Percorrer por autor "Bento dos Santos, Telmo"
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- Assumptions and problems with Fe-Mg garnet - biotite diffusion based petrological cooling rates : a case study in granulites and migmatites from central Ribeira Fold Belt, SE BrazilPublication . Bento dos Santos, Telmo; Munhá, José; Tassinari, Colombo C. G.; Fonseca, Paulo E.O sector São Fidelis - Santo António de Pádua, pertencente à zona central da Faixa Ribeira, é fundamentalmente composto por migmatites, granulitos e blasmilonitos. A aplicação de diferentes metodologias com o objectivo de obetr taxas de arrefecimento baseadas na difusão Fe-Mg entre granada e respectivas inclusões de biotite revelou-se infrutífera. Tal deve-se fundamentalmente a: a) elevada dispersão dos resultados causada pela existência de um sistema aberto; b) estreita variação das temperaturas de fecho do sistema causada por re-homogeneização da granada e altas temperaturas seguida de arrefecimento muito rápido. Os resultados obtidos são fundamentalmente qualitativos, mas estão de acordo com resultados termocronológicos previamente obtidos baseados na integração de múltiplos sistemas isotópicos.
- C-O-H isotopes and fluid studies as tools to constrain granulite petrogenesis on Ribeira Fold Belt (SE Brazil)Publication . Bento dos Santos, Telmo; Munhá, José; Tassinari, Colombo C. G.; Noronha, Fernando; Guedes, Alexandra; Fonseca, Paulo E.; Neto, Coriolano Dias; Dória, Armanda
- C-O-H isotopic evidences for fluid sources of granulites in Ribeira Belt, SE BrazilPublication . Bento dos Santos, Telmo; Munhá, José; Tassinari, Colombo C. G.; Fonseca, Paulo E.
- Complexo anatéctico de Figueira de Castelo Rodrigo-Lumbrales, Zona Centro Ibérica : análise preliminar do metamorfismo e geoquímicaPublication . Pereira, Inês; Bento dos Santos, Telmo; Mata, João; Dias, Rui; Calvo, Rogério; Santos, Renata
- Constraints on the termochronological evolution of Ribeira Fold Belt, SE Brasil : evidence for long-term elevated geothermal gradient of neoproterozoic orogeniesPublication . Tassinari, Colombo C. G.; Munhá, José; Neto, Coriolano Dias; Bento dos Santos, Telmo; Cordani, Umberto G.; Nutman, Allen P.; Fonseca, Paulo E.
- Deformação não-coaxial na Faixa Metamórfica Porto-Viseu : détachement extensional ou par thrust/underthrust contracional?Publication . Rodrigues, José Feliciano; Bento dos Santos, Telmo; Castro, Paulo Ferreira; Meireles, Carlos; Ferreira, Pedro Tavares; Ribeiro, António; Pereira, Eurico; Ferreira, Narciso
- Ediacaran and early-palaeozoic bimodal volcanism in the Ossa-Morena Zone, SW Iberian Massif: New clues for intraplate rifting shortly after the Cadomian OrogenyPublication . Cachapuz, P.; Chichorro, Martim Afonso; Bento dos Santos, Telmo; Carvalho, D.; Linnemann, Ulf; Zieger-Hofmann, M.; Zieger, J.; Dantas, E.; Santos, R. V.; Moita, Patrícia; Beltrame, M.; Solá, A. Rita; Díaz-Azpíroz, M.; Fernández, C.ABSTRACT: This study focuses on bimodal meta-volcanic rocks present in the Iberian Massif, in the Evora-Aracena Metamorphic Belt of the Ossa-Morena Zone (OMZ), near the boundary with the South Portuguese Zone. New petrological, geochemical (whole-rock and Sr-Nd isotopes) and LA-ICP-MS U-Pb zircon geochronology data are presented to track the magmatic evolution of both felsic and mafic rocks and their respective geodynamic setting during the transition between the Cadomian Orogeny and subsequent Palaeozoic rifting events. Our research shows that the Evora-Aracena Metamorphic Belt (EAMB) in the southwestern OMZ possesses a significant record of the transition between the Cadomian and Variscan cycles. U-Pb geochronological data confirm the existence of both felsic and mafic Ediacaran igneous rocks (546 and 556 Ma, respectively), a novelty in the region. The Cadomian-related felsic rocks show geochemical similarities to meta-felsic rocks formed during the initial phases of the Cambrian rifting event, namely very negative epsilon Nd values (-10.1 to -11.8), depleted HREE patterns and orogenic signatures. Such similarities imply that meta-felsic rocks formed in the earliest stages of the Cambrian Rift-to-Drift event resulted from a shallower melting. Moreover, meta-felsic rocks formed in the early stages of the Cambrian rifting (525 Ma) present a significant amount of Ediacaran aged zircons, whereas the Cadomian-related counterparts display a few discordant Cambrian ages, likely a consequence of Pb-loss. This indicates that the convergent, subduction-related regime that prevailed during most of the Cryogenian-Ediacaran times along the boundaries of NW Gondwana was swiftly supplanted by a rift-dominated regime during the Cambrian, with no substantial gap between these two thermal events. Meanwhile, meta-felsic rocks formed during the Rift-to-Drift (525-480 Ma) event exhibit progressively higher epsilon Nd values (-5.0 to +3.0), HREE-enrichment, as well as anorogenic signatures, denoting an increasing contribution of mantle-derived melts. This increasing mantle contribution eventually led to the occurrence of bimodal magmatism in the Middle Cambrian Main Rift event. Such Cambrian mafic rocks, unlike the Ediacaran mafic rocks that present flat REE patterns and continental arc signatures, display varying degrees of LREE enrichment and N-MORB to E-MORB signatures.
- Elemental and Sr-Nd isotope geochemistry : implications on sources and processes for granulite formation of central Ribeira Fold BeltPublication . Bento dos Santos, Telmo; Munhá, José; Tassinari, Colombo C. G.; Fonseca, Paulo E.; Neto, Coriolano Dias
- Estimativas geotermobarométricas e percursos P-T de migmatitos dos Farilhões, Arquipélago das Berlengas, Oeste de Portugal = Geothermobarometric estimates and P-T paths for migmatites from Farilhões Islands, Berlengas Archipelago, W PortugalPublication . Bento dos Santos, Telmo; Ribeiro, Maria Luísa; González-Clavijo, Emilio J.; Díez-Montes, Alejandro; Solá, A. Rita
- Evidências petrológicas e termocronológicas para manutenção de elevado fluxo geotérmico na Faixa Ribeira, SE do BrasilPublication . Bento dos Santos, Telmo; Munhá, José; Tassinari, Colombo C. G.; Fonseca, Paulo E.; Neto, Coriolano Dias