Magmatic-hydrothermal ore deposits are formed in association with aqueous fluids that exsolve from hydrous silicate melts during ascent and crystallization. These fluids are invariably trapped as inclusions in vein-filling minerals associated with hydrothermal fluid flow, and their composition may be modeled based on the H₂O-NaCl system. Thus, if we know the pressure-volume-temperature-composition (PVTX) properties of H₂O-NaCl solutions, it is possible to interpret the PTX trapping conditions, which is important for understanding the processes leading to the generation of the hydrothermal system and ore mineralization. High salinity (> 26 wt. % NaCl) fluid inclusions contain liquid, vapor, and halite at room temperature, and are common in magmatic-hydrothermal ore deposits. These inclusions homogenize in one of three ways: A) halite disappearance (Tmhalite) followed by liquid-vapor homogenization (ThL-V), B) simultaneous ThL-V and Tmhalite, or C) ThL-V followed by Tmhalite. The PVTX properties of H₂O-NaCl solutions three phase (L+V+H) and liquid-vapor (L+V) phase boundaries are well constrained, allowing researchers to interpret the minimum trapping pressure of inclusion types A and B. However, data that describe the pressure at Tmhalite for inclusion type C are limited to a composition of 40 wt. % NaCl. To resolve this problem, the synthetic fluid inclusion technique was used to determine the relationship between homogenization temperature and minimum trapping pressure for inclusions that homogenize by mode C. These results allow researchers to interpret the minimum trapping pressure of these inclusions, and by extension the depth at which the inclusions formed. The temporal and spatial distribution of fluid inclusions formed in associated with porphyry copper mineralization has been predicted using a computer model. A simple geologic model of an epizonal intrusion was developed based on a Burnham-style model for porphyry systems and thermal models of the evolution of epizonal intrusions. The phase stability fields and fluid inclusion characteristics at any location and time were predicted based on PVTX properties of H₂O-NaCl solutions. These results provide vectors towards the center of a magmatic-hydrothermal system that allow explorationists to use fluid inclusion petrography to predict position with the overall porphyry environment when other indicators of position are absent. / Ph. D.

No description available.

The aim of this thesis is to increase our knowledge and understanding of trace water concentrations in nominally anhydrous minerals (NAMs). Special focus is put on the de- and rehydration mechanisms of clinopyroxene crystals in volcanic systems, how these minerals can be used to investigate the volatile content of mantle rocks and melts on both Earth and other planetary bodies (e.g., Mars). Various analytical techniques for water concentration analysis were evaluated. The first part of the thesis focusses on rehydration experiments in hydrogen gas at 1 atm and under hydrothermal pressures from 0.5 to 3 kbar on volcanic clinopyroxene crystals in order to test hydrogen incorporation and loss from crystals and how their initial water content at crystallization prior to dehydration may be restored. The results show that extensive dehydration may occur during magma ascent and degassing but may be hindered by fast ascent rates with limited volatile loss. De- and rehydration processes are governed by the redox-reaction OH- + Fe2+ ↔ O2- + Fe3+ + ½ H2. Performing rehydration experiments at different pressures can restore the water contents of clinopyroxene at various levels in the volcanic systems. Subsequently water contents of magmas and mantle sources can be deduced based on crystal/melt partition coefficients. This thesis provides examples from the Canary Islands, Merapi volcano in Indonesia and the famous Nakhla meteorite. Using NAMs as a proxy for magmatic and mantle water contents may provide a very good method especially for planetary science where sample material is limited. The thesis’ second part focusses on analytical methods to measure the concentration of water in NAMs. Specifically the application of Raman spectroscopy and proton-proton scattering are tested. The hydrated mineral zoisite is thoroughly analyzed in order to be used as an external standard material. Polarized single crystal spectra helped to determine the orientation of the OH-dipole in zoisite. Further, Transmission Raman spectroscopy and a new method for the preparation of very thin samples for proton-proton scattering were developed and tested. The results provide new possibilities for the concentration analysis of water in NAMs such as three dimensional distribution and high spatial resolution.

O magmatismo Penatecaua no Estado do Pará faz parte da Província Magmática do Atlântico Central (CAMP) cuja formação precedeu a ruptura do Pangea, o mais recente supercontinente. Nos arredores das cidades de Medicilândia, Placas, Rurópolis, Monte Alegre e Alenquer afloram uma grande quantidade de soleiras de diabásio e diques observados ao longo de estradas. Idades 40Ar/39Ar recentes atribuem a idade de ~ 201 Ma para o magmatismo CAMP nessa região. Estudo paleomagnético nessas intrusões foi realizado em trinta sítios de amostragem nas cinco áreas acima citadas. A magnetização remanente característica dos sítios estudados é de polaridade normal e foi identificada através de desmagnetizações por campos magnéticos alternados e térmicas e interpretada como termorremanente, adquirida na época do resfriamento da rocha. Os portadores magnéticos são magnetitas ou titano-magnetitas com baixo conteúdo de Titânio. O polo paleomagnético calculado com base em 20 sítios de amostragem e incorporando dados da literatura para o mesmo magmatismo, situa-se a 78 ºN 85.1 ºE (N = 25; 95 = 4.2; k = 47.78) e é coerente com polos de outras ocorrências ígneas da América do Sul já identificadas como pertencentes ao evento CAMP. Essa similaridade de resultados reforça as observações de que o CAMP na América do Sul foi um evento muito rápido e isso é notado claramente no registro magnético das rochas do Penatecaua. / The Penatecaua magmatism occurring in northern Brazil (Pará State) belongs to the so-called Central Atlantic Magmatic Province (CAMP), which preceded the Pangaea breakup. Near the cities of Medicilândia, Placas. Rurópolis, Monte Alegre e Alenquer diabase sills and dikes outcrop along roads. Recent 40Ar/39Ar dating give an age of ~ 201 Ma for the CAMP magmatism in the area. The paleomagnetic study on 20 sampling sites of the Penatecaua magmatism, revealed stable characteristic magnetization components through alternating magnetic field and thermal demagnetizations. The main magnetic carriers are magnetite or low-Ti titanomagnetites. The paleomagnetic pole based on the studied sites and incorporating more data from the literature for the same magmatism is located at 78 ºN 85.1 ºE (N = 25; 95 = 4.2; k=47.78) and is coherent to other South American CAMP paleomagnetic poles for which good age control is available. This similarity of results reinforces the observations that the CAMP in South America was a very fast event and this is noticed in the magnetic record of the Penatecaua rocks.

Orientador: Antonio José Ranalli Nardy / Banca: Marcos Aurélio Farias de Oliveira / Banca: José Paulo Peccinini Pinese / Resumo: Este trabalho trata da investigação petrográfica e geoquímica dos derrames da Formação Serra Geral da Bacia do Paraná, distribuídas em quatro regiões distintas: Jaú, Ribeirão Preto, Franca e Fernandópolis, cobrindo praticamente toda a área de exposição dessas rochas no estado de São Paulo. As amostras coletadas nessas regiões foram analisadas através de microscopia de luz polarizada, evidenciando que os basaltos estudados são constituídos fundamentalmente por plagioclásio (30-40%), piroxênios (20-30%), magnetita (5-15%) e apatita (menos de 1%), apresentando textura predominantemente intergranular e suas variedades (intersertal, hialofítica e pilotaxítica). Os dados geoquímicos revelaram que as amostras estudadas correspondem a basaltos de natureza toleítica, com TiO2 ≥ 1,8%, característicos da região norte da Bacia do Paraná. Dados geoquímicos de elementos traços e terras raras mostraram que as rochas estudadas podem ser agrupadas em três diferentes magmas-tipo: Paranapanema (basaltos de Fernandópolis), Urubici (basaltos de Franca) e Pitanga (basaltos de Ribeirão Preto e de Jaú). Os padrões de distribuição desses elementos mostram que eles não podem ser gerados a partir de fontes mantélicas astenosféricas, mas sim, de fontes litosféricas distintas. / Abstract: A petrographical and geochemistry characterization of flood basalts of Serra Geral Formation of Paraná Basin is here presented. The investigated area is sited in four different regions of São Paulo state: Jaú, Ribeirão Preto, Franca e Fernandópolis. It represents almost the total exposure area of lava flows in São Paulo State. The petrographical data of these rocks reveals that the basalts are constituted mainly by plagioclase (30-40%), pyroxene (20-30%), magnetite (5-15%) and apatite, that characterized a intergranular, intersertal, hialophitic and pilotaxitic textures. The geochemical data show a basic and tholeiitic composition of the studied basalts with TiO2 ≥ 1,8%, characterized of the northern of Paraná Basin. Three different magmatypes were recognized: Paranapanema (basalts of Fernandópolis region), Urubici (basalts of Franca region) and Pitanga (basalts of Ribeirão Preto and Jaú regions). The distribution patterns of these elements in a spider diagram have showed that they are generated by lithospheric mantle. / Mestre

A parte central de Moçambique foi marcada por eventos episódicos consistindo de granitogênese mesoproterozóico e neoproterozóico, magmatismo neoproterozóico, sedimentação neoproterozóica e magmatismo cambriano. Estes eventos produziram unidades geológicas cujas relações espaciais e temporais tem sido controversas no que se refere à Suíte de Guro e ao Complexo de Bárue. Alguns autores defendem a existência de duas unidades geológicas distintas e outros incorporavam a Suite de Guro no Complexo de Bárue formando assim uma e única unidade geológica. Dentro deste contexto este trabalho tenta dar uma melhoria no modelo geocronológico/tectônico das rochas graníticas do Complexo de Bárue e da Suíte de Guro utilizando dados geocronológicos U-Pb SHRIMP em zircão e idades Sm-Nd modelo manto empobrecido (\'T IND.DM\' ), caracterizando as suas respectivas fontes e evoluções tectono-magmáticas com base na geoquímica isotópica Sr e Nd em rocha total e em dados litogeoquímicos em rocha total. Estes dados em conjunto com as informações geológicas e geocronológicas disponíveis na literatura permitiram modelar a evolução da crosta continental da região central de Moçambique. O modelo proposto aponta para eventos de cristalização magmática mesoproterozóico, neoproterozóico e cambriano e de sedimentação neoproterozóico. Em adição, apartir dos dados obtidos e das informações das ocorrências minerais disponíveis para a área de estudo, foi feita a correlação dos processos ígneos e metamórficos relacionados à evolução tectono-magmática dos granitóides com as suas respectivas especializações metalogenêticas, visando o estabelecimento de critérios de prospectividade regional para exploração mineral. Alguns eventos relacionados com intrusão de veios pegmatíticos e alteração de rochas pré-existentes são responsáveis pelas mineralizações na área de estudo. / The central part of Mozambique was marked by Mesoproterozoic and Neoproterozoic granite genesis events followed by Neoproterozoic sedimentation events and Cambrian magmatism. These events produced geological units whose spatial relationship has been controversial in regard to the Guro Suite and the Bárue Complex. Some authors advocate the existence of two distinct geological units and other embodied the Guro Suite in the Bárue complex thus forming one and the same geological unit. Within this context, this work tries to give an improvement in geochronological pattern of granitic rocks of the Bárue Magmatic Arc and Guro Suite using geochronological U-Pb SHRIMP data on zircons and Sm-Nd depleted mantle model ages (\'T IND.DM\'), characterizing their respective sources and tectonic-magmatic evolution based on whole rock Sr and Nd isotope geochemistry and whole rock Lithogeochemical data. These data together with the geological and geochronological data available in the literature allowed modeling the evolution of the continental crust of central Mozambique. The proposed model points to Mesoproterozoic, Neoproterozoic, and Cambrian magmatic crystallization events and followed by Neoproterozoic sedimentation. In addition, from the obtained data and information of mineral occurrences available for the study area, the correlation of igneous and metamorphic processes related to tectonic and magmatic evolution of the granitoids with their respective metallogenetic specialization was made, aiming to establish a regional prospective solutions for mineral exploration. Some events related to pegmatitic veins intrusion and alteration of preexisting rocks are responsible for the mineralization in the study area.

O presente trabalho tem como objetivo estudar a evolução térmica de corpos intrusivos em diferentes níveis da crosta formados por múltiplas injeções de magma em forma de sils, levando em consideração mudança de fase e liberação de calor latente em um intervalo finito de temperaturas. A análise proposta inclui o estudo dos modelos de transferência de calor puramente condutivos utilizando a equação da evolução da entalpia que integra a mudança composicional dos magmas. A evolução térmica do corpo ígneo gerado por introdução do magma basáltico através de sils na crosta inferior obtém-se usando o método das diferenças finitas em uma dimensão, além disso se desenvolvem duas formas de construção do corpo ígneo neste nível: acréscimo por cima e acréscimo por baixo, sendo o primeiro caso o mais eficiente em manter o sistema a temperaturas elevadas durante mais tempo. Na crosta superior a evolução térmica do corpo ígneo de composição próxima ao tonalito introduzido por meio de sils é resolvida em duas dimensões com o método dos elementos finitos utilizando uma geometria com simetria axial no eixo z. O desenvolvimento destes corpos depende do ritmo de acréscimo do magma e das propriedades térmicas tanto da crosta como do magma injetado, podendo desenvolver-se como uma câmara magmática, um repositório de fusão ou um corpo altamente cristalino. A segunda fase do trabalho consistiu na solução da equação de condução de calor com mudança de estado em câmaras magmáticas esféricas, esferóides oblatos e esferóides prolatos com o método de elementos finitos para analisar evolução do sistema crosta-câmara magmática e introduzir o estudo da variação da viscosidade em função da temperatura. A geometria da câmara magmática influencia fortemente os fluxos de calor à crosta e portanto a criação de um halo dúctil que pode afetar a estabilidade dela mesma. / The purpose of this work is to study the thermal evolution of intrusive bodies formed by successive sills injection in different levels of the crust, taking into account the phase change and latent heat release in a finite temperatures interval. Our numerical models involve heat transfer only by conduction. Thermal evolution of the system is found with the energy balance equation of enthalpy that includes phase and composition change of magmas. The thermal evolution of the basaltic igneus body intruded into the lower crust is evaluated using finite difference scheme. At this level of the crust we develop two different ways of igneus body construction: over- accretion and under-accretion. Over-accretion is the more efficient way for keeping high temperatures in the time. In the upper crust, the thermal evolution of a tonalite igneus body formed by successive sils injection is computed with finite elements method in a geometry with rotational symmetry about z axis. Thermal and geological development of this igneus bodys strongly depends on magma emplacement rate and magma and crust thermal proprerties. These features defines if the igneus body develops in a magmatic chamber, a melt reservior or a high crystalline body. In the second part of this work we examine heat transfere from magamatic chambers of different geometries into the country rock, solving the entalphy equation with latent heat release effects with finite element method. The magmatic chambers geometries constructed are oblate spheroid, prolate spheroid and spherical. The viscosity of the rock is also obteined from temperature field.

O presente trabalho tem como objetivo estudar a evolução térmica de corpos intrusivos em diferentes níveis da crosta formados por múltiplas injeções de magma em forma de sils, levando em consideração mudança de fase e liberação de calor latente em um intervalo finito de temperaturas. A análise proposta inclui o estudo dos modelos de transferência de calor puramente condutivos utilizando a equação da evolução da entalpia que integra a mudança composicional dos magmas. A evolução térmica do corpo ígneo gerado por introdução do magma basáltico através de sils na crosta inferior obtém-se usando o método das diferenças finitas em uma dimensão, além disso se desenvolvem duas formas de construção do corpo ígneo neste nível: acréscimo por cima e acréscimo por baixo, sendo o primeiro caso o mais eficiente em manter o sistema a temperaturas elevadas durante mais tempo. Na crosta superior a evolução térmica do corpo ígneo de composição próxima ao tonalito introduzido por meio de sils é resolvida em duas dimensões com o método dos elementos finitos utilizando uma geometria com simetria axial no eixo z. O desenvolvimento destes corpos depende do ritmo de acréscimo do magma e das propriedades térmicas tanto da crosta como do magma injetado, podendo desenvolver-se como uma câmara magmática, um repositório de fusão ou um corpo altamente cristalino. A segunda fase do trabalho consistiu na solução da equação de condução de calor com mudança de estado em câmaras magmáticas esféricas, esferóides oblatos e esferóides prolatos com o método de elementos finitos para analisar evolução do sistema crosta-câmara magmática e introduzir o estudo da variação da viscosidade em função da temperatura. A geometria da câmara magmática influencia fortemente os fluxos de calor à crosta e portanto a criação de um halo dúctil que pode afetar a estabilidade dela mesma. / The purpose of this work is to study the thermal evolution of intrusive bodies formed by successive sills injection in different levels of the crust, taking into account the phase change and latent heat release in a finite temperatures interval. Our numerical models involve heat transfer only by conduction. Thermal evolution of the system is found with the energy balance equation of enthalpy that includes phase and composition change of magmas. The thermal evolution of the basaltic igneus body intruded into the lower crust is evaluated using finite difference scheme. At this level of the crust we develop two different ways of igneus body construction: over- accretion and under-accretion. Over-accretion is the more efficient way for keeping high temperatures in the time. In the upper crust, the thermal evolution of a tonalite igneus body formed by successive sils injection is computed with finite elements method in a geometry with rotational symmetry about z axis. Thermal and geological development of this igneus bodys strongly depends on magma emplacement rate and magma and crust thermal proprerties. These features defines if the igneus body develops in a magmatic chamber, a melt reservior or a high crystalline body. In the second part of this work we examine heat transfere from magamatic chambers of different geometries into the country rock, solving the entalphy equation with latent heat release effects with finite element method. The magmatic chambers geometries constructed are oblate spheroid, prolate spheroid and spherical. The viscosity of the rock is also obteined from temperature field.

The Alisitos arc segment forms part of the western zone of Jura-Cretaceous Peninsular Ranges batholith of Baja California. It extends south from the ancestral Agua Blanca Fault to the state boundary between Baja Norte and Sur. The study area is located within a fold and thrust belt intruded by a number of plutons that were emplaced during and after the deformational event. The northern end of the Alisitos arc is characterized by subvertical tight to isoclinal folds and high-angle reverse faults that define a northwest trending, southwest vergent fold and thrust belt. The aABF defines the northern limit to the Alisitos arc segment. In this study we present the results of a petrographic study of igneous rocks in order to determine the relative timing and the distribution of deformation within the northern Alisitos arc segment. The study includes samples of the mylonitic shear zone of the aABF, and plutonic samples from intrusions proximal to the aABF emplaced later during regional deformation. These samples were investigated in order to characterize the distribution of the subsolidus strain in grain scale and the sense of shear during later phases of deformation in the northern Alisitos arc. The results are presented and discussed based on the mineralogical and textural observations from the Balbuena pluton, the Piedra Rodada pluton, and volcaniclastics that were deformed within the aABF. The Balbuena pluton, emplaced at ~ 108 Ma after the surrounding country rocks had already been folded, exhibits little if any evidence for subsolidus deformation. In contrast, the Piedra Rodada pluton, emplaced at ~ 105 Ma just to the southwest of the aABF, exhibits a strong magmatic fabric overprinted by a moderate subsolidus fabric to the southwest that grades into a strong subsolidus fabric with proximity to the fault. Kinematics observed from lineation parallel-foliation normal sections exhibit consistent top-to-the southwest sense of shear.

Magma-crust interaction in magma reservoirs and conduits is a crucial process during magma evolution and ascent. This interaction is recorded by crustal xenoliths that frequently show partial melting, inflation and disintegration textures. Frothy xenoliths are widespread in volcanic deposits from all types of geological settings and indicate crustal gas liberation. To unravel the observed phenomena of frothy xenolith formation we experimentally simulated the behaviour of crustal lithologies in volcanic conduits. We subjected various sedimentary lithologies to elevated temperature (maximum 916 °C) and pressure (maximum 160 MPa) in closed-system autoclaves. Experimental conditions were held constant between 24h and 5 days. Controlled decompression to atmospheric pressure then simulated xenolith ascent. Pressure release was a function of temperature decline in our setup. Temperature lapse rate proceeded exponentially; the mean rate during the first 30 minutes was 17.8 ˚C/min and the mean decompression rate during the same interval was 3.0 MPa/min, eventually reaching room temperature after approximately 5.5 hours of slow cooling. The experimental products have been analysed for internal textures by synchrotron X-ray μ-CT at a resolution of 3.4 – 9 microns/pixel. This method permits visualisation and quantification of vesicle volumes, -networks and-connectivity in 3D without destroying the sample. Experimental products closely reproduced textures of natural frothy xenoliths in 3D and define anevolutionary sequence from partial melting to gas exsolution and bubble nucleation that eventually leads to the development of three-dimensional bubble networks. Experimental P-T-t conditions and especially rock lithology proved decisive for degassing behaviour and ensuing bubble nucleation during decompression. Progressive bubble nucleation leads to subsequent bubble coalescence to form interconnected bubble networks. This, in turn, enables efficient gas liberation and release. Our results attest to significant potential of even very common crustal rock types to release volatiles and develop interconnected bubble networks upon heating and decompression in magmatic systems. Crustal volatile input from xenoliths affects magma rheology and may drive magmas to sudden explosive eruptions. Our experiments offer insight into the mechanism of how such crustal volatile liberation is accomplished.