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4Doutor em Geologia, Programa de Pós-Graduação em Geologia, Núcleo de Geologia Básica (NGB), Instituto de Geociências, Universidade Federal da Bahia (UFBA), Salvador-BA, Brasil. ORCID: https://orcid.org/0000-0002-2143-5594 Email: mmm@ufba.br Resumo A área de estudo localiza-se na porção extremo norte do Cinturão Salvador-Esplanada-Boquim, nas porções sul do estado de Sergipe e nordeste do estado da Bahia, Brasil. Este Cinturão apresenta três faixas litológicas de rochas metamórficas denominadas Complexo Migmatítico Rio Real-Riachão do Dantas (CMRR), Complexo Granulítico Esplanada-Boquim (CGEB) e Complexo Gnáissico/Migmatítico-Granulítico Costa Atlântica (CGGCA). Esse artigo se restringe aos estudos petrológicos da primeira faixa de migmatitos que foi subdividida em Ortognaisse Migmatítico Granítico Leste (OMGL) e Ortognaisse Migmatítico Granítico Oeste (OMGO). Ambas, macroscopicamente e petrograficamente são similares, cujas paragêneses minerais indicam a ocorrência de processos metamórficos de médio grau, da fácies anfibolito com faixas retrometamórficas. Litoquimicamente, notou-se características particulares das porções claras e escuras de cada um desses tipos de migmatitos e que, embora tenham sofrido migmatização, mantiveram as características dos protólitos, permitindo identificar as porções félsicas como provenientes de magma variando entre cálcio-alcalino normal a cálcio-alcalino de alto K.

Dissertação de mestrado em Geociências (área de especialização em Valorização de Recursos Geológicos), No território português há reservas quantificadas de massas minerais com apetência ornamental, que suportam um catálogo de referências (ROP, LNEG), na sua maioria caracterizadas pela uniformidade petrográfica e textural, nos domínios petrogenéticos dos granitos, mármores, calcários e ardósias. Neste estudo, estes designam-se por litótipos clássicos sendo histórica e culturalmente reconhecidos pelo seu padrão textural, em contextos específicos de aplicação arquitetónica, com função estrutural e decorativa. Atualmente assiste-se a uma procura global por litótipos que apresentam padrões cromáticos e texturais que se destacam dos termos clássicos e beneficiam do desenvolvimento tecnológico, que garante a estabilização estrutural e uma maior valorização estética. Estes são aqui classificados como litótipos exóticos, sendo objetivo deste estudo evidenciar as suas características específicas e a sua aptidão ornamental, concretamente pela análise descritiva de litótipos nacionais não incluídos no catálogo de referência. Entre outros, deu-se maior enfoque aos litótipos: migmatito da Pedra da Moura e migmatito Black in the Sky. Como termo de comparação estudaram-se ainda litótipos internacionais com boa aceitação comercial e alto valor unitário (100- 500€/m2), tais como o quartzofilito Fusion Wow e o migmatito Black Cosmic. O critério geológico aplicado na escolha dos litótipos comerciais foi a identificação de características genéticas, texturais e mineralógicas em comum com algum dos litótipos nacionais estudados. Este trabalho beneficiou da colaboração com empresas do sector que proporcionaram amostras de litótopos comerciais e deram suporte industrial a ensaios de transformação como corte, polimento e resinagem. A metodologia analítica utilizada incluiu a preparação de lâminas e superfícies polidas, tanto de amostras de mão recolhidas em afloramento e em frentes de desmonte, como de amostras de chapa já sujeita a tratamento superficial. Pela observação microscópica e análise modal foi possível discriminar padrões minerais e texturais que particularizam as litologias exóticas, recorrendo à sistematização macro e microscópica dos seus atributos, mediante as normas petrográficas aplicáveis. Dos resultados obtidos conclui-se que os litótipos nacionais estudados possuem apetência ornamental equivalente aos litótipos exóticos internacionais, sendo esta conferida pela sua heterogeneidade estrutural e mineralógica. Estes devem ser incluídos no Catálogo Nacional de Rochas Ornamentais, beneficiando de destaque como litótipo exótico. Considerou-se ainda de carácter essencial, as soluções de reforço estrutural apontadas neste estudo, que potenciam o seu desempenho físico e mecânico e minimizam problemas decorrentes da diversidade mineral, sobretudo o alto contraste de dureza., In the Portuguese territory there are quantified reserves of mineral masses with ornamental potential, which support a catalog of references (ROP, LNEG), mostly characterized by petrographic and textural uniformity, in the petrogenetic domains of granites, marbles, limestones and slates. In this study, they are called classic lithotypes, being historically and culturally recognized for their textural pattern, in specific contexts of architectural application, with structural and decorative functions. Currently, there is a global demand for lithotypes that present chromatic and textural patterns that stand out from the classic terms and benefit from technological development, assuring structural stabilization and greater aesthetic enhancement. These are classified, in this dissertation, as exotic lithotypes. The purpose of this study is to highlight their specific characteristics and their ornamental aptitude, specifically by the descriptive analysis of national lithotypes not included in the reference catalog. Among others, a greater focus was given to the lithotypes: migmatite from Pedra da Moura and migmatite Black in the Sky. As a comparison term, international lithotypes with good commercial acceptance and high unit value (100-500 €/m2) were also studied, such as Fusion Wow quartzphyllite and Black Cosmic migmatite. The geological criterion used in the choice of commercial lithotypes was the identification of genetic, textural and mineralogical characteristics they have in common with some of the national lithotypes studied. This work benefited from the collaboration with companies in the sector that provided samples of commercial lithotypes and gave industrial support to transformation tests such as cutting, polishing and resin. The analytical methodology used included the preparation of thin sections and polished surfaces, both from outcrop hand samples and exploitation face, as well as from slab samples with surface treatment. Through microscopic observation and modal analysis, it was possible to discriminate mineral and textural patterns, distinguishing exotic lithologies by the macro and microscopic systematization of their attributes, based in the applicable petrographic standards. The results obtained shows that the studied national lithotypes have an ornamental potential equivalent to international exotic lithotypes, which is conferred by their structural and mineralogical heterogeneity. These must be included in the National Catalog of Ornamental Stones, benefiting from prominence as an exotic lithotype. The structural reinforcement solutions mentioned in this study were also considered essential, which enhance their physical and mechanical performance and minimize problems arising from mineral diversity, especially the high contrast of hardness.

High-grade metamorphic rocks associated with S-type granites are recorded in the Central Iberian Zone, Iberian Variscides. Though most of these occur as inferred metamorphic core complexes affiliated with detachment faults, others, such as the Figueira de Castelo Rodrigo–Lumbrales Anatectic Complex, crop out between low-grade metamorphic rocks separated by steeply-dipping strike-slip shear zones, such as the Juzbado–Penalva do Castelo Shear Zone. Our structural analysis has been able to constrain two major deformation stages during the Variscan D 3 : (a) D 3a ductile deformation event, with clear sinistral kinematic criteria; and (b) D 3b thrusting ductile–brittle deformation event. The petrological investigation confirmed the jump in metamorphic grade between the host rocks and the anatectic complex. P–T estimates on calc-silicate rocks interlayered with the metapelites of the anatectic complex provided minimum metamorphic peak conditions of T = 761 ± 50°C and P = 5.0 ± 1.0 kbar. However, petrological modelling results show that P–T conditions must have exceeded T > 800°C. Both structural and geothermobarometric data support a two-step model for the exhumation of the Anatectic Complex, including a 5 – 8 km vertical exhumation along a 65 – 100 km horizontal displacement due to a simple shear-dominated transpression mechanism during the Variscan D 3 events. Supplementary material: The petrology data, mineral chemistry analyses of the calc-silicate units and EPMA analytical conditions, and the P–T modelling methodology can be found at https://doi.org/10.6084/m9.figshare.c.3785648

Neste trabalho são apresentados os resultados isotópicos Sr-Nd do Granito do Pedregal e das rochas gnaissomigmatíticas associadas, aflorantes na Zona Centro-Ibérica noroeste de Portugal, no bordo oriental do maciço granítico sin-orogénico do Porto. O granito do Pedregal é um pequeno corpo alongado na direcção NW-SE, intrusivo em micaxistos estaurolíticos do Supergrupo Dúrico-Beirão e em rochas gnaisso-migmatíticas. O granito do Pedregal é um granitóide de duas micas, de grão fino a médio, com pequen os nódulos biotíticos (1 a 2 cm). As rochas gnaisso-migmatíticas associadas são caracterizadas por leucossomas quartzo-feldspáticos predominantes e sem foliação, alternando com paleossomas micáceos onde ocorrem intercrescimento de granada e quartzo (

As características petrográficas e geoquímicas do leucogranito peraluminoso do Complexo de Gouveia (MG), sua relaçãogeológica a migmatitos deste complexo arqueano e a zonas de cisalhamento, bem como sua intensa milonitização, aproximam sua gêneseà dos granitos de ambiente de colisão continental ou da tectônica transcorrente a ela associada. Idades químicas U-Th-Pb em cristaishomogêneos de monazita inclusos em K-feldspato do leucogranito mostram valor médio em torno de 1811 +/- 32 Ma, que marca acristalização do magma leucogranítico derivado da anatexia dos migmatitos. Esta anatexia teria se dado em ambiente hidratado e emcondições de alto grau metamórfico (fácies anfibolito alto) atingidas em função do espessamento crustal e cisalhamentos regionaisrelacionados às fases sin- a tardi-colisionais do evento Transamazônico. Além disso, esta rocha foi submetida ao retrabalhamentoBrasiliano sob fácies xisto-verde, identificado pela cloritização da biotita e da granada e por processos de turmalinização. A monazitaassociada aos corpos tardios de turmalinitos apresenta idade química U-Th-Pb de 634 +/- 20 Ma.Palavras-chave: leucogranito peraluminoso, gouveia, tectônica colisional, transamazônico, brasiliano ABSTRACTThe petrographic and geochemical characteristics of the peraluminous leucogranite of the Gouveia Complex (MG), their association to migmatites of such archean complex and to shear zones and their intense mylonitization approach their genesis to thegranites of continental collision setting or linked transcurrent tectonics. U-Th-Pb chemical ages of 0monazite grains included in K-feldsparof the leucogranite show mean values around 1811 +/- 32 Ma, which reveal its magmatic crystallization from anatexis of the migmatites.The anatexis that generated the leucogranites has been given in hydrated environment and high-grade metamorphic conditions(amphibolite facies) reached during crustal thickening and regional shear related to the syn- to late-collisional phases of theTransamazonian event. However, this rock has been subjected to Brasiliano reworking under green-schist facies, identified by chloritizationof biotite and garnet and by tourmalinization processes. Monazite associated with late tourmalinite bodies has U-Th-Pb chemical age of634 +/- 20 Ma.Keywords: peraluminous leucogranite, gouveia, collisional tectonics, transamazonian, brasiliano.

Made available in DSpace on 2020-12-10T18:03:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-06-01 This paper presents new geochemical and petrological data from the southern portion of the Guaxupe Complex. The research area is characterized by the occurrence of migmatites and an intrusive body of charnockitic granite located on the northeastern portion of the area. Petrological and geochemical studies of the banded migmatites have shown that the paleossome is generally composed by tholeiitic basaltic orthogranulite showing island arc signature. Partial melting of these basic orthogranulites has formed calc-alkalic neossome of granitic to tonalitic composition with high SiO2 content (> 68.9%) and high (La/Lu) N ratios, as well as low K/Rb ratios. These features are coherent to partial melting of Rb-rich basic protholits at temperatures around 820 degrees C producing a felsic melt in presence of orthopyroxene and clinopyroxene. Moreover, a geochemical study of a rocks suite from the charnockitic intrusion has pointed out that its evolution is characterized by magmatic differentiation through crystal fractionation process, which, in turn, has formed a magmatic series starting with porphyritic granite, followed by charnockitic gneiss and leucogneiss as the final product of crystal fractionation. These rocks, located geographically close to the magmatic intrusion, must have been formed by partial melting of granulitic crustal rocks of dioritic composition, represented by banded granulitic gneisses with a geochemical signature similar to the magmatic rocks. Univ Estadual Paulista, UNESP, Inst Geociencias & Ciencias Exatas, Programa Posgrad Geol Reg, Rio Claro, SP, Brazil Univ Estadual Paulista, UNESP, Inst Geociencias & Ciencias Exatas, Dept Petr & Metalogenia, Rio Claro, SP, Brazil Univ Estadual Paulista, UNESP, Inst Geociencias & Ciencias Exatas, Programa Posgrad Geol Reg, Rio Claro, SP, Brazil Univ Estadual Paulista, UNESP, Inst Geociencias & Ciencias Exatas, Dept Petr & Metalogenia, Rio Claro, SP, Brazil

This article presents data and interpretations on the Espinhaço Supergroup in Minas Gerais, emphasizingstratigraphic and structural data of the Serra do Espinhaço, where arise sequences from Archean (granites/gnaisses/migmatites and units of lower metamorphic degree) to Neoproterozoic. Espinhaço Supergroup hasit’s development in the end of the Paleoproterozoic until the Mesoproterozoic, and in the Meridional Sectionit’s base is represented by the Guinda Group, with quartzites, phylites and metaconglomerates/breccias offluvial to shallow marine origins, presenting intercalations of metavolcanics and real paleosoils (part ofhematitic phylites). Above arise eolian metasediments of the Galho do Miguel Formation and the marine tofluvial metasediments of the Conselheiro Mata Group. At the Setentrional Sector, three big groups, mainlypresenting continental characteristics (compatible with the opening of a rift), can be recognized formingthis super group in the setentrional sector of the mountain rage: Metavulcanossedimentar Unit, InferiorMetassedimentar Unit and Superior Metassedimentar Unit. The region is structured by a system of inversefaults/ ductile shear zones that cause frequent stratigraphic inversions and that spread marked blocks internallyby open folds to closed with West vergence. The analysis of quantity of deformation proves the non-axialcharacter of these mass transportations, and confirms the location of part of the shear zones.

Made available in DSpace on 2022-04-29T07:14:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-01-01 This paper presents new geochemical and petrological data from the southern portion of the Guaxupé Complex. The research area is characterized by the occurrence of migmatites and an intrusive body of charnockitic granite located on the northeastern portion of the area. Petrological and geochemical studies of the banded migmatites have shown that the paleossome is generally composed by tholeiitic basaltic orthogranulite showing island arc signature. Partial melting of these basic orthogranulites has formed calc-alkalic neossome of granitic to tonalitic composition with high SiO2 content (> 68.9%) and high (La/Lu)N ratios, as well as low K/Rb ratios. These features are coherent to partial melting of Rb-rich basic protholits at temperatures around 820C producing a felsic melt in presence of orthopyroxene and clinopyroxene. Moreover, a geochemical study of a rocks suite from the charnockitic intrusion has pointed out that its evolution is characterized by magmatic differentiation through crystal fractionation process, which, in turn, has formed a magmatic series starting with porphyritic granite, followed by charnockitic gneiss and leucogneiss as the final product of crystal fractionation. These rocks, located geographically close to the magmatic intrusion, must have been formed by partial melting of granulitic crustal rocks of dioritic composition, represented by banded granulitic gneisses with a geochemical signature similar to the magmatic rocks. Programa de Pós-Graduação em Geologia Regional, Instituto de Geociências e Ciências Exatas, Universidade Estadual Paulista Júlio de Mesquita Filho, Rio-Claro (SP) Departamento de Petrologia e Metalogenia, Instituto de Geociências e Ciências Exatas, Universidade Estadual Paulista Júlio de Mesquita Filho, Rio-Claro SP Programa de Pós-Graduação em Geologia Regional, Instituto de Geociências e Ciências Exatas, Universidade Estadual Paulista Júlio de Mesquita Filho, Rio-Claro (SP) Departamento de Petrologia e Metalogenia, Instituto de Geociências e Ciências Exatas, Universidade Estadual Paulista Júlio de Mesquita Filho, Rio-Claro SP

This is an interpretation of geological, petrological and geochemical data of the Lajinha intrusion,which belongs to the Alto Capim Subsuite of the Espírito Santo Magmatic Suite. The Lajinhaintrusion is a plutonic body of medium extensions (48km2) with diapiric structure and magmaticzoning. Two magmatic groups build up this body, one of granitic affinity and the other group ofdioritic affinity. Between this two groups do not exist “commingling” but a chemical interaction (e.g.: “mixing” in the contact region). The acid rocks, that crop out in a ringlike form, can be observedin two distinct litological groups. The main group is coarse-grained, has a great number of big potassicfeldspar-phenocrysts (up to 15cm), small part of matrix and it do not have a preferencial orientation.In some parts exist a flux orientation of the phenocrystals and at the contact with the host rockapears weak intrusive foliation. The other subordinate group is formed by a middle to coarse grainedmatrix, with isotropic apearence and with a very low content of K-feldspar phenocrystals. Theseparation of the two groups may be a result of “filter-pressing” and/or “gravity separation”. Thegranites are constituted principally of quartz, K-feldspar, plagioclase, biotite, accessory and opaqueminerals. Their chemical composition ranges from alkaligranite to granodiorite. The basic rockgroup,which crops out in an oval formed elonged central nuclei, has a middle to coarse granulometry,homogeneous and isotropic apearence over all of the visited outcrops. This rock is built up byamphibole, biotite, plagioclase, small percentage of pyroxene, accessory and opaque minerals. Thechemical composition vary between syeno-diorite, diorite and gabbrodiorite. The contact betweenthe granitc rockgroup and the basic rockgroup is very well defined and shows only metasomatismeffects and not “commingling”. The host of the intrusion are para-rocks like migmatites, bandedgneisses, quartzites, and ortho-rocks like an homogeneous gneisse (Galileia Intrusive Suite; PocraneComplex) and amphibolitic. They are very strong foliated. The contact between the host and theintrusive rocks is normally formed by gradational evolution (transformation) and in some parts ofthe north western contact by faults. From the host towards the intrusion growth up the number ofblasts and the distribuion of fusion effects. Pegmatitic veins cut the mainbody in the same directionas distension fractures (NE-SW). In the northeastern part this fractures are invaded by a fine grainedalkaline basalt of probably cretaceous age. This veins cut the host and the granites of the intrusion,too. The observations make possible the idea of an intrusive process under late-orogeneous to postcollisionalregime. The differentiation trends of the two rock groups are calco-alkaline (trondhjemiticto monzonitic), with peraluminous to metaluminous and alkaline to subalkaline tendency. Thisintrusion make part of the symetric body distribution within the Espírito Santo Magmatic Arc,beginning with late to post-collisional intrusion in the west and east and early to syn-collisionalintrusions in the central region, the later influenced by compressional and transcorrent movements.

Studies of terranes between the northern Ribeira and southern Dom Feliciano Belts allow the characterization of three geotectonic domains with different evolutions: the Luis Alves, Curitiba and Paranagua terranes. The Atuba Complex occurs in the Curitiba Domain, which has a northwestern limit with metassediments of the Acungui and Setuva Groups and a southwestern limit with the granulitic gneisses of the Luis Alves domains. The contacts are expressive shear zones. The predominant rocks of the Curitiba Domain are banded, migmatitic gneisses in amphibolite grade with biotite-amphibole gneissic mesosomes and tonalitic/granodioritic to granitic leucosomes, here called the Atuba Complex. The migmatites are Paleoproterozoic (2.000 ± 200 Ma) and remigmatized in Neoproterozoic (600 ± 20 Ma). During the latter period temperatures reached more than 500o C. The structural pattem indicated shear-controlled tectonics with an important lateral component, and low-angle, south-southeastwards transport direction. The terranes of the Atuba Complex appear to represent deep-level rocks which were migmatized, granitized and then added to the border of the Luis Alves Microplate during the Neoproterozoic. This late Neoproterozoic tectonic scheme which continued to the Cambro-Ordoviciano seems to be the result of larger-scale processes of continental agglutination which ended with the formation of western Gondwanaland.