Alkalic parental magmas for chassignites?

Abstract Detailed analysis of cumulate and melt inclusion assemblages in the chassignites provide important constraints on the nature of the melt trapped as inclusions in cumulus olivine (and, by extension, parental magma compositions), the pressures of crystallization, and magmatic volatile contents. These mineral assemblages show strong similarities to the experimental fractionation assemblages that produce the sodic silica‐saturated alkalic lavas on Earth (e.g., Ascension Island, Azores, the Nandewar volcano of Australia). The experimental assemblages were produced from silica‐saturated hawaiite at pressures above 4.3 kbar with dissolved water contents above 0.5 wt%. Such pressures are consistent with Ti:Al ratios of the melt‐inclusion pyroxenes in the Chassigny meteorite. Pyroxene compositions suggest early high crystallization temperatures and thus relatively low initial water and F contents. Feldspars indicate that melt evolution proceeded to rhyolite compositions both within the interstices of the cumulate olivine and within the melt inclusions, even though rhyolitic glass is only found within olivine‐hosted polyphase melt inclusions. The observed rhyolite glass is compositionally similar to the alkali‐rich rhyolite of Ascension Island which is produced experimentally by crystallization of hawaiite. It is proposed that the melt trapped in cumulus olivine of the Chassigny dunite was similar to a terrestrial silica‐saturated hawaiite, while that trapped in olivine of the Northwest Africa (NWA) 2727 dunite was less evolved, perhaps mildly alkalic basalt. Melts similar to terrestrial intra‐plate tholeiite could be parental to the cumulus minerals and evolve upon crystallization at pressures above 4.3 kbar and water contents above ?0.4 wt% to mildly alkalic basalt, silica‐saturated hawaiite, and alkali‐rich rhyolite. The melt inclusion assemblages are inconsistent with either crystallization of a low‐Al, high‐Fe basalt, or low‐pressure crystallization of a terrestrial‐like tholeiite.     

Aesthetic justice and urban planning: Who ought to have the right to design cities?*

This paper brings together two diverse approaches to urban planning. The first approach views planning as a means to distribute goods or welfare in society, and therefore considers the promotion of social justice to be the central objective of planning. The second approach highlights the role of planning as a means to produce aesthetically pleasing everyday surroundings. I will explore the concepts of `aesthetic welfare' and `aesthetic justice' developed by the philosopher Monroe Beardsley, and argue that an aesthetically pleasing environment is an important source of aesthetic welfare in society. My contention, then, is that the fair distribution of this welfare should be one of the objectives of public planning policies. This objective, however, is difficult to achieve, since the question cannot only concern the distribution of the aesthetically good environment. This is because there often is no agreement on the criteria for the aesthetically good environment. Thus, I will eventually reject the idea of aesthetic justice as distributive justice that Beardsley advocates. Instead, I will turn to some contemporary theories of justice that question the model of distributive justice, arguing that theories of justice should go beyond the distribution of goods, and encompass also the conception and production of goods. Thus, as I will maintain, aesthetic justice will be eventually best promoted by opening the aesthetic dimension of urban planning (among other dimensions of it) to public participation.     

Automated facies identification by Direct Push-based sensing methods (CPT,HPT) and multivariate linear discriminant analysis to decipher geomorphological changes and storm surge impact on a medieval coastal landscape

In ad 1362, a major storm surge drowned wide areas of cultivated medieval marshland along the north-western coast of Germany and turned them into tidal flats. This study presents a new methodological approach for the reconstruction of changing coastal landscapes developed from a study site in the Wadden Sea of North Frisia. Initially, we deciphered long-term as well as event-related short-term geomorphological changes, using a geoscientific standard approach of vibracoring, analyses of sedimentary, geochemical and microfaunal palaeoenvironmental parameters and radiocarbon dating. In a next step, Direct Push (DP)-based Cone Penetration Testing (CPT) and the Hydraulic Profiling Tool (HPT) were applied at vibracore locations to obtain in situ high-resolution stratigraphic data. In a last step, multivariate linear discriminant analysis (LDA) was successfully applied to efficiently identify different sedimentary facies (e.g., fossil marsh or tidal flat deposits) from the CPT and HPT test dataset, to map the facies' lateral distribution, also in comparison to reflection seismic measurements and test their potential to interpolate the borehole and CPT/HPT data. The training dataset acquired for the key site from coring and DP sensing finally allows an automated facies classification of CPT/HPT data obtained elsewhere within the study area. The new methodological approach allowed a detailed reconstruction of the local coastal landscape development in the interplay of natural marsh formation, medieval land reclamation and storm surge-related land losses.     

Macroscopic impacts of cloud and precipitation processes in shallow convection

This paper presents application of the EULAG model combined with a sophisticated double-moment warm-rain microphysics scheme to the model intercomparison case based on RICO (Rain in Cumulus over Ocean) field observations. As the simulations progress, the cloud field gradually deepens and a relatively sharp temperature and moisture inversions develop in the lower troposphere. Two contrasting aerosol environments are considered, referred to as pristine and polluted, together with two contrasting subgridscale mixing scenarios, the homogeneous and the extremely inhomogeneous mixing. Pristine and polluted environments feature mean cloud droplet concentrations around 40 and 150 mg^?1, respectively, and large differences in the rain characteristics. Various measures are used to contrast evolution of macroscopic cloud field characteristics, such as the mean cloud fraction, the mean cloud width, or the height of the center of mass of the cloud field, among others. Macroscopic characteristics appear similar regardless of the aerosol characteristics or the homogeneity of the subgrid-scale mixing.     

Composition and solubility of precipitated copper(II) arsenates

Equilibrium reactions involving Cu(II) and As(V) have been studied with respect to formation of complexes in aqueous solutions as well as formation of solid phases. Potentiometric titrations performed at 25 °C (I = 0.1 M Na(Cl)) and at different Cu to As ratios gave no evidence for the existence of Cu(II) arsenate complexes in solution below the pH of the precipitation boundaries (pH ≈ 4), irrespective of the Cu to As ratio and pH. Mixing of solutions of Cu(II) and As(V) at different proportions and adjusting pH to values ranging from 4 to 9 resulted in precipitation of five different solid phases. The elemental composition of the solids was determined using X-ray Photoelectron Spectroscopy, and Environmental Scanning Microscopy-Field Emission Gun equipped with an energy dispersive spectroscopy detector. The average Cu/As ratio was determined by dissolving the solids. Total soluble concentrations of the components Cu(II) and As(V), as well as the basicity of the solid phases were determined by analysis of aqueous solutions. Based upon these experimental data the stoichiometric composition of the solid phases and their stability were determined. The resulting equilibrium model includes the solid phases Cu₃(AsO₄)₂, Cu₃(AsO₄)(OH)₃, Cu₂(AsO₄)(OH), Cu₅Na(HAsO₄)(AsO₄)₃ and Cu₅Na₂AsO₄)₄, where Cu₅Na(HAsO₄)(AsO₄)₃ and Cu₅Na₂(AsO₄)₄ have not been reported previously. In 0.1 M Na(Cl), Na⁺ was found to be a significant component in two of the solid phases. The Cu₅Na₂(AsO₄)₄ was formed in weakly alkaline conditions with pNa < 2.5. Stability constants for all solid phases have been determined. Distribution diagrams as well as predominance area (pNa-pH) diagrams are presented to illustrate stability fields of the different solid phases.     

Salt tectonic controls on deep‐water turbidite depositional systems: Miocene,southwestern Lower Congo Basin,offshore Angola

Regionally extensive 3D seismic data from the Lower Congo Basin, offshore Angola, have been used to investigate the influence of salt‐related structures on the location, geometry and evolution of Miocene deep‐water depositional systems. Isochron variations and cross‐sectional lap‐out relationships have then been used to qualitatively reconstruct the syn‐depositional morphology of salt‐cored structures. Coherence and Red‐green‐blue‐blended spectral decomposition volumes, tied to cross‐sectional seismic facies, allow imaging of the main sediment transport pathways and the distribution of their component seismic facies. Major sediment transport pathways developed in an area of complex salt‐related structures comprising normal faults, isolated diapirs and elongate salt walls with intervening intraslope basins. Key structural controls on the location of the main sediment transport pathways and the local interaction between lobe‐channel‐levee systems and individual structures were the length and height of structures, the location and geometry of segment boundaries, the growth and linkage of individual structures, and the incidence angle between structural strike and flow direction. Where the regional flow direction was at a high angle to structural strike, transport pathways passed progressively through multiple intraslope basins in a fill and spill manner. Segment boundaries and structural lows between diapirs acted as spill points, focusing sediment transport between intraslope basins. Channel–lobe transitions are commonly associated with these spill points, where flows expanded and entered depocentres. Deflection of channel‐levee complexes around individual structures was mainly controlled by the length of structures and incidence angle. Where regional flow direction was at a low angle to structural strike, sediment transport pathways ran parallel to structure and were confined to individual intraslope basins for many tens of kilometres. Spill between intraslope basins was rare. The relative position of structures and their segment boundaries was fixed during the Miocene, which effectively pinned the locations where sediment spilled from one intraslope basin to the next. As a result, major sediment transport pathways were used repeatedly, giving rise to vertically stacked lobe‐channel‐levee complexes along the pathways. Shadow zones devoid of coarse clastics developed in areas that were either structurally isolated from the sediment transport pathways or bypassed as a result of channel diversion.     

Quasi-geostrophic shallow-water vortex–patch equilibria and their stability

We examine the equilibrium form, properties, stability and nonlinear evolution of steadily-rotating simply-connected vortex patches in the single-layer quasi-geostrophic model of geophysical fluid dynamics. This model, valid for rotating shallow-water flow in the limit of small Rossby and Froude numbers, has an intrinsic length scale L _D called the “Rossby deformation length” relating the strength of the stratification to that of the background rotation. Here, we generate steadily-rotating vortex equilibria for a wide range of γ?=?L/L _D , where L is the typical horizontal length scale of the vortex. We vary both γ (over the range 0.02?≤?γ?≤?10) and the vortex aspect ratio λ (over the range 0?<?λ?<?1). We find two modes of instability arising at sufficiently small aspect ratio λ?<?λ _c (γ): an asymmetric (dominantly wave 3) mode at small γ (or large L _D ) and a symmetric (dominantly wave 4) mode at large γ (or small L _D ). At marginal stability, the asymmetric mode dominates for γ???3, while the symmetric mode dominates for γ???3. The nonlinear evolution of weakly-perturbed unstable equilibria results in major structural changes, in most cases producing two dominant vortex patches and thin, quasi-passive filaments. Overall, the nonlinear evolution can be classified into three principal types: (1) vacillations for a limited range of aspect ratios λ when 5?≤?γ?≤?6, (2) filamentation and a single-dominant vortex for γ???1, and (3) vortex splitting – asymmetric for 1???γ???4 and symmetric for γ???4.     

Holocene small mammals hunted by owls and humans in southern Brazil: taphonomic evidence and biological significance

Understanding resource utilization and economic diversification amongst Holocene hunter‐gatherers in southern Brazil requires in‐depth taphonomic analysis of faunal assemblages. Three Early to Late Holocene archaeological sites (Garivaldino, Pilger and Sangão) in Rio Grande do Sul State, southern Brazil, revealed large assemblages of small mammal (?1 kg) remains, composed mainly of rodents. To appreciate depositional processes of fauna in relation to human consumption, taphonomic attributes and processes were evaluated. The results indicated that the remains accumulated through different antemortem taphonomic pathways, apparently linked to the size and natural history of the species represented. The small‐ and medium‐sized (<150 g) cricetid rodents (e.g. Pseudoryzomys simplex and Sooretamys angouya) were represented by a low proportion of teeth with lightly digestive corrosion suggesting that they were derived from the predatory activity of owls, possibly Tyto alba. In contrast, large‐sized cricetids (>150 g; Kunsia tomentosus, Gyldenstolpia sp. and Holochilus sp.), and several caviomorph rodents with aggregated spatial distributions (Echimyidae (?Dicolpomys fossor, Phyllomys sp., ?Clyomys riograndensis and ?Euryzygomatomys mordax), Caviidae (Cavia sp.) and Ctenomyidae (Ctenomys sp.)) showed evidence of thermoalteration patterns and cut marks on bones, suggesting human exploitation. A postmortem depositional environment was deduced from dendritic and branched patterns of rootlet etching, apparent mostly at Garivaldino and Pilger. Polished areas and holes on bone surfaces, and impregnation of manganese showed moderate (Sangão) or low (Garivaldino and Pilger) incidence, pointing to water transport under moderate (Pilger) and low (Garivaldino and Sangão) energy over short distances. The results obtained here provide the first clear evidence of early human exploitation of small mammals in southern Brazil, suggesting a diversification of economies. In addition, as several of the recorded rodents are today regionally or biologically extinct, a preliminary discussion about the potential impact of humans on this process is provided.     

Prospects for Solar and Space Weather Research with Polish Part of the LOFAR Telescope

The LOw-Frequency ARray (LOFAR) is a new radio interferometer that consists of an array of stations. Each of them is a phase array of dipole antennas. LOFAR stations are distributed mostly in the Netherlands, but also throughout Europe. In the article we discuss the possibility of using this instrument for solar and space weather studies, as well as ionosphere investigations. We are expecting that in the near future the LOFAR telescope will bring some interesting observations and discoveries in these fields. It will also help to observe solar active events that have a direct influence on the near-Earth space weather.