and mildly alkaline basalts from a similar parent. The nature of the basalt erupted depends upon rate of upwelling and rate of crysallisation within the diapir. Prolonged fractionation at pressures of 8-18 kb may explain the derivation of off ridge-axis alkaline series. Furthermore, the model places limits on the depths of melting within the rising diapir and suggests that crystallisation takes place at depths of less than approximately 60 km. -- Comparison of the Bay of Islands Complex with oceanic lithosphere and other ophiolite suites suggests it is possibly the ideal type example with which to study oceanic crust/mantle relationships.


identifier: Vardy, Sheila R. <https://research.library.mun.ca/view/creator_az/Vardy=3ASheila_R=2E=3A=3A.html>   (1991) The deglaciation and early postglacial environmental history of southcentral Newfoundland: evidence from the palynostratigraphy and geochemical stratigraphy of lake sediments.  Masters thesis, Memorial University of Newfoundland.

abstract: The purpose of this thesis is to reconstruct the chronology of deglaciation and early Holocene environmental change in southcentral Newfoundland. Previous palynological studies have helped to define the timing of deglaciation and the sequence of postglacial environmental change in certain parts of Newfoundland, but a firm chronology of events for the entire island has not yet been established. -- Radiocarbon dating, pollen analysis and geochemical analysis have been carried out on sediment cores from four ponds, including three within the proposed limit of the main Newfoundland ice cap and one from the Hermitage Peninsula, which was apparently affected by a smaller local ice cap. The pollen, sediment and geochemical stratigraphies of the basal sediments of these cores confirm that the basal radiocarbon dates represent early stages in the postglacial sequences. The basal dates from Northwest Gander River Pond (10,200 ± 240 BP; GSC-5027), Moose Pond (10,000 ± 170 BP; GSC-5029) and Pool's Cove (9710 ± 120 BP; GSC-4945) are therefore considered minimum ages of deglaciation, but it is difficult to determine when the Conne River site became ice free since the basal date of 11,300 ± 100 BP (GSC-3436; Blake, 1983) is suspected of being too old. -- All four sites were apparently ice covered during the Late Wisconsinan, and there is no evidence that deglaciation occurred before the Younger Dryas episode. It is inferred that all three sites within the limit of the main Newfoundland ice cap were ice free before 10,000 BP, and that deglaciation progressed by downwasting, possibly beginning by 10,500 BP in areas of high elevation. The basal date of 9710 ± 120 BP (GSC-4945) from Pool's Cove Pond on the Hermitage Peninsula provides a minimum date of deglaciation, but this site may have been ice free by 10,100 BP. -- The reconstruction implies that deglaciation of southcentral Newfoundland began in the middle of the Younger Dryas cold period, and can therefore only be considered tentative, especially in light of doubts about the accuracy of bulk sediment radiocarbon dating of basal lake sediments.


identifier: Kerr, Andrew <https://research.library.mun.ca/view/creator_az/Kerr=3AAndrew=3A=3A.html>   (1989) Early Proterozoic granitoid magmatism and crustal evolution in the Makkovik province of Labrador: a geochemical and isotopic study.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract: The Lower to Middle Proterozoic Trans-Labrador Granitoid Belt in the Makkovik Structural Province is divided on the basis of field relationships and geochronology into Makkovikian and Labradorian plutonic assemblages, representing approximate time intervals of 1840 - 1720 and 1670 - 1600 Ma respectively. The Makkovikian assemblage includes both syn- and post-tectonic associations, but precise U-Pb zircon ages mostly cluster around 1800 Ma, suggesting a single main intrusive episode that transcended the later deformation associated with the Makkovikian orogeny. The Labradorian assemblage is not associated with local deformation or metamorphism, but is probably a distal effect of the ca. 1650 Ma Labradorian orogeny, prevalent south of the study area. Both assemblages are broadly correlative with volcanic sequences of similar age and geochemical affinity. -- The Makkovikian assemblage is dominated by siliceous, potassic, commonly porphyritic, granites and alkali-feldspar granites, associated with subordinate monzonite to quartz syenite. High-silica granite suites are commonly fluorite-bearing. In geochemical terms, most Makkovikian granitoids are metaluminous to slightly peralkaline, Fe-enriched, and enriched in Zr, Nb, Hf, REE, Zn and fluorine. A comparative analysis suggests that they are transitional in character between Phanerozoic post-orogenic (post-collisional) assemblages and "A-type" or "within-plate" granitoid assemblages. Similarly enigmatic characteristics have been reported from Early Proterozoic granitoid batholiths elsewhere in the world. -- The subordinate, bimodal, Labradorian plutonic assemblage comprises gabbro-diorite-monzonite-syenite suites, derived from mafic parental magmas, and an assortment of siliceous, generally leucocratic, granitoid rocks. Mafic rocks resemble high-K calc-alkaline or shoshonitic basalts, and their associated felsic differentiates are enriched in Rb, Cs, Th, and U, as a consequence of protracted fractionation. Other Labradorian granites (s.s.) are metaluminous to peraluminous in composition, and depleted in Zr, Nb, Hf, REE, Zn and fluorine, indicating that they had quite different sources from their Makkovikian counterparts. -- The Makkovikian assemblage displays geographically systematic Nd isotopic variations. In the west, negative εNdCHUR indicates ancient (probably Archean) crustal material in sources, but values are too high to permit derivation entirely from such material. These rocks probably represent mixtures of juvenile, mantle-derived, magma and older polycyclic Archean crust. In the east, positive εNdCHUR indicates juvenile, Proterozoic sources, and gneissic rocks representing possible basement have depleted-mantle Nd model ages of ca. 2100 Ma. Discrete, high-silica, "A-type" granite plutons show an east-west shift in εNdCHUR from +6 to -6, but retain remarkably similar elemental characteristics in both domains. It is concluded that magmas in the east also contained a significant crustal component, but that this component had a short crustal residence period. Nd isotopic data thus define a fundamental crustal boundary between an Archean Craton and a younger (accreted?) Proterozoic crustal province. Makkovikian magmatism accompanied and followed accretion of the younger domain, and is suggested to have resulted from emplacement of anhydrous, hot, mantle-derived mafic magmas into the lower crust, where they crystallized, assimilated and mixed with crustal rocks and melts thereof. -- Labradorian rocks mostly have εNdCHUR of +1 to -2, regardless of composition or location. Olivine-bearing mafic rocks, which cannot represent crustally-derived magmas, have εNdCHUR of ca. +1, significantly below postulated values for concurrent depleted mantle. It is suggested that this crustal component was introduced to depleted mantle via subduction of continent-derived sediment, as suggested for modern arc magmas. However, some Labradorian granites that lack mafic parents could be derived by anatexis of Makkovikian "mixed" crust, or juvenile material underplated during Makkovikian events. Labradorian magmatism is tentatively interpreted as a distal-arc assemblage above a subduction zone that records renewal of tectonic activity following Makkovikian terrane accretion and magmatism. -- The isotopic characteristics of both assemblages underline the importance of the Early Proterozoic as a period of new crustal growth. Makkovikian magmatism reorganized previously generated crust, and added significantly to it, particularly in the "juvenile" eastern domain. Largely ensialic crustal growth of this type may have been more important in a hotter, Proterozoic Earth and, in concert with ensimatic crust generation linked to subduction, may account for the high crustal growth rates deduced for this crucial period in planetary evolution. -- The transitional characteristics of the Makkovikian assemblage may also be a function of greater heat flow. Recent models for "anorogenic" magmatism invoke insulation of the mantle by newly-accreted crust or aggregated megacontinents, resulting in mantle upwelling, plume activity, magmatism and (eventually) rifting. In a hotter Proterozoic Earth, the time-lag between aggregation and mantle upwelling would be shorter, and conditions now associated with "anorogenic" magmatism would prevail widely in post-orogenic environments. It is perhaps significant in this respect that worldwide Lower Proterozoic (1900 - 1700 Ma) orogenic events have recently been interpreted to record the assembly of an early Pangean-type supercontinent. -- KEY WORDS: Labrador; Precambrian Proterozoic; Granitoids; Granite; Batholiths; Petrology Ge chemistry; Comparative; Isotopes; Neodymium; Petrogenesis; Crustal Evolution.


identifier: Davis, William James <https://research.library.mun.ca/view/creator_az/Davis=3AWilliam_James=3A=3A.html>   (1991) Granitoid geochemistry and Late Archean crustal evolution in the central Slave Province.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract:
The Contwoyto-Nose Lakes area in the central Slave Province is a Late Archean granite-greenstone terrain consisting of metavolcanic (Central Volcanic Belt) and metasedimentary rocks extensively intruded by syn- to post-deformation granitoid rocks. The latter, representing over 65% of exposed crust in the area, were emplaced between 2616 and 2585 Ma, post-dating the earlier (ca. 2670-2650 Ma) assemblage by more than 35 m.y. -- Plutonic rocks in the area are subdivided into 8 suites. Four of the suites are strongly deformed and recrystallized, and are temporally linked to the supracrustal assemblage (van Breemen et al., 1990). These include: 1) hornblende diorites of the Central Volcanic Belt (CVB) Suite; 2) quartz porphyritic trondhjemitic plutons of the Gondor Suite; 3) biotite tonalites to monzogranites of the Wishbone Suite; and, 4) biotite tonalites of the Olga Suite. Two suites, the Siege and Concession, are interpreted to have been emplaced syn- to late- during the regional metamorphism and deformation, whereas the Yamba and Contwoyto Suites post-date this event. The Siege Suite consists of leucocratic biotite tonalite. The Concession Suite is predominantly tonalite but ranges from hornblende diorite to biotite granodiorite compositions. These rocks define prominent aeromagnetic highs and commonly form composite bodies. In many cases, plutons are tabular-shaped, with long dimensions parallel to the regional foliation (S₂). Two samples have yielded U-Pb ages of 2608±1 and 2608+5/-3 Ma. The Yamba Suite consists dominantly of red weathering, biotite monzogranites and associated pegmatites. The Contwoyto Suite, on the other hand, contains primary muscovite and biotite (± tourmaline) and is grey-green weathering. Pegmatites are a ubiquitous feature of the suite. One sample of the Yamba and 3 samples of the Contwoyto Suite have yielded U-Pb ages within error of ca. 2582-2585 Ma. -- Rocks of the CVB are calc-alkaline and most have trace element characteristics diagnostic of rocks formed in modern supra-subduction zone settings. The felsic plutonic suites include low-Al₂O₃ (Gondor, Wishbone Suites) and high-Al₂O₃ (Olga Suite) trondhjemites. The former have high abundances of HFSE and REE and are compositionally similar to rocks from Phanerozoic ophiolites, ridges and island arc
settings. They are interpreted to have formed by low pressure, partial melting of mafic protoliths leaving a pyroxene- and plagioclase-dominated residue. In contrast, the high-Al₂O₃ trondhjemites have steep REE patterns with low abundances of the HREE and are interpreted to have formed by melting of garnet-bearing mafic protoliths. -- The Siege Suite has characteristics of high-Al₂O₃ trondhjemites and may also have formed by partial melting of garnet-bearing mafic crust. The Concession Suite is calc-alkaline and varies from metaluminous to weakly peraluminous with increasing SiO₂ content (50-72 wt%). The suite is characterized by high contents of Sr (up to 1600 ppm), Ba (up to 2000 ppm), and Ce (up to 170 ppm), high (Ce/Yb)N, low Rb/Sr (<0.3). no or small negative Eu anomalies and pronounced negative Nb anomalies. Mafic samples are most enriched in trace elements; Sr, Ba, Y and the REE show a continuous decrease with increasing SiO₂. Although the REE characteristics are consistent with those predicted in melts of garnet-bearing mafic crust, the chemical variation within the suite cannot be accounted for by variable degrees of melting of basalt. The tonalites can however, be related to the mafic end members by assimilation and fractional crystallization (amphibole-plagioclase dominated) processes. The composition of potential parental magmas is similar to some high-Mg andesites (HMA; e.g. sanukitoids, bajaites) derived from melting hydrated enriched peridotite. The juvenile εNd(I) values measured for the suite limit the mantle enrichment event to the 200 m.y. preceding magmatism. The HFSE characteristics suggest mantle enrichment may have been subduction-related. -- Post-deformation plutonic suites are high SiO₂ (68 to 78 wt%) and peraluminous. The Yamba Suite is K₂O-rich with high Rb/Sr ratios and strongly negative Eu and Sr anomalies relative to enriched REE patterns. The Contwoyto Suite is, in general, less potassic and more strongly peraluminous. REE patterns are variable, probably reflecting the evolution of fluid phases and pegmatite formation, εNd(I) values for both suites exhibit a wide range from positive (+3.7) to negative values (-5.1). The Contwoyto Suite has been modelled as partial melts of dominantly metasedimentary protoliths, possibly similar to the exposed turbidite sequences. The origin of the Yamba Suite is more equivocal. The spatial association with the earlier mantle-derived Concession Suite and their compositional similarity to granites of hybrid origin suggest that they may be products of the mixing and homogenization of mantle-and crust-derived materials. The negative εNd(I) values for some of these rocks require that the crustal component had a significant pre-history (> 400 m.y.). -- Nd isotopic data from representative rock types along an E-W traverse at 65° N across the central pan of the province reveal distinctly different characteristics in the east compared to the west. Supracrustal and plutonic rocks from the east have positive εNd(I) values consistent with juvenile sources and formation remote from significantly older crust. In contrast, samples of post-deformation granites west of 110°30'W have negative εNd(I) values. The Nd isotopic data for these granitoid rocks reflect the presence of mixed crustal sources dominated by Mid to Early Archean crust or derivative sediments. The asymmetric pattern defined by the Nd isotopic data suggests the presence of distinct crustal blocks beneath the Slave Province, as predicted by models proposing tectonic assembly of the province through accretion of juvenile crust to an older continental mass. -- The secular evolution in the mineralogy and geochemistry of the plutonic suites reflects a change from dominantly mantle- to crustal-derived plutonism. Igneous rocks of the early assemblage are interpreted to be remnants of an allocthonous island arc terrane, which was accreted to a continental block during the late Archean deformation. Crustal shortening and thickening during collision caused melting of previously subduction-modified mantle to generate HMA magmas, possibly by the detachment of the lower part of the lithosphere (e.g. Houseman et al., 1981). Intrusion of these mantle-derived magmas into the crust, in combination with crustal thickening, caused crustal melting and the generation of peraluminous granites. The nature and evolution of the granitoid rocks is comparable to features of more recent collisional orogenic belts. This interpretation suggests that the tectonic and related igneous processes leading to crustal stabilization in the Late Archean Slave Province were relatively similar to those in modern orogenic belts, which implies a continuity in process for the last 2.7 Ga.


identifier: Munro, Mandy <https://research.library.mun.ca/view/creator_az/Munro=3AMandy=3A=3A.html>   (1994) The Quaternary history of the Carmanville (NTS 2E8) area, northeast Newfoundland.  Masters thesis, Memorial University of Newfoundland.

abstract:
The Carmanville (NTS 2E/8) area is located in northeast Newfoundland. It is marked by a complex assemblage of sediments and landforms. These are in order of diminishing areal importance: till which has a variety of geomorphic expressions such as veneers, hummocks, ridges, and lineations; organic deposits; glaciofluvial sand and gravel (also meltwater channels); colluvial sediment; and fluvial deposits. -- Four ice flows are detected in the area: successively eastward, northeastward, northwestward, and northwestward. These are all argued to be Late Wisconsinan in age. Retreat and down-wasting of the third ice-flow, northwestward, was associated with large quantities of meltwater and the formation of the Ragged Harbour Moraine. This formed shortly after 12,000 BP. The final ice-flow event (also northwestward) may be correlative with the Younger Dryas cooling event dated to between approximately 11,000 and 10,000 BP. -- Till deposits are mainly formed by northwestward moving ice and are mostly fine-textured with high percentages of local clasts. They display only minor regional textural and lithological variations. All tills observed and analyzed are basal, and most are interpreted as melt-out or lodgment tills. -- The Ragged Harbour Moraine in the northeast of the study area is approximately 15km long and is composed of the most diverse sedimentary assemblage in the region. High angle-planar cross-bedded gravels, extensively deformed silts and sands, rhythmically and ripple bedded silts and sands, and diamictons are present within this complex and occur directly adjacent to each other. This sedimentary assemblage is interpreted as a sequence of subaqueous
fans which formed proglacially under rapid sedimentation rates, while ice was stagnating. Rogen moraines formed contemporaneously with the Ragged Harbour Moraine. The moraine formation does not represent a lengthy stillstand of glacial ice. -- The marine limit in the area is at least 57m asl (above sea level) based on emerged marine sediment at Noggin Hill and Wing's Point. Five further major sea level stands occurred at 52m, 38m, 34m, 17m, and 11m asl indicated by the presence of emerged beaches. Two terraces at 5m and 2m asl are evident around most of the coastline but may represent major storm events rather than being representative of relative sea-level change. These sea-level stands all occurred between 12,500 and 10,000 BP, Sea levels dropped to below present during the mid-Holocene and then continued to rise until present times.


identifier: Wilton, Derek Harold Clement <https://research.library.mun.ca/view/creator_az/Wilton=3ADerek_Harold_Clement=3A=3A.html>   (1983) Metallogenic, tectonic and geochemical evolution of the Cape Ray fault zone with emphasis on electrum mineralization.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract: The Cape Ray Fault Zone is host to two electrum/base metal sulphide-bearing quartz vein deposits. The deposits occur within an alaskitic granite (the Windowglass Hill Granite) and an intermixed graphite/ chlorite/ sericite schist unit (part of the Windsor Point Group). This study was initiated to determine the origin of these two deposits, but the metallogenesis could not be ascertained until the tectonic and lithogeochemical framework of the entire region was understood. -- The Cape Ray Fault cuts through an area of tectonic complexity in southwestern Newfoundland. The fault occurs within the Windsor Point Group, a northeasterly-striking, intermixed sequence of felsic and mafic pyroclastic/volcaniclastic and associated sedimentary rocks, which is centrally located between a tonalitic terrane to the northwest (the Cape Ray Granite) and an amphibolite facies gneiss unit, with synkinematic granite, to the southeast (the Port aux Basques Complex). The tonalite contains isolated metagabbroic remnants of an ophiolite sequence (the Long Range Mafic/Ultramafic Complex). The Windsor Point Group contains tonalitic fragments in the ignimbritic rhyolite at its base, and is in tectonic contact with the gneiss unit, wherein the gneiss is extensively retrogressed. The Windowglass Hill Granite intrude the Windsor Point Group in the northeastern part of the zone. Both sides of the fault zone were intruded by post-tectonic granites (the Strawberry Granite on the northwestern side and Isle aux Morts Brook Granite on the southeast). -- Geochronological determinations indicate that the tonalitic terrane is Ordovician in age, the Windsor Point Group and Windowglass Hill Granite are late Devonian, and the Strawberry/Isle aux Morts Brook Granites are early Carboniferous. -- Isograds defined in the Windsor Point Group indicate that metamorphic grade increases from lower to upper greenschist facies towards the SE, and that pressures are rather low. Within the Port aux Basques Complex metamorphic isograds record amphibolite facies parageneses, and pressures are estimated to be >2 kb higher. -- Except for the post-tectonic granites, all units in the fault zone were subjected to a three-phase deformational event of Acadian age which overprinted earlier fabrics in the gneiss complex, and produced D1 schistosities axial planar to F1 isoclinal folds with axes parallel to L1 mineral elongation lineations. D2 effected crenulation cleavages and assymmetrical, open to tight, F2 folds. D3 resulted in conjugate kink folding. D1 also produced mylonites within the Windsor Point Group. -- Geochemical evidence suggests that a) the tonalite and associated phases were derived as partial melts of the ophiolitic material with some continental crust involvement, b) the felsic volcanism in the Windsor Point Group, and the Windowglass Hill, Strawberry and Isle aux Morts Brook Granites formed from partial melts of underlying continental crust, and c) the Port aux Basques Complex was derived from felsic volcanic rocks with a probable island arc affinity (though continental crust is also implicated in their origin). The entire Cape Ray Fault Zone region appears to be a completely allocthonous terrane, from tonalite/ophiolite in the northwest to a meta-felsic eruptive igneous complex to the southeast, which was emplaced on Grenvillian basement. -- Wall rocks to the electrum-bearing quartz veins experienced a potassic alteration with LREE-depletion and minor elevations in chalcophile element concentrations. Background Au and Ag abundances are typically low, but there are elevations in those units in the immediate vicinity of the Windowglass Hill Granite. -- Ore metals in the showings are Au, Ag, Cu, Pb and Zn, and distributions resemble those seen in auriferous massive sulphide deposits. The minerals present are galena, sphalerite, chalcopyrite, pyrite and electrum with rare arsenopyrite; all of which are extensively intergrown. Temperatures of ore formation (from arsenopyrite and equilibrium sulphide mineral intergrowths) appear to be around 300°C. -- Sulphur isotope ratios indicate sulphur in the showings is of magmatic origin. Pb isotope ratios in galenas from the showings and felsic volcanic members of the Windsor Point Group are similar and have an oceanic crust/mantle isotopic signature. -- The precious/base metal-bearing quartz veins were deposited by hydrothermal fluids evolved as a vapour phase from the Windowglass Hill Granite. The ultimate origin of the magma was from partial melting of underlying Grenvillian crust. This same crustal material is implicated in the origins of the other granites.


identifier: Coyle, Marylou <https://research.library.mun.ca/view/creator_az/Coyle=3AMarylou=3A=3A.html>   (1990) Geology, geochemistry and geochronology of the Springdale Group, an early Silurian Caldera in central Newfoundland.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract: Volcanic-sedimentary facies and structural relationships of the Silurian Springdale group in west central Newfoundland are indicative of a large collapse caldera, with an area of more than 2,000 km². Basaltic flows, andesite flows and pyroclastics rocks, silicic ash-flow tuffs, high -silica rhyolite domes, and volcanically derived debris-flows and breccias and mesobreccias, fluviatile red sandstones and conglomerates make up the group Five new uranium/lead zircon dates provided in this study show for the lowermost ash-flow tuff of the group an age of 432.4 + 1.7/-1.4 Ma, the Burnt Berry rhyolite dome of 430.8 ± 2 Ma, and the topmost Indian River ash-flow tuff of 425 ± 3 Ma, as well the age of 427 ± 2 Ma for both the King's Point complex and the Cape St. John Group. -- The Springdale Group is bounded on the east and west by up-faulted basement rocks which include gnesisses, amphibolites and pillow lavas derived from Lower Ordovician volcanic rocks, and in the northwest unconformably overlies the equivalent less metamorphosed Lower Ordovician submarine volcanics. These margins are intruded by cogenetic and younger granitoid rocks. The volcanic rocks form a calc-alkaline series, although gaps in silica content between 52 to 56%, 67 to 68%, and 73 to 74% separate them into four groups, basalts, andesites-dacites, rhyolites, and high-silica rhyolites. -- The high-silica rhyolites are chemically comparable to melts thought to form the upper parts of large layered silicic magma chambers of epicontinental regions. Such an environment is also suggested by the large area of the Springdale caldera, and the probability that it is one of at least five calderas which make up a large Silurian volcanic field. An epicontinental tectonothermal environment for central Newfoundland in Silurian-Devonian times is readily explained by the fact that this magmatic activity followed a period of destruction and closure of the Lower Paleozoic Iapetus Ocean, with trapped heat and basaltic magma causing large scale crustal melting in an overall transpressional tectonic regime.


identifier: Connelly, James N. <https://research.library.mun.ca/view/creator_az/Connelly=3AJames_N=2E=3A=3A.html>   (1991) The thermotectonic history of the Grenville Province of western Labrador.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract: The Grenville Orogen in western Labrador has been divided into three lithologically distinct terranes comprising, from the Grenville Front towards the southeast, the Gagnon, Molson Lake and Lac Joseph terranes. Of these terranes, only the Lac Joseph Terrane is devoid of lithologies that may be correlated with units to the north of the Grenville Front in the pre-Grenvillian, stable North American craton. -- In the Lac Joseph Terrane, high grade polydeformed migmatitic pelitic supracrustal rocks contain two distinct leucosomes which have been dated at 1658+36/-8 Ma and 1639 + 12/-7 Ma by U/Pb geochronology; a third migmatitic sample which is retrogressed yielded an age of 1611 + 13/-6 Ma. These ages indicate that the gneisses in the Lac Joseph Terrane all formed during the Labradorian Orogeny, which must have been a protracted event. High grade metamorphism and migmatization of the supracrustal rocks was synchronous with folding and the development of localized shear zones, one of which has yielded a U-Pb age of 1634 + 13/-4 Ma. Sillimanite and/or kyanite-bearing mineral assemblages in the restite of the pelitic migmatites occur throughout Lac Joseph Terrane, and also formed during the Labradorian Orogeny. They yield P-T estimates (garnet - biotite geothermometry and garnet - plagioclase - aluminosilicate - quartz geobarometry) between 575-800°C and 3-8 kbar in the southern Lac Joseph Terrane to 700-850°C and 6-10 kbar in the northwestern part of the terrane. Granitoid rocks were emplaced into the Lac Joseph Terrane throughout the Labradorian Orogeny; a gabbroic pluton of the Ossokmanuan Intrusive Suite has yielded a U/Pb age of 1623±7 Ma. -- Synchronous with Labradorian metamorphism in the Lac Joseph Terrane, granitoid rocks were emplaced into the adjacent Molson Lake Terrane, one body of which yielded a U-Pb zircon age of 1648±7 Ma. No evidence exists to suggest that these granitoid rocks, which are interpreted to represent a southwestern extension of the Trans Labrador Batholith, were tectonized during the Labradorian Orogeny. The Shabogamo Intrusive Suite, the only other unit in the Molson Lake Terrane, intruded into the granitoid rocks at 1431 ± 7 Ma during a period of south-southeast - north-northwest crustal extension; this unit is correlated, on the basis of geochemistry and age, with the Michael Gabbro of eastern Labrador. -- Retrogression of granulite facies basic gneisses in the Lac Joseph Terrane to amphibolite facies assemblages took place, at least locally, at about 1281 Ma, as recorded by U/Pb (titanite) and ⁴⁰Ar/³⁹Ar (hornblende) isotopic systematics. The tectonic significance of this event is not understood. -- The Molson Lake Terrane was extensively recrystallized and deformed during the Grenvillian Orogeny (1001 Ma - 990 Ma; U/Pb sphene and zircon data), locally under high P - moderate T conditions, between 8-12 kbar and 650-850°C (garnet - clinopyroxene geothermometry and gamet - clinopyroxene - plagioclase - quartz geobarometry). The near coincidence of Grenvillian U-Pb and ⁴⁰Ar/³⁹Ar ages from the Molson Lake Terrane suggests that this terrane was rapidly exhumed after peak metamorphism, probably along a crustal scale, frontal thrust zone. The Lac Joseph Terrane experienced only minor heating and non-penetrative deformation during the Grenvillian Orogeny; the preservation of a pre-Grenvillian ⁴⁰Ar/³⁹Ar amphibole age in the Lac Joseph Terrane while Ar was reset in biotite and muscovite, indicates that temperatures during this event were between about 350°C and 530°C. The Lac Joseph Terrane is thought to have been emplaced as a pre-assembled, coherent package over the Molson Lake Terrane late in the Grenvillian Orogeny along a decollement at, or near, the brittle-ductile transition. Rocks in the Lac Joseph Terrane preserving Labradorian, deeper level P-T conditions were thus emplaced over freshly exhumed rocks, recording Grenvillian P-T conditions, in the Molson Lake Terrane.


identifier: Suhr, Gunter <https://research.library.mun.ca/view/creator_az/Suhr=3AGunter=3A=3A.html>   (1991) Structural and magmatic history of upper mantle peridotites in the Bay of Islands Complex, Newfoundland.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract: The Bay of Islands Complex (BOIC) represents a lower Ordovician ophiolite located in western Newfoundland. In the northern part of the BOIC, a 6 km thick mantle section is exposed in the Table Mountain (TM) massif. The structural, micro-structural (including olivine lattice data), and geochemical variation within the mantle section were investigated in order to delineate the tectonic and magmatic history of the peridotites. -- The field structures indicate the presence of six structural units which are defined by distinct trends of the high temperature mineral stretching lineation of harzburgites, lherzolites, and dunites. On the basis of microstructural evidence, the formation of four of these units is assigned to spreading-related events, the remaining two to detachment tectonics. A high level and a low level zone preserving microstructural evidence for melt infiltration are present. The high level peridotites also show mineral chemical evidence for melt infiltration. -- Peridotite microstructures are classified into several 'type microstructures' interpreted to reflect differences in stress, accumulated strain, temperatures of deformation, and presence or absence of melt during deformation. The microstructural behaviour of orthopyroxene and spinel is investigated in more detail. The range of deformation mechanisms inferred from the morphology of orthopyroxene correlates largely with the temperature of deformation. In areas of lower accumulated strain, spinel grains, together with spatially associated phases, appear to preserve morphologies discriminating between different magmatic processes, i.e. spinel formed during partial melting, trapping of melt, and transient melt movement. -- The process of melt infiltration into peridotite is further investigated and two end-member processes can conceptionally be distinguished: (i) simple trapping of primitive melt; (ii) extensive flushing of melt through peridotite associated with fractionation of melt and reaction with the host. Mineralogical and geochemical trends associated with both processes are discussed and compared to the TM peridotites. -- Relative age relationships between the spreading-related structural units support the plate thickening model for formation of oceanic lithosphere. By applying thermal models for formation of oceanic lithosphere to the TM mantle section, the distance from the ridge axis, at which each unit has been structurally frozen in, can be estimated. The additional use of data concerning the relative sense of shear in the peridotites and the relative position of the ridge axis with respect to the TM massif indicates that the high level, early mantle structures in TM are related to plate driven flow. Later, deeper mantle structures formed during forced flow. The latest spreading-related structures are assigned to an off-axis, diapiric motion of the upper mantle which was stopped at the base of the lithosphere at approximately 50 km from the ridge axis. The lower melt infiltration zone is correlated with this event. -- The history of the BOIC can be explained as an evolution during a decreasing spreading rate. The decreasing spreading rate is considered responsible for the emergence of a late, transient, far-reaching forced flow field driven by the buoancy of partially melted peridotite below the ridge during a period of restricted extensional plate movement. As a further consequence of restricted extension, magmatic products ponded at the base of the oceanic crust, resulting in the formation of thick dunite sequences in the late history of the BOIC. This late history is best preserved in the Blow Me Down massif of the BOIC which, based on the preservation of ridge-parallel flow structures up to a depth of several kilometres below the Moho, must have been located close to the ridge axis when spreading ceased. The presence of lherzolites instead of harzburgites at the base of all four massifs of the BOIC may be explained as the result of slower mantle upwelling prevailing during very slow spreading in the final extensional history of the BOIC. Later, the plates converged, causing detachment of the ophiolite. -- The oceanic basin where the BOIC was generated may represent a pull-apart basin (Andaman Sea type) which opened during strike-slip dominated tectonics within an older, arc-type oceanic lithosphere. The boundary between the young lithosphere of the BOIC and the older arc-type lithosphere would correlate with the proposed fracture zone in the Lewis Hills massif.


identifier: Greenough, John David <https://research.library.mun.ca/view/creator_az/Greenough=3AJohn_David=3A=3A.html>   (1984) Petrology and geochemistry of Cambrian volcanic rocks from the Avalon zone in Newfoundland and New Brunswick.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract: This thesis examines the petrology and geochemistry of Cambrian volcanic rocks from the Avalon Peninsula (Newfoundland) and southern New Brunswick as well as Silurian sills and Devonian (?) dikes from the Avalon Peninsula. The geochemistry of these rocks provides new information on Early Paleozoic tectonism affecting Avalonian terrane in eastern North America. The effects of low grade metamorphism on the primary geochemistry of each rock group are also discussed. -- Middle Cambrian basalts on Cape St. Mary's (Avalon Peninsula) were affected by two phases of alteration that resulted in the formation of chlorite and carbonate. The effects of the chlorite formation on element concentrations resemble those observed for basalt/seawater interaction, whereas the effects of carbonate addition are similar to those produced in high CO₂ systems. Basalts in the Beaver Harbour area of New Brunswick show similar two-phase alteration, but phosphorous and yttrium were added during the carbonate addition phase suggesting that there were differences in the metasomatic solutions between the two areas. -- Silurian sills on Cape St. Mary's show primary textural, mineralogical and bulk-rock geochemical characteristics indicative of high volatile contents. Thermogravitative processes probably involving volatile complexing of some elements caused enrichment of these elements in the upper portions of the sills, or removal from the sill system as a whole. The parental sill magma was geochemically somewhat evolved, tholeiitic, and closely resembled compositions observed in flood basalt and rift provinces. -- Dikes in the Cape St. Mary's study area show a range of bulk rock compositions representative of at least two batches of magma that underwent varying degrees of evolution. Some of the rocks appear to have alkaline characteristics whereas others have tholeiitic attributes, but all were probably produced in a tensional environment. These rocks resemble Devonian dikes around Bonavista Bay and could be time equivalent. -- The Cape St. Mary's Cambrian basalts and their feeder pipes display (primary) whole-rock and mineralogical compositions representative of evolved alkali basalts. Lower to Middle Cambrian volcanic rocks in New Brunswick form a bimodal suite, the basaltic portion of which shows compositions ranging from relatively unevolved to highly evolved tholeiites. -- A review of information on the Precambrian stratigraphy, Cambrian lithologies, fauna, stratigraphy, and paleomagnetism in the Acado-Baltic province shows that most of western Europe and eastern North America probably formed a large continental block that remained at lower latitudes throughout the Cambrian. The bimodal nature of the volcanic rocks over this terrane along with their relatively small volume indicates they formed in a continental rifting environment. Basaltic rocks in southern New Brunswick, Cape Breton, Norway, Poland, and on the Avalon Peninsula show compositions consistent with this interpretation. The small volume of the volcanic rocks and platformal character of the associated sedimentary rocks suggest that the area experienced relatively stable tectonic conditions during the Cambrian with small amounts of extension causing the rift-type volcanism. The tension affected a broad area and resulted in a number of narrow basins but few rift valleys. Volcanism was much more common during the Early and Middle Cambrian than during the Late Cambrian suggesting that the tensional tectonic regime may have waned in the Late Cambrian in direct or indirect response to processes which led to (Ordovician) closing of the Iapetus Ocean. Sills and dikes on Cape St. Mary's provide local evidence that the stable tectonic conditions with small-scale tension persisted throughout the Early Paleozoic.


identifier: Ji, Zailiang <https://research.library.mun.ca/view/creator_az/Ji=3AZailiang=3A=3A.html>   (1989) Lower Ordovician conodonts from the St. George Group of Port au Port Peninsula, Western Newfoundland.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract:
The St. George Group on the Port au Port Peninsula of western Newfoundland is little deformed, well exposed and provides a nearly complete sequence through the Lower Ordovician. The about 600 m thick succession records two depositional megacycles, and is divided into four formations in ascending order, the Watts Bight, Boat Harbour, Catoche and Aguathuna formations. -- Over 45,000 conodonts have been recovered from 432 3.5 kg samples from 10 sections comprising two composite sections through the St. George Group. The conodonts show excellent preservation with a low conodont Colour Alteration Index (CAI) of 1. Detailed taxonomic study of these faunas has permitted major revision to the reconstruction of Lower Ordovician multielement apparatuses, new interpretation of the phylogenetic relationships of Lower Ordovician, Midcontinent Province conodonts, and the establishment of a new and more refined Lower Ordovician conodont zonation for the Midcontinent Province. -- One of the major objectives of this study is to examine the Lower Ordovician conodont taxonomy. Seventy-five multielement species, representing 28 genera, have been described and illustrated, among them 7 new genera, 33 new species and 70 newly reconstructed multielement species. The new genera are Glyptodontus, Loxodentatus, Loxoqnathus,
Polycostatus, Striatodontus, Stultodontus and Tricostatus. The new species are: Acodus primus, Clavohamulus lonqicuspis, C. neoelonqatus, C. reniformis, C. sphearicus, Cristodus ethinatoni, Drepanodus nowlani, Glyptoconus felicitii, G. multiplicatus, G. priscus, Glyptodontus constrictus, G. expansus, G. tumidus, Loxodentatus bipinnatus, Loxognathus phyllodus, Loxodus latibasis, Macerodus crassatus, M. gracilis, M. wattsbightensis, Polycostatus falsioneotensis, P. minutus, Protopanderodus prolatus, Scolopodus subrex, Stritodontus lanceolatus, S. prolificus, S retractus, S. teridontus, Stultodontus ovatus, S. pygmaeus, Teridontus obesus, Tricostatus glyptus, Utahconus longipinnatus and Variabiloconus neobassleri. -- Three apparatus types, apparatus Type I, II and III, are redefined. Type I apparatuses consist of only a and e elements, and are characterized by stubby coniforms and extremely flattened forms. Type II apparatuses have three element morphotypes including a, c and e elements. Type III apparatuses contain four or five skeletal morphotypes: a, b, c, e and, commonly f elements. -- Following the taxonomic study, the local, regional and global stratigraphic range of the taxa were examined to help interpret evolutionary lineages. Nearly twenty such lineages have been recognized. Most are closely related to the Teridontus lineage, and belong to the Teridontus evolutionary complex. The evolutionary relationships of multielement taxa in the Teridontus complex show that the Teridontus lineage spread widely, evolving into both the Clavohamulus and Semiacontiodus lineages during the latest Cambrian. The latter probably produced the Variabiloconus and Polycostatus lineages during the earliest Tremadoc. Two important lineages, Glyptoconus and Striatodontus, appear suddenly, spreading widely, and diversifing rapidly during the early and middle Arenig. The late Tremadoc extinction is one of the most profound crises in conodont evolutionary history. This extinction leads to the demise of more than seven lineages including over 35 species. -- The conodonts recovered indicate that the St. George Group ranges in age from earliest Canadian to the earliest Whiterockian. Eight conodont Assemblage Zones have been established for the shallow-water (SW) facies of the typical Midcontinent Province. Six deeper-water (DW) conodont Assemblage or Lineage Zones have been recognized or redefined, and include some taxa with affinities to the North Atlantic Province. All the SW Assemblage Zones represent limited stratigraphic intervals in the Lower Ordovician, most can be recognized with other low latitude cratons, such as Australia, Siberia, and North China. In contrast, the DW Assemblage or Lineage Zones can be correlated through the critical biostratigraphic tie-points with the North Atlantic Province zonation.


identifier: Higgins, Neville Charles <https://research.library.mun.ca/view/creator_az/Higgins=3ANeville_Charles=3A=3A.html>   (1980) The genesis of the Grey River tungsten prospect: a fluid inclusion, geochemical, and isotopic study.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract: Mineralisation in the Grey River Tungsten Prospect, Newfoundland, is contained within a swarm of quartz veins and fractures which traverse the contact between a sheared Devonian (405 ± 10 Ma) K-feldspar megacrystic granite, and metamorphic rocks which are typical of the gneissic terrain of the Gander Zone. The mineralisation is genetically related to a suite of post-tectonic, highly differentiated, alkali-rich leucogranite dykes. -- The tungsten-bearing hydrothermal veins, dated at 330 Ma, range from tensional fractures and veinlets to lodes containing several injections of quartz. The mineralisation is divided into four stages; the Early Stage, characterised by quartz-feldspar-molybdenite veins; the Composite Stage, consisting of five vein types (in paragenetic order), quartz-bismuthinite, quartz-wolframite (Fe-rich), greisen, quartz-sulphide, and quartz-wolframite (Mn-rich) veins; the Sulphide Stage, characterised by silver-bearing quartz-galenasphalerite veins; and the Late Stage, composed of zoned fluorite-calcite-barite veins. A spatial mineral zonation from south to north matches the temporal sequence outlined above, with the exception of the Late Stage veins which crosscut Composite Stage veins. -- Fluid inclusion data indicate a complex evolutionary history for the hydrothermal fluid. Initially a homogeneous supercritical fluid (XCO₂ = 0.4) with a density of 0.65 g/cc deposited quartz-feldspar-molybdenite veins at temperatures of 450-500°C and fluid pressures of 1200-1400 bars (120-140 MPa). The simultaneous trapping of CO₂-rich and H₂O-rich fluid inclusions, as well as solid inclusions of calcite in quartz of the quartz-bismuthinite vein type is evidence for the existence of an immiscible heterogeneous fluid during this stage of mineralisatiion. Fluid phase equilibria indicate immiscibility occurred at temperatures of 390 - 430°C and fluid pressures of 1000-1200 bars (100-120 MPa). Oxygen isotope data indicate that greisen alteration halos of the composite lodes were formed at temperatures between 350-400°C. -- In these lodes quartz-sulphide and quartz-wolframite veins were deposited in open spaces created by normal faulting. These movements prompted rapid decreases in fluid pressure and temperature and caused retrograde boiling of the hydro-thermal fluid (at 350 bars and 300-390°C) during deposition of quartz-sulphide veins. Deposition of wolframite in quartz-wolframite veins occurred at 270-330°C and fluid pressures less than 350 bars, from an aqueous fluid of low salinity (<0.5 wt% NaCl) and CO₂ content (< 10 bars PCO₂), and after separation of a CO₂ vapour phase by retrograde boiling. -- Calculated δ¹⁸OH₂O values indicate a progressive depletion in ¹⁸O isotopic composition of the hydrothermal fluid with time (7.3 °/oo to 0.5 °/oo). The depletion is due to the loss of 40 mol% CO₂ from the hydrothermal fluid by immiscibility and retrograde boiling, and subsequent fractionation effects. The oxygen isotope data suggest that the hydrothermal fluid was dominantly of magmatic origin. -- Heavy REE enrichment and light REE depletion during greisenisation indicate extensive REE mobility, and imply both that CO₃²⁻ was the dominant anionic species in the hydrothermal fluid and that mobilisation of REE occurred by REE carbonate complexing. A positive correlation between heavy REE enrichment and high tungsten concentration suggests that REE mobility is related to tungsten transport. Together with the fluid inclusion evidence these data suggest that the transport of tungsten in hydrothermal fluids might be due to carbonate/bicarbonate complexing. -- The fluid inclusion and isotopic data from the Grey River Tungsten Prospect serve to illustrate the previously unrecognised role of CO₂ in the transport and deposition of tungsten in the hydrothermal environment.


identifier: Howell, Randy Keith <https://research.library.mun.ca/view/creator_az/Howell=3ARandy_Keith=3A=3A.html>   (1990) An algorithm for the extraction of ocean wave spectra from narrow beam HF radar backscatteer.  Masters thesis, Memorial University of Newfoundland.

abstract: An algorithm is developed and tested to interpret ocean wave spectra from the backscatter return of one or more narrow beam HF radars. The basis of this measurement is the inversion of the integral equation representing the second order radar cross section of the ocean surface (Barrick and Lipa, 1986; Srivastava, 1984; Walsh and Howell, 1990). This equation is numerically inverted by approximating it as a matrix equation and factorizing the resultant kernel matrix using a singular value decomposition to obtain its pseudo-inverse. -- Due to the limitations of the assumption used to linearize the integral equation, the proposed inversion algorithm is best suited for general use at high HF frequencies (≈ 20 to 30 MHz). However, this algorithm may still be applied for the crucial task of monitoring large sea state conditions at even very low HF frequencies (< 10 MHz). -- As a test of this algorithm, comparisons are made between wave spectrum estimates obtained from a WAVEC buoy and a set of two 25.4 MHz ground wave radars that were deployed during the 1986 Canadian Atlantic Storms Program (CASP). Overall, the results of this experiment have been positive and have demonstrated both the basic feasibility of the inversion algorithm and the wave sensing capability of HF radar. -- When using the data of a single radar, the principal information that can be obtained is the nondirectional or one-dimensional (1-D) wave spectrum. Although directional information may be obtained from a single radar it suffers from a left/right directional ambiguity. In general, the comparison of single radar estimates for the 1-D spectrum with those of the buoy at CASP have been good. This is demonstrated by the reasonable average difference from the buoy of ≈ 15% for significant waveheight estimates. This figure is roughly the same for all cross section models. -- When using the data of two radars, not only can more accurate estimates of the 1-D spectrum be obtained but full directional information as well. The comparison of dual-radar wave spectrum estimates with those of the buoy at CASP have been very good. For the Walsh and Howell (1990) cross section model, dual-radar significant waveheight estimates differed from the buoy by only 4.6% on average. For the Barrick and Lipa (1986) and Srivastava (1984) models this average difference is 9.1%. For all models, the average difference for dominant direction estimates is ≈ 10°. -- Although all cross section models produced estimates that correlated well with the buoy, it was the Walsh and Howell (1990) model which consistently provided the best agreement. This would seem to indicate that the Walsh and Howell theory provides a better model for the radar spectrum. Due to the somewhat small size of the CASP data set it is not yet possible to be statistically confident of this finding.


identifier: Grenier, Robert <https://research.library.mun.ca/view/creator_az/Grenier=3ARobert=3A=3A.html>   (1990) The Appalachian fold and thrust belt, Northwestern Newfoundland.  Masters thesis, Memorial University of Newfoundland.

abstract: The Appalachian fold and thrust belt was studied from Bonne Bay to Ten Mile Lake in northwestern Newfoundland. This region is a weakly emergent thrust belt that brings Grenville basement (of the Long Range Inlier) above a parautochthonous Cambro-Ordovician carbonate sequence and locally above the Humber Arm Allochthon. Reverse faults are interpreted as steep ramps above a gently east-dipping sole thrust. The most westerly basement-involved thrust is interpreted as occurring offshore throughout most of the study area and probably even occurs west of the Humber Arm Allochthon. Basement-involved thrusting postdates the Ordovician emplacement of the Humber Arm Allochthon and is most likely Devonian. -- Faults within the northwestern Newfoundland fold and thrust belt form a linked system. Along-strike variations in spacing and amount of displacement result in major differences in structural style. Three zones of contrasting structural style are recognized. In the southern zone, between Bonne Bay and Portland Creek Pond, deformation is predominantly confined to a narrow belt involving two thrusts with a hanging wall anticline and an overturned footwall syncline. In the central zone, between Portland Creek Pond and Hawkes Bay, deformation is distributed over a wider area marked by numerous high-angle reverse faults with opposing polarity. In the northern zone, between Hawkes Bay and Ten Mile Lake, deformation is accommodated by displacement on two widely spaced thrusts. -- Transport of Grenville basement above the parautochthonous carbonate sequence and the Humber Arm Allochthon is greatest in the southern zone where horizontal structural shortening has a minimum value of about 9 km., and is predominantly accommodated by the development of a regional-scale syncline-anticline pair. Structural shortening in the central and northern zones has a minimum value of 3 and 2 km., respectively, and is primarily accommodated on faults with only minor folding of strata. Structural shortening is minor at the extreme northern and southern ends of the Long Range Inlier. -- Structural telescoping of units in the Humber Arm Allochthon at St. Pauls Inlet has a minimum value of 32 km., and is interpreted to be related to Taconian emplacement. -- Faults in northwestern Newfoundland are parallel to the Long Range Dyke Swarm which was controlled by rifting during the initiation of the Iapetus Ocean. The position of the fold and thrust belt may be controlled by the reactivation of preexisting rift-related normal faults within basement rocks.


identifier: Hildebrand, Robert S. <https://research.library.mun.ca/view/creator_az/Hildebrand=3ARobert_S=2E=3A=3A.html>   (1982) A continental volcanic arc of early Proterozoic age at Great Bear Lake, Northwest Territories.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract: The 1.875 Ga LaBine Group, which comprises mostly volcanic rocks, outcrops along the western margin of Wopmay Orogen at Great Bear Lake and rests on a deformed and metamorphosed 1.920 Ga sialic basement complex. It is overlain by rocks of the mainly rhyodacitic Sloan Group. Syn- to post-volcanic plutons of the Great Bear batholith intrude both groups. -- Facies relations and the overall evolution of the Group are closely comparable to Cenozoic volcanic fields believed related to subduction. Rocks of the LaBine field were hydrothermally altered by high-level geothermal processes but on the basis of SiO$\sb2$, TiO$\sb2$, REE, and phenocryst mineralogy they can be classified as calc-alkaline. Therefore, it is concluded that the LaBine Group represents an early Proterozoic volcanic arc developed upon continental crust. Laccoliths in Athapuscow Aulacogen together with recent geochronological and field data suggest that the LaBine Group postdates continent-microcontinent collision in Wopmay Orogen and was probably generated above an eastward-dipping Benioff zone which was either segmented or became shallower with time. -- Geochemical data and petrological considerations indicate that the magmatic rocks of the belt were generated by partial melting of lower continental crust and perhaps mixing of those magmas with slab-derived basaltic andesite. Preservation of high-level volcanic and plutonic rocks suggest that the region was never topographically high-standing. Therefore, the zone may be an early Proterozoic analog of the Longitudinal Depression of Chile and other intra-arc synclinal basins which seem to be the loci for major pyroclastic eruptions. The calculated volume of vitric ash removed from the basins by high-level atmospheric transport approximates the estimated volume of basaltic andesite intruded and extruded in island arcs. This may explain why the basins remain in isostatic equilibrium close to sea level. Because the volume of magma erupted and intruded in continental arcs is equal to, or exceeds, the volume of mafic magma rising out of the mantle, batholiths cannot be derived directly from the mantle--they are products of processes occurring in the continental crust.