Geophysical exploration on the subsurface geology of La Garrotxa monogenetic volcanic field (NE Iberian Peninsula)

We applied self-potential (SP) and electrical resistivity tomography (ERT) to the exploration of the uppermost part of the substrate geology and shallow structure of La Garrotxa monogenetic volcanic field, part of the European Neogene–Quaternary volcanic province. The aim of the study was to improve knowledge of the shallowest part of the feeding system of these monogenetic volcanoes and of its relationship with the subsurface geology. This study complements previous geophysical studies carried out at a less detailed scale and aimed at identifying deeper structures, and together will constitute the basis to establish volcanic susceptibility in La Garrotxa. SP study complemented previous smaller-scale studies and targeted key areas where ERT could be conducted. The main new results include the generation of resistivity models identifying dykes and faults associated with several monogenetic cones. The combined results confirm that shallow tectonics controlling the distribution of the foci of eruptive activity in this volcanic zone mainly correspond to NNW–SSE and accessorily by NNE–SSW Neogene extensional fissures and faults and concretely show the associated magmatic intrusions. These structures coincide with the deeper ones identified in previous studies, and show that previous Alpine tectonic structures played no apparent role in controlling the loci of this volcanism. Moreover, the results obtained show that the changes in eruption dynamics occurring at different vents located at relatively short distances in this volcanic area are controlled by shallow stratigraphical, structural and hydrogeological differences underneath these monogenetic volcanoes.     

From Cadomian arc to Ordovician passive margin: geochemical records preserved in metasedimentary successions of the Orlica-Śnieżnik Dome in SW Poland

The chemical composition of metamorphosed siliciclastic rocks in the Orlica-?nie?nik Dome (Bohemian Massif) identifies the main sources for the Neoproterozoic [the M?ynowiec Formation (MF)], Early Cambrian [the Stronie Formation (SF)] and Late Cambrian/Early Ordovician [the Goszów quartzites (GQ)] sediments. The MF developed from erosion of a Cadomian magmatic arc along the northern Gondwana margin. The variegated SF, with supra-subduction affinities, shows chemical characteristics pointing to erosion of the freshly exhumed Cadomian orogen and detritus deposition in the back-arc basin. The very different chemical features of the GQ indicate deposition in a basin sited on a passive continental margin. The explanation proposed for the observed changes in chemical composition involves three main stages: (1) The pre ~540 Ma evolution of an active continental margin and related back-arc basin ceased with the collision and accretion of the magmatic arc to the Gondwana margin; (2) Early Cambrian rift to drift transition (540–500 Ma) and development of a depositional basin filled with detritus derived from remnants of the magmatic arc; (3) Peri-Gondwana break-up leading to the formation of shallow-water passive margin depositional basins filled with quartz-rich detritus resembling Early Ordovician Armorican quartzites known from other parts of the Variscan Belt.     

Extended statistical entropy analysis for the evaluation of nitrogen budgets in Austria

Extended statistical entropy analysis (eSEA) is used to evaluate the nitrogen (N) budgets of two Austrian catchments, the Wulka and the Ybbs, and of entire Austria. The eSEA quantifies the extent of N dispersion in the environment. The results from the eSEA are compared to the corresponding N use efficiencies (NUEs). Application of the eSEA reveals that the Ybbs catchment, compared to the Wulka catchment leads to a greater extent of N dispersion, primarily as a result of increased losses of N compounds to the atmosphere and in leachates to the groundwater. The NUE in the Wulka catchment, at 63 %, is substantially higher than that in the Ybbs catchment, at 43 %, and confirms a more efficient N use in Wulka. Furthermore, it is shown that the adoption of a healthy, balanced diet, as defined by the German Nutrition Society, changes the N budget of Austria in a way that significantly reduces the dispersion of N. Decreased N losses to the atmosphere and to the groundwater are primarily responsible for this result. The national NUE of Austria responds only moderately to the adoption of such a diet increasing from 48 to 53 % and leads to statistically insignificant results if the uncertainty of the input data is taken into account. This study demonstrates the effectiveness of eSEA for the evaluation of N budgets in agricultural regions and suggests that statistical entropy can serve as a reliable agri-environmental indicator to support decisions regarding nutrient management.     

Enhancement of deltamethrin degradation by soil bioaugmentation with two different strains of Serratia marcescens

Deltamethrin is one of the most commonly used pyrethroid in agricultural practice in different geographic regions of the world. It is detected in many environments, especially in soil and water, and can exhibit toxic effect to human and other organisms. In this study, we describe two bacterial strains DeI-1 and DeI-2, isolated from soil, and both identified as Serratia marcescens based on profile of the fatty acid methyl esters, biochemical test, and 16S RNA gene analysis, which were shown to efficiently degrade deltamethrin. Degradation of deltamethrin in mineral salt medium (50 mg l^?1) proceeded by strains DeI-1 or DeI-2 reached the values of 88.3 or 82.8 % after 10 days, and DT50 was 2.8 or 4.0 days, respectively. Bioaugmentation of deltamethrin-contaminated non-sterile soils (100 mg kg^?1) with strains DeI-1 or DeI-2 (3 × 10⁶ cells g^?1 of soil) enhanced the disappearance rate of pyrethroid, and its DT50 was reduced by 44.9, 33.1, 44.4, and 58.2 days or 39.1, 25.8, 35.6, and 46.0 days in sandy, sandy loam, silty loam, and silty soils, respectively, in comparison with non-sterile soils with only indigenous microflora. The three-way ANOVA indicated that DT50 of deltamethrin was significantly (P < 0.01) affected by soil type, microflora presence, and inoculum, and the interaction between these factors. Generally, the lower content of clay and organic carbon in soil, the higher degradation rate of deltamethrin was observed. Obtained results show that both strains of S. marcescens may possess potential to be used in bioremediation of deltamethrin-contaminated soils.     

Dissolution–precipitation processes governing the carbonation and silicification of the serpentinite sole of the New Caledonia ophiolite

The weathering of mantle peridotite tectonically exposed to the atmosphere leads commonly to natural carbonation processes. Extensive cryptocrystalline magnesite veins and stock-work are widespread in the serpentinite sole of the New Caledonia ophiolite. Silica is systematically associated with magnesite. It is commonly admitted that Mg and Si are released during the laterization of overlying peridotites. Thus, the occurrence of these veins is generally attributed to a per descensum mechanism that involves the infiltration of meteoric waters enriched in dissolved atmospheric CO₂. In this study, we investigate serpentinite carbonation processes, and related silicification, based on a detailed petrographic and crystal chemical study of serpentinites. The relationships between serpentine and alteration products are described using an original method for the analysis of micro-X-ray fluorescence images performed at the centimeter scale. Our investigations highlight a carbonation mechanism, together with precipitation of amorphous silica and sepiolite, based on a dissolution–precipitation process. In contrast with the per descensum Mg/Si-enrichment model that is mainly concentrated in rock fractures, dissolution–precipitation process is much more pervasive. Thus, although the texture of rocks remains relatively preserved, this process extends more widely into the rock and may represent a major part of total carbonation of the ophiolite.     

An analysis and comparison of observed Pleistocene South Carolina (USA) shoreline elevations with predicted elevations derived from Marine Oxygen Isotope Stages

Geological maps of South Carolina, covering > 6800 km², confirm the existence of eight preserved Pleistocene shorelines above current sea level: Marietta (+ 42.6 m), Wicomico (+ 27.4 m), Penholoway (+ 21.3 m), Ladson (+ 17.4 m), Ten Mile Hill (+ 10.7 m), Pamlico (+ 6.7 m), Princess Anne (+ 5.2 m), and Silver Bluff (+ 3 m). Current geochronologic data suggest that these eight shorelines correlate with Marine Oxygen Isotope Stages (MIS) as follows: Marietta—older than MIS 77; Wicomico—MIS 55–45; Penholoway—MIS 19 or 17; Ladson—MIS 11; Ten Mile Hill—MIS 7; Pamlico—MIS 5; Princess Anne—MIS 5; and Silver Bluff—MIS 5 or 3. Except for the MIS 5e Pamlico, and possibly the MIS 11 Ladson, the South Carolina elevations are higher than predicted by isotope proxy-based reconstructions. The < 4 m of total relief from the Pamlico to the Silver Bluff shoreline in South Carolina, for which other reconstructions suggest an expected relief of ~ 80 m, illustrates the lack of match. Our results suggest that processes affecting either post-depositional changes in shoreline elevations or the creation of proxy sea-level estimates must be considered before using paleo sea-level position on continental margins.     

Photometric and spectrophotometric observations of Nova Delphini 1967

Photographic, photovisual and photoelectric (V) observations of Nova Delphini 1967 were made from August 8 to October 31 (Table I, Figure 1). Simultaneously spectrophotometric measurements of the continuum were made on objective prism exposures extending to November 26, and spectrophotometric gradients derived (Tables II and III; Figures 3, 4, and 5). The continuum of Nova near its flat maximum is close to that of an early-type star in contrast to late-type absorptionline spectrum.     

Microtopography,water storage and flow patterns in a fine‐textured soil under agricultural use

Agricultural use of soils implies tillage and often compaction and therefore influences processes on soil surface and affects infiltration of water into the subsoil. Although many studies on soil surface processes or flow patterns in soils exist, works relating both are rare in literature. We did two tracer experiments with Brilliant Blue FCF on a tilled and compacted plot and a non‐tilled one to investigate water storage on the soil surface during simulated rainfall and changes of soil microtopography, to analyse the associated flow patterns in the soil and to relate both to tillage and compaction. Our results show that storage was larger on the tilled and compacted plot than on the non‐tilled one. After tillage, transport processes above the plough pan were partly disconnected from those underneath because macropores were disrupted and buried by the tillage operation. However, preferential flow along cracks occurred on both plots and the macropores buried below the tillage pan still functioned as preferential flow paths. Therefore, we conclude that the studied soil is susceptible to deep vertical solute propagation at dry conditions when cracks are open, irrespective of tillage and compaction. Copyright © 2012 John Wiley & Sons, Ltd.     

Use of the Geometric Elements in Numerical Simulations

We derive the transformations to convert the state vector in cartesian coordinates into geometric orbital elements (and conversely the geometric elements into the state vector) for a test particle moving around an oblate planet. These transformations arise from the epicyclic theory and are accurate to second order in eccentricity and inclination. This paper is written to be directly used for computational purposes, such as the numerical study of ring dynamics.