New U-Pb zircon age constraints for the emplacement of the Reguengos de Monsaraz Massif (Ossa Morena Zone)

The Reguengos de Monsaraz massif is located in the Portuguese sector of the Ossa Morena Zone (ZOM), one of the major geotectonic units of the Iberian Variscan Belt. It intruded Lower Paleozoic metasediments, strongly affected by deformation and metamorphism during the Varis-can orogeny. Pluton emplacement was responsible for the development of a contact metamor-phism aureole in the surrounding country rocks. Based on regional constraints, the intrusion was included in the group of the late-post-tectonic granitoids. The pluton shows an inversely zoned pattern and consists of tonalitic to granodioritic rocks with abundant mafic microgranular enclaves, occupying most of the presently exposed intrusion area and minor bodies of gabbro-diorites in the east and centre. Field, petrographical and geo-chemical data reveal that mixing / mingling between mantle- and crustally-derived magmas and fractional crystallization played a major role in the genesis and evolution of these granitoids 1. Early attempts to date the Reguengos de Monsaraz intrusion, using Rb-Sr isotopic data for a feldspar-amphibole pair from one granodiorite sample, yielded an age of 297.5 ± 2.9 Ma. This age was interpreted as a cooling age and provided a minimum estimate for the timing of mag-matic crystallization. In order to better constrain the age and emplacement sequence of the mas-sif, five samples representing the different magmatic units (gabbro diorites, tonalites and mafic microgranular enclaves) were selected for determination of U-Pb zircon ages by isotope dilution techniques. The zircon populations from two samples of the gabbro diorites (one from the central sector and the other from the easternmost body) yielded overlapping 206Pb/238U average ages of 337.4 1.1 Ma and 338.6 ± 0.7 Ma, respectively. Similar ages were obtained in two samples from the main tonalite-granodiorite facies (337.3 ± 2.3 Ma; 337.8 ± 0.7 Ma). Finally, the zircons from the microgranular enclave yielded a 206Pb/238U average age of 336.5 ± 0.5 Ma. A slightly younger age was obtained in two fractions of titanite from the enclave (333.6 ± 2.5 Ma), suggesting either resetting of their original magmatic ages or late stage crystallization. The new U-Pb age data support a coeval emplacement for all the members of this suite, at ap-proximately 337-338 Ma. Such a close space-time association between mafic and felsic grani-toids is consistent with the proposed mixing model. According to recent studies, this sector of the OMZ was affected by three Variscan deforma-tion events 2. The earlier deformation phases (D1 and D2) occurred in Late Devonian ( 380-360 Ma) and Early Carboniferous times ( 360-345 Ma), whilst the latter (D3) has a Pennsylva-nian age (305-295 Ma). Based on the available geochronological information, the emplacement of the Reguengos de Monsaraz magmas took place at a time of tectonic quiescence between D2 and D3. The relatively young Rb-Sr age recorded in the feldspar-amphibole pair may therefore reflect the effects of the last tectonothermal event, also documented by the replacement of horn-blende crystals by actinolite

Geochronology and Isotope Geochemistry of Felsic Marginal Facies of the Reguengos de Monsaraz Pluton (OMZ)

No sector sueste do maciço de Reguengos de Monsaraz (Zona de Ossa-Morena), ocorrem rochas félsicas quer em continuidade espacial com as litologias principais do plutonito quer em pequenos corpos aparentemente separados. Neste trabalho, estudou-se o granito marginal da zona de Arraieiras, bem como o tonalito da zona do ribeiro dos Gagos. Datações U-Pb (em zircão e monazite) revelam que estas litologias são, no essencial, contemporâneas entre si, bem como relativamente às fácies mais comuns do maciço de Reguengos, e que os processos de instalação magmática deverão ter decorrido há 337-338 Ma. Do ponto de vista geoquímico, o granito de Arraieiras parece ter uma relação genética forte com o resto do plutonito, através de processos de mistura de líquidos (de origens mantélica e de anatexia de metassedimentos) e diferenciação magmática, a que se terão seguido fenómenos locais de assimilação do encaixante no nível de instalação final. O paradoxo de haver rochas mais máficas do que o granito com assinaturas isotópicas mais “crustais” poderá ser explicado pela intervenção final destes processos de assimilação. Quanto ao tonalito de Gagos, as suas características geoquímicas, e em particular as razões isotópicas de Sr e Nd, requerem uma origem distinta, com contribuição de fonte infracrustal.Felsic rocks occur in the SE sector of the Reguengos de Monsaraz massif either as a border zone of the pluton or as small satellite bodies. In this work, the Arraieiras granite (from the border zone) and the Gagos tonalite (from a satellite body) were studied for geochronology and geochemistry. The obtained zircon and monazite U-Pb ages show that the two felsic lithologies and the main units of the Reguengos pluton are essentially contemporaneous to each other and that magma emplacement took place at 337-338 Ma. Geochemical features of the Arraieiras granite suggest that it has a strong genetic link with the other lithologies of the pluton, through magma mixing (from mantle and metasedimentary sources) and differentiation processes; in a late evolutionary stage, at the final emplacement level, assimilation of country rock material also took place. The paradox of some more mafic rocks displaying isotope signatures more “crustal” than those revealed by the Arraieiras granite is probably a consequence of late assimilation events. In contrast, the Gagos tonalite, according to the Sr and Nd isotope fingerprints, seems to be related to a different sequence of processes and, in particular, it requires the contribution of an infracrustal source

Sr isotopic signatures of Portuguese bottled mineral waters, their relationships with the geological setting and potential use for product authentication

The Sr isotopic ratios of nine bottled natural mineral waters from Portugal were measured in the Laboratory of Isotope Geology of the University of Aveiro (LGIUA). The results obtained show that the Sr isotopic variability of these waters is strongly correlated with the age and mineralogical composition of the aquifer source rocks. The lowest 87Sr/86Sr ratios are found in water samples from the Monchique aquifer (87Sr/86Sr = 0,70447), located in Late Cretaceous alkaline magmatic rocks of mantle origin. The Vimeiro waters are hosted in carbonate and evaporite formations of Jurassic age and have 87Sr/86Sr values of 0,70808, whereas the waters sourced in Cenozoic siliciclastic sediments tend to exhibit higher 87Sr/86Sr ratios, close to the rainwater value (São Silvestre; 87Sr/86Sr = 0,71078). Finally, the waters coming from granitic and/or metamorphic terrains of the Iberian Variscan basement (Vitalis, Luso, Carvalhelhos, Fastio, Serra da Estrela) display the most radiogenic Sr isotopic signatures (87Sr/86Sr > 0,7136). In the modern commercial context, the differences encountered provide a powerful tool for fingerprinting the mineral water origin and may be used for purposes of mineral water authentication. The use of 87Sr/86Sr ratios may also be extended to studies on the provenance of some foods and beverages, taking into account the influence of the geological / pedological factor on the Sr isotopic composition recorded by the plants

Evaluation Of Biochemical And Serological Methods To Identify And Clustering Yeast Cells Of Oral Candida Species By Chromagar Test, Sds-page And Elisa.

The purpose of this work was to evaluate biochemical and serological methods to characterize and identify Candida species from the oral cavity. The strains used were five Candida species previously identified: C. albicans, C. guilliermondii, C. parapsilosis, C. krusei, C. tropicalis, and Kluyveromyces marxianus, as a negative control. The analyses were conducted through the SDS-PAGE associated with statistical analysis using software, chromogenic medium, and CHROMagar Candida (CA), as a differential medium for the isolation and presumptive identification of clinically important yeasts and an enzyme-linked immunoabsorbent assay (ELISA), using antisera produced against antigens from two C. albicans strains. This method enabled the screening of the three Candida species: C. albicans, C. tropicalis, and C. krusei, with 100% of specificity. The ELISA using purified immunoglobulin G showed a high level of cross-reaction against protein extracts of Candida species. The SDS-PAGE method allowed the clustering of species-specific isolates using the Simple Matching coefficient, S(SM) = 1.0. The protein profile analysis by SDS-PAGE increases what is known about the taxonomic relationships among oral yeasts. This methodology showed good reproducibility and allows collection of useful information for numerical analysis on information relevant to clinical application, and epidemiological and systematical studies.64231732

Scaling anomaly in cosmic string background

We show that the classical scale symmetry of a particle moving in cosmic string background is broken upon inequivalent quantization of the classical system, leading to anomaly. The consequence of this anomaly is the formation of single bound state in the coupling interval \gamma\in(-1,1). The inequivalent quantization is characterized by a 1-parameter family of self-adjoint extension parameter \omega. It has been conjectured that the formation of loosely bound state in cosmic string background may lead to the so called anomalous scattering cross section for the particles, which is usually seen in molecular physics.Comment: 4 pages,1 figur

Stationary quasivariational inequalities with gradient constraint and nonhomogeneous boundary conditions

Publicado em "From particle systems to partial differential equations. Part 2. (Springer proceedings in mathematics & statistics, vol. 75). ISBN 978-3-642-54270-1We study existence of solution of stationary uasivariational inequalities with gradient constraint and nonhomogeneous boundary condition of Neumann or Dirichlet type. Through two different approaches, one making use of a fixed point theorem and the other using a process of regularization and penalization, we obtain different sufficient conditions for the existence of solution.(undefined

Evaluation of turbulent dissipation rate retrievals from Doppler Cloud Radar

Turbulent dissipation rate retrievals from cloud radar Doppler velocity measurements are evaluated using independent, in situ observations in Arctic stratocumulus clouds. In situ validation data sets of dissipation rate are derived using sonic anemometer measurements from a tethered balloon and high frequency pressure variation observations from a research aircraft, both flown in proximity to stationary, ground-based radars. Modest biases are found among the data sets in particularly low- or high-turbulence regimes, but in general the radar-retrieved values correspond well with the in situ measurements. Root mean square differences are typically a factor of 4-6 relative to any given magnitude of dissipation rate. These differences are no larger than those found when comparing dissipation rates computed from tetheredballoon and meteorological tower-mounted sonic anemometer measurements made at spatial distances of a few hundred meters. Temporal lag analyses suggest that approximately half of the observed differences are due to spatial sampling considerations, such that the anticipated radar-based retrieval uncertainty is on the order of a factor of 2-3. Moreover, radar retrievals are clearly able to capture the vertical dissipation rate structure observed by the in situ sensors, while offering substantially more information on the time variability of turbulence profiles. Together these evaluations indicate that radar-based retrievals can, at a minimum, be used to determine the vertical structure of turbulence in Arctic stratocumulus clouds