The Kiosk domain in the Central Gneiss Belt, southwestern Grenville Province, Ontario comprises ca.1655 Ma orthogneisses and volumetrically minor ca. 1480-1460 Ma parag- neisses that were affected by granulite-facies metamorphism between ca. 1480 and ca. 1000 Ma. The objectives of this study are: (i) to determine the protolith ages from the Kiosk domain and the underlying southern Bonfield Batholith; (ii) to determine the tim- ing of major tectonic episodes; (iii) to determine the pressure-temperature conditions of peak metamorphism; and (iv) to use these data to constrain the position of the Allochthon Boundary Thrust in the southwestern Grenville Province.

The Ocoee Supergroup is a sequence of Neoproterozoic, immature, continental rift facies clastic sediments. Potential source rocks were tested by analyzing modes of detrital framework minerals, detrital mineral chemistry, whole rock geochemistry and detrital zircon U/Pb geochronology by LA-ICP-MS for Ocoee siltstone-sandstone dominated formations. Ocoee units are arkosic to subarkosic siltstones/sandstones, and ternary tectonic discrimination diagrams confirm a continental basement uplift source. Alkali feldspar predominates over plagioclase feldspar. Detrital feldspar compositions of Ocoee sediments as a group are similar to feldspar in local basement granitic rocks except for high-Ca plagioclase grains present locally in basement granitic rocks. The high alkali content of the detrital feldspars in the Ocoee Supergroup is consistent with derivation from an A-type granite source terrane. Normative Q-A-P values, calculated from wholerock chemistry, and trace element diagrams are also supportive of an A-type granite source for these rocks. The siltstones and sandstones of the Snowbird Group contain high abundances of heavy minerals (zircon, titanite, ilmenite, epidote and apatite), which are dispersed among other detrital grains and as concentrations of heavy minerals in discrete laminae. ZTR index and titanite mineral chemistry suggest a granitic source for these sediments. Detrital zircon geochronology in Ocoee sediments indicates a dominantly Grenville (1000 to 1300 Ma) source for these sediments. The youngest zircon age in the basal Ocoee Wading Branch Formation (639±8 Ma) is related to rift magmatism and provides a minimum depositional age for the Ocoee Supergroup.

Identifying the crustal affinity of Grenville basement rocks in the Dellwood quadrangle, western NC, provides insight into the tectonic evolution of eastern Laurentia during Grenville orogenesis. U-Pb zircon geochronology of orthogneiss, augen gneiss, and mafic xenoliths in orthogneiss reveal magmatic pulses at 1130, 1180, and 1330 Ma and metamorphic episodes at 450 and 1040 Ma. Xenoliths in 1330 Ma orthogneiss are as old as 1382 Ma and represent the oldest component of Blue Ridge basement identified to-date. Feldspar Pb isotope values span a range between juvenile-Laurentian and southern-central Appalachian basement/Amazonia. Most Pb isotope data define an array consistent with crustal mixing between Laurentia and Amazonia, however, one xenolith has a unique Pb isotopic composition interpreted as Laurentian crust. Sm-Nd isotope data yield depleted mantle model ages ranging from 1.52 to 1.79 Ga (200 to 650 Ma older than their crystallization ages) indicating a broadly non-juvenile heritage for Dellwood basement. Three biotite gneiss samples contain detrital zircon grains derived from 1060, 1160, 1330, and 1750 Ma sources. Multiple magmatic zircon age populations, variable depleted mantle modelages, and regionally unique isotopic Pb signatures are evidence of protracted Grenville magmatism in the southern Appalachians involving both Laurentian and Amazonian crustal components.

My novel The Heaven I Swallowed tells the story of Grace Teresa Mary McAllister, a World War II widow who decides to “save” a young Aboriginal girl, Mary, by adopting her into her home, believing she will be able to redeem the child by giving her all the benefits of white society. In Part I of the novel Mary arrives and it soon becomes obvious that her presence is bringing back the deceptions in Grace’s past. In Part II five years have passed and Grace is struggling to cope with the way she treated Mary. Exploring the myth of “for their own good” The Heaven I Swallowed is a tale of the Stolen Generations, told from the perspective of the white perpetrator. The exegesis accompanying the novel, ‘Whose Shoes? Writing The Heaven I Swallowed’, is also divided into two parts. Part I traces my awareness of the Stolen Generation stories and the reasoning behind the decision to narratively take the perspective of a white woman who steals an Aboriginal child. In Part II, I turn to two contemporary literary texts – Kate Grenville’s The Secret River and Gail Jones’s Sorry – to examine different strategies that the non-indigenous writer might employ to counter-act stereotypical representation of Aboriginality. Further analysis of the novel in the lead up to the final draft is then aided by another two texts: Elizabeth Jolley’s The Well and Joyce Carol Oates’s Black Girl/ White Girl. Using these as models – one in regards to a Gothic re-rendering of the work and the other in regards to the depiction of ambiguous race relations – I find a way to reconcile myself with the representation of Aboriginality in The Heaven I Swallowed. Finally, I come to the conclusion that the novelist might often travel a great deal away from their original intent but that these footsteps have to be taken to ensure motivations are justified and one’s conscience is at ease. / Thesis (Ph.D. ) - University of Adelaide, School of Humanities, 2009

<p> Detailed Neodymium ( Nd ) and Lead ( Pb ) isotopic mapping was performed on gray gneisses from the Lac St. Jean region of Quebec, in the Central Grenville Province. The Nd model ages determined were based upon the Depleted Mantle Model of DePaolo ( 1981c ). The use of this model is justified by a Sm-Nd whole-rock isochron as well as common Pb-Pb whole-rock dating. </p> <p> The field area was divided up into three sections: Western, Central, and Eastern. The boundaries of these divisions corresponded to abrupt changes in Nd model ages. The Western section was located in the Parautochthonous Belt of Rivers et al., ( 1989 ) and almost exclusively consisted of tonalitic gray gneisses with Archean Nd model ages. Whole-rock Pb isotopic analyses produced a Transposed Palaeoisochron, implying that the rocks of the Western section were significantly affected by the Grenville event approximately 1.1 Ga ago. Major and trace element analyses indicate that the Western section represents an arc and may be the exhumed basement of the Abitibi Volcanic Belt to the north, consistent with previous work by Ciesielski ( 1992 ).</p> <p> In contrast to the Western section, the Central section which is separated from the Western section by the Allochthon Boundary Thrust of Rivers et al., ( 1989 ) has a very wide range of Nd model ages from 1.65 Ga to 2.35 Ga. The temporal and spatial range of Nd model ages, coupled with major and trace element analyses, indicates that the Central section represents an Andean style ensialic continental margin arc. The diapirs that reworked these rocks contain varying amounts of Archean material implied by the Early-Proterozoic Nd model ages of some samples, particularly in regions close to the Allochthon Boundary Thrust. Whole-rock Pb isotopic analyses produce a Transposed Palaeoisochron indicating significant U depletion caused by the Grenville orogeny.</p> <p> The Eastern section is composed almost exclusively of gneisses with Nd model ages of ca. 1.5 Ga. The boundary between the Central and Eastern sections is based solely on lithological differences and an isotopic age break form the variable Nd model ages of the Central section, to the consistent model ages of the Eastern section. A Sm-Nd isochron for all samples with ca. 1.5 Ga Nd model ages produces an age of 1.50 +/- 0.07 Ga, in close agreement with previous work ( Dickin and Higgins, 1992 ). The consistency of model ages ( > 100,000 Km^2 when combined with data from Dickin and Higgins, 1992 ) coupled with major and trace element analyses, indicates the presence of an island arc which formed at ca. 1.5 Ga and was sutured on to the Laurentian craton within 100 Ma of its formation.</p> <p> Whole-rock Pb isotope analyses indicate that the Eastern section was not affected by the Grenville event as much as the Central or Western sections were.</p> <p> Pb-Pb zircon dating for samples from the Central and Eastern sections failed to place a tight constraint between crystallization ages and Nd model ages because of excessive Pb loss.</p> / Thesis / Master of Science (MSc)

No description available.

<p> The Grenville Province represents the remains of a collisional orogeny ca. 1.2 - 1.0 Ga and contains the Central Metasedimentary Belt (CMB). Generally thought to represent one or more accreted island arcs, the CMB is located between belts of highgrade gneisses and contains a number of identified structural terranes. Neodymium (Nd) model ages of the high-grade gneisses on either side of the CMB yield similar values (~1.5 Ga) while the average model age within the CMB is usually more juvenile (<1.3 Ga). This distinction, along with observations about the geometrical shape of the juvenile zone, has led to the creation of an alternative model for the development of the CMB in the Grenville Province as developed by Dickin and McNutt, (2007). The new model equates the CMB with an ensimatic rift zone with an en echelon morphology consisting of a series of segments with NNE trends, separated by one or more horsts of older crustal rock. The development of the CMB under these conditions implies that restricted access to seawater may have facilitated limestone deposition prior to major biogenic influences, and thus the morphology of the rift is defined in part by the extent of the Grenville marble outcrops. </p> <p> The present study tests this model through the use of 80 new Nd isotope analyses to map the NW boundary of the CMB, known as the Central Metasedimentary Belt Boundary Zone (CMBBZ), west of Bancroft, Ontario. Within this part of the CMBBZ, the age boundary between pre-Grenvillian and juvenile gneisses is relatively sharp (1 - 4 km wide) and this age boundary makes a near 90-degree tum from a NNE trend near Minden to an E-W trend near Haliburton. Two blocks of older material are located within the juvenile terranes of the CMB, which are interpreted as being blocks of older crust rifted from the walls of the older Muskoka domain to the north of the study region. These structures are analogous to similar horsts of older crustal material found in the Afar region of East Africa. Therefore, we suggest that the locus of the CMBBZ was constrained by older structures, representing a transition from the side of a rift zone segment south of Minden, to the truncated end of this rift segment between Haliburton and Bancroft. Hence, the detailed structure of the CMBBZ in this region provides further evidence in support of the rift zone model. </p> / Thesis / Master of Science (MSc)

Cette étude présente de nouveaux résultats de pétrographie et de géochimie sur les lithologies du terrane de Renzy afin d'en retracer le contexte paléogéodynamique de formation. L'accent est mis sur les caractéristiques pétrographiques et géochimiques des unités d'amphibolite et de l'ensemble métasédiments/métavolcanites hôte appuyées par les résultats intégrés de trois campagnes de terrain et de données géophysiques régionales. Les signatures géochimiques sur l'ensemble des lithologies du terrane de Renzy sont diversifiées et compatibles avec un environnement d'arc océanique/bassin d'arrière-arc. Le terrane de Renzy est interprété comme représentant les vestiges d'un système d'arc océanique/bassin arrière-arc formé autour de 1.5 Ga, hypothèse appuyée par l'affinité du terrane de Renzy avec des environnements similaires modernes tel que l'arc de Scotia dans l'Atlantique sud et ceux connus dans la Province de Grenville tels que le Complexe de Bondy (1.4 Ga) ou le Domaine de Shawanaga (1.45 à 1.33 Ga).

Titre de l'écran-titre (visionné le 29 février 2024) / La Province de Grenville présente un grand potentiel prospectif pour le groupe des éléments de terres rares (ETR). Dans la région de La Tuque, les minéralisations en ETR se divisent en deux catégories : les minéralisations associées à des intrusions alcalines et les minéralisations associées à des pegmatites granitiques. Les mécanismes de formation et la source des magmas de ces pegmatites enrichies en ETR sont toutefois peu compris. Cette étude porte sur l'indice Blanchette-1, qui consiste en un dyke de pegmatite granitique riche en ETR (> 2,7 wt.%) et encaissé dans des paragneiss migmatitisés du Complexe de Wabash. La minéralisation en ETR se concentre principalement au sein d'une zone métrique riche en allanite (> 20 vol.%). Ce projet vise à déterminer la source du magma et l'âge de mise en place de cette pegmatite pour mieux caractériser cet évènement minéralisateur et sa relation avec l'évolution géodynamique de la Province de Grenville. Les zircons de quatre échantillons ont été datés (U-Pb par LA-ICP-MS) en combinaison avec la détermination de leurs signatures isotopiques en hafnium et de leurs compositions en éléments traces: la Syénite de Toad, l'intrusion alcaline la plus proche du dyke de Blanchette-1 (981,6 ± 5,6 Ma), le dyke de pegmatite de Blanchette-1 (1060,8 ± 7,0 Ma), et deux injections granitiques (1057,9 ± 8,3 et 1075,1 ± 3,8 Ma). Les âges montrent que les minéralisations en ETR associées aux syénites et aux pegmatites sont deux évènements distincts. Les analyses isotopiques d'Hf permettent d'estimer un âge modèle de ~1400 Ma pour les injections granitiques et la pegmatite de Blanchette-1. Cet âge est cohérent avec la fusion partielle des gneiss granitiques de la Suite plutonique de Vermillon. Pourtant, une étude précédente dans le Grenville central attribue la formation de pegmatites riche en ETR à la fusion de roches métasédimentaires. Puisque la fusion de roches métasédimentaires ou ignées peuvent entrainer la formation de pegmatites enrichies en ETR au sein du Grenville central, la nature de la source n'est pas le facteur clef favorisant cet enrichissement. / The Grenville Province has great prospective potential for the rare earth element (REE) group. In the La Tuque area, REE mineralization can be divided into two categories: mineralization associated with alkaline intrusions and mineralization associated with granitic pegmatites. However, the formation mechanisms and the source of the magmas of these REE-enriched pegmatites remain poorly understood. This study focuses on the Blanchette-1 showing, which consists of a REE-rich (> 2.7 wt.%) pegmatite granitic dyke hosted in migmatitic paragneiss of the Wabash Complex. The REE mineralization is mainly concentrated within an allanite-rich metric zone. This project aims to determine the magma source and crystallization age of this pegmatite to better characterize this mineralizing event and its place in the geodynamic evolution of the Grenville Province. Zircons from four samples were dated in combination with the determination of their hafnium isotopic signatures and trace element compositions: the Toad Syenite, the nearest alkaline intrusion to Blanchette-1 (981.6 ± 5,6 Ma), the Blanchette-1 pegmatite dyke (1060.8 ± 7,0 Ma), and two granitic injections (1057.9 ± 8,3 et 1075,1 ± 3.8 Ma). The ages show that REE mineralization associated with alkaline intrusions and pegmatites are two distinct events. The Hf isotope analyses allow us to estimate a model age of ~1400 Ma for the granitic injections and the Blanchette-1 pegmatite. This age is consistent with the partial melting of granitic gneisses of the Vermilion Plutonic Suite. However, a previous study in the central Grenville attributed the formation of REE-rich pegmatites to the melting of metasedimentary rocks. Since the melting of metasedimentary or igneous rocks can lead to the formation of REE-enriched pegmatites in the central Grenville, the nature of the source is not the key factor that favors this enrichment.

La propriété de graphite des lacs Guéret et Guinécourt est localisée à environ 300 km au nord-nord-ouest de la ville de Baie-Comeau. Cette propriété se situe dans le Terrane de Gagnon, dans la région Parautochtone de la Province de Grenville. Ce secteur n'est pas étranger à l'exploration minière. En effet, dans les années 1950, plusieurs travaux furent menés, le but de ceux-ci étant de définir le potentiel en formations de fer apparentées à celles du Groupe de Knob Lake comme celles trouvées à Fermont, Labrador City, Schefferville et Gagnon. Puis au début des années 2000, après un hiatus de quarante années, de grandes quantités de graphite furent mises au jour par les compagnies Exploration Esbec, Quinto Technology Inc. et SOQUEM Inc.. On dénombre trois types de graphite dans la région, soit du graphite macrocristallin, du graphite microcristallin et du graphite en veine. La minéralisation graphiteuse est contrôlée par la Formation de Menihek du Groupe de Knob Lake et confinée dans celle-ci. Les trois types de graphite ont une distribution particulière à l'intérieur de la Formation de Menihek. Le graphite macrocristallin est associé à un schiste quartzo-feldspathique tandis que le graphite microcristallin et celui en veine sont associés à un méta-mudstone graphiteux. Le contrôle stratigraphique du graphite s'observe tant au niveau local qu'au niveau régional, soit entre les lacs Guinécourt au Québec et Wabush Lake au Labrador. L'étude de la répatition des gisements de graphite en comparaison avec les types de formations de fer de la Formation de Sokoman a permis l'élaboration d'un outil d'exploration. Cet outil est minéralurgique et met en compte la dichotomie existante entre le graphite et l'hématite. Cette dichotomie montre que la minéralisation graphiteuse est absente lorsqu'il y a présence d'hématite primaire. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Graphite, Hématite, Dichotomie, Formations de fer, Province de Grenville, Terrane de Gagnon, Groupe de Knob Lake.