A restored section of the “southern Variscan realm” across the Corsica–Sardinia microcontinent

A complete section of the southern realm of the Variscan orogenic belt can be restored in the Corsica–Sardinia segment. Northern Corsica exposes a nonmetamorphosed Palaeozoic succession lying on Panafrican mica schist related to a microcontinent (most likely Armorica or from a microcontinent from the Hun superterrane) that had drifted away directly from Gondwana. These formations are thrust over the Variscan Internal Zone composed mainly of anatectic high-grade Palaeozoic formations that crop out from central Corsica to northern Sardinia; the metamorphic peak of the eclogite remnants has been dated at c. 420 Ma. The Variscan Internal Zone interpreted here as a collision zone, and also the Eovariscan suture, was intruded in Corsica by Mg–K granite from 345 to 335 Ma. The thrust of this Internal Zone onto the stack of parautochthonous nappes in central Sardinia is cross-cut by the Posada Asinara dextral shear zone. To the south, parautochthonous nappes overthrust the North-Gondwana margin which displays a possible Panafrican basement topped by an Iglesiente–Sulcis nonmetamorphic/anchimetamorphic Palaeozoic succession.     

Hillslope soil water flowpaths and the dynamics of roadside soil cation pools influenced by road deicers

Over the past 60 years, road deicers (i.e. road salt) have been applied to roadways in high latitudes to improve road conditions in winter weather. However, the dissolution of road deicers in highway runoff creates waters with high concentrations of sodium, which can mobilize soil metals via soil cation‐exchange reactions. While several studies have detailed the interactions of road salt‐rich solutions and surface and ground waters, less attention has been given to how local hydrologic flowpaths can impact the delivery of these solutions to near‐road soils. Between 2013 and 2014, soil water samples were collected from a roadside transect of lysimeter nests in Pittsburgh, Pennsylvania (USA). Soil water samples were analysed for metal concentrations and resulting data used to examine cation dynamics. While patterns in soil water calcium and magnesium concentrations follow patterns in soil water sodium concentrations, additional processes influence patterns in soil water potassium concentrations. Specifically, we observe the highest calcium and magnesium concentrations in the deepest lysimeters, suggesting divalent cations are mobilized to, and potentially accumulate in, deeper soil horizons. In contrast, soil water potassium concentrations do not follow this pattern. Additionally, in all examined elements (Ca, Mg, K, Na, and Cl), the timing of concentration peaks appears be influenced by a combination of both distance from the roadside and sampling depth. These relationships not only suggest that multiple soil water flowpaths interact with our study transect but also confirm that road salt plumes persist and migrate following the road salting season. Characterizing the interactions of sodium‐rich solutions and roadside soil cation pools clarifies our understanding of metal dynamics in the roadside environment. A deeper understanding of these processes is necessary to effectively restore and manage watersheds as high total dissolved solid solutions (e.g. road deicing melt, unconventional natural gas brines, and marginal irrigation water) continue to influence hydrological systems. Copyright © 2016 John Wiley & Sons, Ltd.     

Meteorite finds by EUROMET near Frontier Mountain,North Victoria Land,Antarctica

Abstract— A team from EUROMET (a joint initiative of scientific institutions in Europe interested in meteorites) was sent for the first time to Antarctica in the 1990/91 season to undertake a systematic search for meteorites. The project was organised within the framework of the Italian Antarctic Program (Programma Nationale di Richerche in Antartide, PNRA). The search was carried out in the vicinity of Frontier Mountain (North Victoria Land) and 256 meteorite fragments were discovered, most of which were wind-blown across the blue-ice field to the NE of Frontier Mountain and finally caught in an ice depression about 5 km to the N. The larger meteorites which remained on the ice surface from which they were uncovered may have been transported down to the mountain edge where they have subsequently been destroyed or covered in debris. A search for meteorites at neighbouring Sequence Hills, where similar glaciological conditions as at Frontier Mountain exist, proved unsuccessful. At this location the surface of the blue ice in the valleys with suspected meteorite concentrations was covered by meltwater lakes.     

The curve of growth for stars in the effective temperature range 4000–8500 K

A comparison of different curves of growth derived from available model atmospheres has been done. We found that, in the effective temperature range (4000–8500 K), the differences between models with the same (T _eff, logg) from different authors, do not affect the shape of the curve of growth. Moreoyer, the shifts needed to superpose the curves, for different elements, differ only slightly when model from different authors are used. Then, in the low-temperature range and for the gravities we considered, the particular model atmosphere used to draw the curve of growth is not the main constrain of the method.     

Similarities and differences between the [WC 2] nucleus of NGC 5189 and the WO star Sand 4

Long slit spectra of the planetary nebula NGC 5189 with its [WC2] type central object and the G2.4+1.4 wind bubble around the evolved Pop. I WO star Sand 4 were obtained in order to investigate the observable effects of different initial masses in stars with otherwise similar spectra. Our preliminary results of a comparative spectroscopic study of these two objects shows that the chemical composition of the two nebuale is completely different, even though their morphology is most probably quite similar. In addition, the PN appears much more chemically homogeneous. These features are clearly associated with the evolutionary paths of the stars.     

A tentative evolutionary sequence for carbon stars derived from circumstellar shell parameters

Optically bright and very cool AFGL carbon stars have been analyzed in order to find a common evolutionary sequence according to indications in this sense derived from papers which have treated only the first or the second group of stars separately.An apparent discrepancy existing between the stellar parameters has been overcome following an inverse procedure which provides these values by means of the shell parameters.The results seem to indicate that AFGL stars, whose variability nature is still unknown, should be Mira or Mira-like according to the values of their dust shell temperatures.Dust shell masses have been estimated for both samples of stars finding an inverse dependence with the effective temperature,M _d T _* ^–9.1 .This may be interpreted in terms of evolutionary sequence in the sense that the cooler the stars the larger their shell masses.     

The evidence of circumstellar shells for K type stars

Photometric data between 0.4 and 20 are discussed for K stars. Evidence of IR excess in the 11 region has been found for five stars in a sample of fourteen. The hypothesis of the presence of circumstellar matter in K stars seems to be confirmed.

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Sono stati analizzati dati fotometrici per stelle K tra 0.4 e 20 . Si è riscontrata la presenza di un eccesso infrarosso nella regione intorno a 11 per 5 stelle su 14. Sembra così trovare conferma la ipotesi della presenza di materia circumstellare anche in stelle K.

     

Deep sea diapirs and bottom simulating reflector in Fairway Basin (SW Pacific)

A recent swath-bathymetry and geophysical survey of the R/V L'Atalante in the Fairway Basin between Australia and New Caledonia allowed to confirm the Cretaceous age of the creation of the basin by continental stretching. This first stage of opening of the Fairway Basin is associated with the deposition of a continuous salt/mud layer feeding today numerous diapirs, some of them piercing the 3 to 4 km thick sedimentary cover and reaching the seafloor. In close link with this salt/mud layer a Bottom Simulating Reflector indicator of gas hydrates level occupies a 70000 km² surface at about 500 to 600 m-depth beneath the sea floor. The coexistence of both BSR and diapirs suggests a thermogenic better than biogenic origin for the gas hydrates horizon.