Sondagem de Belverde (Cenozóico, Península de Setúbal, Portugal). Diagrafias

In the aim of the project "Recognition of the Miocene of the distal region of the Lower Tagus Basin through a borehole with continuous sampling", Temperature, Natural Gamma Ray, Neutron (almost in all the borehole), Sonic, SP and SPR (in two small sections in upper and lower parts of the Miocene Series) geophysical logs were carried on. Interpretation of those logs and comparison with chronological, lithostratigraphical, micropaleontological and clay mineraIs data; helped in the definition of depositional sequences and to obtain paleoenvironmental reconstructions that could lead to a better understanding of the evolution of the Setúbal Península and Lisboa regions Miocene gulf. Log data agree with the lithologic succession observed in the Belverde borehole, essentially silty sandstones/sandy siltstones (with variable clay content) to clays, often with marly intercalations. Sonic logs (and Neutron logs, in general) reflect the sediments porosity. The higher acoustic velocities are often related to compact/massive layers as claystones and/or limestones and rather fossiliferous marly layers. Lower values are obtained for porous, silty sandstones (fossiliferous and with scarce clay content) and bio-calcareous sandstones. As indicative, we obtained the mean values of 2500-3000m/s for the higher velocities and 1300-1600m/s for the lowest ones. ln Natural Gamma Ray log, the radiation peaks can be correlated to often fossiliferous marly micaceous layers. Radioactive micas are present. It seems that the gamma peaks and the depositional sequences previously defined for the Lower Tagus Basin (see Antunes et al., 1999, 2000; Pais et al., 2002) can be correlated, taking also into account the whole available micropaleontological, palynological and isotopic evidence.

Spectroscopic characterization of natural dyes by their non-invasive identification on pre-Columbian codices: the Maya yellow

Mesoamerican cultures had a strong tradition of written and pictorial manuscripts, called the codices. In studies already performed it was found the use of Maya Blue, made from a mixture of indigo and a clay called palygorskite, forming an incredibly stable material where the dye is trapped inside the nanotubes of the clay, after heating. However, a bigger challenge lies in the study of the yellows used, for these civilizations might have used this clay-dye mixture to produce their yellow colorants. As a first step, it was possible to provide identification, by non-invasive methods, of two colorants (a flavonoid and a carotenoid). While the flavonoid absorbed between 368-379 nm, the carotenoid would absorb around 455 nm. A temperature study also conducted allowed to set 140ºC as the desirable temperature to heat the samples without degrading them. FT-IR, conventional Raman and SERS allowed us to understand the existence of a reaction between the dyes and the clays (palygorskite and kaolinite), however it is difficult to understand it in a molecular point of view. As a second step, five species of Mexican dyes were selected on the basis of historical sources. The Maya yellow samples were produced adapting the recipe proposed by Reyes-Valerio, supporting the yellow dyes extracted from the dried plants on the clays, with addition of water, and then heated at 140ºC. It was found that the addition of water in palygorskite would increase the pH, hence deprotonating the molecules having a clear negative effect in the color. A second recipe was developed, without the addition of water; however, it was found that the use of water based binders would still alter the color of the samples with palygorskite. In this case, kaolinite without heating yield better results as a Maya yellow hybrid. It was found that the Maya chemistry might not have been the same for all the colors. The Mesoamericans might have found that different dyes could work better to their desires if matched with different clays. It was noticeable that for a clear distinction between flavonoids and carotenoids the reflectance and emission studies suffice, but when clay is added, Raman techniques will perform better. For this reason, conventional Raman and SERS were employed in order to create a database for the Mesoamerican dyestuffs for a future identification.

Rapid assessment of fruit-color selection by birds using artificial fruits at local scale in Central Amazonia

Modeling clays have been used in several ecological experiments and have proved to be an important tool to variables control. The objective of our study was to determine if fruit color in isolated and grouped displays influences the fruit selection by birds in the field using artificial fruits. Data were collected in six plots distributed homogeneously in 3 km long trails with a minimum distance of 0.5 km. We used a paired experimental design to establish our experiments, so that all treatments were available to the local bird community in each plot. Overall, red was more pecked than brown and white. Isolated red and brown displays were significantly more pecked than others display. Even though our study was conducted in small spatial scales, artificial fruits appeared to be efficient in register fruit consumption attempts by bird. Although inconclusive about selective forces that sharp the dynamics of fruit color polymorphisms and choice by frugivorous birds, our findings corroborate recent studies wherein birds showed preferences by high- over low-contrast fruit signals.

Vermiculite bio-barriers for Cu and Zn remediation: an eco-friendly approach for freshwater and sediments protection

The increase in heavy metal contamination in freshwater systems causes serious environmental problems in most industrialized countries, and the effort to find ecofriendly techniques for reducing water and sediment contamination is fundamental for environmental protection. Permeable barriers made of natural clays can be used as low-cost and eco-friendly materials for adsorbing heavy metals from water solution and thus reducing the sediment contamination. This study discusses the application of permeable barriers made of vermiculite clay for heavy metals remediation at the interface between water and sediments and investigates the possibility to increase their efficiency by loading the vermiculite surface with a microbial biofilm of Pseudomonas putida, which is well known to be a heavy metal accumulator. Some batch assays were performed to verify the uptake capacity of two systems and their adsorption kinetics, and the results indicated that the vermiculite bio-barrier system had a higher removal capacity than the vermiculite barrier (?34.4 and 22.8 % for Cu and Zn, respectively). Moreover, the presence of P. putida biofilm strongly contributed to fasten the kinetics of metals adsorption onto vermiculite sheets. In open-system conditions, the presence of a vermiculite barrier at the interface between water and sediment could reduce the sediment contamination up to 20 and 23 % for Cu and Zn, respectively, highlighting the efficiency of these eco-friendly materials for environmental applications. Nevertheless, the contribution of microbial biofilm in open-system setup should be optimized, and some important considerations about biofilm attachment in a continuous-flow system have been discussed.

Use of terrestrial laser scanning for the characterization of retrogressive landslides in sensitive clay and rotational landslides in river banks

Depuis plus de 10 ans les modèles numériques d'altitude (MNA) produits par technologie de « light detection and ranging » (« LIDAR ») ont fourni de nouveaux outils très utiles pour des études géomorphologiques, particulièrement dans le cas des glissements de terrain. Le balayage laser terrestre (« TLS ») permet une utilisation très souple. Le TLS peut être employé pour la surveillance ou dans des situations d'urgence qui nécessitent une acquisition rapide d'un MNA afin d'évaluer l'aléa. Au travers de trois exemples, nous démontrons l'utilité du TLS pour la quantification de volumes de glissements de terrain, la création de profils et l'analyse de séries temporelles. Ces études de cas sont des glissements de terrain situés dans les argiles sensibles de l'est du Canada (Québec, Canada) ou de petits glissements rotationnels dans les berges d'une rivière (Suisse).

Biostratigraphy, mineralogy and geochemistry of the Trabakua Pass and Ermua sections in Spain: Paleocene-Eocene transition

Isotopic, geochemical and bulk mineralogical analyses in the Trabakua and Ermua sections, Basque Basin, reveal major changes across the Paleocene-Eocene transition. Expanded sedimentary records exhibit a gradual decrease of 1.0 parts per thousand in delta(13)C values in the lower part of Zone P5 followed by a more rapid 3 parts per thousand negative excursion. The 3 parts per thousand delta(13)C excursion is associated with an abrupt decrease in carbonate sedimentation, increased detrital flux and decreased grain size which suggest changes in marine/atmospheric currents and/or size and structure of the ocean carbon reservoir. The clays recognized at Trabakua record a deep burial diagenesis as indicated by two generations of chlorite, the presence of mixed-layers chlorite-smectite and illite-smectite, the absence of smectite and the near absence of kaolinite. The very low delta(18)O values (<-3.5 parts per thousand) throughout the Trabakua and Ermua sections reflect diagenetic alteration rather than paleotemperatures. Because of deep burial diagenesis and very poorly preserved microfossils, the Trabakua Pass and Ermua sections are not optimal potential stratotypes for the Paleocene-Eocene boundary.

N-cadherin is essential for retinoic acid-mediated cardiomyogenic differentiation in mouse embryonic stem cells.

Contraction forces developed by cardiomyocytes are transmitted across the plasma membrane through end-to-end connections between the myocytes, called intercalated disks, which enable the coordinated contraction of heart muscle. A component of the intercalated disk, the adherens junction, consists of the cell adhesion molecule, N-cadherin. Embryos lacking N-cadherin die at mid-gestation from cardiovascular abnormalities. We have evaluated the role of N-cadherin in cardiomyogenesis using N-cadherin-null mouse embryonic stem (ES) cells grown as embryoid bodies (EBs) in vitro. Myofibrillogenesis, the spatial orientation of myofibers, and intercellular contacts including desmosomes were normal in N-cadherin-null ES cell-derived cardiomyocytes. The effect of retinoic acid (RA), a stage and dose-dependent cardiogenic factor, was assessed in differentiating ES cells. all-trans (at) RA increased the number of ES cell-derived cardiomyocytes by approximately 3-fold (at 3 x 10(-9) M) in wt EBs. However, this effect was lost in N-cadherin-null EBs. In the presence of supplemented at-RA, the emergence of spontaneously beating cardiomyocytes appeared to be delayed and slightly less efficient in N-cadherin-null compared with wt and heterozygous EBs (frequencies of EBs with beating activity at 5 days: 54+/-18% vs. 96+/-0.5%, and 93+/-7%, respectively; peak frequencies of EBs with beating activity: 83+/-8% vs. 96+/-0.5% and 100%, respectively). In conclusion, cardiomyoyctes differentiating from N-cadherin-null ES cells in vitro show normal myofibrillogenesis and intercellular contacts, but impaired responses to early cardiogenic effects mediated by at-RA. These results suggest that N-cadherin may be essential for RA-induced cardiomyogenesis in mouse ES cells in vitro.

Studies in stoichiometry with compositional data

Geochemical data that is derived from the whole or partial analysis of various geologic materialsrepresent a composition of mineralogies or solute species. Minerals are composed of structuredrelationships between cations and anions which, through atomic and molecular forces, keep the elementsbound in specific configurations. The chemical compositions of minerals have specific relationships thatare governed by these molecular controls. In the case of olivine, there is a well-defined relationshipbetween Mn-Fe-Mg with Si. Balances between the principal elements defining olivine composition andother significant constituents in the composition (Al, Ti) have been defined, resulting in a near-linearrelationship between the logarithmic relative proportion of Si versus (MgMnFe) and Mg versus (MnFe),which is typically described but poorly illustrated in the simplex.The present contribution corresponds to ongoing research, which attempts to relate stoichiometry andgeochemical data using compositional geometry. We describe here the approach by which stoichiometricrelationships based on mineralogical constraints can be accounted for in the space of simplicialcoordinates using olivines as an example. Further examples for other mineral types (plagioclases andmore complex minerals such as clays) are needed. Issues that remain to be dealt with include thereduction of a bulk chemical composition of a rock comprised of several minerals from which appropriatebalances can be used to describe the composition in a realistic mineralogical framework. The overallobjective of our research is to answer the question: In the cases where the mineralogy is unknown, arethere suitable proxies that can be substituted?Kew words: Aitchison geometry, balances, mineral composition, oxides

Geology and correlation of the Mersin mélanges, southern Turkey

Our paper aims to give a thorough description of the infra-ophiolitic melanges associated with the Mersin ophiolite. We propose new regional correlations of the Mersin melanges with other melange-like units or similar series, located both in southern Turkey and adjacent regions. The palaeotectonic implications of the correlations are also discussed. The main results may be summarized as follows: the infra-ophiolitic melange is subdivided into two units, the Upper Cretaceous Sorgun ophiolitic melange and the Ladinian-Carnian Hacialani melange. The Mersin melanges, together with the Antalya and Mamonia domains, are represented by a series of exotic units now found south of the main Taurus range, and are characteristic of the South-Taurides Exotic Units. These melanges clearly show the mixed origin of the different blocks and broken formations. Some components have a Palaeotethyan origin and are characterized by Pennsylvanian and Lower to Middle Permian pelagic and slope deposits. These Palaeotethyan remnants, found exclusively in the Hacialani melange, were reworked as major olistostromes in the Neotethys basin during the Eo-Cimmerian orogenic event. Neotethyan elements are represented by Middle Triassic seamounts and by broken formations containing typical Neotethyan conodont faunas such as Metapolygnathus mersinensis Kozur & Moix and M. primitius s. s., both present in the latest Carnian interval, as well as the occurrence of the middle Norian Epigondolella praeslovakensis Kozur, Masset & Moix. Other elements are clearly derived from the former north Anatolian passive margin and are represented by Huglu-type series including the Upper Triassic syn-rift volcanic event. These sequences attributed to the Huglu-Pindos back-arc ocean were displaced southward during the Late Cretaceous obduction event. The Tauric elements are represented by Eo-Cimmerian flysch-like and molasse sequences intercalated in Neotethyan series. Additionally, some shallow-water blocks might be derived from the Bolkardag para-autochthonous and the Taurus-Beydaglari marginal sequences.

Late Proterozoic thrust tectonics, high-pressure metamorphism and Uranium mineralization in the domes area, Lufilian arc, northwestern Zambia

The following main lithostratigraphic units have been distinguished in the Domes Area. The Kibaran basement complex composed of gneisses, migmatites with amphibolite bands and metagranites is exposed in dome structures; metamorphic features of Kibaran age have been almost completely obliterated by extensive Lufilian reactivation. The post-Kibaran cover sequence is subdivided into the Lower Roan Group consisting of well-preserved quartzites with high Mg content, talc-bearing, extremely foliated schists intercalated with pseudo-conglomerates of tectonic origin and the Upper Roan Group including dolomitic marbles with rare stromatolites, metapelites and a sequence of detrital metasediments, with local volcano-sedimentary components and interlayered banded ironstones. The sediments of the Lower Roan Group are interpreted as continental to lagoonal-evaporitic deposits partly converted into the talc-kyanite + garnet assemblage characteristic of ``white schists''. The dolomites and metapelites of the Upper Roan Group are attributed to a carbonate platform sequence progressively subsiding under terrigenous deposits, whilst the detrital metasediments and BIF may be interpreted as a basinal sequence, probably deposited on oceanic crust grading laterally into marbles. Metagabbros and metabasalts are considered as remnants of an ocean-floor-type crustal unit probably related to small basins. Alkaline stocks of Silurian age intruded the post-Kibaran cover. Significant ancestral tectonic discontinuities promoted the development of a nappe pile that underwent high-pressure metamorphism during the Lufilian orogeny and all lithostratigraphic units. Rb-Sr and K-Ar and U-Pb data indicate an age of 700 Ma for the highest grade metamorphism and 500 Ma for blocking of the K-Ar and Rb-Sr system in micas, corresponding to the time when the temperature dropped below 350-degrees-400-degrees-C and to an age of about 400 Ma for the emplacement of hypabyssal syenitic bodies. A first phase of crustal shortening by decoupling of basement and cover slices along shallow shear zones has been recognized. Fluid-rich tectonic slabs of cover sediments were thus able to transport fluids into the anhydrous metamorphic basement or mafic units. During the subsequent metamorphic re-equilibration stage of high pressure, pre-existing thrusts horizons were converted into recrystallized mylonites. Due to uplift, rocks were re-equilibrated into assemblages compatible with lower pressures and slightly lower temperatures. This stage occurs under a decompressional (nearly adiabatic) regime, with P(fluid) almost-equal-to P(lithostatic). It is accompanied by metasomatic development of minerals, activated by injection of hot fluids. New or reactivated shear zones and mylonitic belts were the preferred conduits of fluids. The most evident regional-scale effect of these processes is the intense metasomatic scapolitization of formerly plagioclase-rich lithologies. Uraninite mineralization can probably be assigned to the beginning of the decompressional stage. A third regional deformation phase characterized by open folds and local foliation is not accompanied by significant growth of new minerals. However, pitchblende mineralization can be ascribed to this phase as late-stage, short-range remobilization of previously existing deposits. Finally, shallow alkaline massifs were emplaced when the level of the Domes Area now exposed was already subjected to exchange with meteoric circuits, activated by residual geothermal gradients generally related to intrusions or rifting. Most of the superficial U-showings with U-oxidation products were probably generated during this relatively recent phase.

A Miocene mud volcano and its plumbing system: A chaotic complex revisited (Monferrato, NW Italy)

Chaotic deposits are frequently reported in the geological literature and are commonly interpreted as olistostromes or tectonic melanges. A chaotic complex in the Cenozoic succession of Monferrato (NW Italy) consists of interbedded mud breccia and burrowed silty clays that are pierced by sheared mud breccias and embed carbonate-cemented blocks. These may be represented by microcrystalline limestones or strongly cemented matrix-supported breccias locally containing remains of chemosymbiotic organisms (lucinid bivalves). Moreover, cylindrical concretions, up to 15 cm in diameter and 1 m long, occur in the chaotic complex and crosscut bedding planes at high angles. The cement of all these lithified portions is mainly dolomite characterized by low delta(13)C values (from -10.3 to -23parts per thousand PDB) and delta(18)O values up to + 7parts per thousand PDB. The delta(13)C values testify to precipitation of carbonates induced by microbial oxidation of methane, whereas the markedly positive delta(18)C signature, ubiquitous in the cylindrical concretions, is the evidence for the presence and destabilization of gas hydrates. The studied section provides a well-exposed example of the geological record of the birth, life, and death of a mud volcano. Unsheared, soft mud breccias represent mud flows along the flanks of the volcano, whereas sheared mud breccias are the result of the injection of unconsolidated overpressured fine-grained sediments, both taking place during ``eruptive'' phases. They were followed by more quiet stages of hemipelagic sedimentation, burrowing, and CH4 seeping. The cylindrical concretions represent the first described ancient example of the chimneys observed in present-day mud-volcano settings. They are the remnants of a cold-seep plumbing network that crosscut the mud volcano edifice. The chimneys were the pathway for the expulsion toward the sea floor of gas- and sediment-charged fluids likely originated from destabilization of methane gas hydrates. The association of mud breccias and methane-derived carbonates may not be due to mass gravity flows but can be primary and, therefore, is a diagnostic criterion for recognizing chaotic deposits due to mud volcano activity in the geological record.

α-Ketoglutarate regulates acid-base balance through an intrarenal paracrine mechanism.

Paracrine communication between different parts of the renal tubule is increasingly recognized as an important determinant of renal function. Previous studies have shown that changes in dietary acid-base load can reverse the direction of apical α-ketoglutarate (αKG) transport in the proximal tubule and Henle's loop from reabsorption (acid load) to secretion (base load). Here we show that the resulting changes in the luminal concentrations of αKG are sensed by the αKG receptor OXGR1 expressed in the type B and non-A-non-B intercalated cells of the connecting tubule (CNT) and the cortical collecting duct (CCD). The addition of 1 mM αKG to the tubular lumen strongly stimulated Cl--dependent HCO3- secretion and electroneutral transepithelial NaCl reabsorption in microperfused CCDs of wild-type mice but not Oxgr1-/- mice. Analysis of alkali-loaded mice revealed a significantly reduced ability of Oxgr1-/- mice to maintain acid-base balance. Collectively, these results demonstrate that OXGR1 is involved in the adaptive regulation of HCO3- secretion and NaCl reabsorption in the CNT/CCD under acid-base stress and establish αKG as a paracrine mediator involved in the functional coordination of the proximal and the distal parts of the renal tubule.

Mesozoic sequence of Fuerteventura (Canary Islands): Witness of Early Jurassic sea-floor spreading in the central Atlantic

The Fuerteventura Jurassic sedimentary succession consists of oceanic and elastic deposits, the latter derived from the southwestern Moroccan continental margin. Normal mid-oceanic-ridge basalt (N-MORB) flows and breccias are found at the base of the sequence and witness sea-floor spreading events in the central Atlantic. These basalts were extruded in a postrift environment (post-late Pliensbachian), We propose a Toarcian age for the Atlantic oceanic floor in this region, on the basis of the presence higher up in the sequence of the Bositra buchi filament microfacies (Aalenian-Bajocian) and of elastic deposits reflecting tectono-eustatic events (e.g,, late Toarcian to mid-Callovian erosion of the rift shoulder). The S-l sea-floor oceanic magnetic anomaly west of Fuerteventura is therefore at least Toarcian in age. The remaining sequence records Atlantic-Tethyan basinal facies (e.g., Callovian-Oxfordian red clays, Aptian-Albian black shales) alternating with elastic deposits (e.g., Kimmeridgian-Berriasian periplatform calciturbidites and a Lower Cretaceous deep-sea fan system). The Fuerteventura N-MORB outcrops represent the only Early Jurassic oceanic basement described so far in the central Atlantic. They are covered by a 1600 m, nearly continuous sedimentary sequence which extends to Upper Cretaceous facies.

Genesis and classification of Oxisols in a highland toposequence of the upper Jequitinhonha Valley (MG)

The Brazilian System of Soil Classification (SiBCS) is a taxonomic system, open and in permanent construction, as new knowledge on Brazilian soils is obtained. The objective of this study was to characterize the chemical, physical, morphological, micro-morphological and mineralogical properties of four pedons of Oxisols in a highland toposequence in the upper Jequitinhonha Valley, emphasizing aspects of their genesis, classification and landscape development. The pedons occupy the following slope positions: summit - Red Oxisol (LV), mid slope (upper third) - Yellow-Red Oxisol (LVA), lower slope (middle third)- Yellow Oxisol (LA) and bottom of the valley (lowest third) - "Gray Oxisol" ("LAC"). These pedons were described and sampled for characterization in chemical and physical routine analyses. The total Fe, Al and Mn contents were determined by sulfuric attack and the Fe, Al and Mn oxides in dithionite-citrate-bicarbonate and oxalate extraction. The mineralogy of silicate clays was identified by X ray diffraction and the Fe oxides were detected by differential X ray diffraction. Total Ti, Ga and Zr contents were determined by X ray fluorescence spectrometry. The "LAC" is gray-colored and contains significant fragments of structure units in the form of a dense paste, characteristic of a gleysoil, in the horizons A and BA. All pedons are very clayey, dystrophic and have low contents of available P and a pH of around 5. The soil color was related to the Fe oxide content, which decreased along the slope. The decrease of crystalline and low- crystalline Fe along the slope confirmed the loss of Fe from the "LAC". Total Si increased along the slope and total Al remained constant. The clay fraction in all pedons was dominated by kaolinite and gibbsite. Hematite and goethite were identified in LV, low-intensity hematite and goethite in LVA, goethite in LA. In the "LAC", no hematite peaks and goethite were detected by differential X ray diffraction. The micro-morphology indicated prevalence of granular microstructure and porosity with complex stacking patterns.. The soil properties in the toposequence converged to a single soil class, the Oxisols, derived from the same source material. The landscape evolution and genesis of Oxisols of the highlands in the upper Jequitinhonha Valley are related to the evolution of the drainage system and the activity of excavating fauna.

Redox index of soil carbon stability

As an alternative to the relatively complex and expensive spectroscopic methods, the redox properties of humic acids, determined by potentiometric titrations, have been used to evaluate the stability of soil organic C. The objective of the present study was to establish a Redox Index of C Stability (RICS) and to correlate it with some properties of the humic acids extracted from different modal soils in Brazil (distinct weathering stages or management) to facilitate system comparison. The RICS was efficient for soil comparison and variations were comparable to those of the chemical and spectroscopic methods used for humic acid characterization. The values of soil pH, point of zero salt effect, sum of bases, exchangeable Ca content, weathering index, as well as the humic acid O/C ratio, quinone and semiquinone free radical contents, aromatic C and fluorescence intensity were closely related with the RICS. The RICS was higher in less weathered soils, with more active clays and higher fertility. The RICS values of soils under long-term sugarcane management were ranked in decreasing order: unburned, burned with vinasse, burned without vinasse.