Military training area in Kras (Slovenia)

 Slovenia's main military training area at Poček is located in the mountainous Javorniki Watershed. This is a karstic district without surface drainage or river valleys. The typical landscapes are conical hills and plateaus with many dolines. The lithology, tectonic structure and speleological data indicate a typical karst aquifer with underground water moving rapidly through fissures and conduits. Little attenuation occurs in such conditions and as a result there is a high risk of pollution. Tracer tests have shown that a significant proportion of the water recharging the Malni and Vipava springs comes from the vicinity of the military training area. As a result any polluting activities taking place within the military training area are likely to affect the two springs. This is a very serious matter as the springs have been developed to provide the water supply for the population of south-western Slovenia. Received: 20 April 1998 · Accepted: 24 August 1998     

Thermal and mechanical behaviour of the orogenic middle crust during the syn‐ to late‐orogenic evolution of the Variscan root zone,Bohemian Massif

We combine structural observations, petrological data and ⁴⁰Ar–³⁹Ar ages for a stack of amphibolite facies metasedimentary units that rims high‐P (HP) granulite facies felsic bodies exposed in the southern Bohemian Massif. The partly migmatitic Varied and Monotonous units, and the underlying Kaplice unit, show a continuity of structures that are also observed in the adjacent Blanský les HP granulite body. They all exhibit an earlier NE?SW striking and steeply NW‐dipping foliation (S3), which is transposed into a moderately NW‐dipping foliation (S4). In both the Varied and Monotonous units, the S3 and S4 foliations are characterized by a Sil–Bt–Pl–Kfs–Qtz–Ilm±Grt assemblage, with occurrences of post‐D4 andalusite, cordierite and muscovite. In the Monotonous unit, minute inclusions of garnet, kyanite, sillimanite and biotite are additionally found in plagioclase from a probable leucosome parallel to S3. The Kaplice unit shows rare staurolite and kyanite relicts, a Sil–Ms–Bt–Pl–Qtz±Grt assemblage associated with S3, retrogressed garnet?staurolite aggregates during the development of S4, and post‐D4 andalusite, cordierite and secondary muscovite. Mineral equilibria modelling for representative samples indicates that the Varied unit records conditions higher than ~7 kbar at 725 °C during the transition from S3 to S4, followed by a P?T decrease from ~5.5 kbar/750 °C to ~4.5 kbar/700 °C. The Monotonous unit shows evidence of partial melting in the S3 fabric at P?T above ~8 kbar at 740–830 °C and a subsequent P?T decrease to 4.5–5 kbar/700 °C. The Kaplice unit preserves an initial medium‐P prograde path associated with the development of S3 reaching peak P?T of ~6.5 kbar/640 °C. The subsequent retrograde path records 4.5 kbar/660 °C during the development of S4. ⁴⁰Ar–³⁹Ar geochronology shows that amphibole and biotite ages cluster at c. 340 Ma close to the HP granulite, whereas adjacent metasedimentary rocks preserve c. 340 Ma amphibole ages, but biotite and muscovite ages range between c. 318 and c. 300 Ma. The P?T conditions associated with S3 imply an overturned section of the orogenic middle crust. The shared structural evolution indicates that all mid‐crustal units are involved in the large‐scale folding cored by HP granulites. The retrograde P–T paths associated with S4 are interpreted as a result of a ductile thinning of the orogenic crust at a mid‐crustal level. The ⁴⁰Ar–³⁹Ar ages overlap with U–Pb zircon ages in and around the HP granulite bodies, suggesting a short duration for the ductile thinning event. The post‐ductile thinning late‐orogenic emplacement of the South Bohemian plutonic complex is responsible for a re‐heating of the stacked units, reopening of argon system in mica and a tilting of the S4 foliation to its present‐day orientation.     

The selection of appropriate spectrally bright pseudo-invariant ground targets for use in empirical line calibration of SPOT satellite imagery

The appropriate utilization of multi-temporal SPOT multispectral satellite imagery in quantitative remote sensing studies requires the removal of atmospheric effects. One widely used and potentially very accurate way of achieving absolute atmospheric correction is the calibration of at-satellite radiance data to field measures of the surface reflectance factor (ρ_s). There are a number of variations in this technique, which are known collectively as empirical line (EL) approaches. However, the successful application of an EL spectral calibration requires the presence and careful selection of appropriate pseudo-invariant ground targets within each scene area. Real surfaces, even those that are man-made and vegetation-free, display non-Lambertian reflectance behaviour to some extent. Because of the ±31° off-nadir incidence angle range of the SPOT sensors, this is a crucial consideration. In favourable circumstances, it may be possible to utilize a goniometer to collect multiangular ρ_s measurements, but for widespread lower cost application of EL approaches currently, the use of a handheld spectrometer to measure nadir only ρ_s is a more realistic proposition. In either case, the selection of targets that have more limited and stable multiangular reflectance behaviour is preferable. Details are given of the reflectance properties of a variety of spectrally bright potential calibration surface types, encompassing sands, gravel, asphalts, and managed and artificial grass turf surfaces, measured in the field using the Finnish Geodetic Institute Field Goniospectrometer (FIGIFIGO). Bright calibration site selection requirements for SPOT data are discussed and the physical mechanisms behind the varying reflectance characteristics of the surfaces are considered. The most desirable properties for useful calibration targets are identified. The results of this study will assist other workers in the identification of likely suitable EL calibration sites for medium and high resolution optical satellite data, and therefore help optimize efforts in the time consuming and costly process of measuring ρ_s in the field.     

New chondrichthyans from the Irati Formation (Early Permian,Paraná Basin), Brazil: origin,paleoenvironmental and paleogeographical considerations

Three genera, known by dorsal finspine, are reported from conglomeratic sandstone at the base of the Lower Permian (Kungurian) Irati Formation (Paraná Basin) near Rio Claro, São Paulo State, Brazil, noteworthy for the great richness of vertebrate fossils. The fossils include: (1) the previously known Sphenacanthus with the species Sphenacanthus sanpauloensis and an indeterminate species; (2) the Permian – Carboniferous genus Amelacanthus; (3) a new indeterminate Chondrichthyes. These fossils are found together with: continental, fresh-water and salt-water vertebrates. The analysis of this assemblage allows inference about the origin of Paraná Basin Chondrichthyes as well as reconstruction of the paleoenvironment and the possible geographic isolation of these fishes during the Permian in Brazil.     

Ejections of Magnetic Structures Above a Spherical Wedge Driven by a Convective Dynamo with Differential Rotation

We combine a convectively driven dynamo in a spherical shell with a nearly isothermal density-stratified cooling layer that mimics some aspects of a stellar corona to study the emergence and ejections of magnetic field structures. This approach is an extension of earlier models, where forced turbulence simulations were employed to generate magnetic fields. A spherical wedge is used which consists of a convection zone and an extended coronal region to ???1.5 times the radius of the sphere. The wedge contains a quarter of the azimuthal extent of the sphere and 150^° in latitude. The magnetic field is self-consistently generated by the turbulent motions due to convection beneath the surface. Magnetic fields are found to emerge at the surface and are ejected to the coronal part of the domain. These ejections occur at irregular intervals and are weaker than in earlier work. We tentatively associate these events with coronal mass ejections on the Sun, even though our model of the solar atmosphere is rather simplistic.     

U–Pb geochronology of the Sondalo gabbroic complex (Central Alps) and its position within the Permian post-Variscan extension

International Journal of Earth Sciences - The end of an orogenic cycle is commonly associated with a general extensional regime, widespread magmatism and complex metamorphic overprints. The...     

ISCO for Groundwater Remediation: Analysis of Field Applications and Performance

A critical analysis of in situ chemical oxidation (ISCO) projects was performed to characterize situations in which ISCO is being implemented, how design and operating parameters are typically employed, and to determine the performance results being achieved. This research involved design of a database, acquisition and review of ISCO project information, population of the database, and analyses of the database using statistical methods. Based on 242 ISCO projects included in the database, ISCO has been used to treat a variety of contaminants; however, chlorinated solvents are by far the most common. ISCO has been implemented at sites with varied subsurface conditions with vertical injection wells and direct push probes being the most common delivery methods. ISCO has met and maintained concentrations below maximum contaminant levels (MCLs), although not at any sites where dense nonaqueous phase liquids (DNAPL) were presumed to be present. Alternative cleanup levels and mass reduction goals have also been attempted, and these less stringent goals are met with greater frequency than MCLs. The use of pilot testing is beneficial in heterogeneous geologic media, but not so in homogeneous media. ISCO projects cost $220,000 on average, and cost on average $94/yd³ of target treatment zone. ISCO costs vary widely based on the size of the treatment zone, the presence of DNAPL, and the oxidant delivery method. No case studies were encountered in which ISCO resulted in permanent reductions to microbial populations or sustained increases in metal concentrations in groundwater at the ISCO-treated site.