Typescript / Maps in back pocket of v. 1 / Microfiches in back pocket of v. 2 / Microfiches contain petrographic descriptions, total rock XRF analyses and microprobe analyses / Bibliography: leaves 160-183 (v. 2) / 2 v. : ill. (some col.), maps (some folded) ; 30 cm. + 8 maps (col. ;71 x 77 cm. folded to 25 x 17 cm.) + 2 microfiches (423 fr. ; 10 x 15 cm) / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Geology and Geophysics, 1987

Appendix 4 and 5 in pocket on back cover. / Bibliography: p. 123-130. / xi, 154 p. : ill. (chiefly col.), maps (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The isotopic data indicates the Harts Range Metamorphic Complex formed within a previously unrecognized intracratonic tectonic province in Central Australia / Thesis (Ph.D.)--University of Adelaide, Dept. of Geology & Geophysics, 2000?

Appendix 4 and 5 in pocket on back cover. Bibliography: p. 123-130. The isotopic data indicates the Harts Range Metamorphic Complex formed within a previously unrecognized intracratonic tectonic province in Central Australia

Made available in DSpace on 2015-03-26T13:28:36Z (GMT). No. of bitstreams: 1 texto completo.pdf: 9035273 bytes, checksum: 309210e2946157c33b9a3a555deaca1b (MD5) Previous issue date: 2014-10-24 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Rock mass classification is a important procedure for the analysis of the mechanical behavior of a rock and its discontinuities, under the several applications on engineering projects such as, for example, underground mining. The present study has the aim of perform a geomechanical classification of the rock masses occurring under surface at Volta Grande mine, located in Nazareno, Minas Gerais State, Southeast Brazil, in order to evaluate the technical feasibility of development of an underground mine. Currently Volta Grande mine operates only an open pit mine for Tantalum in a pegmatitic body. Because its high waste-ore ratio both operational and commercial feasibility can become impracticable, as this ratio is expected to increase with open pit depth. All data necessary to classify the underground rock mass by using the two most widespread classification systems RMR and Q were collected to accomplish the proposed goals. Data were collected in 28 boreholes located on geological cross-sections, spread all over the area, previously selected in order to allow an adequate geological and geomechanical characterization of the study area for the initial underground proposed depth (150m). Sampling was done both for different rock and weathering grades types, in a quantity sufficient to perform all physical, point load, compressive strength, triaxial and wave velocity propagation tests. All tests were performed according to International Society for Rock Mechanics (ISRM) 2007 methods. Results were compared with similar rock- types results from the literature in order to evaluate its applicability. Results shows that both classification systems are in accordance with rock masses from superficial field observations. Nevertheless, it was observed that Q system was much more sensitive then RMR system, resulting in a higher number of rock mass classes. This higher sensitivity results mainly from RQD, Jn, Ja and Jr parameters, resulting in a very compartmentalized rock mass, considered not feasible for design purposes. Based on that assumption, RMR system is more recommended for using during feasibility studies as it encompasses several thin different class layers, resulting in a more applicable and handle system. It must be highlighted that the present study results are for feasibility studies only and cannot be applied for executive purposes, as much more quantity of data would be necessary. The final result points to a technical feasibility of underground mining, resulting in an increase of mine lifetime, reduction of waste-ore ratio, and provision of important initial mechanical information for excavation and support studies. / A classificação de maciços rochosos é um procedimento importante para a análise do comportamento mecânico das rochas e suas descontinuidades frente às solicitações que lhes serão impostas em decorrência de projetos de engenharia como, por exemplo, os de minas subterrâneas. O presente estudo teve por objetivo realizar a classificação geomecânica dos maciços rochosos da mina de Volta Grande, Nazareno-MG, Brasil, em profundidade, visando a avaliação da viabilidade técnica de implantação de lavra subterrânea. Atualmente, a mina opera a céu aberto a lavra de um corpo Pegmatítico intrusivo, em Anfibolito como rocha encaixante, para obtenção de Tântalo, que é um produto de alto valor agregado. A retirada do Pegmatito através de lavra a céu aberto pode se tornar inviável operacional e economicamente, pois o corpo do minério possui um mergulho de 20 graus para Sudeste, resultando em um aumento significativo da relação estéril-minério com o aumento da profundidade da cava. Para a realização do estudo foram coletados dados necessários à classificação dos maciços existentes em profundidade pelos dois métodos mais difundidos no mundo inteiro para este propósito - o sistema RMR e o sistema Q. A aplicação destes métodos demandou a caracterização geológico-geotécnica da área de estudo por meio da interpretação de testemunhos de sondagem obtidos em 28 furos, cuja distribuição espacial está relacionada à mRock mass classification applied to Volta Grande underground mine site, Nazareno, Minas Geraisalha de seções geológicas selecionadas previamente ao início do trabalho de campo, de maneira a permitir uma adequada caracterização da geologia e da geomecânica em profundidade para a área de estudo. A coleta de dados foi sistematizada fazendo-se o uso de uma planilha específica para obtenção dos parâmetros de classificação. Foram realizadas amostragens em testemunhos de sondagem, por litotipos e graus de alteração, em quantidade suficiente para a realização dos ensaios de caracterização física, de determinação da resistência à compressão puntiforme, compressão uniaxial, compressão triaxial e determinação da velocidade de propagação de ondas, todos realizados de acordo com as metodologias sugeridas pela International Society for Rock Mechanics ISRM. Os resultados destes ensaios foram comparados com os resultados de trabalhos semelhantes encontrados na literatura, a fim de se avaliar sua aplicabilidade. Os resultados da classificação geomecânica mostram que ambos os sistemas representam muito bem os maciços da mina de Volta Grande. No entanto, percebeu-se que o sistema Q é muito mais sensível em relação ao sistema RMR, principalmente nas mudanças de litologia, e essa sensibilidade aumentada para os parâmetros RQD, J n , J r e J a se traduz em resultados que, em alguns intervalos analisados, não se traduzem em ganho significativo em relação à condição geral observada para os maciços. Por isso, recomenda-se a utilização do sistema RMR em detrimento do sistema Q no intuito de diminuir a subdivisão do maciço em pequenas faixas com classes diferentes aumentando a segurança nas decisões uma vez que os resultados do sistema RMR permitiram a individualização, para a maioria dos intervalos, de uma menor subdivisão em faixas com pouca espessura, sendo considerado, por este motivo, o modelo geomecânico mais coerente para etapa de estudos de viabilidade técnica de uma lavra subterrânea. Ressalta- se que as classes de maciço foram definidas em etapa de projeto de viabilidade, não sendo, portanto, sugerida sua utilização na fase de projeto executivo, para o que se necessitaria de uma maior quantidade de dados. Do ponto de vista geotécnico o modelo final da classificação geomecânica dos maciços da mina de Volta Grande demonstra a viabilidade do início de uma lavra subterrânea, o que resultaria em aumento da vida útil da mina e diminuição da geração de estéril; além de fornecer informações iniciais para se inferir sobre tempo de auto-sustentação e tipos de contenção, se necessário, para um possível projeto de lavra subterrânea.

Les processus de subduction sont une étape clé de la formation des orogènes et induisent un métamorphisme de haute pression, localisé dans les faciès des schistes bleus et éclogites. Caractériser la durée et l’intensité de ce métamorphisme est ainsi une étape cruciale puisque amenant des contraintes quantitatives sur la géodynamique d’un orogène. Par une étude pétrologique et géochronologique, cette thèse a ainsi pour objectif de préciser les conditions et durées du métamorphisme de haute pression dans le sud du Massif Central Français (chaîne Varisque), à travers l’étude des massifs de Najac, de la Montagne Noire et du Lévézou. Cette thèse associe ainsi une géochronologie multiméthodes (U-Pb sur zircon, rutile et apatite, Lu-Hf et Sm-Nd sur grenat, 40Ar-39Ar sur biotite et muscovite) à des analyses pétrologiques impliquant des modélisations numériques d’équilibres de phases (Theriak-Domino et THERMOCALC). L’étude d’une éclogite du massif de Najac a ainsi permis de déterminer des conditions de 15 à 20 kbar et 560 à 630°C pour le métamorphisme de haute pression. Le début du faciès éclogite y est daté à ~383 Ma, tandis que le pic du métamorphisme éclogitique est atteint à 375.7 ± 1.2 Ma. La datation des éclogites de la Montagne Noire n’a pas permis de préciser un âge solide de l’évènement de haute pression. Néanmoins, les conditions de pression et température du faciès éclogite y sont estimées à ~ 21 kbar et ~ 750°C. L’étude des massifs de Najac et de la Montagne Noire a mis en évidence de potentiels découplages entre les systèmes de terres rares et le système isotopique U-Pb. Les protolithes des terrains éclogitiques du massif du Lévézou, tant mafiques que felsiques, se sont mis en place à ca. 470 Ma. Le métamorphisme éclogitique affectant les roches mafiques est estimé à 21-23 kbar pour 680- 800°C et atteint à ~358 Ma. L’exhumation, bien caractérisée, y est rapide : les terrains éclogitiques atteignent 8-9.5 kbar et ~600°C à ~352 Ma, impliquant une exhumation très rapide, suivie d’un refroidissement de plus de 50°C/Ma. Les granites du massif du Lévézou présentent des pseudomorphoses de cordiérite à disthène-grenat-muscovite-quartz, développées lors du métamorphisme de haute pression et équilibrées à ca. 15-17 kbar et ~670°C. La déformation majeure observée dans ces granites peut s’accompagner de fusion localisée, et semble se produire en différentes étapes, depuis ~352 Ma à ~340 Ma. Replacées dans un contexte général, ces données s’inscrivent pleinement dans les gammes d’âges de la haute pression décrites pour la chaîne varisque et permettent de reconsidérer la tectonique du Massif Central. / Subduction is one of the key stages of the mountain building processes. It leads to the development of high-pressure (HP) metamorphism in the rocks that typically equilibrate in the blueschist or eclogite-facies conditions. Dating the HP metamorphism and estimating its intensity is therefore a major challenge when reconstructing geodynamics through time. Through a petrological and geochronological study, this PhD dissertation aims to better constrain conditions, durations and timings of HP metamorphism in the southern French Massif Central (European Variscan Belt). The massifs of Najac, Montagne Noire and Lévézou were investigated by a multi-method geochronological approach (zircon, rutile and apatite U-Pb dating, garnet Lu-Hf and Sm-Nd dating, biotite and muscovite 40Ar-39Ar dating) associated with a petrological analysis including numerical modelling of phase equilibria (Theriak-Domino and THERMOCALC). The Najac eclogites reached 560-630 °C at 15-20 kbar and the prograde part of the highpressure metamorphic event lasted for ~ 7 Myr starting at ~ 383 and peaking at ~ 376 Ma. Eclogites hosted in sillimanite-bearing migmatites in the Montagne Noire dome (French Massif Central) reached c. 750°C, 21 kbar before significant decompression at high temperatures. However, none of the obtained geochronological dates could be associated with the HP event. The study of the Najac massif and the Montagne Noire Dome highlight potential decoupling between the REE and the U-Pb isotopic systems. The emplacement of the protoliths of felsic and mafic HP rocks in the Lévézou Massif was estimated at ca. 470 Ma. HP metamorphism peaked at 21-23 kbar and 680-800°C at ~358 Ma. The subsequent fast exhumation reached 8-9.5 kbar and ~600°C at ~352 Ma, highlighting a very fast exhumation followed by a cooling rate of 50°C/Ma. Granites from the Lévézou massif display kyanite-garnet-muscovite-quartz pseudomorphs after cordierite that equilibrated at ca. 15-17 kbar and ~670°C. The major deformation in these granites is associated with the exhumation stage, locally accompanied by partial melting, and seems to occur in different episodes, from ~352 Ma to ~340 Ma. On a larger scale, these results are fully in line with the HP ages described in the Variscan Belt and allow to reconsider the tectonics in the French Massif Central.

Abstract The metamorphosed Palaeoproterozoic Orivesi gold deposit in southern Finland is located within the Tampere Schist Belt, which belongs to the Svecofennian domain. The Orivesi mine, run by Outokumpu Mining Oy, was in production from 1994 to 2003, during which time a total of approximately 1.7 million tons of ore was extracted, with an Au content of 9.31 g/t, implying a total output 13.115 tons of gold in concentrate. The hydrothermal alteration halo can be divided successively into chlorite-dominant, sericite-dominant and quartz-dominant rocks from the outer zone inwards. The host rocks of the ore are quartz rocks with andalusite-rich quartz rocks. Topaz-bearing rocks also occur in the inner part of the alteration halo. In addition to Au, the elements Ag, Te, Bi, Sb, S, As, Se, Cu, Zn, Pb, Sn and Mo are enriched to varying degrees within the alteration halo. The main ore minerals include base metal sulphides, sulphosalts and tellurides. Pyrite is the most common sulphide. The sulphosalts are represented by tetrahedrite, bournonite, boulangerite and meneghinite. The most common gold, gold-silver and silver tellurides are calaverite, montbrayite, petzite, kostovite, sylvanite and hessite. Other known tellurides include tellurobismuthite, altaite, melonite, frohbergite, tsumoite, tetradymite and rucklidgeite. Gold occurs mostly in fine-grained native grains containing an average of 5% Ag. The native gold is usually of very small grain size, generally < 20 µm. Most of the gold grains in the deposit occur as intergrowths with tellurides. The adjacent hypabyssal intrusion is an obvious source of both hydrothermal fluids and metals. A comb quartz layering has been discovered in the transition zone between the intrusion and the alteration halo. The Orivesi deposit is thought to belong to the high-sulphidation epithermal type. Soon after its formation the deposit encountered deformation and metamorphism that amounted to lower amphibolite facies conditions. The subsequent retrograde metamorphism caused the reappearance of some hydrothermal minerals typical of high-sulphidation epithermal deposits.

Rocks of the Quesnel Lake area are divided into three units: unit 1, a continental margin sequence; unit 2, The Crooked Amphibolite (an ocean-floor sequence); and unit 3, the Quesnel sedimentary and volcanic sequence. Two conglomerate localities within unit 3 contain clasts identified as being derived from deformed rocks of units 1 and 2. Deformation of the combined package of units 1 and 2 must have accompanied the emplacement of unit 2 onto unit 1 sometime between the deposition of unit 2 (Mississippian - Permian) and the deposition of unit 3 (Triassic - Jurassic). Rocks of unit 1 have been divided by earlier workers into the Barkerville and Cariboo terranes, separated by the Pleasant Valley Thrust. An extensive review shows that the two terranes are stratigraphically similar and share most of their structural history. The Pleasant Valley Thrust, if it exists, is an extremely early structure. These data do not satisfy the criteria for naming these units 'terranes'. The rocks of unit 1 and 2 experienced an extra phase of deformation not seen in rocks of unit 3. A total of five phases of folding are present. Phases 1 through 4 are approximately coaxial with northwest axes and variably oriented axial planes. Phase 5 has northeast trending axes and vertical axial planes. F₁ is seen in units 1 and 2 only and is visible in outcrop as rootless isoclinal folds and a transposed foliation. In thin section, S₁ is only preserved within the earliest garnet porphyroblasts. F₂ folding is the major deformational event. Peak metamorphism accompanied and outlasted it. Major F₂ folds are present in the field and are accompanied by an axial planar foliation. In thin section, S₂ wraps around earlier porphyroblasts but is overgrown by later ones (staurolite, kyanite). F₃ folding is responsible for the major map-scale structures. It postdated the peak of metamorphism and isograds axe folded by it. In thin section S₃ is commonly a crenulation cleavage or transposed foliation. Some late mineral growth accompanied the early stages of F₃. F₄ and F₅ are buckle folds and kinks and may be conjugate fold sets from a single deformational event. They are not generally visible in thin section. The assemblage silica - garnet - aluminosilicate - mica (SGAM) is common in amphibolite grade meta-pelitic rocks, and can be used as a thermobarometer if the activities of muscovite and biotite can be calculated accurately. A new method of calculating the ideal activity of mica components is proposed. Standard models do not adequately account for the degree of coupled substitution that takes place. The proposed method stores the site occupancies in a 4-dimensional array and manipulates the entries to satisfy three criteria. 1: That non-permitted ionic configurations (species) have an activity of zero. 2: That the sum of all activities is unity. 3: That the sum of all activities of species containing a particular ion in a particular site is the site occupancy of that ion. The method is computationally simple and yields activity values that satisfy the distribution of species equations of an ideal complex solution model. Standard state properties for annite and Margules solution parameters for biotite are determined using mathematical programming techniques on published experimental and natural assemblage data. Published volume data indicate that Fe-Mg mixing in biotite is ideal. The data permit the calculation of four Margules parameters (MgTi, FeTi, MgAl, FeAl). The differences MgTi - FeTi and MgAl - FeAl are similar to those found by previous workers but the treatment of the data suggests moderately large individual values for the Margules parameters (up to 75 kJ/mol). Using these activity models the SGAM thermobarometer is applied to several sets of published analyses which show that this calibration offers distinct improvements over previous calibrations. Pressures determined using the new calibration are consistent with other barometers and the aluminosilicate polymorph present. In addition, several data sets show field gradients, particularly in P, not previously recognized and which agree with field observations. The SGAM barometer applied to the analytical data from the Quesnel Lake area yields pressures and temperatures that are consistent with the mapped isograds. The pressure and temperature gradients indicate that the final setting of the thermobarome-ter was diachronous across the area and during the early stages of F₃ folding. Hot rocks in cores of anticlines 'set' at later times and at shallower depths than cooler rocks in adjacent synclines. Tight spacing of isograds is more consistent with post-metamorphic folding than with high thermal gradients. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

D.Phil. (Geology) / Please refer to full text to view abstract

Notre recherche en Sciences de l’Education s’inscrit dans le champ de l’éducation métamorphique, à savoir visant la transformation du sujet par lui-même, en prenant appui sur l’analyse du dispositif de l’Experiment. Il s’agit, pour les étudiants ingénieurs de l’Institut Catholique des Arts et Métiers, de réaliser un projet de voyage d’une durée de quatre mois, en lien avec un désir personnel dont les formes peuvent varier. Nous restituons le contexte de ce dispositif dans un premier temps. L’Experiment relevant d’une pédagogie ignatienne, nous sommes amenés à examiner l’anthropologie d’Ignace de Loyola, en l’éclairant par des approches contemporaines pour engager la question de la métamorphose du sujet et la construction de son éthicité, dans un second temps. Enfin, nous montrons, par une double approche méthodologique, c'est-à-dire l’analyse structurale d’entretiens et la mise en place d’un atelier d’écriture, que la conjonction du voyage et de l’écriture peut faire de l’Experiment un exercice spirituel émancipatoire pour les étudiants. Nous questionnons donc l’articulation de la formation de soi et du rôle de l’institution, en vue de l’émancipation du sujet. / This research in the Education is part of the metamorphic education field which aims at the transformation of a subject by himself. It’s based on the analysis of the device of the “Experiment”. The student-engineers from the “Institut Catholique des Arts et Métiers” are to organise a 4-month travel project in relation with their personal yearnings. This project can take different forms. First of all, we will account for the context of this device. Then, we will examine the anthropology of Loyola since the “Experiment” is based on his pedagogy. Enlightening this anthropology by current approaches, the questions of the metamorphosis of the subject and the construction of his eticity will be considered. Finally, using a double methodology ie both a structural analysis of interviews and the setting of a writing workshop, we will show to what extend the mix between the writing and the travel leads the “Experiment” to a spiritual exercise of emancipation for the students. The articulation between self training and the role of the Institution - aiming at the emancipation of the subject - will be questioned

English abstract The investigation of high- to ultrahigh-pressure rocks in the Bohemian Massif occurring as small bodies enclosed in surrounding rocks with a low degree of metamorphism was always focused on their main metamorphic event in granulite facies conditions at very high temperatures. However, recent studies have shown that these rocks underwent a high-pressure metamorphism that preceded the subsequent high-temperature overprint and exhumation of those rocks. The scientific publications that comprise this dissertation thesis present petrological, mineralogical and geochemical research of these (ultra)high pressure rocks from various parts of the Bohemian Massif that have the potential to preserve information about their pre-exhumation history. The findings of the inclusions of high-pressure phases in metamorphic minerals and, in particular, the study of major and trace elements zoning in garnets together with thermodynamic modelling allowed us to describe new temperature-pressure conditions and to refine the metamorphic paths of these rocks. The felsic and mafic granulites of the Kutná Hora Complex in the Moldanubian Zone and the Rychleby Mountains in the East Sudetes preserve the evidence of prograde metamorphism. In addition to the inclusions of phengite and omphacite in the garnet cores, the...