Veins and pervasive wall-rock alteration composed of coarse muscovite +/- quartz +/- pyrite are documented for the first time in a porphyritic granite at Luhr Hill in the Yerington District, Nevada. Coarse muscovite at Luhr Hill occurs at paleodepths of similar to 6-7 km in the roots of a porphyry copper system and crops out on the scale of tens to hundreds of meters, surrounded by rock that is unaltered or variably altered to sodic-calcic assemblages. Coarse muscovite veins exhibit a consistent orientation, subvertical and N-S striking, which structurally restores to subhorizontal at the time of formation. Along strike, coarse muscovite veins swell from distal, millimeter-thick muscovite-only veinlets to proximal, centimeter-thick quartz-sulfide-bearing muscovite veins. Crosscutting relationships between coarse muscovite veins, pegmatite dikes, and sodic-calcic veins indicate that muscovite veins are late-stage magmatic-hydrothermal features predating final solidification of the Luhr Hill porphyritic granite. Fluid inclusions in the muscovite-quartz veins are high-density aqueous inclusions of similar to 3-9 wt% NaCl eq. and < 1 mol% CO2 that homogenize between similar to 150 and 200 A degrees C, similar to fluid inclusions from greisen veins in Sn-W-Mo vein systems. Our results indicate that muscovite-forming fluids at Luhr Hill were mildly acidic, of low to moderate salinity and sulfur content and low CO2 content, and that muscovite in deep veins and alteration differs in texture, composition, and process of formation from sericite at shallower levels of the hydrothermal system. Although the definition of greisen is controversial, we suggest that coarse muscovite alteration is more similar to alteration in greisen-type Sn-W-Mo districts worldwide than to sericitic alteration at higher levels of porphyry copper systems. The fluids that form coarse muscovite veins and alteration in the roots of porphyry copper systems are distinct from fluids that formed copper ore or widespread, shallower, acidic alteration. We propose that this style of veins and alteration at Luhr Hill represents degassing of moderate volumes of overpressured hydrothermal fluid during late crystallization of deep levels of the Yerington batholith.

Tungsten is listed on the European Commission list of critical raw materials that are crucial to Europe’s economy. By raising awareness of tungsten as a critical raw material the EU can prioritise to enhance exploration, mining and recycling of tungsten. In this thesis the structural relationship between wall rock and veins, in a greisen-tungsten vein deposit, were analysed with the intention to interpret how tectonic deformation events control the emplacement of tungsten-bearing veins. The objective of this thesis is to investigate if and how structures controlled hydrothermal fluid flow and ore formation in the Peña del Seo tungsten-greisen vein deposit. Greisen systems are associated with tin and tungsten-bearing minerals and are related to intrusive magmatic bodies of granitic composition. Greisen-related granites (leucogranites), form at shallow depths in the crust (1.5-4 km) generally in intracontinental tectonic settings such as orogenic belts. The study site is located in the West Asturian-Leonese Zone in northwest Spain. This zone marks the transition between the foreland and the hinterland and is recognized as being part of a continental margin, where Palaeozoic rocks were deposited unconformably. These rocks were subsequently subjected to folding during the Variscan orogeny (370-290 Ma). Three main types of structures were generated due to three deformational phases (D1, D2 and D3) during the Variscan orogeny. D1 resulted in east-verging recumbent folding and formation of a related axial-planar parallel cleavage (S1), D2 resulted in displacement along large thrust sheets and D3 produced upright folding and refolding of F1 folds. Geological mapping with a focus on structural geology was carried out in March 2019, covering an area of approximately 0.25 km2. Structural measurements and oriented rock samples for microstructural study in thin sections were collected in the field. Additionally, photogrammetric mapping of structures was performed on a 3D photogrammetry model derived from a UAS survey. The geometry of the Peña del Seo tungsten-greisen vein deposit is interpreted to result from two major deformation events. The axial planar foliation (S1) at Peña del Seo is correlated to the regional fabric that developed during D1 of the Variscan orogeny. The related F1 folds are caused by buckling accompanied by flexural slip folding mechanism during D1. Forceful intrusion of the granite underlying the Peña del Seo deposit caused bending of the overlying rocks layers during D2. Layer-parallel stretching is likely to have caused tension fractures perpendicular to bedding in the outer arc of the F2 fold hinge. The formation of local crenulation and related spaced cleavage can be explained by layer-parallel shortening in the inner arc of the F2-fold. Local transposition of S1-foliation occurred during emplacement of quartz veins and explains the different orientation of strike of foliation between the northern and southern parts of the area. Fractures forming during formation of F2-fold are likely to have worked as conduits for ascending hydrothermal, ore-bearing fluids forming the Peña del Seo tungsten-greisen vein deposit.

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

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

Orientadores: Alberto Vazquez Saa, Marcus Aloízio Martinez de Aguiar / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-17T22:25:51Z (GMT). No. of bitstreams: 1 Freitas_GabrielBernardide_M.pdf: 1988646 bytes, checksum: 0b4661aa158c2d9e054e30fd044ba4d9 (MD5) Previous issue date: 2011 / Resumo: O objetivo deste trabalho é a investigação do efeito Greisen-Zatsepin-Kuzmin (GZK) na presença de buracos negros, contemplando, dessa forma, uma correção de natureza astrofísica à propagação de raios cósmicos de ultra-alta energia. Inicia-se com uma descrição das principais características dos dois elementos cruciais envolvidos no efeito: os raios cósmicos de ultra-alta energia e a radiação cósmica de fundo. Posteriormente, é feita uma revisão sistemática do efeito GZK, mostrando as interações mais relevantes e a abordagem utilizada para o cálculo das perdas de energia. Também é dada especial atenção às correções de natureza cosmológica que devem ser incorporadas ao considerar fontes de raios cósmicos muito distantes. Em seguida, analisa-se o problema na presença de um buraco negro. O estudo é feito considerando a situação mais simples: a radiação cósmica de fundo é tratada como um banho térmico no qual um buraco negro de Schwarzschild está imerso, constituindo um sistema cuja evolução pode ser tratada na aproximação quase estática (mudanças adiabáticas). Uma aproximação para as trajetórias de raios cósmicos nesse espaço-tempo é proposta, e a partir dela são calculadas as perdas de energia de cada partícula em função da distância de máxima aproximação em relação ao buraco negro. Finalmente, são apresentadas as conclusões do autor, e as perspectivas futuras de investigação são discutidas / Abstract: The aim of this work is the investigation of the Greisen-Zatsepin-Kuzmin (GZK) effect in the presence of black holes, thereby consisting of an astrophysical correction for the propagation of ultrahigh energy cosmic rays. Firstly, a description of the main features of the two crucial elements involved in the effect, the ultrahigh energy cosmic rays and the cosmic microwave background, is given. Then, a systematic review of the GZK effect is presented, showing the most relevant interactions and the approach used for the calculation of energy losses. Also, special attention is given to the cosmological corrections that must be incorporated when very far cosmic-ray sources are considered. After that, the problem is analysed in the presence of a black hole. The study is based upon the simplest situation: the cosmic microwave background is treated as a thermal bath in which a Schwarzschild black hole is immersed, constituting a system whose evolution can be treated in the quasi-static approximation (adiabatic changes). An approximation for the cosmic-ray particles¿ trajectories is proposed, and then used to calculate the energy loss for each particle as a function of the maximum approximation distance to the black hole. Finally, the author¿s conclusions are presented, as well as perspectives for future investigations / Mestrado / Relatividade e Gravitação / Mestre em Física

The Peña del Seo tungsten deposit in northwestern Spain is situated in the tin (Sn)-tungsten (W) metallogenic province of Europe − one of the richest tin-tungsten (tantalum-lithium) mineral provinces in the world. The European Union’s current goal is to become self-sufficient of these commodities in the near future and the iTARG3T project was launched in order to improve the understanding and provide innovative exploration methods of these types of deposits. This master thesis will contribute to the iTARG3T project. The aim was to determine which physico-chemical conditions (temperature, pressure, salinity) that prevailed during the emplacement of the Peña del Seo deposit. A geochemical study was done consisting of a fluid inclusion study on the quartz veins from the deposit, and a whole-rock geochemistry analyse of the granitic rock. Homogenisation temperatures ranged between 97,6° C to 325,6° C and salinities (NaCl % equiv.) between 0,2% to 21,3%. The fluid was determined to consist of a two-component system of H2O and NaCl based on eutectic temperature. Based on its geochemical classification the granitic rock was considered to be an alkali granite, strongly peraluminous with S-type characteristics. At least two different types of fluids were present during the emplacement of the Peña del Seo deposit, one that was hot and with a moderate salinity, and one that had a lower temperature than the other fluid and a lower salinity, possibly meteoric water. The depositional mechanism of tungsten is thought to be caused by a combination between mixing between two fluids and cooling of the fluids, with the main depositional mechanism being cooling since the change in salinity was not of such magnitude that it would change the fluid chemical composition, while the decrease in temperature was. It is uncertain whether the granitic rock found at Peña del Seo is part of the granitic cupola of the greisen system. The granitic rock has similar characteristics as the leucogranites of the West Asturian-Leonese Zone and based on quartz vein morphology, which cut the D2 foliation, time of emplacement of the deposit could be linked to the syntectonic event at 320-310 Ma. If the relation between the granitic rock and the greisen system can be determined the time of emplacement would be possible.

O Leucogranito Inhandjara é um pequeno e diferenciado stock Ediacarano (~570 M.a.) que constitui a borda nordeste do Batólito de Itu (estado de São Paulo, SE Brasil), um corpo rapakivi tipo A, composto principalmente por quatro intrusões (Indaiatuba, Salto, Itupeva e Cabreúva). O stock aflora como granitos hololeucocráticos, com teores radiométricos diferenciados (mais enriquecidos em Th e U do que as unidades vizinhas). Ele apresenta as maiores altitudes da região, sendo separado das outras unidades graníticas por um cinturão de gnaisses do embasamento. É constituído por dois litotipos: (1) monzogranito inequigranular a porfirítico com biotita, apresenta megacristais de feldspato potássico em uma matriz de granulação média a grossa; e (2) álcali-feldspato granito equigranular médio a fino, definido como a fácies mais evoluída, consistindo de albita subédrica (An<5) e quartzo, feldspato potássio e Li-siderofilita anédricos. Como fases magmáticas acessórias, apresenta fluorita, topázio, zircão, ilmenita e columbita-tantalita. O Leucogranito é metaluminoso do tipo A (subtipo A2), com caráter alcali-cálcico a alcalino, da série ferroana. Ele apresenta natureza reduzida, sendo classificado como da série ilmenita. As fácies apresentam enriquecimento progressivo em SiO2, Al2O3, Na2O, F, Cs, Rb, Nb, Ta e Y, enquanto os teores de TiO2, Fe2O3, MgO, CaO, Sr, Ba e Zr tendem a diminuir em direção ao Topázio Granito. Para os elementos terras raras (ETR), a fácies evoluída apresenta ligeiro enriquecimento nos elementos pesados, com conteúdo ETRTOTAL em torno de 150 ppm e razão (La/Yb)N de 0,6. Apresenta um padrão quase retilíneo quando normalizada por condrito, com forte anomalia negativa de Eu (Eu/Eu* = 0,003), se destacando das demais unidades do Batólito Itu. Análises químicas de zircão corroboram diretamente com o modelo de diferenciação, apresentando composição enriquecida em Hf, Y, Nb, Th e U nas bordas de cristais no Biotita Granito e por todos cristais do Topázio Granito, o que pode indicar cristalização tardia em presença de fase fluida. O stock apresenta evidências de intenso metassomatismo, principalmente albitização pervasiva e greisenização fissural, onde a paragênese de muscovita com Li, quartzo e clorita (± fluorita) ocorre associada a sulfetos disseminados (pirita, esfalerita e galena, ± calcopirita e molibdenita). O processo de alteração também afetou as rochas gnáissicas encaixantes, transformando-as em corpos de topázio-Li micas-quartzo greisen, associados a veios de quartzo-topázio mineralizados com hübnerita (wolframita rica em Mn) e cassiterita. Portanto, o Leucogranito de Inhandjara apresenta evidências mineralógicas e químicas de forte diferenciação, resultante da cristalização de um magma tardio, enriquecido em fases voláteis e elementos incompatíveis e acentuada pela interação com fluidos hidrotermais ricos em F exsolvidos do magma. Essas características colocam o stock no espectro mais evoluído dentro do Batólito Itu, relacionando-o com os processos de mineralização em metais raros (Nb-Ta-W-Sn) presentes na área da antiga Mina de Inhandjara. / The Inhandjara Leucogranite is a small and differentiated Ediacaran stock (ca 570 Ma) that constitutes the northeaster border of the Itu Batholith (São Paulo state, SE Brazil), an A-type rapakivi body, composed of four main intrusions (Indaiatuba, Salto, Itupeva and Cabreúva). The stock outcrops as hololeucocratic granites, with distinguished radiometric contents (more enriched in Th and U than the surrounding units). It presents the highest altitudes of the region, occurring separated from the other granitic plutons by a belt of basement gneisses. It is made of two main units: (1) inequigranular to porphyritic biotite-bearing monzogranite, with potassium feldspar megacrysts in a medium to coarse-grained matrix; and (2) medium to fine-grained equigranular alkali feldspar granite, defined as the most evolved facies, consisted of subhedral albite and anhedral quartz, potassium feldspar and Li-bearing siderophyllite. As accessory magmatic phases, it shows fluorite, topaz, zircon, ilmenite and columbite-tantalite. The Leucogranite is metaluminous of A-type (A2 subtype), with alkali-calcic to alkalic character, from the ferroan series. It presents reduced nature and is classified into the ilmenite series. The facies show progressive increase of SiO2, Al2O3, Na2O, F, Cs, Rb, Nb, Ta e Y, while contents of TiO2, Fe2O3, MgO, CaO, Sr, Ba e Zr tend to decrease to the alkali-feldspar granite. For the rare earth elements (REE), the evolved facies shows slight enrichment in the heavy elements, with REETOTAL content around 150 ppm and (La/Yb)N ratio of 0.6. It displays an almost flat pattern in chondrite-normalized plots, with strong negative Eu anomaly (Eu/Eu* = 0.003), highlighting itself from the other units from the Itu Batholith. Zircon chemical analyses directly corroborate to the differentiation model, presenting composition enriched in Hf, Y, Nb, Th and U at the crystal borders in biotite granite and throughout the crystals of the alkali-feldspar granite, what may indicate late crystallization in the presence of fluid phase. The stock shows evidences of intensive metasomatism, mainly as pervasive albitisation and fissure to pervasive greisenisation, where the paragenesis of Li-bearing muscovite, quartz and chlorite (± fluorite) occurs associated with disseminate sulphides (pyrite, sphalerite and galena, ± chalcopyrite and molybdenite). The alteration process also affected the gneissic country rocks, transforming them to topaz-Li-bearing micas-quartz greisen bodies, associated with quartz-topaz veins mineralised with hübnerite (Mn-rich wolframite) and cassiterite. Therefore, the Inhandjara Leucogranite presents mineralogical and chemical evidences of strong differentiation, resulting from the crystallization of a late magma, enriched in volatile phases and incompatible elements, and enhanced by interaction with exsolved F-rich hydrothermal fluids. Those characteristics place the stock in the most evolved spectrum inside the Itu Batholith, relating it with the rare-metal (Nb-Ta-W-Sn) mineralization processes which occur in the area from the old Inhandjara Mine.

O Leucogranito Inhandjara é um pequeno e diferenciado stock Ediacarano (~570 M.a.) que constitui a borda nordeste do Batólito de Itu (estado de São Paulo, SE Brasil), um corpo rapakivi tipo A, composto principalmente por quatro intrusões (Indaiatuba, Salto, Itupeva e Cabreúva). O stock aflora como granitos hololeucocráticos, com teores radiométricos diferenciados (mais enriquecidos em Th e U do que as unidades vizinhas). Ele apresenta as maiores altitudes da região, sendo separado das outras unidades graníticas por um cinturão de gnaisses do embasamento. É constituído por dois litotipos: (1) monzogranito inequigranular a porfirítico com biotita, apresenta megacristais de feldspato potássico em uma matriz de granulação média a grossa; e (2) álcali-feldspato granito equigranular médio a fino, definido como a fácies mais evoluída, consistindo de albita subédrica (An<5) e quartzo, feldspato potássio e Li-siderofilita anédricos. Como fases magmáticas acessórias, apresenta fluorita, topázio, zircão, ilmenita e columbita-tantalita. O Leucogranito é metaluminoso do tipo A (subtipo A2), com caráter alcali-cálcico a alcalino, da série ferroana. Ele apresenta natureza reduzida, sendo classificado como da série ilmenita. As fácies apresentam enriquecimento progressivo em SiO2, Al2O3, Na2O, F, Cs, Rb, Nb, Ta e Y, enquanto os teores de TiO2, Fe2O3, MgO, CaO, Sr, Ba e Zr tendem a diminuir em direção ao Topázio Granito. Para os elementos terras raras (ETR), a fácies evoluída apresenta ligeiro enriquecimento nos elementos pesados, com conteúdo ETRTOTAL em torno de 150 ppm e razão (La/Yb)N de 0,6. Apresenta um padrão quase retilíneo quando normalizada por condrito, com forte anomalia negativa de Eu (Eu/Eu* = 0,003), se destacando das demais unidades do Batólito Itu. Análises químicas de zircão corroboram diretamente com o modelo de diferenciação, apresentando composição enriquecida em Hf, Y, Nb, Th e U nas bordas de cristais no Biotita Granito e por todos cristais do Topázio Granito, o que pode indicar cristalização tardia em presença de fase fluida. O stock apresenta evidências de intenso metassomatismo, principalmente albitização pervasiva e greisenização fissural, onde a paragênese de muscovita com Li, quartzo e clorita (± fluorita) ocorre associada a sulfetos disseminados (pirita, esfalerita e galena, ± calcopirita e molibdenita). O processo de alteração também afetou as rochas gnáissicas encaixantes, transformando-as em corpos de topázio-Li micas-quartzo greisen, associados a veios de quartzo-topázio mineralizados com hübnerita (wolframita rica em Mn) e cassiterita. Portanto, o Leucogranito de Inhandjara apresenta evidências mineralógicas e químicas de forte diferenciação, resultante da cristalização de um magma tardio, enriquecido em fases voláteis e elementos incompatíveis e acentuada pela interação com fluidos hidrotermais ricos em F exsolvidos do magma. Essas características colocam o stock no espectro mais evoluído dentro do Batólito Itu, relacionando-o com os processos de mineralização em metais raros (Nb-Ta-W-Sn) presentes na área da antiga Mina de Inhandjara. / The Inhandjara Leucogranite is a small and differentiated Ediacaran stock (ca 570 Ma) that constitutes the northeaster border of the Itu Batholith (São Paulo state, SE Brazil), an A-type rapakivi body, composed of four main intrusions (Indaiatuba, Salto, Itupeva and Cabreúva). The stock outcrops as hololeucocratic granites, with distinguished radiometric contents (more enriched in Th and U than the surrounding units). It presents the highest altitudes of the region, occurring separated from the other granitic plutons by a belt of basement gneisses. It is made of two main units: (1) inequigranular to porphyritic biotite-bearing monzogranite, with potassium feldspar megacrysts in a medium to coarse-grained matrix; and (2) medium to fine-grained equigranular alkali feldspar granite, defined as the most evolved facies, consisted of subhedral albite and anhedral quartz, potassium feldspar and Li-bearing siderophyllite. As accessory magmatic phases, it shows fluorite, topaz, zircon, ilmenite and columbite-tantalite. The Leucogranite is metaluminous of A-type (A2 subtype), with alkali-calcic to alkalic character, from the ferroan series. It presents reduced nature and is classified into the ilmenite series. The facies show progressive increase of SiO2, Al2O3, Na2O, F, Cs, Rb, Nb, Ta e Y, while contents of TiO2, Fe2O3, MgO, CaO, Sr, Ba e Zr tend to decrease to the alkali-feldspar granite. For the rare earth elements (REE), the evolved facies shows slight enrichment in the heavy elements, with REETOTAL content around 150 ppm and (La/Yb)N ratio of 0.6. It displays an almost flat pattern in chondrite-normalized plots, with strong negative Eu anomaly (Eu/Eu* = 0.003), highlighting itself from the other units from the Itu Batholith. Zircon chemical analyses directly corroborate to the differentiation model, presenting composition enriched in Hf, Y, Nb, Th and U at the crystal borders in biotite granite and throughout the crystals of the alkali-feldspar granite, what may indicate late crystallization in the presence of fluid phase. The stock shows evidences of intensive metasomatism, mainly as pervasive albitisation and fissure to pervasive greisenisation, where the paragenesis of Li-bearing muscovite, quartz and chlorite (± fluorite) occurs associated with disseminate sulphides (pyrite, sphalerite and galena, ± chalcopyrite and molybdenite). The alteration process also affected the gneissic country rocks, transforming them to topaz-Li-bearing micas-quartz greisen bodies, associated with quartz-topaz veins mineralised with hübnerite (Mn-rich wolframite) and cassiterite. Therefore, the Inhandjara Leucogranite presents mineralogical and chemical evidences of strong differentiation, resulting from the crystallization of a late magma, enriched in volatile phases and incompatible elements, and enhanced by interaction with exsolved F-rich hydrothermal fluids. Those characteristics place the stock in the most evolved spectrum inside the Itu Batholith, relating it with the rare-metal (Nb-Ta-W-Sn) mineralization processes which occur in the area from the old Inhandjara Mine.

A review of the geotectonic settings of granitoids and various tin-tungsten provinces in Europe, Malaysia and southern Africa shows a close spatial and temporal association of mineralisation to S-type ilmenite series granitoids. Granitoids with these affinities are derived from crustal anatexis and are most commonly found in continental collision and different ensialic, intraplate orogenic settings, (e.g. SW England, Malaysia, Namibia) as well as in association with anorogenic magmatism (Nigeria, Brazil, South Africa). Tin-tungsten mineralisation is related to late- to post-tectonic granites, emplaced into areas of substantial tectonic thickening. Crustal anatexis leads to an observable calcalkaline chemical trend, with a source of gabbroic or amphibolite composition through anatexis to; mafic-intermediate enclaves, para-autochthonous anatectic granitoids (tonalite, granodiorite), to intermediate level quartz monzonite, granodiorite, biotite-granite, to late-tectonic highly fractionated muscovite-bearing granites, and high level porphyry intrusions. Mineralisation is spatially related to apical protrusions of the youngest most differentiated granite. Various mineralised environments are recognised, including endogranitic veins, primary disseminations, pegmatites and pipes, and exogranitic stockwork and fissure veins, and replacement bodies. A common factor to all these deposits is the inherent greisen environment, characterised by postmagmatic metasomatic alteration and mineral deposition. Common alteration mineral assemblages include albite, quartz, muscovite, tourmaline, and fluorite ∓ topaz. Ore mineral assemblages commonly display a paragenetic sequence of oxides (cassiterite, wolframite, scheelite), followed by sulphides (molybdenite, pyrite, pyrrhotite, chalcopyrite sphalerite, arsenopyrite/loëllingite, Pb-Bi(Ag) sulphosalts) and then lower temperature carbonates (calcite, siderite, ankerite). Analysis of Pan African orogenic provinces in southern Africa (Damara and Saldanian Provinces) shows there is good potential for applying integrated exploration techniques in search of endo-exogreisen Sn-W systems. Careful analysis and interpretation of granitoid geochemistry (K₂0, Na₂0, FeO/Fe₂0₃, F, B, Sn, W, Mo, Cu, Rb, Sr, Ti, Zr) should aid delineation of Sn-W and Mo-Cu metallogenic provinces in these regions. Magnetic susceptibility determinations should also aid distinction of S-type ilmenite series (less than 1 x lO⁻⁴emu/g ) from I-type magnetite series (more than 1 x lO⁻⁴emu/g ) granitoids

Orientador: Washington Barbosa Leite Júnior / Resumo: O plúton Saubinha (1.316 ± 16 Ma.) compõe uma das intrusões graníticas do maciço São Lourenço que em conjunto com outros maciços (Caripunas, Abunã e São Simão) representam as áreas de exposição de rochas graníticas, com ou sem depósitos de estanho associados, pertencentes a Suíte Intrusiva São Lourenço-Caripunas (1.32 – 1.30 Ga.). O núcleo de ocorrência dos depósitos primários de estanho ocorre na forma de um stock granítico alongado NW – SE. Constitui-se por biotita-álcali feldspato granitos, cartografados em duas unidades mapeáveis, 1:10.000, e em contatos, aparentemente, transicionais entre si. A Unidade A (UA) que integra tipos heterogranulares a equigranulares de granulação média e, subordinamente porfiríticos de matriz fina; e a Unidade B (UB), restrita a borda leste do plúton, com tipos equigranulares a porfiríticos de matriz fina. Adiciona-se ainda uma lente delgada e não contínua de granito miarolítico a sudeste do plúton e diques de microgranito e aplito que seccionam preferencialmente as rochas da UB. Geoquimicamente são granitos ferrosos, pós-colisionais, tipo A (subtipo A2), de caráter metaluminoso que permeia entre os campos peralcalino e peraluminoso com alcalinidade álcali-cálcica a cálcio-alcalina. Apresentam características de magmas oriundos de anatexia de protólitos quartzo-feldspáticos, de mais alta temperatura (~827,0ºC), pouco hidratados e que se posicionaram em níveis crustais rasos. A variação dos elementos maiores e traços por SiO2 sugere um trend ev... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Saubinha pluton (1.316 ± 16 Ma.) composes one of granitic intrusions of São Lourenço massif, which together with other massifs (Caripunas, Abunã and São Simão) represent the areas of exposure granitic rocks, with or without associated tin deposits, belonging to the evolution of São Lourenço-Caripunas Intrusive Suite (1.32 – 1.30 Ga.). The core of occurrence of primary tin deposits occurs as an NW – SE elongated granitic stock. It consists of biotite-alkali feldspar granites, mapped in two mappable units, in scale 1:10.000, and in apparently transitional contacts. Unit A (UA) that integrates heterogranular to equigranular medium grain types and subordinately porphyritic of fine matrix; and Unit B (UB), restricted to the eastern edge of the pluton, with equigranular to porphyritic fine grain types. In addition, a thin non-continuous lens of miarolitic granite to the southeast of the pluton and dykes of microgranite and aplite that preferentially crosscut the rocks of UB. Geochemically, they are ferrous granites, post-collisional, A-type (subtype A2), of a metaluminous character that permeates between the peralkaline to peraluminous fields with alkali-calcic to calcic-alkali alkalinity. The granites have characteristics of magmas originated from anatexy of quartz-feldspar protoliths, of higher temperature (~827,0ºC), poorly hydrated and positioned in shallow crustal levels. Variation of major and traces elements by SiO2 suggests an evolutionary trend from porphyritic types (UB) ... (Complete abstract click electronic access below) / Mestre