Thesis (B.A.(Hons.))--University of Adelaide, Dept. of English, 1995. / Includes bibliographical references.

The geological history of southeast Labrador has been resolved into four major orogenic events based on U-Pb dating: the Makkovik orogeny (1880-1790 Ma), the Labradorian orogeny (1710-1600 Ma), the Pinwarian (1520-1460 Ma) and the Grenville orogeny (1085-985 Ma). Although U-Pb ages represent the time of igneous and metamorphic events, they do not necessarily reflect the time of extraction of crustal material from the mantle. Nd isotopic data provide a tool for doing this, hence permitting regions having differing (and perhaps older) crustal formation ages to be recognized, even if this is not apparent in U-Pb geochronological data. In this study, suites of Depleted Mantle model (TDM) ages were determined for three large regions of southern Labrador. These comprise an east-west suite across the eastern Makkovik Province (Cape Harrison domain); a north-south suite along the Labrador coast of the Grenville Province (Groswater Bay, Hawke River, Lake Melville, Mealy Mountains and the Pinware terranes); and a reconnaissance suite from the Grenville Province in the interior of southern Labrador (Mealy Mountains, Pinware and Wilson Lake terranes, as well as the Trans Labrador Batholith). New Nd isotope data for the eastern Makkovik Province suggest that accreted juvenile Makkovik crust was generated in the Cape Harrison domain during a single crust-forming event around 2.0 Ga. Based on these data, a tectonic model is proposed for the Paleoproterozoic Makkovikian orogeny that is similar to the Ketilidian orogeny. In the eastern Grenville Province, Nd data indicate a southern extension of juvenile Makkovik crust, but with strong Labradorian reworking. A WNW-ESE boundary is proposed between Makkovik crust and juvenile Labradorian crust within the northern part of the Pinware terrane near Red Bay. This boundary separates the Pinware terrane into a Pinware North block (TDM ages often above 1.85 Ga), consisting of reworked Makkovik crust, and a Pinware South block (TDM ages below 1.85 Ga), representing juvenile Labradorian arc crust. A new tectonic model is then proposed for the accretion of this juvenile terrane during the Labradorian orogeny. Finally, Nd isotope data were determined in the interior of southern Labrador in order to trace the crustal boundary seen at the coast westwards. To the north of the Labrador-Quebec border, reworked Makkovik crust (TDM ages > 1.85 Ga) is present within a large regional fold in the north-western Pinware terrane, indicating that Makkovik basement does continue westwards in the northern part of this terrane. The new Nd data indicate that juvenile Makkovik arc crust, of the type seen north of the Grenville Province, extends southwards across much of the Grenville Province of southern Labrador, but with increasing degrees of Labradorian reworking southwards. It is believed that the original edge of the Makkovik continental margin was located just north of Red Bay, with an approximately WNW-ESE trajectory. This crustal boundary is believed to continue westwards approximately along the provincial boundary, reflecting the presence of Makkovik basement in the northern Pinware terrane. / Thesis / Doctor of Philosophy (PhD)

Mémoire (M.Sc.T.) -- Université du Québec à Chicoutimi, 1987. / Document électronique également accessible en format PDF. CaQCU

No description available.

Thesis (B.A. (Hons.))--University of Adelaide, Dept. of English, 1994? / Includes bibliographical references (leaves 42-45).

Thesis advisor: Ethan F. Baxter / The Proterozoic Kipawa Syenite Complex and Red Wine Intrusive Suite have both been explored as potential REE ore bodies and are a heretofore unexploited REE resource. This study improves upon the internal-isochron eudialyte geochronology method developed by Sjöqvist et al. (2020) through the addition of Electron Microprobe mapping prior to precise MicroMill sampling to build Sm/Nd internal mineral isochrons to directly date this potential rare earth element ore mineral. We show that Nb and Ta concentrations correlate well with Sm/Nd ratios in zoned eudialyte crystals, providing a qualitative map to guide microsampling. At the Kipawa Syenite Complex two internal eudialyte isochrons yield ages of 1066±56 Ma (MSWD=1.7) and 1109±53 Ma (MSWD=1.2) while a multi-sample eudialyte bulk isochron produces an age of 1092±53 Ma (MWSD= 1.5). The weighted average of the three isochrons is 1090±31 Ma, and gives the age of eudialyte formation across the Kipawa Syenite Complex. Nd model ages confirm derivation from older continental crust with TDM=2.28. At the Red Wine Intrusive Suite single internal eudialyte isochron yields an age of 765±240 Ma (MSWD=3.7) while the high-Nb sector of this crystal yields an age of 704±120 Ma (MSWD=1.6). A multi-sample eudialyte and mosandrite bulk isochron produces an age of 989± 150 Ma (MSWD=15). The latter age reflects original Grenvillian crystallization of REE ore-minerals, while the age of the high-Nb zone reflects a younger, heretofore unrecognized recrystallization event. Nd model ages suggest derivation from the Proterozoic crust with TDM=1.80. Examination of Nd model ages and geochemical data from five agpaitic deposits (Red Wine, Kipawa, Ilímaussaq, Norra Kärr, Lovozero) reveals three distinct deposit types identified as the Lovozero type, the Grenville type, and the Kipawa type. / Thesis (MS) — Boston College, 2020. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Earth and Environmental Sciences.

No description available.

<p> The aureole surrounding the Loon Lake pluton, notable for the presence of scapolite, is situated in an upper amphibolite facies terrane in the Grenville Province of southern Ontario. Four distinct scapolite-bearing parageneses are found to surround the pluton in more or less concentric zones. Furthest from the pluton a clinopyroxene-scapolite gneiss grades into Ca-amphibole gneiss, Ca-amphibole-biotite gneiss and biotite gneiss. Scapolite is also found in the marbles surrounding the aureole, as well as in all gneisses of the aureole. As the mineralogy of the gneisses change from clinopyroxene through biotite, the textures grade from granoblastic polygonal to a granoblastic polygonal texture modified by abundant acicular and platy minerals. </p> <p> As the pluton is approached, scapolite often assumes a ragged fine-grained nature with alteration to sericite. The whole rock chemistry is characteristic of that derived from a mixture of intermediate volcanics (latite) and carbonate-evaporites. This sequence was undoubtedly deposited in a shallow marine environment. Subsequent metamorphism to upper amphibolite facies produced a band of clinopyroxene gneiss. As the Loon Lake pluton was emplaced increasing temperature and volatiles in an aqueous solution caused the clinopyroxene-scapolite gneiss to undergo retrograde metamorphism and formed the Ca-amphibole, Ca-amphibole-biotite and biotite gneisses. </p> <p> Studies of mineral chemistry indicate that the minerals coexist in equilibrium and that they are related, to some degree, to whole rock composition. As the retrograde metamorphsim occurred elements within the minerals redistributed themselves according to the nature of the new phases produced. Finally, the partitioning between phases followed the ideal binary solution model. Chlorine is found to be partitioned between scapolite, Ca-amphibole and biotite, and all three phases contain chlorine, the relative amounts present being controlled by the crystal structure of the minerals. The relation of Lin and Burley (1973a) between lattice parameter and scapolite composition is confirmed. </p> / Thesis / Master of Science (MSc)

The Grenville Province represents a complex, highly metamorphosed orogenic belt at the southeastern margin of the Canadian Shield that is composed of different lithotectonic domains of various ages that have all been affected by the 1.0 Ga Grenville Orogeny. The present study focuses on one of the youngest regions, the Quebecia terrane, and through reconnaissance neodymium isotope mapping, investigates the extent of an old crustal block that predates the Grenville Orogeny. The Quebecia Terrane is found within Central Quebec and is a Mesoproterozoic arc terrane that was constructed around 1.5 Ga. Utilizing the Samarium-Neodymium dating method, previous research had identified a few isolated neodymium signatures of older crustal ages, and through reconnaissance mapping, several of these Paleoproterozoic crustal blocks are suggested to represent a single fragmented crustal panel. The study focused on more detailed mapping of these blocks in the areas of Baie Comeau, Forestville, Labrieville and Pipmuacan in Central Quebec. The full extent and connection between the fragments has been mapped as a series of Paleoproterozoic crustal blocks extending longitudinally through the Quebecia terrane. These blocks are embedded within the younger terrane, suggesting that the old panel was incorporated sometime during the accretion of Quebecia to Laurentia. It is possible that the old panel broke off from older Laurentian crust and reattached during the accretion of the Quebecia terrane via strike slip tectonics, implying that the Quebecia terrane itself consists of more than one accreted unit. The present study found that the older neodymium isotope signatures were consistent with the Berthe Terrane in the Manicouagan region to the north, providing evidence for the origin of the older panel within Quebecia. However, by invoking a division of Quebecia into a north and south segment, this implies a Composite Arc Belt model for the Central Grenville Province. / Thesis / Master of Science (MSc)

<p> Detailed Neodymium isotopic mapping was performed on grey gneisses from the Algonquin Park area of Ontario, in the Central Gneiss Belt of the southwestern Grenville Province. The Neodymium model ages determined were based upon the Depleted Mantle Model of DePaolo ( 1981c ) . The use of this model is supported by Lead-Lead dating of zircons obtained from an orthogneissic sample. </p> <p> The wide range of model ages found ( 1.5 - 1.86 Ga ) is attributed to the presence of a northwestward dipping, Andean style, ensialic continental margin arc that was active in the Mid-Proterozoic between 1.50 Ga and 1.65 Ga. The diapiric rise of plutons produced by the subduction zone intruded continental margin at least as old as 1.86 Ga as indicated by the oldest pluton in the field area. Variable amounts of mixing occurred between these orogenic rocks and the existing crustal rocks as illustrated by the variable Neodymium model ages determined for grey gneisses collected between 10 Km and 60 Km north of the Central Metasedimentary Belt Boundary Zone. Major element analysis and subsequent tectonic and petrographic discrimination diagrams such as the AFM plot and the granitoid discrimination diagram of LeFort and Debon ( 1983 ) also indicate that the rocks in the Algonquin Park area are calc-alkaline, and are similar to the Peruvian Coastal Batholith. </p> <p> For grey gneisses analyzed within 10 Km of the Central Metasedimentary Belt Boundary Zone, the range of ages is far more restricted, suggesting that an island arc approximately 1.45 Ga was transported by the subducting slab and later sutured onto the existing continental margin. </p> / Thesis / Bachelor of Science (BSc)