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

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

Valorização agrícola de lamas de origem têxtil

Valorização agrícola de lamas de origem têxtil

Características petrográficas y geoquímicas de los paragneises de Granja (Dominio Medio Coreaú, NW Ceará, Brasil)

The Granja Granulite Complex (GGC) exposed in the Médio Coreaú Domain (NW Ceará, Brasil) consists mainly of garnet and sillimanite migmatitic paragneisses enclosing discontinuous lenses of mafic granulites and enderbites. According to the published geochronological data, this high-grade metamorphic belt represents a segment of the Paleoproterozoic basement intensely reworked during the Brasiliano/Pan-African Orogeny in the Neoproterozoic (600 Ma). The Granja paragneisses are strongly foliated rocks characterized by the alternance of dark garnet-biotite-sillimanite-rich layers and millimeter-thick leucocratic quartz-feldspathic bands, interpreted as indicative of incipient melting. As melt contents increase, layer-parallel leucosomes become thicker and a well-developed stromatic layering is defined. Both the gneissic and stromatic fabrics are strongly overprinted by a penetrative mylonitic foliation correlated to the last reactivation of the dextral NE-SW trending Granja Shear Zone (GCZ) that cuts across the studied area. Mineral assemblages and microstructures indicate that these rocks were affected by granulite-facies metamorphism and anatexis followed by decompression and cooling. In order to constrain the protolith composition of the Granja paragneisses, twelve whole-rock samples from the parts of the migmatitic paragneisses that appear to have undergone little or no melt extraction were analysed for major and trace elements. In the classification diagram of Herron (1988), the samples plot in the transition between the greywacke and the pelite fields, suggesting that the pre-metamorphic sequence was dominantly composed by shales and immature clastic sediments (greywackes). Their chondrite normalized REE patterns show a moderate LREE enrichment (LaN/YbN = 9.46-15.50), flat HREE profiles and negative Eu anomalies (Eu/Eu∗= 0.63-0.82), closely resembling those of PAAS (Post-Archean average Australian Shale) and Early Proterozoic Greywackes. Geochemical data also suggest that the precursor sediments of the Granja paragneisses derived from source areas of felsic to intermediate composition and were deposited in a tectonically active continental margin/continental island arc setting.El Complejo Granulítico de Granja (GGC), expuesto en el Dominio Medio Coreaú (NW del Estado de Ceará, Brasil), está constituido predominantemente por paragneises granatíferos con silimanita en cuyo seno se intercalan cuerpos lenticulares, discontinuos, de granulitas máficas y enderbitas. De acuerdo con los datos geocronológicos publicados, este terreno metamórfico de alto grado representa un segmento de un basamento Paleoproterozoico que fue intensamente retrabajado en el Neoproterozoico, durante la Orogénesis Brasiliense / Panafricana (600 Ma). Los paragneises de Granja son rocas con una fuerte foliación, caracterizadas por la alternancia de niveles oscuros, ricos en granate-biotita-silimanita, y bandas milimétricas leucocráticas cuarzo-feldespáticas interpretadas como resultado de fusión incipiente. Con el incremento del componente fundido, aumenta el espesor de los leucosomas concordantes y las rocas adquieren un aspecto estromático. A estas estructuras se superpone una foliación milonítica asociada a la última reactivación de la Zona de Cizalla de Granja, un accidente con dirección NE-SW y movimiento dextral que atraviesa la zona estudiada. Las asociaciones minerales y las texturas de reacción indican que después de alcanzar las condiciones de fusión parcial en la facies granulítica, las rocas sufrieron descompresión y enfriamiento. Con el fin de caracterizar la composición de los protolitos de los paragneises de Granja, se analizaron los elementos mayores y tierras raras de doce muestras de aquellas partes de los paragneises migmatíticos en los que la extracción de fundido parece haber sido nula o muy limitada. En el diagrama de clasificación de Herron (1988), las muestras se sitúan en la transición entre los campos de las grauvacas y pelitas, sugiriendo que en la secuencia pre-metamórfica dominaban sedimentos arcillosos y sedimentos clásticos poco maduros (grauvacas). Los patrones de tierras raras normalizados a condrita muestran un moderado enriquecimiento en las tierras raras ligeras (LaN/YbN=9.46–15.50), perfiles planos en tierras raras pesadas y anomalías negativas de Eu (Eu/Eu*=0.63–0.82), con pautas muy próximas tanto a las del PAAS (Post-Archean average Australian Shale) como a las del EP GREY (Early Proterozoic Greywackes). Los datos geoquímicos sugieren también que los sedimentos precursores de los paragneises de Granja tuvieron su origen en un área fuente con composición félsica a intermedia y fueron acumulados en un ambiente de margen continental activo / arco insular continental

Utilização agrícola e compostagem de lamas de origem têxtil

Utilização agrícola e compostagem de lamas de origem têxtil

The impact of deep-sea fisheries and implementation of the UNGA Resolutions 61/105 and 64/72. Report of an international scientific workshop

The scientific workshop to review fisheries management, held in Lisbon in May 2011, brought together 22 scientists and fisheries experts from around the world to consider the United Nations General Assembly (UNGA) resolutions on high seas bottom fisheries: what progress has been made and what the outstanding issues are. This report summarises the workshop conclusions, identifying examples of good practice and making recommendations in areas where it was agreed that the current management measures fall short of their target

Energy Conditions in f(G)f(G) Modified Gravity with Non-minimal Coupling to Matter

In this paper we study a model of modified gravity with non-minimal coupling between a general function of the Gauss-Bonnet invariant, $f(G)$, and matter Lagrangian from the point of view of the energy conditions. Such model has been introduced in Ref. [21] for description of early inflation and late-time cosmic acceleration. We present the suitable energy conditions for the above mentioned model and then, we use the estimated values of the Hubble, deceleration and jerk parameters to apply the obtained energy conditions to the specific class of modified Gauss-Bonnet models.Comment: 12 pages, no figur, Accepted for publication in Astrophysics and Space Scienc

Thermodynamics of Modified Chaplygin Gas and Tachyonic Field

Here we generalize the results of the work of ref. [10] in modified Chaplygin gas model and tachyonic field model. Here we have studied the thermodynamical behaviour and the equation of state in terms of volume and temperature for both models. We have used the solution and the corresponding equation of state of our previous work [12] for tachyonic field model. We have also studied the thermodynamical stability using thermal equation of state for the tachyonic field model and have shown that there is no critical points during thermodynamical expansion. The determination of $T_{*}$ due to expansion for the tachyonic field have been discussed by assuming some initial conditions. Here, the thermal quantities have been investigated using some reduced parameters.Comment: 10 page