Encontrados 12 documentos, a visualizar página 1 de 2
Palaeomagnetism in the Sines massif (SW Iberia) revisited: evidences for Late C...
Ribeiro, Paulo; Silva, Pedro; Moita, Patrícia; Kratinova, Zuzana; Marques, Fernando; Henry, BernardThis study revisits the palaeomagnetism of the Sines massif (∼76 Ma) in the southwestern Iberian Margin (Portugal). The palaeomagnetic analysis was complemented by a comprehensive study of the magnetic mineralogy by means of rock magnetic measurements and petrographic observations. The overall dispersion of palaeomagnetic directions (declination ranging between ∼N0º and ∼N50º) and their migration observed durin...
Notas sobre a geologia da zona de Arraiolos
Moita, Patrícia; Mirão, JoséCom todas as capacidades tecnológicas que as sociedades modernas nos deslumbram, temos tendência a esquecer como o meio que nos rodeia condiciona ou devia condicionar algumas das nossas decisões. O planeamento urbano e rural, a partir das duas últimas décadas do século XX, e algumas catástrofes naturais vieram lembrar-nos como dependemos do meio físico para a nossa segurança, para a obtenção de recursos essenci...
New U-Pb ages for syn-orogenic magmatism in the SW sector of the Ossa Morena Zo...
Moita, Patrícia; Santos, José Francisco; Costa, Mafalda; Corfu, FernandoThe Ossa-Morena Zone (OMZ) is a major geotectonic unit within the Iberian Massif (which constitutes an important segment of the European Variscan Belt) and one of its distinguishing features is the presence of a noteworthy compositional diversity of plutonic rocks. In the SW sector of the OMZ, the tonalitic Hospitais intrusion (located to the W of Montemor-o-Novo) is considered a typical example of syn-orogenic...
New geochemical and isotopic constraints on the genesis of the Oliveira Azeméis...
Santos, José Francisco; Mendes, Maria Helena; Gonçalves, Ana Catarina Dias; Moita, PatríciaThe Porto-Tomar Shear Zone (PTSZ) is a very important tectonic structure that separates, in central-western Portugal, two of the major tectonic units of the Iberian Variscan Chain: the Ossa-Morena Zone, to the west, and the Central Iberian Zone, to the East. The Oliveira de Azeméis area lies in the northern sector of the PTZC and it is characterized by the occurrence of strongly deformed granitoids. Country roc...
Close or not so close? Provenance studies of megalithic monuments from Alentejo...
Boaventura, Rui; Moita, PatriciaThere has been a significant amount of studies about megalithic tombs conducted in the Alentejo region. However the geological provenance of monoliths used in the construction of those tombs usually was not a priority among researchers with rare exceptions (Dehn, Kalb and Vortisch, 1991; Boaventura, 2000). Recent studies of dolmens (Oliveira, 1997 and 2006; Gonçalves, 2003) refer only to a brief characterizatio...
Isotopic data from the Pomarinho enclave swarm (SW Iberian Chain)
Moita, Patrícia; Santos, José Francisco; Silva, PedroMafic microgranular enclaves are a common feature of calc-alkaline granitoids (e.g. tonalites and granodiorites) in active continental margins and collisional orogens. They correspond to dark-coloured globules that, although widespread throughout the host rock, usually constitute only a small proportion of the whole volume of the intrusion. When the enclaves occur strongly concentrated in a restricted area, th...
Geochemical signature of the Pomarinho enclave swarm (Ossa-Morena Zone, Portugal)
Moita, Patrícia; Santos, José Francisco; Silva, Pedro; Pardal, EduardoThe enclave swarm of Pomarinho is located in the SW edge of Évora granitoid (Carvalhosa, 1983), in the SW sector of the Ossa-Morena Zone (Iberian Variscides). The Granialpa quarry constitutes a privileged exposure of that swarm and, therefore, it was used to collect samples for AMS, petrographic and geochemical studies. The dominant rock in the quarry is a medium-grained granodiorite, composed of plagioclase, ...
Layered granitoids: Interaction between continental crust recycling processes and
Moita, Patricia; Santos, J. Francisco; Pereira, M. FranciscoIn this paper, field, petrographic, mineralogical, geochemical and isotopic (Rb–Sr and Sm–Nd) information from three areas within the Évora Massif (Iberian Variscan Orogen) is presented and discussed aiming at to unravel the relationships between granitoids and units mapped as migmatites and also to evaluate the interplay between mantle and crustal derived magmas. One of the areas – Almansor – displays a well-d...
Crustal growth and deformational processes in the northern
Pereira, M. Francisco; Silva, Jose B.; Chichorro, Martim; Moita, Patricia; Santos, J. Francisco; Apraiz, Arturo; Ribeiro, CristinaThe aim of this article is to present a compilation of available information on the Évora Massif based on structural mapping, whole-rock geochemistry, recognition of metamorphic mineral assemblages, and geothermobarometry. In our view, transcurrent movements responsible for strong orogen-parallel stretching were dominant and had a major role in the geodynamic evolution of this part of Ossa-Morena zone (southwes...
Evolução tectonomagmática da Zona de Ossa-Morena durante o ciclo Varisco: Estar...
Pedro, Jorge; Moita, Patricia; Araújo, Alexandre; Fonseca, Paulo; Munhá, JoséA evolução tectonomagmática varisca da Zona de Ossa-Morena mostra evidências claras dos estádios iniciais (“rifting”) e finais (colisionais) de um ciclo de Wilson, estando o estádio intermédio de magmatismo oceânico, em bacias com margens passivas, representado pelas Sequências Ofiolíticas Internas. As variações no tempo das características geológicas/geoquímicas do magmatismo no ramo SW da Cadeia Varisca Ibéri...
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