The potentially hazardous nature of open pit mining requires the application of sound geotechnical engineering practice to mine design, for the purpose of permitting safe and economic mining of any commodity within any rock mass. The Lerala Diamond Project is situated in the south west of Botswana near the Martin’s Drift Border Post. A 2m-soil cover made surface mapping of geological features impossible, so a number of geotechnical holes were drilled to evaluate the characteristics of the kimberlite pipes and the Granite/gneiss host rock. The Lerala Diamond Project is a typical example of the geotechnical assessment of a kimberlite pipe in Greenstone belt granites. The explosive nature of the formation of these pipes was seen in the various types of joint and fracture pattern identified during this study that could have an influence on the stability of the open pit. Estimating the stability of rock slopes is required by the mining engineering industry for a wide variety of projects. Of importance in this regard is the preliminary evaluation of slope stability at the feasibility stage, excavation stage, and operating stage. The Lerala Diamond Project is currently undertaking a preliminary evaluation as part of a feasibility study. The aim of the geotechnical assessment was to divide the local rock into easily identifiable types that could be geotechnically evaluated. Two classification systems were used during the quantification of the rock mass types. These are the Rock Mass Rating (RMR) system of Bieniawski (1976) and the Mining Rock Mass Rating (MRMR) system of Laubscher (1990). Observations and recordings of the drill core were carried out and these, in conjunction with laboratory results, enabled the determining of the characteristics of the rock mass that will be exposed in the slopes. Computer modelling programmes such as ROCKPAK III were used to test the designs against potential failures. The various potential failures were identified for the different highwalls. Recommendations including the continuous logging of geotechnical features were proposed for the purpose of developing a sound geotechnical model for identifying potential unstable areas within the pit. / Dissertation (MSc)--University of Pretoria, 2008. / Mining Engineering / unrestricted

Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Earth’s oldest preserved granitoid crust dates back to the Paleoarchean and consists predominantly of sodic tonalite-trondhjemite-granodiorite (TTG) granitoids that arose through the partial melting of hydrated metabasalts. In contrast, granites (sensu stricto) typically postdate the TTG and appear late in the plutonic record of the old cratons. However, the existence of Hadean zircons with mineral inclusion suites that are consistent with crystallization from peraluminous granitic magmas indicates that granitic rocks formed part of the earliest felsic crust; although we have direct evidence, this earliest felsic crust is not preserved. In this PhD I present an unusual variety of markedly CaO-poor, K2O-rich, rutile-bearing, peraluminous granite and rhyolite that are located in the basal conglomerate of the Moodies Group (South Africa). These rocks challenge the common view of the Archean craton evolution as they were produced concurrently with TTG magmas during three magmatic cycles in the Barberton Greenstone Belt (BGB) and were later emplaced, as clasts, in a younger conglomerate. The study of mineral inclusions located in the zircons present within the granites and rhyolites, shows that alkali feldspar inclusions are abundant relative to plagioclase inclusions and demonstrates that the main characteristics of these granites, i.e. they are K-rich and Ca-poor, are a magmatic signature. The oxygen isotope signature of these zircon grains reveals that the zircons have preserved the δ18O value of the magma from which the granites originated and that the source of the granites had a magmatic oxygen isotope value close to the one of the regional coeval TTG. Further study of the zircons shows that their Lu-Hf isotopic system reflects the crustal signature of the magma into which they grew. Sm-Nd study of the granites and rhyolites whole rock indicates that the minimum age of the source’s protolith of the granites and rhyolites is close to 3.9 billion years, which is in agreement with the zircons’ Lu-Hf signature. Additionally I show in this thesis that the peraluminous character of the granites and rhyolites, along with their high Sr and low Ca content associated to their Eu/ Eu* ~ 1 is a consequence of phengite melting in a metagreywacke source at pressures in excess of plagioclase stability. My work therefore illustrates that K-rich, Ca-poor peraluminous granites were generated in the Paleo and Meso Archean, alongside with the sodic TTG, through partial melting of sediments at high pressures. Not only has this process demonstrated the ability of the early Earth to recycle relatively young material since 3.9 billions years ago, but it has also contributed to each episode of continental crustal growth through the Paleoarchean to Mesoarchean in the BGB, despite leaving no plutonic record at the typical mid-crustal level of exposure that the TTG plutons around the belt represent. / AFRIKAANSE OPSOMMING: Die aarde se oudste bewaarde granitoïed kors dateer terug na die Paleo Argeïkum en bestaan hoofsaaklik uit natrium-ryke tonaliet-trondhjemiet-granodioriet (TTG) granitoïede wat ontstaan het deur die gedeeltelike smelting van gehidreerde metabasalte. In teenstelling hiermee is graniete (sensu stricto) tipies jonger as die TTG’s en verskyn laat in die plutoniese rekord van die ou kratons. Die bestaan van Hadeaanse zirkone met mineraal insluitsels wat ooreenstem met die kristallisasie van peralumineuse granietiese magma dui egter daarop dat granietiese gesteentes deel gevorm het van die vroegste felsiese kors. Alhoewel daar direkte getuienis is hiervoor het hierdie vroegste felsiese kors nie behoue gebly nie. In hierdie dissertasie toon ek ‘n ongewone verskeidenheid van merkbaar CaO-arm, K2O-ryk, rutiel-draende, peralumineuse graniet en rioliet wat in die basale konglomeraat van die Moodies Groep (Suid-Afrika) voorkom. Hierdie gesteentes daag die algemene siening van Argeïkum kraton evolusie uit omdat hulle gelyktydig met TTG magma geproduseer is tydens drie TTG magmatiese siklusse in die Baberton-groensteenstrook en later ingeplaas is as klaste in ‘n jonger konglomeraat. Die studie op minerale insluitsels in zirkone binne die graniete en rioliete toon dat alkaliveldspaat insluitsels volop is relatief tot plagioklaas insluitsels. Dit toon ook dat die hoof eienskap van hierdie graniete, hulle K-ryke en Ca-arme samestelling, ‘n onderskeidende magmatiese kenmerk is. Die suurstof-isotoop samestelling van hierdie zirkoon minerale onthul dat die zirkone die δ18O waarde van die magma waaruit die graniet gevorm is behou het en dat die bronnemateriaal van die graniete ‘n magmatiese suurstofisotoop waarde gehad het nader aan dié van die plaaslike sinchroniese TTG waardes. Verdere studie van die zirkone dui daarop dat hul Lu-HF isotoopstelsel die aardkorseienskappe weerspieël van die oorspronklike magma waarin hulle gegroei het. Sm-Nd studie van die graniete en rioliete heelgesteente dui daarop dat die minimum ouderdom van die protoliet van graniete en rioliete ongeveer 3,9 biljoen jaar is, wat ooreenstem met die zirkone se Lu-HF eienskappe. Daarbenewens het hierdie dissertasie bewys dat die peralumineuse karakter van die graniete en rioliete, tesame met hulle hoë Sr- en lae Ca-inhoud geassosieer tot hul Eu/Eu * ~ 1, ‘n gevolg is van “phengite” smelting in’ n metagrouwak bron by drukking hoër as plagioklaas stabiliteit. Hierdie studie illustreer dus dat K-ryke, Ca-arme peralumineuse graniete gegenereer is in die Paleo en Meso Argeïkum, saam met die natrium-ryke TTG’s, deur middel van parsiële smelting van sedimente teen ‘n hoë druk. Hierdie proses het nie slegs getoon dat die vroeë aarde sedert 3,9 biljoen jaar gelede die vermoë gehad het om relatief jong materiaal te herwin nie; dit het ook bygedra tot elke episode van kontinentale korsgroei deur die Paleo en Meso Argeïkum in die Barberton groensteenstrook, ten spyte daarvan dat geen plutoniese rekord gelaat is teen die tipiese mid-kors vlak van blootstelling wat die TTG plutone in die strook verteenwoordig nie. / RESUMÉ: La croûte de granitoïdes de la Terre Primitive la plus ancienne qui ait été préservée remonte au Paleoarchéen et se compose principalement de granitoïdes sodiques tonalite-trondhjémite-granodiorite (TTG) qui se sont formés par la fusion partielle de métabasaltes hydratés. En revanche, les granites (stricto sensu) sont en général postérieurs aux TTG et apparaissent tardivement dans les cratons anciens. Cependant, l’existence de zircons Hadéens préservant des suites d’inclusions minérales qui sont compatibles avec la cristallisation à partir d’un magma granitique peralumineu, indique que les roches granitiques faisaient aussi partie de la croûte felsique de la Terre Primitibe; même si nous n’avons pas de preuves directes et que cette dernière n’ait pas été conservée. Dans cette thèse, je présente une variété inhabituelle de granites et rhyolites peralumineux qui sont marquée par une forte teneur en K2O et une faible teneur en CaO et qui possèdent du rutile. Ces roches sont situées dans le conglomérat basal du Groupe du Moodies (Afrique du Sud). Elles défient la vision commune que l’on a de l’évolution des cratons Archéens puisqu’elles ont été produites en même temps que des magmas TTG, pendant trois cycles magmatiques qui ont affecté la ceinture de roches vertes de Barberton (CRVB). Ces roches ont été par la suite mises en place, comme galets, dans un conglomérat plus jeune. L’étude des inclusions minérales localisées dans des zircons présents dans les granites et les rhyolites qui font le sujet de cette étude, montre que les inclusions de feldspaths alcalins sont plus abondantes que les inclusions de plagioclases et démontre que les principales caractéristiques de ces granites, c’est à dire qu’ils sont riches en K et pauvres en Ca, sont une signature magmatique. La signature isotopique de l’oxygène de ces zircons révèle que ceux-ci ont conservé la valeurdu δ18O du magma à partir duquel les granites se sont formés. De plus ceci montre que la valeur du δ18O de la source des granites était proche de celle de TTG contemporains. La poursuite de l’étude des zircons montre que leur système isotopique Lu-Hf reflète la signature crustale du magma dans lequel ils ont cru. L’étude Sm-Nd des granites et rhyolites indique que l’âge minimum du protolithe de leur source est de près de 3,9 milliards d’années, ce qui est en accord avec la signature Lu-Hf des zircons. De plus, je montre dans cette thèse que le caractère peralumineux des granites et des rhyolites, avec leurs forte teneur an Sr et basse teneur en Ca associé à leur Eu / Eu * ~ 1, est une conséquence de la fusion partielle de phengite dans une source métagrauwacke à des pressions supérieures a celle de la stabilité du plagioclase. Mon travail montre donc que des granites peralumineux riche en K et pauvre en Ca ont été générés durant le Paléo et Méso-Archéen, aux côtés des TTG sodiques, par la fusion partielle de sédiments, à haute pression. Non seulement ce processus a démontré la capacité de la Terre Primitive à recycler du matériel relativement jeune et ce, dès 3,9 milliards d’années; mais il a également contribué à chaque épisode de croissance crustale à travers le Paleo- et Méso-Archéen dans la CRVB, malgré l’absence de pluton mis en place profondeur à des profondeurs identiques à celles des TTG.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A Suíte Intrusiva Santa Clara está inserida na Província Estanífera de Rondônia, na porção SW do Cráton Amazônico. Essa suíte intrusiva é composta pelos maciços Santa Clara, Oriente Velho, Oriente Novo, Manteiga-Sul, Manteiga-Norte, Jararaca, Carmelo, Primavera e das Antas. Os litotipos que perfazem a Suíte Santa Clara ocorrem hospedados nas rochas do Complexo Jamari, uma associação polideformada composta por gnaisses ortoderivados e paraderivados. Características observadas em campo e em análises petrográficas permitiram subdividir o Maciço Santa Clara em cinco fácies distintas: fácies porfirítica, fácies isotrópica, fácies fina, fácies piterlítica e fácies viborgítica. Os litotipos observados correspondem a hornblenda-biotita granitos e biotita granitos intermediários a ácidos, com composições médias semelhantes àquelas verificadas para sienogranitos e monzogranitos. Geoquimicamente, três magmas podem ser identificados. O magma menos evoluído corresponde às rochas das fácies porfirítica e equigranular, e o mais evoluído compreende as fácies de granulometria fina e piterlítica. A fácies viborgítica representa o terceiro líquido magmático, e aparentemente é diferente de todas as outras fácies em termos de aspectos de campo e geoquímica. A análise litogeoquímica indica que estes granitoides são subalcalinos, bastante empobrecidos em MgO e exibem caráter metaluminoso a fracamente peraluminoso. Os padrões de elementos-traços evidenciam que tais granitóides possuem alto conteúdo em elementos incompatíveis (Rb, Zr, Y, Ta, Ce) e ETR, com exceção do Eu. Além disso, também exibem leve enriquecimento em LILE, forte depleção em elementos como Sr e Ti, e leve empobrecimento de Ba, indicando que o fracionamento de minerais como plagioclásio e titanita foi importante na evolução do líquido magmático analisado. A anomalia negativa de Nb indica envolvimento de material crustal nos processos magmáticos que geraram estes granitoides. Os litotipos analisados possuem características típicas de granitos tipo-A ferroan, e as razões FeOt/MgO entre 4,27 e 26,22 sugerem tratar-se de uma série de granitos félsicos fracionados. Os padrões de ETR observados para os litotipos analisados exibem um considerável enriquecimento em ETRL, e anomalia negativa de Eu, sugerindo fracionamento de feldspato durante o processo de diferenciação do líquido magmático. Diagramas discriminantes de ambientes tectônicos sugerem que os litotipos do Maciço Intrusivo Santa Clara são típicos de ambiente intraplaca, do tipo-A2, isto é, associados a ambientes pós-colisionais/pós-orogênicos. As características isotópicas observadas para os granitoides do Maciço Santa Clara sugerem que os mesmos foram gerados a partir da fusão parcial de uma crosta inferior pré-existente. As idades U-Pb entre 1,07 e 1,06 Ga são compatíveis com um magmatismo ocorrido nos estágios finais da colagem do supercontinente Rodínia (1,2-1,0 Ga) e estágios finais do Ciclo Orogênico Sunsás-Aguapeí (1320-1100 Ma). Sugere-se ainda que na verdade o Maciço Santa Clara seja formado por uma coalescência das três intrusões graníticas que são representadas pelos três magmas anteriormente descritos. / The Santa Clara Intrusive Suite in the Rondônia Tin Province (SW Amazonian Craton) comprises the Santa Clara, Oriente Velho, Oriente Novo, Manteiga-Sul, Manteiga-Norte, Jararaca, Carmelo, Primavera and das Antas massifs. The rocks of the Santa Clara Intrusive Suite are emplaced in the Jamari Complex, an association of ortho and paragneisses which underwent several and complex metamorphic processes. Characteristics observed during both geological mapping and petrographic analyses allowed, for the first time, to subdivide the Santa Clara Massif (SCM) granitoids into five different facies: porphyry, equigranular, fine-grained facies, pyterlitic and wiborgitic facies. These lithotypes comprise hornblende-biotite granites and biotite granites that range from intermediate to acids, and show compositions similar to syenogranites and monzogranites. Geochemical analyses suggest that these granitoids may be divided into three different magmas, considering field aspects and geochemical characteristics. Therefore, the less evolved magma is represented by porphyritic and equigranular facies, and the most evolved magma comprises both fine-grained and pyterlitic facies. The wiborgitic facies representd the other magma, and is geochemically different from all the others facies. Geochemical analyses also show that the granitoids of the Santa Clara Massif are subalkaline, have very low MgO contents and have metaluminous to slightly peraluminous character. Trace elements patterns show that these granitoids have high contents of incompatible elements (Rb, Zr, Y, Ta, Ce) and REE, with exception of Eu. Moreover, they are also slightly enriched in LILE, strongly depleted in elements such as Sr and Ti, and slightly depleted in Ba, pointing out the importance of plagioclase and titanite fractioning during the evolution of these magmatic liquids. Negative anomalies of Nb, along with other geochemical features, suggest the participation of crustal material in the magmatic processes responsible for these granitoids generation. The lithotypes have typical characteristics of ferroan A-type granites, and FeOt/MgO ratios ranging from 4.27 to 26.22 indicate that these are fractionated felsic granites. REE patterns show a remarkable enrichment in LREE along with negative Eu anomaly. Tectonic discriminant diagrams for the Santa Clara Massif granitoids suggest that these are intraplate granitoids, A2-type, that is, related to post-collisional/post-orogenic settings.The isotopic characteristics observed for the Santa Clara Massif granitoids suggest that these were generated through partial melting of a preexistent lower crust. The U-Pb ages between 1,07 e 1,06 Ga are compatible with a magmatism taken place during the final stages of the supercontinent Rodinia agglutinations and the final stages of the Sunsás-Aguapeí Orogenic Cycle. It is also suggested that the Santa Clara Massif represents the coalescence of three different granitic intrusions, which comprise the magmas described above.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A Suíte Intrusiva Santa Clara está inserida na Província Estanífera de Rondônia, na porção SW do Cráton Amazônico. Essa suíte intrusiva é composta pelos maciços Santa Clara, Oriente Velho, Oriente Novo, Manteiga-Sul, Manteiga-Norte, Jararaca, Carmelo, Primavera e das Antas. Os litotipos que perfazem a Suíte Santa Clara ocorrem hospedados nas rochas do Complexo Jamari, uma associação polideformada composta por gnaisses ortoderivados e paraderivados. Características observadas em campo e em análises petrográficas permitiram subdividir o Maciço Santa Clara em cinco fácies distintas: fácies porfirítica, fácies isotrópica, fácies fina, fácies piterlítica e fácies viborgítica. Os litotipos observados correspondem a hornblenda-biotita granitos e biotita granitos intermediários a ácidos, com composições médias semelhantes àquelas verificadas para sienogranitos e monzogranitos. Geoquimicamente, três magmas podem ser identificados. O magma menos evoluído corresponde às rochas das fácies porfirítica e equigranular, e o mais evoluído compreende as fácies de granulometria fina e piterlítica. A fácies viborgítica representa o terceiro líquido magmático, e aparentemente é diferente de todas as outras fácies em termos de aspectos de campo e geoquímica. A análise litogeoquímica indica que estes granitoides são subalcalinos, bastante empobrecidos em MgO e exibem caráter metaluminoso a fracamente peraluminoso. Os padrões de elementos-traços evidenciam que tais granitóides possuem alto conteúdo em elementos incompatíveis (Rb, Zr, Y, Ta, Ce) e ETR, com exceção do Eu. Além disso, também exibem leve enriquecimento em LILE, forte depleção em elementos como Sr e Ti, e leve empobrecimento de Ba, indicando que o fracionamento de minerais como plagioclásio e titanita foi importante na evolução do líquido magmático analisado. A anomalia negativa de Nb indica envolvimento de material crustal nos processos magmáticos que geraram estes granitoides. Os litotipos analisados possuem características típicas de granitos tipo-A ferroan, e as razões FeOt/MgO entre 4,27 e 26,22 sugerem tratar-se de uma série de granitos félsicos fracionados. Os padrões de ETR observados para os litotipos analisados exibem um considerável enriquecimento em ETRL, e anomalia negativa de Eu, sugerindo fracionamento de feldspato durante o processo de diferenciação do líquido magmático. Diagramas discriminantes de ambientes tectônicos sugerem que os litotipos do Maciço Intrusivo Santa Clara são típicos de ambiente intraplaca, do tipo-A2, isto é, associados a ambientes pós-colisionais/pós-orogênicos. As características isotópicas observadas para os granitoides do Maciço Santa Clara sugerem que os mesmos foram gerados a partir da fusão parcial de uma crosta inferior pré-existente. As idades U-Pb entre 1,07 e 1,06 Ga são compatíveis com um magmatismo ocorrido nos estágios finais da colagem do supercontinente Rodínia (1,2-1,0 Ga) e estágios finais do Ciclo Orogênico Sunsás-Aguapeí (1320-1100 Ma). Sugere-se ainda que na verdade o Maciço Santa Clara seja formado por uma coalescência das três intrusões graníticas que são representadas pelos três magmas anteriormente descritos. / The Santa Clara Intrusive Suite in the Rondônia Tin Province (SW Amazonian Craton) comprises the Santa Clara, Oriente Velho, Oriente Novo, Manteiga-Sul, Manteiga-Norte, Jararaca, Carmelo, Primavera and das Antas massifs. The rocks of the Santa Clara Intrusive Suite are emplaced in the Jamari Complex, an association of ortho and paragneisses which underwent several and complex metamorphic processes. Characteristics observed during both geological mapping and petrographic analyses allowed, for the first time, to subdivide the Santa Clara Massif (SCM) granitoids into five different facies: porphyry, equigranular, fine-grained facies, pyterlitic and wiborgitic facies. These lithotypes comprise hornblende-biotite granites and biotite granites that range from intermediate to acids, and show compositions similar to syenogranites and monzogranites. Geochemical analyses suggest that these granitoids may be divided into three different magmas, considering field aspects and geochemical characteristics. Therefore, the less evolved magma is represented by porphyritic and equigranular facies, and the most evolved magma comprises both fine-grained and pyterlitic facies. The wiborgitic facies representd the other magma, and is geochemically different from all the others facies. Geochemical analyses also show that the granitoids of the Santa Clara Massif are subalkaline, have very low MgO contents and have metaluminous to slightly peraluminous character. Trace elements patterns show that these granitoids have high contents of incompatible elements (Rb, Zr, Y, Ta, Ce) and REE, with exception of Eu. Moreover, they are also slightly enriched in LILE, strongly depleted in elements such as Sr and Ti, and slightly depleted in Ba, pointing out the importance of plagioclase and titanite fractioning during the evolution of these magmatic liquids. Negative anomalies of Nb, along with other geochemical features, suggest the participation of crustal material in the magmatic processes responsible for these granitoids generation. The lithotypes have typical characteristics of ferroan A-type granites, and FeOt/MgO ratios ranging from 4.27 to 26.22 indicate that these are fractionated felsic granites. REE patterns show a remarkable enrichment in LREE along with negative Eu anomaly. Tectonic discriminant diagrams for the Santa Clara Massif granitoids suggest that these are intraplate granitoids, A2-type, that is, related to post-collisional/post-orogenic settings.The isotopic characteristics observed for the Santa Clara Massif granitoids suggest that these were generated through partial melting of a preexistent lower crust. The U-Pb ages between 1,07 e 1,06 Ga are compatible with a magmatism taken place during the final stages of the supercontinent Rodinia agglutinations and the final stages of the Sunsás-Aguapeí Orogenic Cycle. It is also suggested that the Santa Clara Massif represents the coalescence of three different granitic intrusions, which comprise the magmas described above.

La chronologie de la formation de la croûte continentale est débattue mais la plupart des modèles convergent sur le fait qu'une bonne partie de la croûte continentale présente à la surface de la Terre aujourd'hui est présente depuis le Protérozoïque (2,5 - 0, 54 Ga) et qu'elle a essentiellement subit un remaniement au cours d'orogénèses. L'uranium, qui est un élément incompatible, est un traceur de cette évolution depuis son fractionnement initial par fusion partielle du manteau jusqu'à son remaniement dans les niveaux crustaux supérieurs. La ceinture orogénique Néoprotérozoïque Pan-africaine (0,5 ± 0,1 Ga) du Damara en Namibie constitue une cible géologique pour tester les relations entre croissance / évolution crustale et métallogénie de l'uranium. Elle s'est formée suite à la collision des cratons archéens du Congo et du Kalahari (plaque subductante). Ce travail de thèse montre que l'évolution de la croute continentale de la ceinture du Damara durant l'orogènese Pan-africaine au Néoprotérozoïque se fait par remaniement de roches ayant été extraites du manteau depuis l'Archéen et que leur fusion partielle est le mécanisme prépondérant pour la minéralisation uranifère primaire associée à la cristallisation de granites intrusifs. Les granites in-situ issus de la fusion partielle des sédiments dans les niveaux crustaux supérieurs sont peu ou pas propices à de fortes concentrations d'uranium du fait 1) de la faible préconcentration de leur protolithes et 2) de leur migration relativement limitée. Les granites intrusifs minéralisés correspondent à des injections tardi- à post-collision (ca. 520 - 480 Ma dans la zone centrale) et sont liés aux phases de relaxation thermique et d'effondrement gravitaire subséquentes à l'épaississement crustal de l'orogène dans un contexte de convergence de plaques / The chronology of continental crust formation is debated but most models converge on the fact that much of the continental crust on the surface of the Earth is present since the Proterozoic (2.5 - 0, 54 Ga) and has essentially undergoes reworking during orogenesises. Uranium which is an incompatible element is a tracer of this crustal evolution, since its initial fractionation by partial melting of the mantle to its reworking in higher crustal levels. Neoproterozoic Pan-African (0.5 ± 0.1 Ga) orogenic belt of the Damara in Namibia is a good geological target to test the relationship between crustal growth and evolution and metallogeny of uranium. It was formed after the collision of the Archean cratons of Congo and Kalahari (subducting plate). This thesis shows that the evolution of the continental crust during the Neoproterozoic Damara Orogen is by reworking of Archaean to Neoproterozoic crustal domains and partial melting of rocks is the predominant mechanism for primary uranium mineralization associated with crystallization of intrusive granites derived from anatexis of paleo- to mesoproterozoic basement fragments. The intrusive granites issued from partial melting of sediments in the upper crustal levels are low or not favorable to high concentrations of uranium because of 1) the low preconcentration of their protoliths and 2) their relatively limited migration. The mineralized intrusive granites correspond to late- to post-collision injections (ca. 520-480 Ma in the central area) and are related to thermal relaxation phases and gravitational collapse subsequent to thickening in crustal orogen in a context of plates convergence

Les granites peralumineux sont les acteurs principaux de la différentiation de la croûte continentale et représentent un enjeu sociétal important car ils sont associés à de nombreux gisements métallifères. Dans la chaîne hercynienne européenne, la majorité des gisements hydrothermaux d'uranium (filons ou épisyenites) sont associés à des leucogranites peralumineux d'âge tardi-carbonifère. Ainsi dans le Massif armoricain, 20000 t d'uranium (U) (~20% de la production historique française), ont été extraites des gisements associés aux leucogranites de Mortagne, Pontivy et Guérande. L'objectif de ce travail est de mieux comprendre le cycle de l'uranium dans la chaîne hercynienne armoricaine depuis la source des leucogranites, leur évolution et leur mise en place dans la croûte supérieure jusqu'à leur lessivage par des fluides, la formation des gisements puis leur exhumation en sub-surface. Dans ce but, des données pétro-géochimiques, géochronologiques et thermochronologiques ont été obtenues sur les leucogranites de Guérande, Pontivy et leurs gisements d'uranium associés. Les leucogranites de Guérande et de Pontivy se sont mis en place, respectivement, à ca. 310 Ma dans une zone de déformation extensive dans le domaine interne de la chaîne et ca. 315 Ma dans le domaine externe le long du cisaillement sud armoricain (CSA), une faille décrochante d'échelle lithosphérique. Les deux leucogranites sont issus d'un faible taux de fusion partielle de métasédiments détritiques et d'orthogneiss peralumineux, la fusion de ces derniers ayant vraisemblablement joué un rôle majeur dans la richesse en uranium des leucogranites. La fusion de la croûte continentale dans la zone interne de la chaîne a été induite par l'extension tardi-orogénique alors que la fusion de la croûte mais aussi du manteau dans la zone externe était probablement contrôlée par une déformation décrochante diffuse. La cristallisation d'oxydes d'uranium magmatiques dans les facies les plus évolués des leucogranites au moment de leur mise en place a été vraisemblablement rendue possible grâce à l'action combinée de la cristallisation fractionnée et d'une activité magmatique-hydrothermale diffuse. De ca. 300 Ma à 270 Ma, une activité tectonique fragile le long du CSA et des détachements a permis l'infiltration de fluides météoriques oxydants en profondeur induisant la mise en solution des oxydes d'uranium des leucogranites. Ensuite, les fluides ont précipité leur U dans des failles ou des fentes de tension à proximité du contact avec des lithologies sédimentaires avec un caractère réducteur variable. Les leucogranites étaient toujours en profondeur à des températures supérieures à 120°C au moment de la formation des gisements et leur exhumation en sub-surface n'est pas enregistrée avant le Trias ou le Jurassique. Ce modèle métallogénique n'est probablement pas exclusif au Massif armoricain car la période de formation des gisements d'U dans la région entre 300 et 270 Ma est la même que dans l'ensemble de la chaîne hercynienne européenne. / Peraluminous leucogranites are the principal actors for the differentiation of the continental crust and play an important economic role because they are commonly associated with significant metalliferous deposits. Most hydrothermal uranium (U) deposits (vein or episyenite types) from the European Hercynian belt are spatially associated with Carboniferous peraluminous leucogranites and in the French Armorican Massif (western part of the European Hercynian belt) 20000 t of U (~20 % of the French production) were extracted from the deposits associated with the Mortagne, Pontivy and Guérande leucogranites. The objective of this work is to improve our knowledge about the U cycle in the Armorican Hercynian Belt from the leucogranites sources, their evolution and emplacement in the upper crust to U leaching, deposit formation and leucogranites exhumation at the subsurface level. For that purpose, petro-geochemical, geochronological and thermochronological data were obtained on the Guérande and Pontivy leucogranites as well as their spatially associated U deposits. The Guérande leucogranite was emplaced ca. 310 Ma ago in an extensional deformation zone in the internal domain of the belt whereas the Pontivy leucogranite was emplaced ca. 315 Ma ago in the external domain along the South Armorican Shear Zone (SASZ), a lithospheric scale wrench fault. Both leucogranites were formed by a low degree of partial melting of detrital metasediments and peraluminous orthogneisses; the fusion of the latter probably played a major role in the generation of U rich leucogranites. Partial melting of the crust in the internal zone of the belt was triggered by late orogenic extension whereas partial melting of the crust but also the mantle in the external zone was likely controlled by pervasive wrenching. The crystallization of magmatic uranium oxides in the most evolved leucogranitic facies was induced by fractional crystallization and probably enhanced by magmatic-hydrothermal processes. From ca. 300 to 270 Ma, a fragile tectonic activity along detachments and the SASZ, allowed for the infiltration at depth of meteoric oxidizing fluids, able to dissolve magmatic uranium oxides in the leucogranites. These fluids have then precipitated their U in faults or tension gashes close to the contact with sediments having a variable reducing character. The leucogranites were at depth above 120°c during the formation of U deposits and the exhumation of these intrusions did not occur before the Trias or the Jurassic. The proposed metallogenic model is likely not exclusive to the Armorican Massif as the timing of U deposits formation in the region from ca. 300 to 270 Ma is similar to the main U mineralizing event in the whole European Hercynian belt.

O pluton Desemborque, de idade neoproterozóica, é parte do denominado Maciço Guaraú, aflorante na região sul do de estado de São Paulo e está inserido no contexto geológico da Província Graciosa. É composto por biotita sienogranito a álcali feldspato granito, metaluminosos a moderadamente peraluminosos, que apresentam assinaturas geoquímicas típicas de granitos de tipo-A, como conteúdos relativamente altos de álcalis, além de concentrações significativas de elementos LIL e HFS. Apresentam alteração hidrotermal em graus variáveis, claramente evidenciados tanto pelas texturas quanto pelas composições registradas em seus minerais essências e acessórios, destacando-se a albitização e a greisenização. Os feldspatos alcalinos são pertitas ou mesopertitas zonadas. Algumas composições químicas integradas exibem valores entre \'Or IND 53-58\'\'Ab4 IND 42-46\' (núcleos) e \'Or IND 68-71\'\'Ab4 IND 29-32\' (bordas). A maior parte das composições obtidas dos plagioclásios correspondem a albita, com poucos cristais classificados como oligoclásio sódico. Albita pura e pós magmática ocorre intersticialmente aos feldpastos ou como microvenulações. São encontradas duas fases micáceas estritamente magmáticas: biotitas castanhas (annita) e esverdeadas (protolitionita-siderofilita). Associadas ao processo de greisenização que substitui biotitas e feldspatos encontram-se micas verdes claras a incolores anteriormente definidas como zinnwaldita, que aqui são reclassificadas como fengita. Minerais acessórios foram examinados e estudados com imageamento BSE e análises quantitativas por EDS. Os mais comuns são: zircão, allanita, torita, cassiterita, galena, hematita, ilmenita, monazita, , columbita e fluoretos de terras raras. Entre eles, os primários (e.g zircão, allanita e cassiterita) exibem microestruturas ou transformações químicas relacionadas à processos tardios de alteração hidrotermal, enquanto outros foram desenvolvidos durante este processo, como torita, xenotímia e fluoretos de elementos terras raras e de ítrio. Os granitos típicos do Desemborque são bastante evoluídos e relativamente homogêneos com um estreito intervalo composicional, como \'SiO IND 2\' (76-77% em peso), álcalis (\'Na IND 2\'O até 4,1 % e \'K IND 2 O\' até 4,5 %), \'Al IND 2\'\'O IND 3\' (ca. 12%) e \'Fe IND 2\'\'O IND 3\' (~1%). Outros óxidos comuns contribuem com concentrações bem baixas como CaO e MgO. As rochas hidrotermais exibem relativo enriquecimento em\' Fe IND 2\'\'O IND 3\' (5,27 % em peso para o greisen) além de F, Rb, Sn e Li e empobrecimento em \'Na IND 2\'O (0,26%). As temperaturas de saturação em Zr fornecem valores entre 750-860º C, e que pode ser extrapolada como uma aproximação para a temperatura do líquido do sistema magmático. Dados geológicos, petrográficos e normativos indicam colocação em níveis rasos, com pressões não muito maiores que 1 kbar. Suas características remetem a cristalização em fugacidades de oxigênio relativamente baixas, uma exceção entre a associação aluminosa da Província Graciosa. As determinações de idades isotópicas U/Pb são problemáticas devido aos aspectos texturais dos cristais de zircão e componentes herdados. Após o tratamento dos dados chegou-se a uma idade estatisticamente mais confiável (590 ± 12 Ma) e em parte, coerente com a literatura. / The Neoproterozoic Desemborque Pluton is a part of the so-called Guaraú Granitic Massif, which crops out in the southern region of the state of São Paulo and is inserted in the geological context of Graciosa Province. It is made of metaluminous to moderately peraluminous biotite sienogranites and alkali-feldspar granites which present geochemichal signatures most typical of A-type granites, as for the relatively high total alkali, LILE and HFSE contents. It shows hydrothermal alteration imprinted to a variable grade, as clearly evidenced by textural as well as compositional features registered in its essential and accessory minerals, standing out albitization and greisenization. Alkali-fedspars are zoned perthite or meso-phertite. Some integrated chemical compositions gave values between \'Or IND 53-58\'\'Ab IND 42-46\' (crystal cores) and \'Or IND 68-71\'\'Ab4 IND 29-32\' (crystal rims). Most of the obtained plagioclase compositions correspond to albite, a minor number being classified as sodic oligoclase. Post-magmatic, almost pure albite, occurs intersticialy to feldspars or as minor veinlets. Two main types of magmatic micas were recognized: red-brown annitic biotite and a green protolitionite-siderofilite. Light green to colorless micas associated with the greisenization process that replaces biotite and feldspars previously called a zinwaldite-like mica were reclassified to fengite type. Accessory minerals were examined and studied with BSE imaging and EDS qualitative analysis. The most common are zircon, allanite, thorite, cassiterite, galena, hematite, ilmenite, monazite, xenotime, columbite, fluorite and REE fluorides. Among them, the primary ones (e.g., zircon, allanite, cassiterite) show micro-structural or chemical transformations related to the hydrothermal alteration, while others were developed during such process, as for thorite, xenotime, and the REE and Y fluorides. The main Desemborque granites are highly evolved and relatively homogenous, with a narrow chemical compositional range as for \'SiO IND 2\' (76-77% wt %), alkalis (\'Na IND 2O\' up to 4.1 % e \'K IND 2O\' up to 4.5 %), \'Al IND 2\'\'O IND 3\' (ca. 12%) e \'Fe IND 2\'\'O IND 3\' (~1%). Other common oxides contribute with very low concentrations like CaO and MgO. Hydrothermal rocks show relatively \'Fe IND 2\'\'O IND 3\'enrichment (up to 5.2 wt.% in the greisen sample) in addition F, Rb, Sn e Li and depletion in \'Na IND 2 O\' (down to 0.26 wt.%) Zircon saturation temperature gives values in the 750-800º C range, which approaches well the liquidus of such magmatic system. Geological, petrographic, and normative data indicate relative shallow emplacement levels, at pressures no greater than ca. 1 Kbar, and crystallization under a relatively low \'f IND O2\' , a exception in the aluminous association of the Graciosa Province. U/Pb isotopic age determinations are problematic due textural aspects of zircon cristals and inherited components. After the treatment of the data was reached a statistically more confiable age (590 ± 12 My) and, in part, coherent with the literature.

O Brasil ocupa hoje posição de destaque na produção mundial de rochas ornamentais e de revestimento. Essa indústria gera diferentes tipos de resíduos, podendo atingir cerca de 83% de perda de matéria-prima. Nesse contexto o que tem causado mais transtornos é a denominada lama abrasiva, gerada no processo de desdobramento de blocos em placas sendo constituída de água, cal, pó de rocha e restos de limalha de aço e de lâminas. Esse material é produzido em grandes quantidades e pode ser estocado no pátio das empresas, ocupando vastas áreas ou podem ser armazenados em aterros o que é mais oneroso. Com vista a este problema, o objetivo desta pesquisa foi caracterizar o resíduo do corte de blocos de rochas ornamentais visando a possibilidade de diferentes aplicações na geotecnia. Para tanto, foram realizadas a classificação do resíduo conforme ABNT NBR 10004, caracterização química/mineralógica e geotécnica, avaliação de resistência e ensaios da metodologia Miniatura Compactada Tropical (MCT) da lama abrasiva produzida em uma empresa do interior do Estado de São Paulo. A partir desses ensaios foi possível classificar o resíduo como não perigoso e inerte, sendo que os parâmetros geotécnicos indicaram uma granulometria com cerca de 64% de silte, índice de plasticidade de 5%, massa específica dos sólidos de 2,823 g/cm³, massa específica máxima seca de 1,650 g/cm³ com umidade ótima de 21% na energia intermediária e 1,645 g/cm³ com 25,6% de umidade na energia normal. A resistência à compressão simples alcançou aos 28 dias de cura 0,354 MPa com o resíduo puro, 1,174 MPa com 2% de cimento e 2,294 MPa com 5% de cimento. Os ensaios de cisalhamento direto mostraram uma coesão de 54 kPa e 35º de ângulo de atrito. De acordo com a metodologia MCT o resíduo foi classificado como NS\' (silte não laterítico) de baixa permeabilidade que aumentou com o acréscimo de cimento, e baixa perda de suporte por imersão. Em linhas gerais a partir dos ensaios observou-se que esse material pode ter aplicações geotécnicas, mas para tanto outros ensaios deverão ser realizados. / Brazil currently occupies a prominent position in world production of dimension stones and coating. This industry generates different types of waste and may reach 83% loss of the raw material. In this context, the main problem of these wastes is the abrasive slurry, generated in the block sawing process on plates consisting of water, lime, stone powder and abrasive remaining. This material is produced in large quantities and can be stored in the companies courtyards, occupying vast areas or stored in landfills, which is more costly. Thus, the objective of this study was to characterize the waste of cutting blocks of dimension stones analyzing the possibility of different applications in geotechnics. Therefore, it was carried out a environmental classification according ABNT NBR 10004, geotechnical and chemical/mineralogical characterization, strength assessment and Miniature, Compacted, Tropical methodology (MCT) of sawing abrasive slurry in the State of São Paulo. It was found the waste was classified as a non-hazardous and inert. The geotechnical parameters indicated 64% of silt, 5% of plasticity index, 2,823 g/cm³ of density of solids, maximum dry density of 1,650 g/cm³ with optimum moisture content of 21% in the intermediate energy and 1,645 g/cm³ with 25,6% moisture at normal energy. Unconfined compressive strength achieved after 28 days of curing 0,354 MPa with pure residue, 1,174 MPa with 2% of cement and 2,294 MPa with 5% cement. The direct shear tests showed a cohesion of 54 kPa and 35º of friction angle. According to the MCT results the residue was classified as NS\' (silt not lateritic), low permeability\'s that increased with the addition of cement, and a low loss of support by immersion. Thus, it was observed that this material may have geotechnical applications, however should be conducted further testing.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Foram estudados corpos graníticos localizados no setor Monsenhor Bastos, porção sudoeste da Província Uranífera de Lagoa Real (PULR). A amostragem foi desenvolvida nas pedreiras de Lagoa Linda (LL), Pedreira Nova (PN) e no granitoide Lajedo (GR) este ultimo que aflora imediatamente a leste da anomalia uranífera AN02. O trabalho focaliza aspectos mineralógicos, geoquímicos, tipológicos e de fluidos desses granitoides, a fim de classificá-los mineralogica, textural e quimicamente. Foram utilizadas as metodologias de petrografia, microssonda eletrônica, geoquímica, termobarometria e estudo de inclusões fluidas (IF). As amostras de granitos apresentam uma paragênese magmática composta por feldspato potássico, plagioclásio, quartzo, piroxênio, ilmenita 1 e zircão. Também foram identificadas duas fases pós-magmáticas compostas por anfibólio, biotita, granada, allanita, ilmenita 2, kainosita, parisita. A ocorrência desses eventos pós-magmáticos propiciou também a formação de uma segunda geração de plagioclásio, zircão, além da formação de mirmequitas e a recristalização de parte dos feldspatos e quartzo. O anfibólio estudado foi formado por alteração do piroxênio em contato com o fluido do primeiro evento pós-magmático. A biotita foi gerada a partir da alteração do anfibólio. No mesmo período de formação do anfibólio foi gerada a allanita, sendo que a parisita e kainosita formaram-se pela alteração desta durante um evento pós-magmático. O evento pós-magmático mais antigo está associado a fluidos ricos em F e Cl, com baixo fO2, pressão próxima a 7 Kbar e temperatura inferior a 700 oC. A parte final desse evento esta associado a soluções alcalinas, ricas em CO2, com temperaturas no intervalo entre 480 C e 600 oC. O estudo de IF permitiu caracterizar fluidos tardios aprisionados no quartzo, que podem estar relacionados com o segundo evento pós-magmático. Esses fluidos, de provável origem hidrotermal, é bastante semelhante ao encontrado por Fuzikawa et al (1988), nas IF dos veios de quartzo que cortam os gnaisses da PULR. A geoquímica permitiu classificar os granitos como sienogranitos / quartzo sienitos, metaluminosos, alcalino-cálcicos (na fronteira dos calci-alcalinos), plotando na série shoshonitica. Também foram classificados como granitos Tipo A, não evoluídos e ferroan. Os dados obtidos não permitem classificar os granitos São Timóteo como rapakivi. Entretanto, a composição desses granitos é equivalente, em termos de elementos maiores e elementos traços, aos granitos rapakivi Cigano e Serra dos Carajás, fases menos especializadas da Suíte Serra dos Carajás. Finalmente, ressalta-se a clara necessidade do desenvolvimento de estudos metalogenéticos, geoquímicos e isotópicos que permitam conhecer com aprofundamento a composição e evolução da Suíte magmática de Lagoa Real e sua relação com as mineralizações de urânio. / Granitic bodies located in the Monsenhor Bastos sector, southwestern portion of the Lagoa Real Uranium Province (PULR) were studied. The sampling was developed in the quarries of Lagoa Linda, Pedreira Nova and Lajedo granitoids that outcrop immediately east of the uranium anomaly (AN02). The work focused on the mineralogical, geochemical, and fluid typological aspects of these granitoids in order to classify them mineralogical, textural and chemically. Petrography, electron microprobe, geochemical, thermobarometry and study of fluid inclusions (FI) methods were performed. The granite shows a magmatic paragenesis with potassium feldspar, plagioclase, quartz, pyroxene, ilmenite and zircon. Two post-magmatic stages composed of amphibole, biotite, garnet, allanite, ilmenite, kainosite, parisite were also identified. The occurrence of post-magmatic events has also led to the formation of a second generation of plagioclase, zircon, besides mirmequites formation and recrystallization of feldspar and quartz. The amphibole was formed by the alteration of pyroxene in contact with the first post-magmatic fluid event. The biotite was generated from the alteration of the amphibole. Allanite was generated in the same period of the amphibole formation, while parisite and kainosite were formed from allanite alteration during a pós-magmatic event.. The post-magmatic oldest event is associated to low fO2, near 7 Kbar pressure, below 700 oC temperature F and Cl rich fluids. The final part of this event is associated to alkaline solutions, rich in CO2, with temperatures between 480 C and 600 oC. The FI studies allowed to characterize late fluids trapped in quartz, which may be related to the second post-magmatic event. This fluid, probably of hydrothermal origin, is quite similar to one found by Fuzikawa et al (1988), in FI found in quartz veins cutting the PULR gneisses. The geochemistry allowed to classify the granites as sienogranites / quartz syenites, metaluminous, alkali-calcic (the border of calc-alkaline) and plotting in shoshonitic field. Granites were also classified as Type A, unevolved and ferroan. The data do not allow the classification of São Timóteo granite as rapakivi type. However, the composition of these granites is equivalent, in terms of major and trace elements, to the Cigano and Serra dos Carajas rapakivi granites, less specialized phases of Serra dos Carajás suite. Finally, it emphasizes the clear need for further metallogenesis, geochemical and isotopic studies depth as to show the composition and evolution of magmatic suite of Lagoa Real and its relationship to uranium mineralization.

O desdobramento de blocos de granitos, em teares multilâminas, é uma das mais complexas operações da indústria da pedra. A qualidade das superfícies das chapas obtidas no processo de serragem (rugosidade) determina o tempo e os insumos gastos nas operações posteriores de polimento, implicando diretamente no custo final. Embora o Brasil seja um dos maiores produtores mundiais de granitos ornamentais (quatro milhões de 'M POT.2'/mês de placas), surpreendentemente, não se têm na literatura científica trabalhos que dão o devido destaque às propriedades intrínsecas dos granitos no processo de serragem. A presente pesquisa tem como objetivo principal correlacionar parâmetros petrográficos com as características físicas e mecânicas de granitos, dando ênfase ao estudo da influência da mineralogia e da anisotropia textural/estrutural, com vistas à melhor orientação desta etapa industrial. Foram escolhidos tipos de granito consagrados comercialmente e acompanhados os desdobramentos de blocos para medidas diretas da rugosidade das superfícies serradas com o auxílio de um equipamento especialmente construído para esta finalidade. Os resultados mostraram que os aspectos texturais (granulação, arranjo, imbricação, grau de microfissuramento) e de alteração dos minerais são os responsáveis pelas diferenças na rugosidade das chapas e na velocidade de processamento / The sawing of granites blocks using multiblade gangsaws is one of the most complex operations in the stone processing industry. The slab surface quality (roughness) obtained after the sawing process determines the time and the inputs required in subsequent polishing operations and thus has a direct implication on the final product cost. Although Brazil is one of the largest world producers of ornamental granites (four million 'M POT.2'/month of slabs), it is surprising to note that there are very little or no scientific literature works available that address major aspects of the intrinsic properties of granites and their role during the sawing process. The present research has the major objective of correlating petrographic parameters with physical and mechanical characteristics of granites with a major emphasis on the role played by mineralogy and textural/structural anisotropy focusing mainly on how to obtain the best orientation during this industrial stage. The samples used are the most widely used granite of high commercial value in Brazil. The sawing process was monitored and subsequent direct measures of the roughness of the sawed surfaces carried out using an equipment specially built for this purpose. The results obtained show that textural (granulation, arrangement, imbrication, degree of microcracking) and alteration aspects of the minerals are responsible for the observed differences in slab roughness and processing speed