Dissertations / Theses on the topic 'Granitoïde'

De vastes surfaces et volumes de socle granito-gneissique sont albitisés sur toute la chaîne hercynienne de l'Afrique du Nord à la Scandinavie. L'interprétation supergène de ces faciès a déjà avancée par le passé. La question supergène/endogène doit être établie de façon indubitable avant de pouvoir aller plus avant dans le sujet. Démontrer que les faciès albitisés sont d'origine supergène et liés à la paléosurface triasique renouvelle profondément les idées sur l'évolution des socles hercyniens. La connaissance de la paléosurface triasique sur de vastes régions de socle de l'Ouest de l'Europe fournira un repère spatio-temporel qui permettra de contraindre les taux d'ablation des massifs depuis le Trias. Elle sera une contribution majeure à la modélisation de la géodynamique de ces régions. Cette albitisation s'accompgne d'une "carbonatation" du Ca des feldspathes plagioclases. Elle intervient donc dans le stockage du CO2 pendant le Trias et ceci de manière significative, eu égard du volume des roches affectées. En toile de fond est aussi posée la question de la spécificité sodique de cette paléoaltération, en rechercher l'origine, la relier à la gigantesque accumulation de chlorure de sodium pendant le Permo-Trias, ... est-ce la marque d'un évènement global ?

De vastes surfaces et volumes de socle granito-gneissique sont albitisés sur toute la chaîne hercynienne de l'Afrique du Nord à la Scandinavie. L'interprétation supergène de ces faciès a déjà avancée par le passé. La question supergène/endogène doit être établie de façon indubitable avant de pouvoir aller plus avant dans le sujet. Démontrer que les faciès albitisés sont d'origine supergène et liés à la paléosurface triasique renouvelle profondément les idées sur l'évolution des socles hercyniens. La connaissance de la paléosurface triasique sur de vastes régions de socle de l'Ouest de l'Europe fournira un repère spatio-temporel qui permettra de contraindre les taux d'ablation des massifs depuis le Trias. Elle sera une contribution majeure à la modélisation de la géodynamique de ces régions. Cette albitisation s'accompgne d'une "carbonatation" du Ca des feldspathes plagioclases. Elle intervient donc dans le stockage du CO2 pendant le Trias et ceci de manière significative, eu égard du volume des roches affectées. En toile de fond est aussi posée la question de la spécificité sodique de cette paléoaltération, en rechercher l'origine, la relier à la gigantesque accumulation de chlorure de sodium pendant le Permo-Trias, ... est-ce la marque d'un évènement global ?<br>Wide surfaces and huge volumes of granito-gneissic basements of the Hercynian massifs are albitized from North-Africa up to Scandinavia. The supergenic origin of these facies has already been forwarded in the past. The supergenic/endogenic question has to be substantiated beyond doubt before going further in this subject. Demonstrating that the albitized facies are of supergenic origin and bound to the Triassic palaeosurface renews deeply the ideas about the evolution of the Hercynian basements. The recognition of the Triassic palaeosurface on wide basement areas of western Europa will provide a spatio-temporal bench marks to constrain the ablation of these massifs since the Trias. This will be a major contribution to the geodynamic modelling of these areas. This albitization comes with a "carbonation" of the Ca from the plagioclase feldspars. In this manner, albitisation plays a significant rule in the CO2 storage during the Trias, with regard to the giant volume of rocks in consideration. Furthermore, in the backdrop arises the questions of the specificity of this sodium-rich paleoaweathering features, find out their origin, and bound them to the giant sodium chloride accumulation during the Permo-Triassic times… is this the record of a global event ?

Beypazari Granitoid is a low temperature and shallow-seated batholite intruded the Tepek&ouml<br>y metamorphic rocks of the Central Sakarya Terrane. Composition of the granitoid varies from granite to diorite. The granitoid is unconformably overlain by Palaeocene and Eocene rock units. Thus the age is probably Late Cretaceous. The Beypazari Granitoid comprises mafic microgranular enclaves. The granitoid mainly consists of quartz, plagioclase, orthoclase and minor amphibole, biotite, chlorite, zircon, sphene, apatite, and opaque minerals. Plagioclase shows sericitation whereas biotite and hornblende, chloritization. Holocrystalline and hypidiomorphic are characteristic textures of the granitoid. Geochemically, the Beypazari Granitoid is calc-alkaline, metaluminous and I-type. REE data indicate that it may have been generated from a source similar to the upper continental crust. The trace element data of the Beypazari Granitoid suggest a volcanic arc tectonic setting. The possible mechanism of Beypazari granitoid is the northdipping subduction of Neo-Tethyan northern branch under Sakarya continent during Late Cretaceous. The Beypazari Granitoid may be related with Galatean volcanic arc granitoids.

La chaîne hercynienne française résulte de la collision continentale entre le Gondwana au Sud et la Laurussia au Nord. Le Massif Central constitue un fragment méridional de la chaîne dans lequel l'agencement structural indique un développement polycyclique. La lithologie est composée de micaschistes de l'Unité Para-autochtone, de Gneiss para et orthodérivés de l'Unité Inférieure, des Gneiss de l'Unité Supérieure et l'Unité de Thiviers-Payzac composée de métagrauwacke, de rhyolites et de quartzite. La chaîne comporte des migmatites et des granitoïdes qui ont été datés par la méthode de datation ponctuelle de monazite à la sonde électronique pour situer l'anatexie dans son contexte dynamique. Le caractère ponctuel des datations (point de ~2 µm de diamètre) permet de mettre en évidence plusieurs événements enregistrés sur un grain unique et éviter les problèmes de mélange rencontrés avec d'autres méthodes de datation. Trois événements thermiques sont identifiés : un évènement entre 385 et 375 Ma, un autre autour de 330 et 325 Ma et un dernier vers 310 et 290 Ma. Ils sont contrôlés par l'épaississement et le des-épaississement crustal et des injections asthénosphériques.

Les gisements d'u et mo de streltsovka (Russie), représentent les plus grandes ressources en u du monde associées a des volcanites (200000 tu). Les inclusions vitreuses des phénocristaux de quartz, ont permis de caractériser le magma rhyolitique avant tout phénomène d'altération. Il est per alcalin (1. 04 < (k+na)/al < 1. 10), riche en f (1. 4-2. 7%), pauvre en cl (0. 2%). Il est pauvre en h 2o (1. 9 0. 6%), riche en u (15-23 ppm), th (33-49 ppm). L'analyse des éléments traces et des terres rares a la microsonde ionique à montre qu'il est enrichi en y et nb, caractéristiques des magmas alcalins très fractionnés. En considérant 7 ppm d'u dans les rhyolites altérées et 17 ppm dans le magma initial, l'altération hydrothermale de 1 km 3 de rhyolite libère 26000 tu. Une efficacité de 25% du processus de dépôt d'u a partir des solutions hydrothermales ayant altère l'ensemble rhyolitique peut expliquer la totalité des réserves d'u des gisements. Dans le socle granitique, l'étude minéralogique et géochimique montre que les granodiorites, les granites porphyroïdes et les granites a biotite peuvent appartenir a une même suite magmatique subalcaline sodi-potassique. Le leuco granite profond montre une typologie alcaline du fait de ses teneurs élevées en sio 2 (75. 6-77. 2%), na 2o+k 2o (8. 4-8. 9%), nb (12-28 ppm), y (70-94 ppm), th (32-53 ppm), de ses faibles teneurs en ba (10-20 ppm), sr (6-16 ppm). L'altération hydrothermale très importante des granites subalcalins et alcalins de streltsovka montre que l'u, difficilement lessivable dans les minéraux accessoires, a été toutefois libéré. Un calcul de bilan de masse montre qu'1 km 3 de granite peut libérer 650 tu lors de l'altération de l'allanite. Cette estimation est minimale car le fluide oxydant ayant mobilise l'u de l'allanite a pu dissoudre les autres porteurs d'u éventuellement présents dans les granites, tels que l'uraninite.

En Turquie-nw, trois localités types ont été sélectionnées afin de montrer la diversité des skarns bi-metasomatiques et les minéralisations qui leur sont respectivement associées: à Karakoy, entre la granodiorite du pluton d'Euciler et les horizons calcareux du groupe de Kazdag, nous observons les paragenèses du skarn calcique et des cornéennes qui mettent en évidence les conditions de formation du facies des cornéennes à pyroxène (600-600c, (1,5-2,0 kb). L'important dépôt de wollastonite s'est forme au-dessus de 500c en raison de la forte activité de si et de h#2o ainsi que d'un dégagement rapide de co#2. A Bakirlik Tepe, entre la monzonite du pluton de gurece et les olistostromes calcareux de la formation de Karakaya, nous observons un skarn à pyroxène à minéraux manganésifères et une minéralisation zincifère dans les conditions suivantes: tc<400c, fugacité élevée de l'oxygène, environnement enrichi en h#2o. A Derekoy, entre la monzonite et la dolomie de Kapakli (jurassique supérieur), nous observons un endoskarn à composition de monzonite à olivine et un skarn magnésien à forsterite fassaite, ainsi qu'une importante minéralisation de magnétite

Cette thèse présente une étude pétrologique des granitoïdes du socle du Damagaram (S. Niger), situé dans un segment interne de la chaîne pan-africaine trans-saharienne, bordé par des mega-cisaillement N-S qui s’étende de l’Aïr au Niger dans de segment se sont mis en place au Phanérozoïque des complexes annulaires alcalins sursaturés en silice. Le premier chapitre est une introduction comportant un bref exposé du cadre géologique du Damagaram et une description des familles de granitoïdes et des relations entre elles. Le deuxième chapitre présente des descriptions pétrographiques de granitoïdes : 1- granites anatectiques de Birinin Kazoé. 2- granites à biotite et granites à amphibole et pyroxène de Tynza. 3- granites porphyroïdes à biotite et ses enclaves granodiorite. 4- granites à grains fins à biotite. 5- granites à deux micas. Le troisième chapitre est une étude minéralogique. La nature magnésienne et calcique de la paragènèse diopside-actinote-phiogopite du granite à amphibole et pyroxène est en accord avec une origine par contamination des gneiss calciques. Chaque faciès de la série calcoalcaline présente des biotites spécifiques contrôlées par le rapport Fe/Mg. Le cristallinité de la muscovite dans le granite à deux micas se prolonge en passant par les stades magmatiques, tardi-magmatique, post-magmatique. Le quatrième chapitre traite de l'aspect géochimique. Les granitoïdes appartiennent à une série calco-alcaline classique; série dont certains faciès ont subi une contamination crustale importante. Le cinquième chapitre résume les résultats géochronologiques obtenus en Rb/Sr par J. P. LIEGEOIS (MRAC-ULB) et les discute en tenant compte des résultats pétrographiques. Enfin la conclusion générale: les granitoïdes du socle de Damagaram sont tous d'âge pan-africain. En conteste avec ceux des Iforas proche du craton ouest-africain qui sont essentiellement d'origine mantellique (Ri 0,705), ceux du Damagaram montrent une variété d'interaction manteau-croûte (Ri 0,705-0,716) ce qui est confirmé par l'étude pétrographique.

Esta dissertação faz parte de um projeto que tem como objetivo investigar a origem e evolução do magmatismo de arco e pós-colisional do Escudo Sul-rio-grandense (ESRG), caracterizando a partir de estudos geoquímicos, estruturais e petrográficos os Granitóides Sanga do Areal (GSA), localizados na região de Quitéria, porção leste do Escudo Sul-rio-grandense. Estes granitóides consistem de dois corpos principais, alongados na direção NE-SW, com aproximadamente 14 km de extensão e 2 km de largura, e também de diversas intrusões menores, posicionadas, preferencialmente, na porção mediana de alta deformação cisalhante do Complexo Arroio dos Ratos. Estão em contato na porção NW com metatonalitos, metagranodioritos e gnaisses tonalíticos a dioríticos de idade paleoproterozóica do referido complexo e com horblenda-biotita granodioritos da unidade neoproterozóica Granodiorito Cruzeiro do Sul. Na porção SE o contato se dá com tonalitos a dioritos relacionados aos Granitóides Arroio Divisa de idade neoproterozóica. Os GSA são biotita monzogranitos de textura porfirítica em seu termo principal, com cerca de 30% de megacristais de até 5 cm de comprimento de plagioclásio e K-feldspato. A matriz heterogranular média a grossa é composta por quartzo fitado, feldspato parcialmente recristalizado e biotita. Subordinadamente, observam-se corpos de espessura centimétrica a métrica de biotita granodiorito equigranular médio, com fenocristais esparsos de feldspatos alinhados na foliação. Raramente ocorrem enclaves microgranulares máficos. A foliação milonítica é bem marcada pela orientação da biotita, dos megacristais lenticulares e do quartzo fitado e tem direção E-W, com alto ângulo de mergulho para N e para S, contendo lineação de estiramento direcional, com baixo caimento para W a SW. A foliação ígnea primária, concordante a sub-concordante com a foliação milonítica, tem ocorrência restrita e é marcada pela orientação dos megacristais não deformados e das lamelas de biotita. Estruturas S-C, caudas assimétricas em porfiroclastos de feldspatos, biotita fish e fitas assimétricas de quartzo são consistentes e indicam movimento transcorrente sinistral. Os Granitóides Sanga do Areal têm afinidade sub-alcalina médio a alto K, provavelmente toleítica, compatível com ambiente pós-colisional, onde foram deformados e controlados por zonas de cisalhamento transcorrente sub-verticais. Foi obtida uma idade U-Pb em zircão dos granitóides de 626,6±4,9 Ma (MSWD=2.2), coerente com as relações de campo.<br>This research investigates the evolution of arc to post-collisional magmatism in the Sul-rio-grandense Shield (ESGR), using geochemistry, structural and petrographic studies of the Sanga do Areal Granitoids (GSA). These granitoids are located in the Quitéria region, east of ESRG. The GSA form two main, NE-striking intrusions, and several other small ones, mainly within the shear zone croscutting the central portion of the Arroio dos Ratos Complex. The two main bodies are about 14 km long and 2 km wide. To the northwest, the GSA rocks are in contact with Paleoproterozoic metatonalites, metagranodiorites, tonalitic to dioritic gneisses of the Complex, and Neoproterozoic horblende-biotite granodiorites of the Cruzeiro do Sul unit. To the southeast, they are surrounded by tonalitic to dioritic rocks, related to the Neoproterozoic Arroio da Divisa Granitoids. The GSA rocks are composed mainly of porphyritic biotite monzogranites, with about 30% megacrysts of plagioclase and 5 cm long K-feldspar. The medium to coarse grained heterogranular groundmass is composed of microcrystalline ribbon quartz, partially re-crystallized feldspar and biotite. Medium-grained equigranular granodiorite occurs as centimeter to meter- thick bodies, with sparse feldspar megacrysts aligned on the foliation plane. Microgranular mafic enclaves are rarely observed within the GSA rocks. The mylonitic foliation is well-developed and marked by biotite, oriented lenticular megacrysts, as well as quartz ribbons. It strikes E-W and dips at high angles either N or S. The stretching lineation within the foliation shows shallow plunges, preferentially W-SW. A primary igneous foliation is sometimes observed, and it is concordant or sub-concordant with the mylonitic one, and marked by orientation of igneous megacrysts and biotite lamellae. S-C structures, asymetric tails in feldspar porphyroclasts, biotite fish, and asymetric quartz ribbons indicate transcurrent movement with consistent sinistral shear sense. The Sanga do Areal Granitoids show subalkaline medium- to high-K affinity, probably tholeiitic, and trace element composition consistent with sources related to post-collisional settings, which were deformed and controlled by E-NE and NE sub-vertical transcurrent shear zones. A U-Pb age in zircon grains from Sanga do Areal Granitoids of 626.6 ± 4.6Ma ((MSWD=2.2) was obtained and considered coherent with stratigraphic relations.

La région du Valsenestre dans le Haut Dauphiné (Massifs Cristallins Externes des Alpes Occidentales) offre quatre plutons granitiques distincts avec les massifs des Quatre Tours-Belle Cote, d'Alfrey, du Rochail et du Ramu. Les corps de Quatre Tours-Belle Cote, et du Rochail sont étroitement associés à des intrusions mineures de roches basiques représentées par des syénites à amphibole et des monzodiorites à quartz. Ces matériaux s'apparentent aux roches des cortèges "vaugnéritiques" de la chaîne varisque. L'étude géochimique des plutons intrusifs montre que les granites des Quatre Tours-Belle Cote, du Rochail et d'Alfrey différent légèrement. Toutefois ils peuvent être regroupés à une même lignée magmatique. Dans la nomenclature de Harris et al. , (1986), ils se rapportent au type subalcalin post-collisionnel (groupe 3). Les petites différences des magmas d'origine peuvent être imputées à des différences du matériel source originel. Les granites d'Alfrey et du Rochail montrent une différenciation chimique centripète avec des facies fins externes peu fractionnés et des facies porphyroïdes internes recoupés par quelques pegmatites ultimes. Les compositions minéralogiques et chimiques du granite du Ramu s'individualisent très nettement. Elles peuvent être rapportées au type des granites syncollisionnels (groupe 2) de la classification de Harris et al. , et rattachées aux leucogranites d'origine anatectique. Les nouvelles données isotopiques Rb/Sr et la réinterprétation des données géochronométriques antérieures permettent de dater les intrusions du Rochail et des Quatre Tours-Belle Cote à 302 ± 16 Ma. Cet âge s'accorde parfaitement avec le caractère post-collisionnel de ces plutons. Un âge Rb/Sr de 304 Ma est également proposé pour les roches basiques associées indiquant une intrusion légèrement tardive du corps daté. Toutefois l'existence locale de figures de mélange mécanique entre les deux types magmatiques plaide en faveur de leur pénécontemporanéïté à l'échelle de l'histoire orogénique. Les quatre granitoïdes ont été replacés dans le contexte des intrusions varisques des Massifs Cristallins Externes Alpins auxquelles ils se rapportent. Sur la base d'éléments minéralogiques et géochimiques une zonation est-ouest de la province peut être déinie dans le Haut Dauphiné. Les liquides granitiques d'origine crustale se sont mis en place principalement dans la région occidentale de la province. Les granites du domaine oriental présentent au contraire une composante mantellique notable. La situation géodynamique d'origine et la mise en place des granitoïdes du Haut Dauphiné correspondent à un contexte post-collisionnel extensif ou le géotherme est perturbé par un puissant flux de chaleur. Cet épisode thermique induit la fusion partielle de la croûte inférieure. A la faveur d'une remontée de la lithosphère sous-continentale contemporaine de l'extension et de la dénudation de la chaîne, le manteau généré des magmas basiques subordonnés à l'origine de la lignée appinito-vaugnéritiques

Situés dans la partie Nord-orientale de la Dorsale Reguibat (Afrique de l'Ouest, Mauritanie) et s'étendant sur un vaste territoire limité par les parallèles 23° et 26° N et les méridiens 7° et 11° W, les granitoïdes birimiens s'organisent en un large éventail allant des tonalites aux granites hyperalcalins. Ils se subdivisent en deux grands groupes. Le premier groupe ou groupe des granitoïdes anciens est formé par les faciès du Ghallaman et du Karet et a subi au moins une phase de déformation. Il présente une tendance granodioritique voire tonalitique relativement marquée. Le second est constitué par les formations non déformées, post-tectoniques de Ain Ben Tili, d'Archéouat et de Tiguesmat qui, par leur grand volume et leur association avec des formations effusives très volumineuses, représentent une spécificité de la Dorsale Reguibat par rapport à la Dorsale de Léo (partie Sud du craton Ouest africain). L'ojectif visé dans ce mémoire est de caractériser pétrographiquement et géochimiquement ces granitoïdes, de contribuer à la compréhension des mécanismes de genèse des granitoïdes birimiens de la Dorsale Reguibat qui représentent un apport déterminant à la croissance crustale au Protérozoïque inférieur. A partir de la caractérisation pétrographique, minéralogique et géochimique des granitoïdes birimiens du Nord de la Mauritanie nous pouvons retenir ce qui suit : les granitoïdes birimiens de la Dorsale Reguibat constituent une association discontinue ; la géochimie des éléments majeurs les fait distinguer des granites de la suite TTG archéenne. En revanche le comportement en terres rares des faciès anciens est comparable à celui observé par Martin (1987) dans les granitoïdes archéens (YbN faible, rapports (La/Yb)N élevés) ; l'origine la plus plausible des granitoïdes anciens est à rechercher dans des processus de fusion partielle d'une croûte basaltique juvénile, transformée en amphibolites à grenat. Ce processus doit nécessairement intervenir dans un laps de temps très bref après la formation de cette croûte pour rendre compte des caractères isotopiques précedemment établis (Boher et al. , 1992) ; en ce qui concerne le groupe des granites récents, sub-alcalins et potassiques, ils ne peuvent relever du même processus de formation que les précedents, ni de leur différenciation. Ils pourraient provenir de la fusion partielle, en l'absence de fluides (fusion-déshydratation) des formations tonalitiques ou granodioritiques représentées par les granitoïdes anciens.

The purpose of this study is to investigate the origin, source characteristics, evolution petrogenesis and emplacement mechanisms of Beypazari-Oymaaga&ccedil<br>granitoids. These granitoids are intruded into a metamorphic basement and nonconformably overlain by Neogene clastic rocks. Field work, petrographical and geochemical studies are carried out to determine the petrologic features and tectonic setting of the granitoid body. The Beypazari-Oymaaga&ccedil<br>pluton is a composite pluton with its host batholith, enclaves, aplite dykes and a pegmatite. The batholith is generally composed of quartz, K-feldspar, plagioclase and hornblende. Field observations and petrographic investigations indicate that the host batholith has granodiorite composition and shows distinct differences in the abundances of quartz, amphibole minerals (e.g., hornblende) and of enclaves. The samples taken from TavuktaSi Tepe contain relatively less amphibole and enclaves but more quartz. Compared with them, samples from the rest of the batholith have relatively abundant amphibole, K-feldspar megacrysts, and enclaves but less quartz. Enclaves derived from magma mixing/mingling processes are dioritic in composition. Geochemical data obtained from whole rock analyses show that the pluton is shallowly emplaced and has calc-alkaline, metaluminous to peraluminous chemistry. It is characterized by enrichments in LIL and LREE, especially in K, Rb and Th. Although, there is a distinct petrographic variation in the batholith, the geochemical characteristics are uniform throughout the pluton. The Oymaaga&ccedil<br>Granitoids which have I-type identity are typical representatives of magmatic arc environment. The present study suggests that the possible source of magma is the upper crust and can be compared with the coeval volcanism in Galatean Volcanic Arc.

Le complexe intrusif de Bono (association calco-alcaline corso-sarde, Sardaigne septentrionale) se caractérise par la mise en place successive de 3 intrusions de nature pétrographique différente faisant apparaitre une structure de type apparemment concentrique. De la périphérie vers le centre du complexe, on distingue l'intrusion tonalitique différenciée de Burgos, l'intrusion granodioritique à amphibole de Bottida puis l'intrusion granodioritique à biotite d'Emauru. Les enclaves microgrenues sombres constituent par leur abondance un trait caractéristique des granitoïdes du complexe de Bono, chaque population d'enclaves se caractérisant par un rapport FEOT/MGO constant. Cette association composite acide-basique (roche hôte-enclave) est interprétée en terme de mingling (mélange incomplet par opposition au mixing lorsque l'homogénéisation est complète). Les travaux antérieurs sur les granitoïdes de l'association calco-alcaline du batholite montrent que le mélange magmatique y constitue un processus largement répandu. Les enclaves de chaque intrusion, se caractérisent par 2 populations de cristaux : l'une relique ante-mélange, appartenant au magma basique : CPX+OPX+PLAP dans les enclaves de Burgos, CPX+PL dans les enclaves de Bottida, PL+HB brune dans les enclaves d'Emauru, est interprétée en terme de différenciation ante-mélange du liquide basique. La seconde population, volumétriquement prédominante et similaire à celle de la roche hôte correspondante, est synchroné à post-mélange. Dans le liquide basique générateur des enclaves de Burgos, les couples CPX-OPX sont cristallisés à 900-950 oc dans des conditions de PH2O relativement élevées. Dans les enclaves d'Emauru, les conditions de cristallisation de la HB sont de 850-920 oc pour 6-7 Kbar, soit environ 21 à 25 km de profondeur. De plus, la présence de reliques de cumulats dans certaines enclaves de Burgos en particulier, permet d'invoquer la différenciation par cristallisation fractionnée d'un basalte alumineux (HAB) en position basi-crustale. Ce processus se marque par un très net enrichissement en eau du HAB indépendamment du processus de mélange : de 1 à 4% d'eau dans Burgos, jusqu'à 5% dans Emauru. Nous observons ainsi un contraste très net entre la paragénèse ante-mélange du liquide basique de Burgos où elle est anhydré et celle des enclaves d'Emauru où elle est hydratée. Cet enrichissement en fluide qui se traduit par l'apparition de la HB brune, induit de nombreuses répercutions pétrologiques, en particulier l'arrêt de l'enrichissement en fer du liquide basique

Accessory minerals in granitoids are major repositories of several geochemically-important trace elements and isotopes and in order to quantify the influence that they have over granitoid petrogenesis it is necessary to characterize fully their behaviour. In particular it is necessary to understand accessory mineral/melt partitioning of trace elements and within grain elemental diffusivities, the latter is of relevance when assessing the state of isotopic equilibration between a refractory accessory phase and a contacting melt. In this study the backscattered electron (BSE) imaging technique, coupled with quantitative electron microprobe analysis indicate that granitoid zircons and titanites (mainly taken from Caledonian intrusive complexes) are commonly compositionally zoned. The zoning textures observed in these minerals, namely crystal face-parallel zoning, non-planar compositional zoning (included here are subhedral and anhedral core structures) and compositional sector zoning, indicate that the kinetic factors of crystal growth, i.e. within magma elemental diffusion rates, crystal growth rates, interface kinetics and dissolution kinetics, are largely responsible for the patterns of compositional zoning that have been observed. This fording is in marked contrast to other studies which have assumed that kinetics are not important in crystallizing plutonic granitoid magmas. Accessory mineral growth histories have been studied in a few well constrained samples from the Caledonian-age Strontian Complex of NW Scotland. The zircons from the central intrusion of this composite pluton have abundant inherited cores. The cores contain a variety of zoning structures and have a wide range of composition, which are taken to indicate that the cores had a wide variety of ultimate sources. Titanites from both the outer and inner intrusions have compositional sector zoning and the range of composition shown by the titanites is largely due to this fact. In this pluton magma composition appears to have little influence on titanite chemistry. The REE abundances in both parts to the intrusion are largely controlled by the accessory phases and each of these phases have very different rock-normalised REE distribution patterns. These abundance patterns are dependent on the relative partition coefficients that each phase has for the REE, the accessory mineral assemblage present and the crystallization order of that assemblage. The zircons from the central acid member of the Strontian Complex, which are known to have substantial U-Pb inheritance were extracted and analysed for their Sm-Nd isotopic composition. The results apparently indicate that refractory zircons can also preserve their Sm-Nd isotopic composition, a phenomenon not previously reported. That is diffusion of Sm and Nd (and presumably the other REE) within refractory zircon at elevated temperatures appears to be sufficiently slow that complete isotopic equilibration between a zircon and a contacting melt may not always occur. Such disequilibrium potentially enables granitoid magma provenance to be studied with much greater resolution than hitherto possible.

Dans la Zone Hercynienne Centro Ibérique au Nord du Portugal des massifs granitoïdes biotitiques sont spatialement associés au cisaillement de Vigo-Régna et sont considérés comme syntectoniques de la phase hercynienne 8. Ce sont des granodiorites à monzogranites à biotite, porphyroïdes, renfermant des enclaves microgrenues. Du Sud vers le Nord 5 massifs ont été étudiés: Ucanha-Vilar, Lamego, Felgueiras, Sameiro et Refoios do Lima. L'analyse structurale détaillée de ces massifs révèle l'existence d'une structure interne essentiellement d'origine magmatique. La fabrique des granites résulterait de la déformation des magmas, lors de leur Inise en place, par aplatissement dans un régime tectonique dominé par une composante compressive subhorizontale NW -NE dominante avec une faible composante rotationnelle, sans mouvement significatif du cisaillement Vigo-Régua. Les granites sont modérément peralumineux avec des compositions quasi identiques. Toutefois, ils définissent, pour la majorité des éléments, des séries évolutives indépendantes (excepté pour le granite de Sameiro qui ne présente aucune évolution significative). Les caractéristiques morphologiques et géochimiques des zircons indiquent, pour le granite de Refoios do Lima, une origine essentiellement crus tale et, pour les autres granites, une origine calcoalcaline associée à un processus d'hybridation avec un magma crustal anatectique. Les données géochronologiques V-Pb sur fractions de zircon et monazite montrent que les massifs étudiés se sont Inis en place de façon sub-synchrone à 317 ± 2 Ma. Calculés à 317 Ma, les rapports isotopiques initiaux de Sr et Nd (Sri et eNd) mettent en évidence le caractère hybride, associant matériaux mantelliques et cristaux, de ces granites avec une significative évolution du Sud vers le Nord exprimant une croissance progressive de la contribution crustale. Par contre, les très faibles variations des rapports isotopiques initiaux au sein de chaque massif ainsi que les caractéristiques des évolutions chimiques et minéralogiques observées montrent que, postérieurement à leur genèse, les différents magmas granitiques ont évolué en système isotopique clos par un processus de cristallisation fractionnée.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-09-20T12:04:31Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Usma Cuervo 2016_Dissertação Mestrado Geociências UFPE.pdf: 11366215 bytes, checksum: ea3d3e75aa36f118697420651fd55f20 (MD5)<br>Made available in DSpace on 2016-09-20T12:04:31Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Usma Cuervo 2016_Dissertação Mestrado Geociências UFPE.pdf: 11366215 bytes, checksum: ea3d3e75aa36f118697420651fd55f20 (MD5) Previous issue date: 2016-02-22<br>FACEPE<br>Ao nordeste de São Jose de Belmonte, Pernambuco, o Complexo Riacho Gravatá Meso- a Neoproterozoico e o Grupo Cachoeirinha Neoproterozoico afloram. Ambas unidades de origem sedimentar e com intercalações de carbonato (mármore), formações de ferro bandado (BIF) e metavulcânicas são limitadas pela Zona de Cisalhamento Serra do Caboblo com direção NE. Outra importante caraterística da região é a abundante ocorrência de plutons graníticos criogenianosediacaranos que intruem o Grupo Cachoeirinha. O Complexo Riacho Gravatá com maior contribuição de material vulcânico, registra um evento extensional de formação de bacias relacionado com uma zona próxima de magmatismo de arco. O Grupo Cachoeirinha corresponde a uma sequência metaturbidítica, é dividido em Formação Santana dos Garrotes (unidade basal) e Formação Serra Olho d’Água (unidade superior) depositado numa bacia de retro arco. Quimioestratigrafia elemental e isotópica de seções selecionadas foi realizada objetivando estabelecer condições deposicionais de formação de carbonatos e formações ferríferas e estimar sua cronologia. Petrologia de plutons graníticos teve a intenção de elucidar ambiente tectônico e condições de cristalização destes corpos. A seção Barro do Complexo Riacho Gravatá é composto principalmente de mármores dolomíticos. A composição isotópica destes carbonatos com δ13C de -2,8 a -0,7‰ e δ18O de -15.0 a -15.8‰ podem ser correlatos com seções de final do Esteniano a inicio do Toniano. Os padrões de ETRY permitem inferir um ambiente deposicional marinho sob condições anóxicas e contribuição de fluidos hidrotermais. Da Formação Santana dos Garrotes, mármores calcíticos das localidades de Pedreira e Oiti mostram δ13C médios de +4,9‰ e +4,1‰, respectivamente, além de anomalias negativa de Ce e positiva de Y, sugerindo uma idade de deposição Criogeniano médio a tardio num ambiente levemente oxigenado. Os padrões de ETRY normalizados em relação ao PAAS para o BIF da Localidade Oiti são a favor de uma precipitação hidrogenética com influência hidrotermal. Química em rocha total e mineralde plutons granodioriticos com epidoto magmático ao norte do povoado Carmo permitem identifica-los como cálcio-alcalino principalmente, e cálcio-alcalinos de alto K, de origem mista. Estes granodioritos provavelmente forma intruidos durante a fase final de um regime de subdução, cristalizando sob pressões de 6,6 – 9,3 kbar e temperaturas entre 720 e 765°C, a uma profundidade ao redor de 22 Km.<br>To the northeast of the São Jose de Belmonte, Pernambuco, the Meso- to Neoproterozoic Riacho Gravatá Complex and the Neoproterozoic Cachoeirinha Group outcrops. Both units of sedimentary origin and with carbonate (marble), banded iron formation (BIF) and metavolcanic intercalations are limited by the Serra do Caboclo Shear Zone with a NE direction. Another important characteristic of the area is the abundant occurrence of Cryogenian-Ediacaran granitic plutons that intrude the Cachoeirinha Group. The Riacho Gravatá Complex with great contribution of volcanic material, record an extensional event of basin formation related to a nearby zone of arc magmatism. The Cachoeirinha Group corresponds to a metaturbiditic sequence, it is divided into the Santana dos Garrotes Formation (basal unit) and the Serra Olho d’Água Formation (upper unit) deposited in a back-arc basin. Elemental and isotope chemostratigraphy of selected sections was carried out aiming at precising the depositional conditions of carbonate and iron-bearing sediment formation and estimating their chronology. Petrology of granitic plutons had the intention of elucidate tectonic environment and crystallizing conditions of these bodies. The Barro section of Riacho Gravatá Complex is composed mainly of dolomitic marbles. The isotopic composition of these carbonates with δ13C varying from -2.8 to -0.7‰ and δ18O from -15.0 to -15.8‰ can be correlated with late Stenian – early Tonian sections. The REE+Y patterns led to infer a marine depositional environment under slightly anoxic conditions and hydrothermal fluids contribution. From Santana dos Garrotes Formation, calcitic marbles at the Pedreira and Oiti localities display average δ13C, respectively, of +4.9‰ and +4.1‰, besides negative Ce anomaly and positive Y anomaly, suggesting a middle to late Cryogenian depositional age in a slightly oxygenated environment. The PAAS normalized REE + Y patterns for BIFs at the Oiti locality favor a hydrogenetic precipitation with hydrothermal influence. Bulk and mineral phase chemistry analyses of magmatic epidote-bearing granodioritic plutons to the north of the Carmo village allow identify them as calc-alkalic and high K calc-alkalic, of mixed origin. These granodiorites were likely intruded during final stages of a subduction regime, crystallizing under pressures of 6.6–9.3 kbar and temperatures in the 720–765°C range, at depths around 22 Km.

O período pós-colisional Neoproterozoico no sul do Brasil é marcado por intensa atividade tectônica transcorrente. Neste contexto, a Zona de Cisalhamento Quitéria Serra do Erval, uma das inúmeras estruturas que compõe o Cinturão de Cisalhamento Sul-brasileiro, controlou o aporte, a ascensão e o posicionamento de diversos granitoides, dentre eles, os Granitoides Arroio Divisa, intrusivos no Complexo Arroio dos Ratos. Os Granitoides Arroio Divisa compreendem uma associação de rochas predominantemente granodioríticas, com termos dioríticos e tonalíticos ocorrendo em menor expressão. Apresentam textura heterogranular média a grossa e são sempre foliadas. Ao longo da intrusão, são distinguidas zonas de mais alta e mais baixa deformação, distribuídas de forma heterogênea, o que é evidenciado pelo grau de desenvolvimento e morfologia das estruturas planares e lineares. Nas zonas de mais baixa deformação, concentradas nas porções centrais do corpo granítico, predominam as estruturas magmáticas e a componente deformacional é menos intensa, enquanto que em direção à borda norte da intrusão, a morfologia destas estruturas progride por aumento na intensidade da deformação, com a geração de foliação milonítica bem desenvolvida A evolução estrutural dos Granitoides Arroio Divisa é marcada por estruturas tardi-magmáticas que avançam progressivamente para estruturas subsolidus, e subsequentemente para estruturas de mais baixa temperatura, evidenciando a cristalização com concomitante história deformacional sob condições de temperatura decrescente. Feições microestruturais de alta temperatura incluem o desenvolvimento do padrão tabuleiro de xadrez em cristais de quartzo, e a geração de subgrãos grandes em cristais de K-feldspato e plagioclásio, compatíveis com temperaturas da fácies anfibolito superior e com a temperatura solidus de composições graníticas. As feições microestruturais de baixa temperatura consistem na recristalização dos cristais de quartzo por bulging, neoformação de grãos finos ao redor dos cristais de feldspato, e desenvolvimento de pertitas em chamas nos K-feldspato, compatíveis com temperaturas da fácies xistos verdes, bem abaixo da solidus. Enquanto as microestruturas de alta deformação estariam associadas aos estágios iniciais da cristalização e resfriamento do magma, as de mais baixa estariam relacionadas aos estágios pós-cristalização, quando rocha e encaixante alcançam equilíbrio térmico.<br>The Neoproterozoic post-collisional period in southern Brazil is marked by intense transcurrent tectonic activity. In this context, the Serra do Erval Quitéria Shear Zone, one of the several structures that compose the South Brazilian Shear Belt, controlled the input, ascent and emplacement of several granitoids, among them the Arroio Divisa Granitoids, intrusive in the Complex Arroio dos Ratos. The Arroio Divisa Granitoids consist an association of predominantly granodioritic rocks, with dioritic and tonalitic terms occurring in lesser expression. They presented medium to thick heterogranular texture and are always foliated. Along the intrusion, zones of higher and lower deformation are distinguished, distributed in a heterogeneous way, which is evidenced by the degree of development and morphology of the planar and linear structures. In the lower deformation zones, which are concentrated in the central portion of the granitic body, the magmatic structures prevail and the deformation component is less intense, whereas towards the north margin of the intrusion the morphology of these structures progresses by increase in the intensity of the deformation, with the generation of well-developed milonitic foliation The structural evolution of the Arroio Divisa Granitoids is marked by progressively advance of the late-magmatic to subsolidus structures, and subsequently to structures of lower temperature, evidencing the crystallization with concomitant deformational history under conditions of decreasing temperature. High-temperature microstructural features include the development of the chessboard pattern in quartz crystals, and the generation of large subgrains in K-feldspar and plagioclase crystals, compatible with temperatures of amphibolite high-grade facies and with the solidus temperature of granite compositions. The low temperature microstructural features consist of recrystallization of the quartz crystals by bulging, neoformation of fine grains around the feldspar crystals, and development of flaming pertite in the K-feldspar, compatible with temperatures of the greenschist facies, well below the solidus. While the high deformation microstructures would be associated to the initial stages of crystallization and cooling of the magma, the one of lower deformation would be associated to the post crystallization stages, when rock and host rock reach thermal balance.

Chemical, textural, and isotopic heterogeneity within granitic magmas/rocks, and their extrusive equivalents, are common phenomena. This is to be expected since the source materials, from which the granitic magmas were created by partial melting, are themselves heterogeneous. Micro-sampling of feldspar crystals within granites has revealed complex internal Sr and Nd isotope variations thought to reveal subtle variations in the isotopic composition of the melt from which particular zones crystallised. These previous studies provide evidence of both macro-scale (regional) and micro-scale isotopic variation within granitic magmas. What is unknown is the scale and nature of chemical and isotopic variation occurring on the meso-scale (metre, decametre, hectometre). In this study, high-precision geochemical and isotopic (Sr, Nd, and O) data is obtained for spatially well-constrained samples, from three granitic intrusions from the UK, to study the scales over which isotope heterogeneities are preserved, and the maximum volumes of magma over which isotope and elemental homogenisation may have been achieved. This information provides important constraints on the physical and chemical characteristics of processes that occur during magma genesis, ascent, and emplacement. The regional-scale geochemical and isotopic heterogeneity in the Criffell pluton (SW Scotland) has been well documented and ascribed to 'incomplete hybridisation' between magmas derived from the melting of mantle and/or 'new' basic crust and metasediments. Sampling on the 10 to 100 m scale in this study demonstrates major-, trace- and rare earth element homogeneity between samples of similar petrography. Within the Dalbeattie Quarry granodiorite, subtle heterogeneity in initial ([sup]87Sr/[sup]86Sr)[sub]397 Ma compositions exist (0.70582 to 0.70615), between samples collected ~ 150 m apart. The small-scale heterogeneity is outside of analytical error (± 0.0001). [delta][sup]18O heterogeneity also occurs on similar small scales (~ 120 m), with values ranging from 8.9 to 10.7 %. The larger error on the [epsilon][sub]Nd(397 Ma) values do not allow any small-scale heterogeneity to be resolved. The geochemical and isotopic heterogeneity of the Cairnsmore of Fleet pluton, another Southern Upland granite, is also well known, and considered to be a result of similar processes to that of Criffell. This study demonstrates that the Cairnsmore granite is more petrographically variable in terms of grain-size, mafic/felsic mineral proportions, and accessory mineral assemblages over scales ranging between 100 and 350 m. The existence of more petrographic and geochemical heterogeneities on smaller scales suggests that homogenisation processes were less effective in this pluton compared to Criffell. On scales < 1 km, ([sup]87Sr/[sup]86Sr)[sub]392 Ma compositions and [epsilon][sub]Nd(397 Ma) values are essentially homogeneous. Forest Track samples PAHCF23 (0.70796) and PAHCF25A (0.70672) are ~ 1 km apart and can only just be distinguished outside of analytical error. However, [delta][sup]18O data demonstrate the existence of both regional-scale and locality-scale [delta][sup]18O heterogeneity on the 100 m, decametre and even cm-scale (8.3 to 9.7%0, error ± 0.1%0). The two main granite varieties of the Dartmoor pluton (SW England) are generally, homogeneous in terms of their petrography and geochemistry on 100 m, decametre, meter and even cm scale. However, isotope heterogeneity, outside of analytical error is shown to exist on even the cm-scale. The samples PAHD34A and P AHD34B, from Blackenstone Quarry, have ([sup]87Sr/[sup]86Sr)[sub]280Ma compositions of O.70949 and 0.71292 respectively, and were collected 50 cm apart. Samples PAHD35A and PAHD35B have ([sup]87Sr/[sup]86Sr)[sub]280 Ma compositions of 0.70960 and 0.71205, and were collected 100 cm apart. Variation in [delta][sup]18O and [epsilon][sub]Nd(280 Ma) values also exist. PAHD34A and PAHD34B have [delta][sup]180 compositions of 10.01 and 10.98 %0 (± 0.1%0), and SNd(280 Ma) values of -3.8 and -3.3 (± 0.2), respectively. Either the distinct magma batches, that coalesced to form the pluton, were much smaller in Dartmoor (compared to the Criffell and Cairnsmore plutons), or these heterogeneities may represent volumes of magma, within larger domains, that escaped homogenisation by mixing and diffusion. The existence of discrete, isotopically distinct batches of magma within the Criffell, Cairnsmore and Dartmoor plutons favours the dyke model for granitoid magma ascent through a pulsed magma delivery, in which separate magma batches (or pulses) coalesce to form plutons at or near their final emplacement levels. The scale over which such magma pulses can still be recognised varies within each pluton. The magma pulses are likely to have been larger in size, but subsequent homogenisation processes in the chambers led to a reduction in their size. However, homogenisation was not complete. In all three plutons, it is generally only the isotope ratios that display significant small-scale heterogeneity. Processes such as fractional crystallisation, are considered to be secondary, overprinting geochemical and isotopic heterogeneity from much deeper regions.

The Irumide belt is an elongate crustal province characterised by Mesoproterozoic tectonism and magmatism that stretches over a distance of approximately 900 kilometers from central Zambia to the Zambia-Tanzania border and northern Malawi. It is bounded to the northwest by largely undeformed Palaeoproterozoic basement lithologies of the Bangweulu block and is truncated to the northeast by Mesoproterozoic and Neoproterozoic transcurrent shear zones within reactivated parts of the Palaeoproterozoic Ubendian belt. To the southeast and south, Irumide lithologies were reworked within the Neoproterozoic Lufilian and Zambezi belts, and to the east by the East African Orogen. Lithologies in the Irumide belt comprise a Palaeo- to Mesoproterozoic complex of gneisses and granitoids and a supracrustal succession of quartzites and pelites. A three-fold subdivision was accepted prior to this study; (1) Palaeoproterozoic granites and gneisses forming the Irumide basement, (2) a supracrustal succession of quartzites and metapelites called the Muva Supergroup, (3) various deformed and undeformed granitoids intruding both the Palaeoproterozoic basement and Muva Supergroup and considered to be pre-Irumide (1.4 Ga) and syn-, late- to post-Irumide (1.1-0.95 Ga). The age of Irumide tectonism itself was poorly constrained between 1.4 and 1.0 Ga. The basement units comprise the Mkushi Gneiss in the southwest and the Luwalizi Granite, Mwambwa River and Mulungwizi Gneisses in the northeast. These units have been correlated with the Palaeoproterozoic Bangweulu block and Ubendian belt in the past. These basement units are structurally and in places unconformably overlain by a metasedimentary succession of quartzites and metapelites, which in the southwest has been called the Kanona Group, and in the northeast the Manshya River Group.Both sequences have been correlated with similar quartzite-pelite successions on the Bangweulu block, termed the Mporokoso Group, and, together with a second cycle reworked unit on the Bangweulu block called the Kasama Formation, were collectively grouped into the Muva Supergroup. Both basement and supracrustals have been deformed, metamorphosed and intruded by a host of granitoids which, based on structural fabrics, were subdivided into pre-, syn-, late- and post-tectonic suites with respect to Irumide tectonism. Due to the lack of reliable geochronological constraints, this subdivision had remained untested until now. All units in the Irumide belt have been strongly affected by compressional tectonics, resulting in northwest-directed thrusting onto the Bangweulu block basement and extensive crustal shortening. Minor southeast-verging structures form part of locally developed backthrusts within an overall northwest-vergent tectonic regime. At least parts of the Irumide basement were affected by Irumide tectonism, but large-scale thrusting was mainly accommodated along a basal decollement at the basement-cover interface. Extensive shortening is exemplified by tight- to isoclinal folding within the supracrustal sequence, ranging from upright to recumbent. Thrusts developed where shortening could not be accommodated by tight folding, which produced tectonic duplication within the metasedimentary pile, making formation-to-formation correlations across the belt tenuous at best. Irumide tectonism has been reported to affect the base of the Mporokoso Group on the Bangweulu block, where folding along the Luongo shear zone occurred contemporaneously with thermal resetting of biotite dated at ~1.0 Ga (K-Ar dates). Metamorphic parageneses record low- to medium-pressure/medium- to high-temperature conditions.Metamorphic grades range from greenschist facies in the northwestern foreland, to upper amphibolite facies in the southeast, with local granulites. Peak Irumide metamorphism, recorded in metamorphic zircon rim overgrowths, has been dated in this study at 1.02 Ga. Metamorphism to the southeast, across the younger Karoo grabens, had previously been constrained at 1.05 Ga, indicating an across strike diachronous development of metamorphism for the Irumide belt. The lithological units identified and dated as part of this study in the Irumide belt include: (1) limited Neoarchaean rocks emplaced at 2.73 Ga and representing the oldest rocks in the Bangweulu block; (2) ca. 2.05-1.85 Ga volcano-plutonic complexes and gneisses representing the most important components in the Bangweulu block; (3) an extensive quartzite-metapelite succession with minor carbonate forming the Mporokoso, Kanona and Manshya River groups, and deposited at ca. 1.8 Ga; (4) granitoids emplaced between 1.65-1.55 Ga; (5) deposition of the Kasama Formation between 1.43 and 1.05 Ga (second-cycle reworking of the Mporokoso Group); (6) voluminous syn- to post-kinematic Irumide granitoids emplaced between 1.05-0.95 Ga. In addition, a minor suite of 1.36-1.33 Ga anorogenic plutons (nepheline syenite and biotite granite) have been identified in the far northeastern Irumide belt, but were not included in this study. Whole-rock geochemical data for magmatic rocks in northern Zambia, predominantly from within the Irumide belt, indicate uniform crust-dominated patterns. Overall high REE contents and trace element characteristics indicate the significant participation of older crust in the generation of all magmatic suites.The data are insufficient to conclusively demonstrate that this crustal melting was associated with either intra-plate, volcanic arc or post-collisional/extensional collapse. A limited number of Sm/Nd isotopic data for the entire range of magmatic suites corroborate the highly reworked nature of parent magmas, with all samples characterised by strongly negative åNd(T) values and TDM model ages between 2.2 and 3.2 Ga. The geochronological data presented in this thesis show that the Irumide belt includes a Palaeoproterozoic basement complex comprising units as old as 2.73 Ga, but mostly made up of granitic gneisses ranging in age between 2.05 and 1.93 Ga, while granitic and volcanic units of the Bangweulu block to the northwest were dated at 1.87-1.86 Ga. Detrital zircon age data from quartzites and zircon crystallisation ages of interlayered tuffs within the Muva Supergroup indicate a depositional age of between 1.88 and 1.85 Ga, with local derivation from locally recognised basement units, although similarly aged rocks of the Tanzania craton to the northeast are also a possible source. The detrital record of the Muva Supergroup shows that the various components of the Bangweulu block, including 2.73, 2.05-1.93 and 1.87-1.86 Ga units, were assembled by the time of deposition of the Muva Supergroup at around 1.8 Ga. Both the basement units and the Muva Supergroup were intruded by a previously unknown magmatic suite of biotite granites between 1.65-1.55 Ga, the first record of such a magmatic event in central Africa. The new data presented in this thesis allow a critical assessment of previously proposed regional correlations between Mesoproterozoic teranes in central and southern Africa.Significant temporal differences between the Irumide belt and the Kibaran belt, Choma-Kalomo block and Namaqua-Natal belts had previously not been detected due to the poor quality, low resolution or limited size of isotopic data sets. The new data set produced in this study indicates a distinct and separate tectono-magmatic history for each of these terranes, therefore precluding previously suggested correlations. In particular, the presumed southeastward continuation of the Irumide belt across the Neoproterozoic Zambezi belt into the Choma-Kalomo block is precluded by the data presented in this thesis. This new geochronological framework allows for significant spatial separation of the Kalahari and Congo cratons prior to the Neoproterozoic closure of the Damara-Lufilian-Zambezi ocean, and is therefore in support of palaeogeographic models of Rodinia which either place the Congo and Kalahari cratons as distinct and separate fragments within the supercontinent, or show one or both of the two cratons not to form part of it. Currently, available data are not able to determine the tectonic setting or the palaeogeographic location of the Irumide belt, and as a result it is unclear whether it developed within Rodinia as a collisional orogen, at its margin as an accretionary orogen, or was not associated with Rodinia at all.

La région de Dabakala (Côte d'Ivoire), cartographiée à 1/200. 000ème, est composée de terrains paléoprotérozoïques granitiques séparant des formations volcano-sédimentaires. Les granitoïdes se répartissent en quatre groupes. Les granitoïdes de Dabakala sont métalumineux (1. 07<Na20/K20<3. 88 ; 1. 39<CaO<7. 58%) et définissent une lignée trondhjémitique. Les spectres des REE sont fractionnés [30 < (La/Yb)N < 45]. Les granitoïdes de Finéssigué sont métalumineux, plus sodiques que potassiques (Na20/K20 = 1. 77-2. 73 ; 2. 19<CaO<7. 32%) et définissent une tendance calco-alcaline avec des spectres de REE fractionnés [20 < (La/Yb)N < 71]. Les granitoïdes rubanés et porphyriques sont métalumineux à faiblement peralumineux (- 109 < A < 16), plus sodiques que potassiques (Na20/K20= 0. 86-1. 33 ; 0. 66<CaO<6. 1 %). Les spectres de REE sont fractionnés [25 «La/Yb)N < 67]. Les granites de Sarala sont plus potassiques que sodiques (K20/Na20=1. 14-1. 43) sauf pour Kowara (0. 44), faiblement peralumineux (1. 6 < A < 23. 5; Kowara = 49). Les spectres des REE sont homogènes et très fractionnés [62 < (La/Yb)N < 113]. Les assemblages de l'encaissant métamorphique sont, loin des plutons, ceux du faciès schiste-vert et, à proximité des plutons, liés au métamorphisme thermique (pressions voisines de 3. 5 - 4 kbars). Deux groupes d'âges (U-Pb) ont été identifiés: 2100-2120 Ma pour la lignée calco-alcaline et 2150-2170 pour la lignée trondhjémitique avec pour cette dernière un héritage voisin de 2300 Ma mais sans héritage archéen. La plupart des granitoïdes ont un caractère juvénile (données isotopiques Sr-Nd). Aucun socle ancien gneissique remobilisé ni de migmatites n'ont été observés.

Mapping, petrography and geochemistry show that the Cruachan Granitoid, which forms the outer part of the Caledonian Etive Complex, consists of seven intrusive units, mostly quartz monzodiorites. They form three groups with chemically distinct magma sources. The first five units are a set of intersecting flat-topped bell-jar intrusions, which intrude to higher levels with decreased S.G., and whose centres migrate north-eastward. The other two are sets of inclined sheets. A NNE-SSW wrench fault bisects the complex, producing 0.8 km. displacements of the units. The emplacement of one set of sheets is seen to be related to the stress field of this fault. Subsidence of the centre of the complex subsequent to emplacement of the seven units has occurred. The magmas were mostly liquid when emplaced. Their PH[sub]20 values reached 1.0 kB during crystallisation. Oxygen fugacity of late-stage magmas in successive bell-jar units increased progressively regardless of their chemical composition. Increasing access to the surface is inferred. Variability within units is mainly due to in-situ crystal fractionation, but examples of magma mixing and probable contamination are also identified. A magma chamber evolving from basic to acid compositions throughout the life of the Complex supplied one group of Cruachan units. Intrusions of the other two groups, which are richer in K, La, Ce and Zr, intervene between stages of intrusion from this first source. One of the two formed quartz monzodiorites higher in Al than the first group; the other, quartz monzoni te with over 7000 ppm Ba. Three Lorne basalt compositions can yield all three magma groups independently by crystal fractionation and crustal granulite assimilation. It appears that the Etive Complex and the Lorne Lavas are contemporaneous. The work extends knowledge of regional chemical trends among Caledonian magmas which are significant for understanding their genesis.

L’obiettivo dello studio è quello di caratterizzare i filoni granitoidi affioranti in alta Val Codera, definiti in letteratura come “micrograniti”, dal punto di vista petrografico e geochimico. Inoltre si intende stabilire i rapporti di intersezione tra i filoni granitoidi e i filoni pegmatitici ed aplitici che caratterizzano l’area e confrontare i dati ottenuti con quelli riguardanti il granito di S. Fedelino, descritto in letteratura come lo stock magmatico che ha generato i filoni granitoidi dell’alta Val Codera.

This thesis investigates the morphological, chemical and growth characteristics of zircon mineral in relation with the granitoid petrology. Physical and chemical variations recorded within zircon crystals during evolution of the Central Anatolian Granitoids are discussed. The thesis focuses on twelve granitoid samples from the Ekecikdag, Aga&ccedil<br>&ouml<br>ren and Terlemez regions from western part of central Anatolia. These granitoids are differentiated into S- and H-type granitoids on the basis of field, petrographical and whole-rock geochemical aspects. In granitoids concerned, zircon is associated with biotite, allanite and plagioclase, and zircon populations mainly comprise P- and S-type zircon crystals, with rare G-, L- and J-types. Typology method combined with cathodoluminescence imaging revealed that S- and H-type granitoids show intrusive aluminous autochthonous and hybrid character, respectively. Zircons generally have euhedral to subhedral cores exhibiting zoning, although sometimes faint, but inherent and embayed cores also exist. Large scale, first order, and/or small-scale second order oscillatory zoning and effects of late stage recrystallization are observed within zircon crystals. Multi-corrosion zones within zircons are characterized by sharp changes in crystal forms with decreased Zr and Si, and increased U, Th and REE+Y contents, beside infrequent increase in Hf, Sc, Ta, Ti, Ca, Al and Fe elements. These zones are interpreted to be formed by transient heating of the resident felsic magma due to mafic melt contribution, at the time of mixing/mingling processes of the H-type granitoids, and then zircons re-grow in magma source reflecting a mafic character. Corrosion stages within zircons of S-type granitoids, on the other hand, were probably formed by mantle-derived melts producing heat for resorption of zircons without direct contribution.

Submitted by Flasleandro Oliveira (flasleandro.oliveira@cprm.gov.br) on 2014-04-24T18:38:04Z No. of bitstreams: 1 Dissertação Desaix - 2013 captec.pdf: 13991378 bytes, checksum: d58eac77692f9e149e3e49e5de640be6 (MD5)<br>Approved for entry into archive by Flasleandro Oliveira (flasleandro.oliveira@cprm.gov.br) on 2014-04-24T18:38:16Z (GMT) No. of bitstreams: 1 Dissertação Desaix - 2013 captec.pdf: 13991378 bytes, checksum: d58eac77692f9e149e3e49e5de640be6 (MD5)<br>Approved for entry into archive by Flasleandro Oliveira (flasleandro.oliveira@cprm.gov.br) on 2014-04-24T18:38:24Z (GMT) No. of bitstreams: 1 Dissertação Desaix - 2013 captec.pdf: 13991378 bytes, checksum: d58eac77692f9e149e3e49e5de640be6 (MD5)<br>Made available in DSpace on 2014-04-24T18:38:30Z (GMT). No. of bitstreams: 1 Dissertação Desaix - 2013 captec.pdf: 13991378 bytes, checksum: d58eac77692f9e149e3e49e5de640be6 (MD5)<br>O reconhecimento geológico da região de Tartarugalzinho se deu com técnicas de mapeamento geológico, estudos petrográficos, estruturais, geoquímicos e geocronológicos em granitoides da região. Com isso, tornou-se possível a individualização de cinco principais unidades, sendo as recém definidas neste trabalho, Suíte Intrusiva Rio Ariramba e Granitoide Janary, além da Suíte Intrusiva Flexal, Grupo Tartarugalzinho e Suíte Intrusiva Cigana. Dados estruturais reforçam o caráter regional das foliações observadas segundo direção NW-SE, a partir da qual se orientam os corpos intrusivos marcadamente os da Suíte Intrusiva Rio Ariramba. As foliações são de médio a alto ângulo de mergulho segundo trajetórias que podem mostras inflexões em razão de limites de corpos intrusivos e deformação da rocha hospedeira. Atitudes de lineação 15º / 115° Az indicam transporte de massa de SE para NW causado por provável colisão obliqua NNE-SSW, finalizando em sistema transpressivo sinistral (DELOR et al., 2003). Texturas microtectônicas marcam campo de tensões a altas temperaturas evidenciadas por feições texturais interlobares e recristalização de grãos de feldspato que seguramente evidenciam um aquecimento destes corpos a 600 ºC. Dados petrográficos definem a Suíte Intrusiva Rio Ariramba segundo biotita hololeuco granodioritos porfirítico a biotita hololeuco monzogranitos porfiríticos, e o Granitóide Janary como epidoto quartzo monzonito a monzogranito. Biotia anfibólio tonalitos são dominantes na Suíte Intrusiva Flexal. No Grupo Tartarugalzinho ocorrem mica xistos, quartzitos e dioritos milonitizados. O estudo litogeoquímico permitiu separar com clareza as diversas unidades onde as duas mais expressivas (Suíte Intrusiva Rio Ariramba e Suíte Intrusiva Flexal) são quimicamente diferentes quanto à série magmática, índice de alumina, ambiente tectônico e tipologia. A Suíte Intrusiva Rio Ariramba define quimismo peraluminoso, sendo associada a serie cálcio-alcalina de alto potássio gerada em arco magmático pré a pos-colisional. Foram obtidas idades entre 2087 ± 4 Ma e 2081 ± 7,5, pelo método Pb-Pb (em zircão), para a Suíte Intrusiva Rio Ariramba, os quais quando interpretados em conjunto com o dados litogeoquímicos, aponta uma granitogênes cálcio alcalina de médio a alto potássio, ligada a ambiente de arco magmático de margem continental ativa durante o estagio sin a pos-colisional, evidenciando uma evolução geodinâmica algo distinta da descrita por Delor et al. (2003), que não encontrou evidencias do desenvolvimento de arcos magmáticos continentais na Guiana Francesa. Os diagramas petrogenéticos indicam o envolvimento (retrabalhamento) de crosta continental superior em ambiente de arco magmático na geração dos granitoides da Suíte Intrusiva Rio Ariramba, associados a mistura de líquidos, sendo de um provável magma máfico juvenil a fase contaminante. Tal afirmação é sustentada pelos dados isotópicos de Sm-Nd obtidos por Avelar (2002) em granitóides do nordeste do Amapá. Os tonalitos, trondhjemitos e granodioritos da Suíte Intrusiva Flexal marcam um segmento crustal formado por reciclagem de crosta oceânica juvenil em arco de ilhas insular durante o Eoriaciano como mostram as idades U-Pb LA e Sm-Nd TDM obtidas por Rosa-Costa et al. (2012) para esta Suíte em conjuntos com o dados litogeoquímicos.

Les roches ornementales sont d'un usage généralisé dans les agglomérations urbaines notamment dans la région d'Abidjan où leur beauté la dispute à leur diversité. Dès lors, le souci qui habite l'utilisateur potentiel de ces matériaux ornementaux, est de savoir quel peut être leur comportement, face aux intempéries et autres changements climatiques qui sont le lot permanent ou quasi quotidien des zones tropicales humides. C'est la recherche d'une réponse à cette préoccupation qui a motivé ce travail, dont l'objectif final est de conduire, sous conditions météorologiques de la zone tropicale humide reproduites au laboratoire, des expérimentations relatives à l'évolution des certains types de matériaux ornementaux. Le présent travail a donc porté sur la formalisation d'un modèle de climat tropical humide, ainsi que, sur des expérimentations in vitro, en vue de tester le dispositif expérimental devant mettre en œuvre les conditions climatiques subséquentes. De ce fait, la conception de ce dispositif expérimental a pris en compte les paramètres que sont: la vitesse d'impact des gouttes de pluie (2,3 m.s-1), l'énergie calorifique et ses fluctuations qui s'expriment en des températures à la surface du sol variant entre 24 °C et 76°C, l'environnement hygrométrique qui oscille entre les saturations (pluies, et rosées nocturnes) et HR (humidité relative) égale à 85%, ainsi que la pluviosité (51 mètres d'eau par heure). Des plaques polies issues des gisements ivoiriens de roches ornementales d'Okrouyo (syénite) et de Yakala (granite rose) ont servi d'échantillons pour tester le dispositif expérimental. Au bout de 6, 9, et 12 mois, on a numérisé des images de la surface polie des échantillons. Par la suite, à l'aide des logiciels Visilog 5.4 (Noesis, 2001) et Paint Shop Pro 5.0 (Jasc Software, 1998), on a mis en œuvre l'analyse colorimétrique d'images numérisées, retenue comme le mode d'investigation le plus approprié pour comparer les images obtenues à 12 mois, avec celles de départ. Cette comparaison a procédé par soustraction des images de départ, de celles à l'issue de 12 mois d'essai L'étude des images issues des opérations de soustraction a dégagé qu'il existe une analogie entre le milieu de ferrallitisation, conséquence de l'altération météorique en climat tropical humide, et le milieu généré par la mise en œuvre du dispositif expérimental qu'on propose. Elle a aussi permis de se rendre compte que l'utilisation du matériau d'Okrouyo devrait se limiter à des revêtements intérieurs. Par contre celui de Yakala pourrait être utilisé à la fois pour des revêtements intérieurs et extérieurs.

Les granitoïdes du massif des Maures (Var, France) sont divisés en quatre groupes principaux selon leur minéralogie. Ils sont tous peralumineux. Certains proviennent de fusion partielle fractionnée, d'autres de cristallisation fractionnée. D'autre part d'après la géochimie de la biotite trois groupes appartiennent aux associations alumino-potassiques, le 4eme aux associations calco-alcalines. Suivant la typologie on peut aussi classifier différemment ces granitoïdes, suivant un schéma géodynamique base sur les zonalités magmatiques

Ce travail porte sur la formalisation d’un modèle de climat tropical humide, ainsi que sur des expérimentations in vitro, en vue de tester le dispositif expérimental devant mettre en œuvre les facteurs climatiques modélisés. De ce fait, la conception de ce dispositif expérimental a pris en compte les paramètres que sont : la vitesse d’impact des gouttes de pluie (2,3 m. S-1), l’énergie calorifique et ses fluctuations qui s’expriment en des températures à la surface du sol variant entre 24°C et 76°C, l’environnement hygrométrique qui oscille entre les saturations (pluies, et rosées nocturnes) et HR (humidité relative) égale à 85%, ainsi que la pluviosité (396 mètres d’eau par heure). Des plaques polies issues des gisements ivoiriens de roches ornementales d’Okrouyo (syénite) et de Yakala (granite rose) ont servi d’échantillons pour tester le dispositif expérimental. Au bout de 12 mois, on a numérisé des images de la surface polie des échantillons. Par la suite, à l’aide des logiciels Visilog 5. 4 (Noesis, 2001) et Paint Shop Pro 5. 0 (Jasc Software, 1998), on a mis en œuvre l’analyse colorimétrique d’images numérisées, retenue comme le mode d’investigation le plus approprié pour comparer les images obtenues à 12 mois, avec celles de départ (0 mois). Cette comparaison a procédé par soustraction des images de départ, de celles à l’issue de 12 mois d’essai. L’étude des images issues des opérations de soustraction a dégagé qu’il existe une analogie entre le milieu de ferrallitisation, conséquence de l’altération météorique en climat tropical humide, et le milieu généré par la mise en œuvre du dispositif expérimental<br>This work consists in designing a model of humid tropical climate and performing experiments in vitro to test the apparatus used to create the relevant weather conditions. To do this, the following variables were taken into account in the study: the speed of raindrop impacts (2. 3 m. S-1), calorific energy and its fluctuations expressed in surface temperature ranging from 24°C to 76°C, the hygrometric environment which varies from saturations (rains and nightly dewdrops) and RH of 85%, as well as wetness (396 metres of water per hour). Prototypes of flagstone made of Ivorian ornamental rock deposits from Okrouyo (syenite) and Yakala (rose granite) were used as samples to test the apparatus. At a stage of 12 month experiment, the samples where digitalised. Later, using Visilog 5. 4 (Noesis, 2001) and Paint Shop Pro 5. 0 (Jasc Sofware, 1998), the colour image analysis of the digitalised images was started as the most appropriate mode of investigation for comparing the images obtained at the different stages of the experiment and those existing at the start. This comparison exercise consisted in removing the initial images from those obtained at the stage of 12 month. The study of the images derived from the removal of the initial ones revealed that there exists a similarity between the areas of ferrallitisation a consequence of the weathering into humid tropical climate, and the area generated through the experimental device proposed herein

Submitted by Israel Vieira Neto (israel.vieiraneto@ufpe.br) on 2015-03-04T17:34:48Z No. of bitstreams: 2 DISSERTAÇÃO Lucilene dos Santos.pdf: 10057943 bytes, checksum: 487d4e94f2325e876643a0f22bf56873 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5)<br>Made available in DSpace on 2015-03-04T17:34:48Z (GMT). No. of bitstreams: 2 DISSERTAÇÃO Lucilene dos Santos.pdf: 10057943 bytes, checksum: 487d4e94f2325e876643a0f22bf56873 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2013-07-26<br>CNPq<br>Os granitoides estudados (plutons Serra Branca - GPSB e Coxixola - GPC) intrudem ortognaisses e migmatitos paleoproterozóicos a arqueanos, e rochas supracrustais Neoproterozóicas. Os GPSB, sienogranitos leucocráticos, equigranulares, contendo localmente enclaves de granitos porfiríticos (GPC) e dioritos, compreendem intrusão alojada em terminações extensionais de zonas de cisalhamento NE-SW transcorrentes sinistrais, ramificações da zona de cisalhamento Coxixola (ZCC), destral com direção E-W. Os GPC compreendem quartzo sienitos, quartzo monzonitos e sieno a monzogranitos, porfiríticos, deformados no estado sólido, com anfibólio de composição ferro - edenita, edenita e Mg - hornblenda. Enxames de enclaves máficos, quartzo dioritos a quartzo monzonitos, ocorrem orientados na direção E - W. A fO2 varia de intermediária (GPSB) a elevada (GPC). Estimativas de temperaturas liquidus utilizando saturação em zircão, variam entre 836 °C - 893 °C (GPC) e 783 °C - 843 °C (GPSB). Os granitoides estudados mostram valores fortemente negativos de εNd(t) e idades modelo (TDM) paleoproterozóicas. U-Pb em zircão por SHRIMP definiu uma idade de 560 ± 5 Ma para os GPSB, e por LA-ICP-MS definem idades de 573 ± 3 Ma para um dique de leucogranito que corta os GPC e de 580 ± 7 Ma para os GPC. Os GPSB são ricos em SiO2 (> 70%), levemente peraluminosos, com padrões ETR fracionados, mostrando profundas anomalias negativa de Eu, e padrões Spidergram com depressões em Nb, Ta, Sr, P e Ti. São classificados como granitoides trans-alcalinos ferrosos, tipo-A pós-orogênico. Os GPC mostram teores intermediários de SiO2 de 55-67 %, são metaluminosos, magnesianos, tipo-I mostrando padrões de ETR fracionados e caracterizados pela ausência ou anomalias fracamente positivas de Eu, e padrões Spidergram com depressões em Th, Nb, Ta, Ti. Assinaturas isotópicas e geoquímicas sugerem que os granitoides estudados foram originados pela mistura de magmas gerados pela fusão de crosta paleoproterozóica ou arqueana e pequena fração de material Neoproterozóico em diferentes épocas da história evolutiva da ZCC.

Le site HDR de Soultz-sous-Forêts se présente sous la forme d'un doublet géothermique (un puits d'injection et un puits de production), hydrauliquement connecté par un réseau de fractures situé à plus de 3500 m de profondeur. La température en fond de puits a été mesurée à 162 °C environ à 3800 m de profondeur. Les objectifs d'un tel projet sont de récupérer la chaleur contenue dans le massif rocheux fracturé en établissant une circulation forcée de fluide entre les puits. Au passage dans le réseau de fractures, le fluide est réchauffé, et cette énergie calorifique est récupérée en surface pour être transformée, à l'aide d'une turbine, en électricité. Afin d'augmenter la perméabilité du réservoir et d'améliorer la connexion entre les puits, des essais de fracturation hydraulique ont été menés sur chacun des forages. Ces injections de fluide à forte pression (plusieurs dizaines de MPa), induisent une activité sismique de faible magnitude (inférieure à 4), appelée "microsismicité". Dans cette étude, l'utilisation des micro-événements permet de développer deux thématiques distinctes: - Le développement d'une méthode permettant d'inverser les données microsismiques en terme de perméabilité équivalente de la zone stimulée. Durant l'injection de fluide, la surpression engendrée dans le milieu se propage dans l'espace à une certaine vitesse. La célérité de cette onde est quantifiée en interprétant la répartition dans le temps et dans l'espace des micro-événements. En appliquant les lois de la poroélasticité, une perméabilité du milieu poreux équivalent au volume de roche fracturé est estimée. De cette estimation selon la direction de l'espace, un tenseur de perméabilité est défini. Cette méthode a été appliquée sur deux autres sites géothermiques, Fenton Hill aux USA et Ogachi au Japon. - La construction d'un modèle 3D capable de simuler les écoulements de fluide dans le massif ainsi que de quantifier les échanges de chaleur associés. Ce modèle intègre un maximum d'informations de différentes natures, observées et mesurées dans les puits: débit et pression, pendage et azimut des fractures, températures. . . Une fois le modèle hydraulique obtenu, le champ de vitesses de Darcy associé est utilisé pour la simulation numérique du refroidissement du volume de roche initialement chaud (échangeur géothermique), paramètre conditionnant la durée de "vie" de l'échangeur géothermique. Une estimation des courbes de refroidissement du futur échangeur prévu à 5000 m est également proposée. Ces paramètres techniques sont importants pour la détermination de la rentabilité économique d'un tel projet.

La suite post-tectonique du batholite hercynien de Celorico de Basto est composée de roches basiques en enclaves dans des granodiorites hétérogènes et dans le granite G2, et de granites fins tardifs associés à des aplopegmatites minéralisées en Sn-Nb-Ta-Li-Be. Les granodiorites résultent du mélange entre des magmas basiques, dont leurs enclaves dioritiques sont des témoins, et un magma acide de type granite G2. Les enclaves des granodiorites et du granite G2 sont des termes d'une série basique qui pourrait être un équivalent plutonique des séries shoshonitiques. Les magmas parents de cette série, probablement issus d'un manteau subcontinental enrichi en éléments incompatibles par recyclage de matériel crustal, se sont differenciés à haute pression ce qui conduit à des termes dioritiques proches des vaugnerites du Massif Central français. Le granite G2 est un terme différencié de cette serie mais contient une contribution crustale en accord avec les rapports 87Sr/86Sr initiaux intermédiaires d'autres granites hercyniens à biotite dominante. Les magmas parents des granites fins tardifs ont une origine crustale. Les aplopegmatites associées sont des termes extrêmement différencies de ces granites dont la composition peralumineuse, la richesse en phosphore et en volatils conduit à une évolution terminale de type sodolithique. Le massif post-tectonique de Lamas de Olo est composé d'adamellites calco-alcalines potassiques et a une architecture du type exogranite-endogranite à Stocksheider. Les minéralisations en Mo-W-Be sont les manifestations d'un circuit hydrothermal engendré par l'endogranite.

The main aim of this study was to develop a model for the sources of sulphur in Late Caledonian granitoids of Northern Britain in relation to their tectonic framework, and to constrain the sources of sulphur, fluids and metals in related mineralization. Using an approach of combined stable isotopic (S, C, H and O), fluid inclusion, geochemical (XRF) and mineralogical (electron probe, XRD, microscopy) techniques, it has been possible to estimate temperatures and conditions of formation. A further aim was to group the mineralization "styles" and to develop a model for each with implications for the sources of their host granitoids. The relative importance of magmatic processes and terrane characteristics in the formation of ore deposits of Northern Britain has been evaluated. The study of 23 mineralized granitoids amongst four terranes has yielded a range of δ³⁴S values between -21‰ and +24‰, and values for host rock lithologies between -22‰ and +29‰. Porphyry-style mineralization has δ³⁴S H₂S values restricted to the range -2‰ to +2‰. Fluid inclusions in porphyry related mineralization homogenize at temperatures up to 580°C with salinities of 5-60 eq.wt.% NaCl, and CO₂ is rare. Fluid inclusions, sulphur isotope geothermometry and mineral stabilities suggest that late veins hosted by plutonic rocks formed below 450°C, contained salinities of <15 eq.wt.% NaCl, and that CO2 was often an important primary component. External fluids commonly entered the magmatic systems at temperatures below 200°C in both porphyry systems and deeper veins. Parageneses of the porphyry-style mineralization generally contains early pyritohedra, followed by quartz, chalcopyrite, tetrahedrite, bornite and carbonate. The plutonic-hosted veins contain a more complex mineralogy, commonly including galena and sphalerite, and accompanied by minerals new to Scotland including berryite, gladite, hammarite, joseite-B, krupkaite, matildite, pearcite and tetradymite. Calcite is commonly the only carbonate present in plutonic-hosted mineralization, and wallrock alteration is restricted to propylitic type, except for vein selvages. Porphyry systems show more intensive wallrock alteration of sericitic or phyllic type, dolomite is the primary carbonate and is followed by late calcite. A model for the Late Caledonian mineralization has been developed. The sulphur and metals involved in the formation of a granitoid-related mineral deposit are commonly derived from the same sources. In the Northern Highland Terrane the Lewisian craton was an important source, whereas most components in the Grampian Terrane were derived from the sub-crustal magmas. In the Southern Uplands and North of England Terranes, the Lower Palaeozoic sediments hosting the granitoids provided a major component of metals, sulphur and fluids, either at the level of intrusion or as a source for S-type magmas at depth. The 834S values of the granitoids and related mineral deposits in the paratectonic Caledonides reflect the signatures of the host sediments. It is concluded that only in the Grampian Terrane do the characteristics of mineralization predominantly represent magmatic processes. In the remaining terranes, a significant contribution of fluids, sulphur and metals, from the craton or upper crustal sediments, modified magmatic and fluid conditions which controlled subsequent mineralizing processes. As a consequence of the behaviour of sulphur isotopes in sediment formation and with variation of ƒO₂ and pH in the mineralizing fluids, the sulphur isotope technique provides a robust indicator of magma sources and major crustal discontinuities such as terrane boundaries. The technique developed in this study may find wider application.

A área de estudo possui cerca de 100 Km² e localiza-se entre os municípios de Atibaia e Bom Jesus dos Perdões no Estado de São Paulo. O Maciço de Atibaia, estudado em maior detalhe, cobre área aproximada de 65 Km². Coloca-se em terreno metamórfico (rochas da fácies anfibolito) com foram de cunha, limitado por duas grandes zonas de cisalhamento e suas manifestações colaterais (uma à noroeste e outra à sul do maciço). Dentro do maciço são descritas 3 fácies principais. A primeira, ocupando cerca de 98% da área, é representada por um sienogranito porfiróide róseo acinzentado de textura inequigranular média-grosseira e índice de cor (IC) em torno de 10. A segunda fácies é composta por um monzogranito cinza de granulação fina a média cuja característica marcante é a presença de nódulos esbranquiçados quartzo-feldspático de até 2 cm de diâmetro. A terceira fácies, monzogranito cinza claro (granulação fina a média), é muito semelhante a anterior mas em lugar dos nódulos surgem esporadicamente alguns cristais de feldspato alcalino. Associados ao sienogranito porfiróide ocorrem diques sinplutônicos de granulação fina-média, bolsões graníticos, enclaves e xenólitos. Marginais ao maciço são observadas várias fácies de granitoides consideradas pré-Atibaia. Dentre elas destacam-se ocorrências mapeáveis de uma variedade de granito branco a duas micas com granada como acessório principal. Outra ocorrência marginal importante é um granitóide (monzogranito a granodiorito) cinzento porfirítico (IC em torno de 15); aparece constituindo corpos de centenas de metros apenas na porção a oeste do maciço. Ocorrem ainda um sienogranito cinza (IC \'QUASE IGUAL A\' 10) de granulação fina-média localizado á leste do maciço e um sienogranito cinza avermelhado porfirítico (IC \'QUASE IGUAL A\' 10) localizado à norte. Rochas granodioríticas, tonalíticas e quartzo-dioríticas aparecem à oeste do maciço e ocorrem geralmente como corpos alongados na direção NNE; possuem uma foliação penetrativa bem visível em rochas alteradas. A existência de um paralelismo das estruturas tectônicas regionais com as de fluxo magmático, observada no interior do maciço, além da própria geometria alongada em sentido NNE sugerem uma deformação contínua desde a colocação do granito (fase dúctil) até a sua cristalização final com a formação de milonitos e cataclasitos (fase rúptil). A intensidade dessa deformação distribui-se de forma anastomosada criando subtipos texturais-estruturais no interior do maciço, onde a foliação tectônica é mais ou menos marcante. As análises químicas (14 amostras) apontam tendências alcali-cálcica (diagrama de Peacock) e metaluminosa (diagrama de Maniar & Piccoli). Nos diagramas de discriminação (e.g., R1 versus R2) as amostras aparecem representadas na transição dos campos tardi-orogênicos a sin-orogênicos. Os teores de Ba, Sr, Rb e Zr, entre outros, são semelhantes aos observados em outros granitoides do cinturão Itu. A homogeneidade observada dos tipos encontrados (principalmente sienogranito porfiróide) sugere uma fonte também homogênea ou uma quase completa homogeneização do líquido magmático antes da cristalização. No contexto regional o Maciço de Atibaia (idade de 573 \'+ OU -\' 15 M.a., isócrona Rb/Sr) relaciona-se provavelmente ás associações mais jovens que constituem o cinturão Itu de granitóides tardi- a pós-orogênicos, cujas manifestações mais recentes têm idades próximas a 580 M.a. A razão inicial do sienogranito porfiróide (0,7132) é relativamente elevada indicando contribuições significativas de áreas fontes isotopicamente mais evoluidas.<br>The mappea área, covering about 100 Km² in the Atibaia and Bom jesus dos Perdões townships, eastern São Paulo State, shows as its main geologic feature the Atibaia granitoid massif (outcrop area about 65 Km²). It appears as a wedge (general NNE orientation) within amphibolite-facies metamorphic rocks, limited by two large shear zones and associated faults, one to the NW, the other to the S. Three main facies are described as the massif\'s constituents. The predominant one (about 98% of outcrops) is an inequigranular medium-coarse grained porphyroid syenogranite, grayish pink, with a color index (CI) of about 10. The second facies is a fine to medium-grained grey monzogranite presenting whitish quartzo-feldspathic nodules, up to 2 cm in diameter. The third facies is very similar to the former, but devoid of nodules; sporadically, some larger k-feldspars appear. The main syenogranite shows synplutonic dykes and granitic (pegmatitic to aplitic) irregular smaller bodies, as well as microgranular enclaves and metamorphic xenoliths. Several smaller occurrences of older pre-Atibaia granites are found within metamorphic rocks. Mappable units of a garnet-bearing two-mica whitish granite are observed as well as a greyish porphyritic monzogranitic to granodioritic rock (CI about 15); one larger unit (several hundred m) of this facies occurs to the W of the Atibaia massif. To the E a grey finegrained syenogranite (CI \'QUASE IGUAL A\' 10) is found; a porphyritic grey-reddish syenogranite (CI \'QUASE IGUAL A\' 10) occurs to the N. Appearing within basement rocks to the W of the massif, several penetratively foliated granodioritic, tonalitic and quartzo-dioritic rocks are observed as smaller bodies with a NNE elongation. A general parallelism between the regional NNE tectonic structures and a sporadically found magmatic foliation within the Atibaia granite, as well as the predominant NNE elongation of the massif itself, suggest a continuous deformation pattern controlling the intrusion of magmas (ductile phase) as well as the final generation of mylonites and cataclasites (ruptile phase) by deformation of the crystallized syenogranite. The deformation, concentrated along fine anastomosed bands, is responsible for the formation of various textural subtypes (from underformed granite to ultramylonites and even phyllonites). The predominant syenogranite is very homogeneous, thus indicating that the source region was a uniform protolith or, alternatively, that the magma was thoroughly homogenized before intrusion. Chemical data (14 samples) show and alkali-calcic tendency (Peacock\'s diagram) and a metaluminous character (diagram by Maniar & Piccoli). In discriminant diagrams (e.g., R1 versus R2) the data plot within the fields of late orogenic granites. Contents of some trace elements (Ba, Sr, Rb, Zr) are similar to those cited for other Itu belt occurrences. The Atibaia massif (with a Rb-Sr isochron age of 573 \'+ OU -\' 14M.a.). is probably synchronous with the younger granitoids that make up the Itu Belt of late to post-orogenic granites; an age of about 580 M.a. is proposed in the literature for these intrusions. The observed 86Sr/87Sr initial ratio, though, is uncharacteristically high (0, 7132), pointing to significant contributions from isotopically evolued source regions.

Un diagramme binaire mg/al permet une excellente discrimination entre les principales lignees magmatiques, que l'on peut rattacher par ailleurs a certains contextes geodynamiques. Un diagramme fe/mg/ti permet de reconnaitre le caractere primaire ou evolue des biotites et de tenir compte eventuellement des derives de composition. Application au massif armoricain et au maroc. La deuxieme partie est de nature experimentale

The present study investigates the effects of basement variations on the geochemical composition of the Laramide plutonic belt of northwestern Mexico, and implications for the development of the associated porphyry copper mineralization. In the north part, the belt intruded rocks of the North America and Caborca terranes representing cratonic basements juxtaposed by Mid-Jurassic strike-slip faulting. The central part of the belt was emplaced in the Cortes terrane which contains Paleozoic eugeoclinal sequences accreted to North America between Mid-Permian and Late Triassic times. The southern part of the belt intruded island arc-related sequences of the Guerrero terrane, accreted to North America during the Late Cretaceous. A suite of 30 samples of granitoids were studied to characterize the geochemical composition of the belt. The samples range from 56% to 75% SiO₂ and have mid to high-K calc-alkaline and mostly metaluminous compositions. REE results show more evolved chondrite-normalized plots in the north part of the belt, characterized by higher ΣREE and La(N)/Yb(N) ratios, and more pronounced negative Eu anomalies. Southward, the samples show a progressive flattening, eventually with almost no Eu anomalies in the Guerrero terrane. ⁸⁷Sr/⁸⁶Sr initial ratios higher than 0.7062 and initial εNd below -4 characterize the granitoids from the north part of the belt. Slightly less evolved isotope signatures occur in the central part, whereas ⁸⁷Sr/⁸⁶Sr ratios below 0.7063 and more positive εNd values characterize the samples from the south. The data suggest a garnet-bearing source for the granitoids emplaced in the north and central parts of the belt, whereas much less garnet fractionation is needed in the southern part. The effect of different crustal domains on the porphyry copper mineralization is less obvious. Hypogene Cu grades do not vary much along the belt, but the associated metals such as Mo, W, and Au show a certain degree of spatial control. Higher Mo grades are associated with the North America and Caborca terranes. Tungsten deposits are not terrane-constrained, but the more conspicuous mineralization occurs in central Sonora, mainly associated to the Caborca terrane. Higher Au values seem to occur in porphyry copper and associated breccia deposits in the Guerrero terrane. In general, the associations Cu-Mo-WO₃ in terranes of North America affinity, and Cu-Au in the Guerrero terrane suggest basement control.

Two groups of mafic volcanic rocks and three types of granitoids have been identified in the Yalgoo area of Western Australia. Granodiorite records ages of ~2760 Ma and biotite monzogranite ages of 2636 Ma. A 1.85 Ga dolerite dyke is the first Paleoproterozoic dyke identified from the Yilgarn Craton. An indirect age of ~2.63 Ga is inferred for gold mineralization. Geochemical data indicate formation in a continental marginal arc with traces of Hadean crust.

The Vrondou pluton is an Oligocene high-K calc-alkaline composite granitoid body emplaced in the Lower Tectonic Unit of the Western Rhodope Massif, adjacent to its western margin, and borders the Strymon and Serres basins to the west and south, respectively. Hornblende-biotite quartz-monzonite and biotite-hornblende granite s.s. crop out in the central-western and southern areas, whereas biotite-hornblende granodiorite crops out in the southeastern areas. Clinopyroxene-hornblende monzonite and porphyritic monzonite occur in the central-eastern and northeastern areas. Minor rock types include gabbro, microgranular enclaves and amphibole-bearing lamprophyre dykes. Textural evidence, especially the abundant presence of plagioclase with disequilibrium zoning features (patchy zoning, calcic spikes) in the granitoids and their enclaves, suggests that hybridisation was responsible for their genesis. Enclaves are interpreted as magmatic, probably with a multi-stage crystallisation history, the final stage of crystallisation taking place in chemical and thermal equilibrium with their hosts, as is also indicated by the close chemical affinities between enclave and host ferromagnesian minerals. Major and trace element modelling suggest that the quartz-monzonites, granites and granodiorites are inter-connected by the fractionation of parental quartz-monzonite, and possibly that the monzonites and porphyritic monzonites are inter-connected by the fractionation of a parental monzonitic magma. Rare earth element and trace element patterns of the granitoids suggest that they have a common source and have features similar to magmas generated in active continental margins or post-collisional settings. The basic rock-types show subduction-related trace element enrichments and a garnet-absent source, and are inferred to have been generated from subcontinental mantle lithosphere, enriched during subduction. The Sr and Nd isotopic compositions of the granitoids and the gabbro rule out a single stage basic-to-acid fractionation process. Instead, it is proposed that basic magmas underwent fractional crystallisation concurrent with assimilation in a transient deep magma chamber to produce an initial quartz-monzonite batch, parental to the evolved rocks.

O magmatismo granitóide neoproterozóico do sudeste brasileiro compreende uma ampla variedade de suites com características geoquímicas peculiares, indicativas de uma complexa evolução tectônica. De particular interesse entre estas suites encontram-se grandes batólitos alongados sin-orogênicos, que constituem associações composicionalmente expandidas, e entre os quais se destaca o Batólito Pinhal-lpuiúna. O Batólito Pinhal-Ipuiúna abrange uma área de cerca de 930Km², e se estende do extremo nordeste do Estado de São Paulo ao sudoeste do Estado de Minas Gerais. Numa orientação de W para E, o batólito acompanha o limite do segmento setentrional da Nappe de Empurrão Socorro-Guaxupé, definido pela zona de cisalhamento de Jacutinga, até a região de lpuiúna (MG), quando então se inflete para NW, seguindo as estruturas regionais. Os granitóides do maciço são intrusivos em orto- e paragnaisses migmatíticos e sua colocação é anterior (a contemporânea?) tanto ao desenvolvimento da foliação principal, quanto ao auge da migmatização regional. Apresentam uma foliação tectônica marcante, de direção predominante WNW, desenvolvida sob temperaturas elevadas, e marcada pelo alinhamento de megacristais de feldspato alcalino e de minerais máficos. Três associações distintas de granitóides, aflorantes nas vizinhanças do batólito, foram consideradas geneticamente independentes das rochas do maciço: (a) os biotita monzogranitos e granodioritos porfiríticos atribuídos ao Complexo Pinhal; (b) os granitos equigranulares a inequigranulares anatéticos \"tipo\" Pinhal; (c) os hornblenda-biotita monzonitos e quartzo monzonitos que constituem o Maciço Monzonítico Maravilha. O Batólito Pinhal-lpuiúna compreende um conjunto de rochas granitóides dominantemente porfiríticas a porfiróides, com uma ampla e contínua variação composicional (de quartzo monzodioritos a sienogranitos), que define uma tendência modal cálcio-alcalina de alto potássio. O mapeamento faciológico deste granitóides permitiu o reconhecimento de vinte e três fácies petrográficas distintas, que foram agrupadas em três grandes unidades, em função de suas características texturais e composicionais. A unidade mais antiga, São José da Prata, corresponde a termos intermediários, com amplo predomínio de quartzo monzodioritos e com os minerais máficos representados por hornblenda (\'+ ou -\' clinopiroxênio) e biotita, totalizando cerca de 20%. A segunda unidade, denominada lpuiúna, é predominante e compreende essencialmente quartzo monzonitos que mostram variações gradacionais a monzogranitos, e têm anfibólio e biotita como minerais máficos principais, perfazendo, em média, 15% do volume da rocha; \"augen-gnaisses\" desenvolvem-se numa faixa próxima à zona de cisalhamento de Jacutinga, na porção S-SW do batólito. A terceira unidade, Serra do Pau d\'Alho, com as rochas mais diferenciadas do conjunto, é constituída por monzogranitos e sienogranitos com biotita como mineral máfico principal em proporções próximas a 5% nas fácies de maior expressão areal. Enclaves máficos dominantemente quartzo dioríticos, comuns em todas as unidades, podem constituir ocorrências mapeáveis na região de lpuiúna (MG). Apresentam relações de contato e interação com os granitóides do maciço que sugerem a contemporaneidade dos magmas máficos e félsicos. O magmatismo máfico parece ter caráter recorrente, tendo persistido até a cristalização das rochas mais tardias do batólito. A caracterização geoquímica dos granitóides do Batólito Pinhal-lpuiúna definiu uma suite cálcio-alcalina a álcali-cálcica de alto potássio, que estabelece uma seqüência contínua desde os termos intermediários das unidades São José da Prata e lpuiúna até os granitos mais diferenciados da unidade Serra do Pau d\'Alho. As rochas granitóides apresentam padrões geralmente fracionados de elementos terras raras, com anomalias negativas de Eu negligenciáveis a pronunciadas, concentrações relativamente elevadas de elementos LlL, bem como altas razões isotópicas de Sr, que refletem uma influência importante de materiais crustais mais evoluídos na gênese dos granitóides. Os enclaves máficos apresentam algumas feições geoquímicas similares aquelas dos granitóides encaixantes, mas fogem à tendência geral definida pelas rochas mais fracionadas do batólito, sugerindo um grupo químico distinto e geneticamente independente. Parte da diversidade faciológica que caracteriza o batólito reflete a influência de processos complexos na evolução dos magmas parentais, envolvendo mecanismos de cristalização fracionada entre as diferentes fácies que definem a tendência evolutiva principal do maciço. Os modelamentos geoquímicos sugerem o fracionamento de plagioclásio, clinopiroxênio (\'+ ou -\' anfibólio), biotita e ilmenita na derivação das rochas intermediárias do batólito, enquanto que o fracionamento de feldspato alcalino, ao lado de proporções significativas de anfibólio, é indicado na derivação dos monzogranitos mais diferenciados da unidade Serra do Pau d\'Alho.Processos adicionais envolvendo interação entre os granitóides e os enclaves máficos, no extremo leste do maciço, podem explicar variações faciológicas localizadas, e pulsos magmáticos distintos parecem caracterizar os sieno- e monzogranitos da porção oeste do batólito, que constituem grupos químicos distintos. O grande volume de rochas granitóides com composição média relativamente primitiva, o caráter sin-orogênico, e as altas razões LILE/HFSE indicam feições de magmatismo de margens continentais ativas, envolvendo a contribuição de fontes enriquecidas em \"componentes de subducção\" na gênese dos granitóides do batólito. O acentuado enriquecimento no conteúdo de elementos LIL deve refletir fontes de manto litosférico enriquecido, ainda que uma contribuição substancial de crosta continental seja indicada pela elevada proporção de Sr radiogênico. Os granitóides do Batólito Pinhal-Ipuiúna representam parte do extenso magmatismo cálcio-alcalino potássico regional, de caráter sin-orogênico ao Ciclo Brasiliano. São interpretados como anteriores à principal etapa de colocação da Nappe de Empurrão Socorro-Guaxupé, e suas características geológicas, petrográficas e geoquímicas são comparáveis àquelas dos granitóides tipo l- Cordilheiranos, gerados em ambientes tectônicos pré-colisionais de arco magmático, e relacionados a regimes de subducção do tipo-B.<br>Neoproterozoic granitic magmatism of southeastern Brazil comprises a wide variety of rock suites with peculiar geochemical signatures, that are indicative of a complex tectonic evolution. Among these suites are those making up the large and elongated syn-orogenic batholiths, formed by compositionally expanded granitic suites, of which the Pinhal-Ipuiúna batholith is of particular interest. The Pinhal-Ipuiúna batholith, that comprises an area of about 930 Km², extends from the northeastern part of São Paulo State to the southwestern of Minas Gerais State. lts orientation is close to E-W, following the limit of the northern segment of the Socorro-Guaxupé Thrust Nappe, here defined by the Jacutinga shear zone, with an inflection to NW at lpuiúna region (MG).The granitoids of the batholith are intrusive in migmatitic ortho- and paragneisses, and were emplaced before the main foliation and the regional migmatization were developed (or contemporaneously to both?). They show a remarkable tectonic foliation trending WNW, developed under high-temperatures and characterized by the orientation of K-feldspar megacrysts and mafic minerals. Three associations of distinct granitoid units outcrop in the batholith vicinities and were considered genetically independent from the rocks of the massif: (a) porphyritic monzogranites and granodiorites that comprise the Pinhal complex; (b) anatectic biotite granite of the Pinhal-type, and (c) hornblende-biotite monzonites and quartz monzonites of the Maravilha Monzonitic massif. The Pinhal-lpuiúna batholith comprises of porphyritic granitoids and displays a large and continuous compositional variation (from quartz monzodiorites to sienogranites) that defines a high-K calc-alkaline modal trend. Twenty three distinct petrographic facies were recognized in these granitoids and, accordingly to their textural and compositional characteristics, were grouped into three major rock units. The oldest is São José da Prata unit and it consists of rocks of intermediate composition, with the predominance of quartz monzodiorites in which the mafic minerals, represented by hornblende (\'+ ou -\' clinopyroxene) and biotite, correspond to 20%. The second unit, named lpuiúna, predominates and comprises essentially of quartz monzonites, with 15% of amphibole and biotite, and show gradational variations to monzogranites. Augen-gneisses occur close to the Jacutinga shear zone, at the S-SW portion of the batholith. The third unit, Serra do Pau d\'Alho, is represented by the most differentiated rocks, consisting of monzogranites and sienogranites. The mafic mineral is biotite and it is up to 5%. Mafic quartz dioritic enclaves are commonly observed in the granitoids of all units and can be mapped at the lpuiúna region (MG). They show contact relationship and interaction with the regional quartz monzonites, suggesting that the magmas responsable for the crystallization of both rocks are contemporaneous. The mafic magmatism seems to have persisted until the later units of the batholith have crystallized. The geochemical behaviour of the granitoids of the Pinhal-lpuiúna batholith indicates a high-K calc-alkaline to alkali-calcic suite, suggesting a continuous sequence from the intermediate members of the São José da Prata and lpuiúna units to the most differentiated granites of the Serra do Pau d\'Alho unit. Remarkable features are also the fractionated REE patterns with negative Eu anomalies, weakly to strongly developed, and a significant LILE-enrichment, as well as high isotopic Sr ratio. This radiogenic Sr may indicate the influence of the continental crust in the genesis of the granitoids. The mafic enclaves share some chemical and isotopic signatures with the granitoids, but their composition depart, howewer, from the back-extrapolations of the chemical trend defined by the fractioned rocks of the batholith, suggesting a distinct and genetically independent chemical group. Part of the faciological diversity of the batholith indicates the influence of complex processes in the parental magma evolution, involving mechanisms of fractional crystallization between the different facies that define the main evolutive trend of the massif. Geochemical models suggest a fractionation of the plagioclase, clinopyroxene (\'+ ou -\' amphibole), biotite and ilmenite in the derivation of the intermediate rocks of the batholith, whereas the fractionation of K-feldspar and amphibole indicates the derivation of the most differenciated monzogranites of the Serra do Pau d\'Alho unit. Additional processes involving the interaction of granitoids and mafic enclaves, at the easternmost part of the massif, may explain some faciologial variations. The sieno- and monzogranites of the west portion of the batholith constitute different chemical groups that may represent distinct magmatic intrusions. The great volume of granitoid rocks with relatively primitive average composition, the syn-orogenic character, and the high LILE/HFSE ratios indicate signatures of magmatism of active continental margins, with the contribution of sources rich in subduction components. The remarkable higher LILE contents may suggest the influence of LILE-rich source areas in the lithospheric mantle, although a large contribution from continental crust is implied by the high Sr isotopic ratio. The granitoids of the Pinhal-lpuiúna batholith represent a portion of the extensive regional high-K calc-alkaline to alkali-calcic magmatism, which is syn-orogenic to the Brasiliano Cicle. These rocks have been interpreted as being formed before the main emplacement stage of the Socorro-Guaxupé Thrust Nappe, and their geological, petrographical and geochemical characteristics are comparable to the Cordilleran l-type granitoids, thought to be generated in B-type subductional environments.

Cette étude concerne le décryptage des événements successifs enregistrés dans les granitoïdes d'ages compris entre 2,16 et 2,07 Ga, qui forment le bloc de Serrinha, craton de São Francisco, Bahia, Brésil. Ce bloc forme une dorsale de direction NS qui tourne brusquement vers la direction EW dans sa portion sud où se trouve la région de Teofilândia. Cette région, caractérisée par une association de roches volcano-sédimentaires, de granitoïdes et de gneiss, héberge le district aurifère de Fazenda Brasileiro dont les minéralisations sont contrôlées par les structures EW. Les événements magmatiques liés à l’orogenèse transamazonienne sont représentés dans cette région par deux épisodes plutoniques paléoprotérozoïques: un magmatisme (TTG)-calco-alcalin juvénile dans un contexte d'arc (2,13 Ga), et un magmatisme plus tardif alcalin (2,07 Ga). Trois événements tectoniques paléoprotérozoïques ont été identifiés: le premier, D1, caractérisé par des microstructures magmatiques de direction NS, est probablement contemporain de l'arc magmatique qui a borné la limite ouest du bloc de Serrinha;. Le second, D2, identifié par ses structures HT-orthogneissiques, de direction EW, est attribué à l'accrétion du bloc de Serrinha à la frontière est du craton de São Francisco; et l'événement D3, plus local, de direction EW et microstructures mylonitiques, est responsable des minéralisations aurifères. On propose un pôle paléomagnétique (Long=314°E, Lat=1°N) d’âge 2. 080±17 Ma, qui comparé à d’autres pôles obtenus pour le craton Congo-São Francisco, indique que ce bloc n'était pas réuni aux cratons Amazonia et Ouest-Afrique pendant le Paléoprotérozoïque. Cette étude mène à une synthèse du cycle transamazonien dans le bloc de Serrinha. Cette orogenèse et le plutonisme associé sont, au Brésil et en Afrique Centrale, contemporains de l'intense activité magmatique identifiée en Afrique de l'Ouest, conséquence d'un super-événement du manteau vers 2,1 Ga. Les données paléomagnétiques indiquent que cette activité est indépendante de leur position dans le globe<br>This study aims at decoding the successive events that are recorded in the Palaeoproterozoic granitoids of the Serrinha block, São Francisco craton (Bahia, Brazil), that are age-dated between 2. 16 and 2. 07 Ga (Transamazonian orogeny). This block forms a NS-directed ridge, which rotates abruptly towards EW in its southern part where the Teofilândia area is located. This area is characterized by volcano-sedimentary formations that are associated with granitic and gneissic rocks. It hosts the Fazenda Brasileiro gold mine whose mineralization is controlled by the EW-trending structures. The magmatic events related to the Transamazonian orogeny are represented in this area by two plutonic episodes that were identified: a former juvenile arc-related calc-alkaline (TTG) magmatism (2. 13 Ga), and a late alkaline magmatism (2. 07 Ga). Three Paleoproterozoic tectonic events were identified: the first one, D1, NS-directed magmatic fabric, is attributed to the magmatic arc that bordered the western limit of the Serrinha block; the second one, D2, identified by its pervasive EW-directed HT-orthogneissic structures, is attributed to the accretion of the Serrinha block at the eastern border of the São Francisco craton; and the more local D3 event, characterized by EW mylonitic structures, in presence of fluids, is responsible by gold mineralizations. A paleomagnetic pole (Long = 314°E, Lat = 1°N) for the Congo-São Francisco craton at 2,080±17 Ma is proposed. This pole, compared with other poles obtained in the Congo-São Francisco craton, indicates that the Serrinha block was not assembled with Amazon and West-Africa cratons in the Paleoproterozoic times. This study leads to a synthesis of the Transamazonian cycle in the Serrinha block. This orogeny and the associated plutonism in Brazil and Central Africa is coeval with an intense magmatic activity in West Africa, as a consequence of a mantle superevent around 2. 1 Ga. The paleomagnetic data indicate that this activity is irrespective of their position in the globe

Submitted by Everaldo Pereira (pereira.evera@gmail.com) on 2017-06-16T19:55:37Z No. of bitstreams: 1 Tese Hosanira Nascimento.pdf: 13412204 bytes, checksum: e9174202d74d631497129ddfc5dece50 (MD5)<br>Made available in DSpace on 2017-06-16T19:55:37Z (GMT). No. of bitstreams: 1 Tese Hosanira Nascimento.pdf: 13412204 bytes, checksum: e9174202d74d631497129ddfc5dece50 (MD5)<br>Este estudo refere-se a identificação dos eventos sucessivos registados em granitóides de idades compreendidas entre 2,16 e 2,07 Ga que formam o Bloco Serrinha, cráton do São Francisco, Bahia, Brasil. Este bloco forma uma dorsal de direção NS que rotaciona bruscamente para a direcção EW na sua porção sul onde encontra-se a região de Teofilândia. Esta região, caracterizada por uma associação de rochas vulcano-sedimentares, granitóides e gnaisses, hospeda o distrito aurífero de Fazenda Brasileiro cujas mineralizações são controladas pelas estruturas EW. Para desvendar a história polifásica dessas rochas foram realizados estudos de microestrutura, tramas magnéticas e minerais, mineralogia, geoquímica e paleomagnetismo. Os eventos magmáticos ligados à Orogênese Transamazônica são representados por dois episódios plutônicos paleoproterozóicos identificados no sul do Bloco Serrinha. Primeiro um magmatismo (TTG)-cálcio-alcalino juvenil num contexto de arco, representado pelo granodiorito Teofilândia e pelo trondhjemito Barrocas (2,13 Ga), e em seguida um magmatismo mais tardio ferropotássico alcalino representado pelo granito Santa Rosa (2,07 Ga). Sugere-se que os granitoides (TTG)-cálcio-alcalinos da região de Teofilândia e do Bloco Serrinha sejam semelhantes aos granitóides birimianos juvenis do Oeste da África. A existência de três eventos tectônicos paleoproterozoicos no Bloco Serrinha foi demonstrada a partir do estudo sistemático das tramas magnéticas e microestruturas dos granitóides, combinado a dados isotópicos e de pressão. O primeiro, D1, caracterizado a partir da identificação de um núcleo granítico que conserva a sua estrutura magmática NS original nos granitóides cálcio-alcalinos, é provavelmente contemporâneo do arco magmático localizado no limite ocidental do Bloco Serrinha. O segundo, D2, identificado pelas suas pervasivas estruturas ortognáissicas de alta temperatura, de direção EW na região de Teofilândia, é atribuído à colisão entre o Bloco Serrinha e a fronteira leste do Cráton do São Francisco. Enfim, o evento D3 mais localizado, de direção EW, que ocorreu à baixa temperatura (Fácies Xisto Verde), em presença de fluidos, é responsável pelas mineralizações auríferas. Ele marca o fim da orogênese transamazônica na região de Teofilândia. Propõe-se um pólo paleomagnético (Long=314°E, Lat=1°N; dp=16,3, dm=16,6) de idade 2.080±17 Ma para o cráton do Congo-São Francisco. Os dados indicam que a magnetização remanente foi adquirida exatamente após o pico térmico do metamorfismo na Fácies Anfibolito, que corresponde ao evento D2. Este pólo paleomagnético, uma vez comparado com os pólos obtidos por outros autores para o Cráton do Congo-São Francisco, indica que este bloco não estava amalgamado com os crátons Amazônico e Oeste Africano durante o Paleoproterozóico. O estudo petrológico, a compilação dos dados isotópicos existentes, e as observações estruturais conduzem à uma síntese do Transamazônico no Bloco Serrinha. A Orogênese Transamazônica e o plutonismo associado são, no Brasil e na África Central, contemporâneos da intensa atividade magmática identificada no Oeste da África. Eles são a consequência de um super-evento do manto à 2,1 Ga. Os dados paleomagnéticos indicam que esta atividade, responsável da grande quantidade de crosta juvenil paleoproterozóica presente nestes cratons, é independente de suas posições no globo.<br>ABSTRACT - This study aims at decoding the successive events that are recorded in the Palaeoproterozoic granitoids of the Serrinha block, São Francisco craton (Bahia, Brazil), that are age-dated between 2.16 and 2.07 Ga (Transamazonian orogeny). This block forms a NS-directed ridge, which rotates abruptly towards EW in its southern part where the Teofilândia area is located. This area is characterized by volcano-sedimentary formations that are associated with granitic and gneissic rocks. It hosts the Fazenda Brasileiro gold mine whose mineralization is controlled by the EW-trending structures. The polyphase history of these rocks has been unraveled through studies of theirs microstructures, magnetic and mineral fabrics, mineralogy, geochemistry and paleomagnetism. The magmatic events related to the Transamazonian orogeny are represented by two plutonic episodes that were identified in the south of the Serrinha block. A former juvenile arcrelated calc-alkaline (TTG) magmatism, very similar to the juvenile Birimian granitoids of West Africa, is represented by the Teofilândia granodiorite and the Barrocas trondhjemite (2.13 Ga). A late subalkaline ferro-potassic magmatism is represented by the Santa Rosa granite (2.07 Ga). Three Paleoproterozoic tectonic events were identified in the Serrinha block granitoids from the systematic study of magnetic fabrics and microstructures, together with the isotopic and pressure data. The first event, D1, is characterized from the identification of a granitic core which preserves its original NS magmatic fabric. This magmatic activity and fabric is attributed to the magmatic arc that bordered the western limit of the Serrinha block. The second event, D2, identified by its pervasive HT-orthogneissic structures, EW-directed in the Teofilândia area, is attributed to the accretion of the Serrinha block at the eastern border of the São Francisco craton. The more local D3 event took place at lower temperature, in presence of fluids, at greenschist facies conditions. It marks the end of the Transamazonian orogeny in the area. A paleomagnetic pole (Long = 314°E, Lat = 1°N; dp =16.3, dm = 16.6) for the CongoSão Francisco craton at 2,080±17 Ma is proposed. Our data indicate that the magnetization was acquired after the climax of the amphibolite facies metamorphism, related to the high-T gneissic deformation event D2. This pole, together with the poles obtained by other authors in the CongoSão Francisco craton, indicates that the Serrinha block was not assembled with Amazon and West-Africa cratons in the Paleoproterozoic times. The petrological study, along with the compilation of existing isotopic data and the structural observations lead to a synthesis of the Transamazonian cycle in the Serrinha block. The Transamazonian orogeny and associated plutonism in Brazil and Central Africa is coeval with an intense magmatic activity in West Africa, as a consequence of a mantle superevent around 2.1 Ga. This mantle activity was responsible for the large amount of Paleoproterozoic juvenile crust that is present in these cratons irrespective of their position in the globe.<br>RÉSUMÉ Cette étude concerne le décryptage des événements successifs enregistrés dans les granitoïdes d'ages compris entre 2,16 et 2,07 Ga qui forment le bloc de Serrinha, craton de São Francisco, Bahia, Brésil. Ce bloc forme une dorsale de direction NS qui tourne brusquement vers la direction EW dans sa portion sud où se trouve la région se Teofilândia. Cette région, caractérisée par une association de roches volcano-sédimentaires, de granitoïdes et de gneiss, héberge le district aurifère de Fazenda Brasileiro dont les minéralisations sont contrôlées par les structures EW. Pour démêler l'histoire polyphasée de ces roches nous avons réalisé des études de leurs microstructures, de leurs fabriques magnétiques et minérales, de leur minéralogie, de leur géochimie et de leur paléomagnétisme. Les événements magmatiques liés à l’orogenèse transamazonienne sont représentés par deux épisodes plutoniques paléoprotérozoïques identifiés dans le Sud du bloc de Serrinha. D'abord un magmatisme (TTG)-calco-alcalin juvénile dans un contexte d'arc, représenté par la granodiorite de Teofilândia et la trondhjémite de Barrocas (2,13 Ga), et ensuite un magmatisme plus tardif ferro-potassique alcalin représenté par le granite de Santa Rosa (2,07 Ga). On suggère que les granitoïdes (TTG)-calco-alcalins de la région de Teofilândia et du bloc de Serrinha sont semblables aux granitoïdes birimiens juvéniles de l'Afrique de l'Ouest. L'existence de trois événements tectoniques paléoprotérozoïques dans le bloc de Serrinha a été démontrée à partir de l'étude systématique des fabriques magnétiques et des microstructures des granitoïdes, alliée aux données isotopiques et de pression. Le premier, D1, caractérisé à partir de l’identification d'un cœur granitique qui conserve sa structure magmatique NS originale dans les granitoïdes calco-alcalins, est probablement contemporain de l'arc magmatique qui a borné la limite ouest du bloc de Serrinha. Le second, D2, identifié par ses structures HTorthogneissiques, de direction EW dans la région de Teofilândia, est attribué à l'accrétion du bloc de Serrinha à la frontière est du craton de São Francisco. Enfin, l'événement D3 plus local, de direction EW, qui a fonctionné à plus basse température (faciès schistes verts), en présence de fluides, est responsable des minéralisations aurifères. Il marque la fin de l'orogenèse transamazonienne dans la région de Teofilândia. On propose un pôle paléomagnétique (Long=314°E, Lat=1°N; dp=16,3, dm=16,6) d’âge 2.080±17 Ma pour cette partie du craton Congo-São Francisco. Les données indiquent que l’aimantation a été acquise juste après le maximum thermique du métamorphisme de faciès amphibolite correspondant à l’événement D2. Ce pôle paléomagnétique, une fois comparé aux pôles obtenus par d´autres auteurs pour le craton Congo-São Francisco, indique que ce bloc n'était pas réuni aux cratons Amazonia et Ouest-Afrique pendant le Paléoprotérozoïque. L´étude pétrologique, la compilation des données isotopiques existantes, et les observations structurales mènent à une synthèse du cycle transamazonien dans le bloc de Serrinha. L'orogenèse transamazonienne et le plutonisme associé sont, au Brésil et en Afrique Centrale, contemporains de l'intense activité magmatique identifiée en Afrique de l'Ouest. Ils sont la conséquence d'un super-événement du manteau vers 2,1 Ga. Les données paléomagnétiques indiquent que cette activité, responsable de la grande quantité de croûte juvénile paléoprotérozoïque présente sur ces cratons, est indépendante de leur position dans le globe.

Thesis (Ph. D.)--University of Adelaide, Dept. of Geology & Geophysics, 1997.<br>Errata pasted onto front end paper. Two folded maps in pocket on back cover. Four microfiches in pocket on back cover. Includes bibliographical references (leaves 251-289).

Les granitoïdes associés aux skarn à Cu-Pb-Zn et au W, dérivent, respectivement, de la fusion partiellede roches mafiques à amphiboles dans la croute inférieure et de roches métas-édimentaires riches enmuscovite dans la croute moyenne-supérieure. Ces sources fertiles mobilisées pour la formation de cesplutons a permis la formation de gisements à Cu-Pb-Zn, et W au cours du Jurassique moyen. L’originedans la croûte moyenne de la granodiorite de Tongshanling, associée aux minéralisations à Cu-Pb-Zn, aété montrée par l’étude des enclaves microgranulaires dioritiques qui sont des restites remaniées issuesde la fusion partielle des amphibolites de la croûte inférieure. Le Cu et le Zn associées à ces plutons sontprobablement issus de la croûte inférieure et ces métaux ont probablement étés remobilisés au cours dela fusion partielle. Le Pb issue de la croute supérieur a été collecté lors de l’ascension du magma qui adonné la granodiorite. Lors de leur mise en place ces granitoïdes ont exprimé leur potentielminéralisateur. L’étude structural montre que la géométrie des corps minéralisés et en lien avec ladéformation induite par la mise en place des plutons. Les différentes expressions de la minéralisationdans le district à Cu-Mo-Pb-Zn-Ag de Tongshanling sont génétiquement lié à l’hydrothermalisme et à sonévolution lors du développement du skarn. Le granite de Weijia a cristallisé à partir d’un magma saturéen eau et riche en Fluor. Les facteurs qui ont contrôlé la formation de ce skarn magnésien riche en W,suppose l’existence d’une source enrichie en W dans les sources métasédimentaires et d’un magmariche en Fluor très différentia par cristallisation fractionnée<br>The Middle-Late Jurassic Cu-Pb-Zn-bearing and W-bearing granitoids in the Nanling Range were mainlyderived from non-simultaneous partial melting of the mafic amphibolitic rocks in the lower crust and themuscovite-rich metasedimentary rocks in the upper-middle crust, respectively. The fertile sources in theNanling Range are beneficial to the formation of Cu-Pb-Zn and W deposits during Middle-Late Jurassic.The lower-crust origin of the Cu-Pb-Zn-bearing granodiorites is further demonstrated by the dioriticmicrogranular enclaves in the Tongshanling granodiorite which are reworked restite enclaves derivedfrom partial melting of the mafic amphibolitic source. The Cu and Zn associated with these intrusionswere most probably released from the mafic amphibolitic lower crust by partial melting, whereas, Pb wasextracted from the upper crust by ascending granodioritic magmas. The emplacement of these orebearinggranitoid magmas may have a structural connection with the subsequent polymetallicmineralization in some way. For instance, the exoskarn and sulfide-quartz veins in the Tongshanling Cu-Pb-Zn deposit are evidently controlled by magma emplacement-induced wall-rock deformation. Thedifferent mineralization types and ore deposits in the Tongshanling Cu-Mo-Pb-Zn-Ag ore district aregenetically linked together in the same skarn system as the productions of evolution and zonation. TheWeijia granite was crystallized from a F-rich and water-saturated magma. The key factors controlling theoccurrence of unusual magnesian skarn W mineralization during Late Jurassic in the Nanling Rangemainly include a W enriched metasedimentary source, a fluorine-rich magma, a strong crystalfractionation, and a fluorine-rich hydrosaline melt

On individualise six associations magmatiques formant trois grandes familles ; une famillet calcalcaline d'origine lithosphérique appartenant au Pharusien 1 une famille subalcaline claire du pharusien 2, de type marge continentale ; une famille alcaline, d'une nouvelle source osthémosphérique. La province alcaline orogénique du timgaouine est originale par ses minéralisations en W, SR, AU, V, TH. . .

Le but de ce travail est double : étudier un magmatisme traversant un paléoprisme d'accrétion et clarifier le contexte géodynamique du Japon SO au cours du Miocène. Le magmatisme étudié présente un âge miocène moyen, une grande variété d'affinités magmatiques (calco-alcalin, alcalin, Morb-E-T, thpléite d'arc) et recoupe les terrains sédimentaires de la chaîne de Shimanto (Japon SO). L'analyse s'est déroulée en quatre étapes : - établissement d'une chronologie relative et caractérisation des pétrotypes, - établissement du contexte tectonique régional contemporain au magmatisme, - analyse géochimique en vue de contraindre la genèse des différentes lignées, - intégration du magmatisme dans un modèle d'évolution géodynamique. Les principaux résultats sont : - le pluton de Yakushima s'est mis en place par injection de magma au droit d'une "fente de tension" et sous une tectonique régionale compressive. - Le magmatisme alcalin est principalement issu de la cristallisation fractionnée à partir d'un magma basique provenant de la fusion du manteau asthénosphérique. - Les complexes calco-alcalins se différencient par cristallisation fractionnée à partir de magmas issus du mélange entre sources mantelliques et crustales. - Le modèle géodynamique le plus favorable est celui de la restructuration du prisme d'accrétion de Shimanto par une collision avec un microbloc venant du Sud. Les moteurs du magmatisme sont la naissance d'une nouvelle subduction et la remontée de matériel asthénosphérique au front du plan de subduction.