New geochemical and isotopic constraints on the genesis of the Oliveira Azeméis granitoid melts (Porto-Tomar Shear Zone, Iberian Variscan Chain, Central-Western Portugal).

The 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 rocks are dominantly pelitic metasediments which, according to recent geological mapping (Pereira et al., 2007), belong to the Precambrian Lourosa Formation and the Ordovician São João de Ver Formation. Using Rb-Sr whole-rock isotopic data, Pinto (1979) proposed an age of 379 12 Ma for the Oliveira de Azeméis granitoids. In this work, new results were obtained on these granitoids in the area between the villages of Travanca and Curval, especially in the Sacramento quarry. In this critical outcrop, strongly deformed two-mica granite (displaying S-C structures, with dextral NNW-SSE shear planes) pass into diatexites and metatexites with garnet, cordierite and sillimanite-bearing melanosomes. Leucosomes seem to have mainly granitic s.s. compositions, but cm-thick bands of leucotonalite were also found. Major element geochemistry of granite samples shows the following ranges: 71.4% SiO2 74.2%; 0.74% Fe2O3t 2.48%; 0.35% MgO 0.60%; 0.49% CaO 1.32%; 2.90% Na2O 3.11%; 4.70% K2O 5.47%; 1.17 ASI 1.36. Trace element data reveal a strong fractionation between highly incompatible LILE and less incompatible HFSE (248 PM normalized Rb/Y 671) and between LREE and HREE (18.6 PM normalized La/Lu 54.7). These features, in particular the peraluminous composition, the high K contents and the distinct rare-earth fractionation suggest that the Oliveira de Azeméis granites are mostly the result of partial melting of metasediments with a large pelitic component and that garnet is a likely residual phase. Isotope geochemistry data show that the previously reported isochron should not correspond to a true age since the 87Sr/86Sr(380Ma) obtained in the granite samples analysed in the present work are very low, varying from 0.6978 to 0.7063, with an average value of 0.7023, which are unrealistic in S-type granitic melts. Probably, the 380 Ma date is the consequence of mixing of different melt source components in the samples used in its calculation. Using the granite whole-rock samples collected in this work, a 328 28 Ma errorchron (MSWD=4.0; initial 87Sr/86Sr=0,7106 0.0045) is now obtained. Assuming a typical syn-tectonic Variscan age of 320 Ma for the studied granites, 87Sr/86Sr and "Nd range from 0.7100 to 0.7133 and from -6.5 to -7.9, respectively. A micaschist sample collected in this area displays 87Sr/86Sr(320Ma) = 0.7146 and "Nd(320Ma) = -9.2. Therefore, the Sr and Nd isotope composition agrees with the clearly dominance of a melt component derived by anatexis of a metapelitic source. Two samples of a garnet-bearing (and comparatively zircon-rich) diatexite show 87Sr/86Sr(320Ma) values (0.7120 and 0.7102) similar to those found in granites, but have higher "Nd(320Ma): -2.0 and -1.6. This may be explained by either (a) the involvement of a different source in the genesis of this diatexite or (b) the occurrence of Nd isotope disequilibrium during the melting process, with the preservation of high 143Nd/144Nd ratios in refractory phases such as garnet and/or zircon. A Rb-Sr wr-feldspar-biotite-muscovite isochron of 301.2 5.6 Ma (MSWD=0.42; initial 87Sr/86Sr=0,71516 0.00074) in a granite sample is interpreted as recording the final stage of the operation of the shear zone, which was accompanied by mica recrystallization. Funding: projects Petrochron (PTDC/CTE-GIX/112561/2009) and Geobiotec (PEst-C/CTE/UI4035/2011). References Pereira E. et allia (2007) – Carta Geológica 1/50000 de Oliveira de Azeméis. INETI, Lisboa. Pinto M.S. (1979) – PhD Thesis. Univ. Leed

Sr and Nd isotope composition of the Alcáçovas calc-alkaline rocks (Ossa-Morena Zone, Portugal)

The Alcáçovas area is located in the SW sector of the Ossa-Morena Zone (OMZ), close to a major fault that separates this geotectonic unit from the South Portuguese Zone (SPZ). Along this boundary, in the OMZ, testimonies of low-K tholeiitic and calc-alkaline magmatism are common and have been interpreted as being related to the operation of a subduction zone between OMZ and SPZ during the Variscan cycle [1]. Two main igneous lithologies, both displaying calc-alkaline compositions, can be found in the studied area: gabbro-diorites and dacitic-rhyolitic porphyries [2,3]. Outcrop conditions have not yet allowed to establish unequivocally the sequence of magma emplacement. In previous geochronological studies on the porphyries, whole-rock Rb-Sr dates and K-Ar ages cluster around 320 Ma [4,5,6]. According to field observations, sometimes felsic dykes cut mafic rocks, but there are also gradual transitions from gabbroic to tonalitic compositions, within bodies mapped as gabbro-diorite, revealing that different melts coexisted. In this study, rock samples of both gabbro-dioritic bodies and porphyries were analysed for Rb-Sr and Sm-Nd isotopes. Considering the whole set of samples, no isochron was obtained, showing that they can not be simply related by crystal fractionation processes. Rb-Sr data of porphyries from a single quarry (at Lameira, 7 km to the SW of Alcáçovas) give 323±16 Ma (MSWD=1.9; initial 87Sr/86Sr=0.7097±0.0018). Taking into account that the rocks of the Lameira outcrop show strong hydrothermal alteration, this date must be viewed as a consequence of a very efficient redistribution of mobile elements during aqueous fluid circulation and, as such, it places a minimum limit to the actual magmatic age. The plot of compositions of the gabbro-dioritic bodies, including their transitions to tonalites and the associated felsic dykes, in the εNd-87Sr/86Sr diagram, define an almost perfect hyperbole (from εNd323 = +3.9 and 87Sr/86Sr323 = 0.7058 to εNd323 = -3.8 and 87Sr/86Sr323 = 0.7085), as expected in a mixture between mantle-derived melts and crustal materials. In the same diagram, samples from the Lameira quarry show an almost constant εNd323, between -2.4 and -2.9, and 87Sr/86Sr323 varying from 0.7092 to 0.7106. Therefore, the Lameira porphyries could represent a member of the same mixture, with the Sr signature modified by hydrothermal fluids with a stronger crustal component

Metodologia para seleção de hortaliças com resistência à nematóides: alface/Meloidogyne spp.

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Limiting performance analysis of a vehicle restraint system

Trabalho apresentado em ICEDyn 2013, International Conference on Structural Engineering Dynamics, 17-19 June 2013, Sesimbra, PortugalN/

Tonalitas del Macizo de Hospitais (Zona de Ossa Morena, SO Macizo Ibérico, Portugal): I: Encuadre geológico y petrografía

The Hospitais Massif is an elliptical-shaped plutonic body, with a WNW-ESE long axis, located in the western Ossa-Morena Zone domains in Portugal. This massif, composed essentially of tonalites, is part of an igneous association, ranging from gabbros to granites, intrusive in a gneissic-migmatitic complex, as part of the Évora High-grade Metamorphic Terrains. The tonalites present magmatic fabrics associated with a moderately developed foliation, recording syntectonic crystallization and cooling, co-planar to steep foliations observed within the surrounding sheared gneisses and migmatites. From field and petrographic studies, it is possible to suggest that the deformation of the tonalites and associated basic rocks was synchronous with Variscan progressive shearing of the gneisses and migmatites envelope.El Macizo de Hospitais corresponde a un plutón elíptico de orientación ONO-ESE localizado en los domínios occidentales de la Zona de Ossa Morena, en Portugal. Este macizo, constituido por una asociación ígnea que incluye desde gabros hasta granitos y en la que son dominantes las tonalitas, está intruida en un complejo de gneises y migmatitas perteneciente a los Terrenos de Alto-grado Metamórfico de Évora. Las tonalitas muestran fabricas magmáticas asociadas a una foliación moderadamente desarrollada durante la cristalización y enfriamiento, paralelas a la foliación subvertical observada en los gneises y migmatitas del encajante. Las evidencias de campo y los estudios petrográficos permiten sugerir que la deformación de las tonalitas y rocas básicas asociadas que afloran cerca de Montemor-o-Novo, fue contemporánea con el progresivo cizallamiento Varisco observado en los gneises y migmatitas del encajante

Tonalitas del Macizo de Hospitais (Zona de Ossa Morena, SO Macizo Ibérico, Portugal): II: Geoquímica y petrogénesis

As described in the first part of this work (Moita et al., this volume), the Hospitais Massif belongs to a synorogenic Variscan magmatic association, intrusive in a gneissic-migmatitic complex of the Évora High-Grade Metamorphic Terrains. In this paper, geochemical data obtained on tonalites and dioritic enclaves, from the Hospitais Massif, and on gabbros, from smaller plutonic bodies in the neighbourhood of that massif, are used to constrain hypotheses on the petrogenetic processes responsible for the mentioned lithologies. Major and trace element geochemistry reveal calc-alkaline affinities and suggest that gabbros, diorites and tonalites belong to a magma suite derived dominantly by fractional crystallization. The presence of microgranular mafic enclaves, within the tonalites, could be interpreted as representing an additional process of mingling/mixing for the evolution of these rocks. According to their geochemical features, the enclaves may have resulted from an intermediate differentiation product internally mixed with the tonalite melt. A filter-pressing process can explain the amphibole-dominated cumulate REE pattern displayed by the enclaves.Como se ha descrito en la primera parte del trabajo (Moita et al. en este volumen), el Macizo de Hospitais pertenece a una serie magmática sinorogénica Varisca intruida en un complejo de gneises y migmatitas perteneciente a los Terrenos de Alto-grado Metamórfico de Évora. Se han utilizado datos geoquímicos de las tonalitas, de los enclaves dioríticos y de pequeños cuerpos, espacialmente asociados, de gabro, para caracterizar los procesos petrogenéticos relacionados con esta serie magmática. La geoquímica de elementos mayores y traza muestra una afinidad calco-alcalina y sugiere que los gabros, dioritas y tonalitas pertenecen a una serie magmática originada mediante procesos de cristalización fraccionada. La presencia de enclaves microgranulares máficos en tonalitas, puede ser interpretada como el resultado de un proceso adicional de “mingling/mixing” en la evolución en estas rocas. De acuerdo con sus características geoquímicas los enclaves serián el resultado de un producto intermedio de diferenciación internamente mezclado con el magma tonalítico. Un proceso de “filter-pressing” puede explicar los patrones de tierras raras de cumulados anfibólicos característicos de los enclaves estudiados

Layered granitoids: Interaction between continental crust recycling processes and

In 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-developed compositional layering (concordant with the regional Variscan structure) which was considered, in previous works, as an alternation of leucosome and melanosome. In this study, the layering is described as intercalation of diatexites, weakly foliated granitoids and trondhjemitic veins. Diatexites have characteristics of crustal melts plus restitic material and, according to geochemical and isotopic evidence, result from anatexis of Ediacaran metasediments. Weakly foliated granitoids and trondhjemitic veins from Almansor have calc-alkaline signatures and may be related to each other by crystal fractionation processes; however, the mixing between mafic (mantle-derived) and felsic (diatexitic melt) magmas revealed by the isotopic data may also explain their genesis. In the Alto de São Bento area, several igneous lithologies (tonalites, granodiorites, porphyritic granites and leucogranites) are present and show typical isotropic igneous textures. Despite structural and textural differences, geochemical data support, for most rocks, an origin from the same calk-alkaline suite, also present at Almansor. The Alto de São Bento leucogranites have an isotopic signature that, although different from that obtained in the Almansor diatexites, is still compatible with an origin involving melting of Ediacaran metasediments; compositions, with very low contents of usually incompatible elements, flat normalized REE patterns and strong negative Eu anomalies, suggest that the anatectic melt has undergone crystal fractionation processes before reaching the composition of the leucogranite magma. The Almansor outcrop is then interpreted as the remnants of a shear zone that operated as a pathway for melts that moved upward through the crust providing the locus for differentiation and mingling/mixing of magmas, whilst Alto de São Bento would correspond to the zone, at a higher crustal level, where magmas were trapped and forced to spread horizontally. At Valverde (the third area) foliated and non-foliated granitoids are spatially related and field criteria links these rocks to metamorphic protolith and anatectic melt, respectively. However, petrographic, geochemical and isotopic information shows that they all are compositionally identical trondhjemites with no evidence of metamorphic fabric. In the foliated rocks, mesoscopic features are interpreted as resulting from melt segregation structures formed in a crystallizing mush. In contrast to the previous areas, the Valverde trondhjemites probably do not belong to the main calc-alkaline plutonic suite of the Évora Massif, since they have a distinct Sr and Nd isotope signature

Optimal design of thin-walled laminated beams with geometrically nonlinear behaviour

Com o apoio RAADRI.The purpose of this paper is to present a finite element model for optimal design of composite laminated thin-walled beam structures, with geometrically nonlinear behaviour, including post-critical behaviour and accounting warping deformation. A general continuum formulation is presented for the structural nonlinear analysis, based on the virtual work principle, and using the Updated Lagrangean procedure to describe the deformation of the structure. In order of defining the post-critical behaviour, a generalized displacement control method has been implemented. The thin-walled beam cross-section is considered as made from an assembly of flat layered laminated composite panels. The cross-section bending-torsion properties are integrals based on the cross-section geometry, on the warping function and on the individual stiffness of the laminates that constitute the cross-section. In order to determine its bending-torsion properties, the cross-section geometry is discretized by quadratic isoparametric finite elements. Along its axial direction, the beam is modelled throughout two-node Hermitean finite elements with seven degrees-of-freedom a node. Design sensitivities are imbedded into the finite element modelling and assembled in order to perform the design sensitivity analysis of various structural performance measures by using the adjoint method. As design variables one considers laminate thickness, lamina orientations and the global cross-section geometry. This geometry is defined by the position of master nodes related to the cross-section finite element mesh. Design optimization is performed throughout nonlinear programming techniques

Avaliação de acessos do banco de germoplasma de mandioquinha-salsa da Embrapa Hortaliças para resistência a Meloidogyne spp. no campo.

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COPD control: Can a consensus be found?

AbstractThere are currently no reliable instruments for assessing the onset and progression of chronic obstructive pulmonary disease (COPD) or predicting its prognosis. Currently, a comprehensive assessment of COPD including several objective and subjective parameters is recommended. However, the lack of biomarkers precludes a correct assessment of COPD severity, which consequently hampers adequate therapeutic approaches and COPD control. In the absence of a definition of “well-controlled disease”, a consensus regarding COPD control will be difficult to reach. However, COPD patient assessment should be multidimensional, and anchored in five points: control of symptoms, decline of pulmonary function, levels of physical activity, exacerbations, and Quality of Life.Several non-pharmacological and pharmacological measures are currently available to achieve disease control. Smoking cessation, vaccination, exercise training programs and pulmonary rehabilitation are recognized as important non-pharmacological measures but bronchodilators are the pivotal therapy in the control of COPD. This paper discusses several objective and subjective parameters that may bridge the gap between disease assessment and disease control. The authors conclude that, at present, it is not possible to reach a consensus regarding COPD control, essentially due to the lack of objective instruments to measure it. Some recommendations are set forth, but true COPD control awaits further objective assessments