Melting and subsolidus reactions in the system K2O-CaO-Al2O3-SiO2-H2O: corrections and additional experimental data

Melting relationships in the system K₂O-CaO-Al₂O₃-SiO₂-H₂O have been reinvestigated using Schreinemakers analysis and hydrothermal experiments. The reaction sanidine+muscovite+zoisite+quartz+vapor =melt has been bracketed at 10, 15, and 20 kbars and 670–680, 680–690, and 690–700° C, respectively and it marks the lowest solidus temperatures in the system investigated.Below 10 kbars, experimental data on the beginning of melting in zoisite- or muscovite-bearing anorthite+sanidine assemblages have been obtained, which are not showing any differences and therefore point to melt compositions close to the feldspar-quartz join.     

Interferometric studies of the twilight and nightglow sodium D-line profiles

A 150 mm aperture, pressure scanned Fabry-Perot interferometer has been used to study the midlatitude twilight and nightglow sodium D-line profiles. The line width measurements during evening and morning twilight indicate that the sodium layer temperature rises to a midwinter maximum (～230 K) and then falls to a midsummer minimum (～150 K), in qualitative agreement with the CIRA 1972 model predictions. Nightglow intensity measurements obtained with the interferometer indicate a highly variable behaviour, ranging from near-constant intensities, to monotonically falling, and to rising and falling intensities during the night. Broadening of the nightglow line profiles yields a sodium atom dissociation kinetic energy of (46 ± 4) meV. This suggests that the Chapman NaO + O chemiexcitation process, rather than dissociative recombination of “corkscrewing” ions and electrons, gives rise to the nightglow.     

The Barents Sea impact study (BASIS): methodology and first results

Global and climate changes are subject to scientific, societal and political debates. Recent observational evidence and results of global climate models have identified the circumpolar North as a region particularly susceptible to future climate change. To understand and assess the consequences of these changes for environmental and societal components of the European Arctic, the Barents Sea Impact Study (BASIS), an EU-funded integrated regional impact study (IRIS) has been carried out (ENV4-CT-97-0637). In common with global integrated assessments (IAs), IRISs also take a holistic view on climate change and its impact. Contrary to IAs, however, IRISs adopt a regional to sub-regional spatial scale. BASIS was carried out by an interdisciplinary team of specialists from 13 institutions in 6 countries. Major results pertain to impacts of possible climate change on marine and terrestrial ecosystems, freshwater hydrology, marine trace gas budgets, forestry and fishery. However, in this paper we focus on the major methodological aspects of an IRIS in general and on methods applied in BASIS in particular.     

Intercomparison of Boron Isotope and Concentration Measurements. Part I: Selection, Preparation and Homogeneity Tests of the Intercomparison Materials

In 1999 the Istituto di Geoscienze e Georisorse (IGG), with the support of the International Atomic Energy Agency (IAEA), undertook the collection, preparation and distribution of eight geological materials intended for a blind interlaboratory comparison of measurements of boron isotopic composition and concentration. The materials came from Italian sources and consist of three natural waters (Mediterranean seawater and two groundwaters) and five rocks and minerals (tourmaline, basalt, obsidian, limestone and clay). The solid materials were crushed, milled and mixed, in preparation for distribution. Extensive assays performed at the IGG on these materials demonstrated that their boron isotopic and chemical compositions are homogeneous.
Additional homogeneity tests were carried out on solid material fragments at the GeoForschungsZentrum Potsdam, with the specific objective of investigating the suitability of some of them for the calibration in situ of micro-analytical techniques. Two materials, B4 (tourmaline) and B6 (obsidian), proved to be isotopically homogeneous and may become excellent references for in situ microanalyses of boron isotopes.
The materials described here were used as the basis of a major laboratory intercomparison study and are now available for further distribution from either the IAEA (solid materials) or the IGG (waters).     

Buildings in GI: How to deal with building models in the GIS domain

Digital building information is important during a building's lifecycle, it is needed from first design until demolition. The two domains that mainly contribute are AEC (architecture, engineering, and construction) during design, construction, and operation, and GIS as a supporting discipline for analysis and further integration of the building's environment. However, there is a challenge in information exchange between the two domains, resulting in the remodeling of digital building information in GIS. In this article, we identify three major data sources from the AEC domain and show transformation processes to enable the integration of such models into the geographical environment in the form of one transition model. Furthermore, we show that this model can either be used directly or exported in the form of de facto standards that allow for further analysis.     

Seismostratigraphy and structural framework of the SW Baltic Sea

The SW part of the Baltic Sea between Scania, Rügen, Bornholm and Mön constitutes a complex crustal transition between the Baltic Shield and the accreted Phanerozoic provinces of the West European Platform. An integrated interpretation of marine reflection seismic data sets from the BABEL AC line and two commercial surveys offshore NE Germany and S Sweden have resulted in a complete view of the structural framework in the area. The general seismic picture can best be detected by two characteristic sets of reflection phases. The lower set is dominated by slightly dipping and vertically displaced prominent reflectors corresponding to downfaulted Lower Palaeozoic strata on top of the Precambrian basement. The upper set represents Mesozoic and Cenozoic coherent reflection phases including a thick Upper Cretaceous unit. The Caledonian deformation front is identified in the southern part of the investigated area as the border against which basement rocks have been affected by Caledonian metamorphism and deformation. Major structural elements also include the N–S trending Agricola–Svedala Fault and North Rügen-Skurup Fault. Several NW–SE trending faults are also identified including the Nordadler–Kamien Fault, Jutland–Mön Fault, Carlsberg Fault, Romeleåsen Fault Zone and the Fyledalen Fault Zone. The sedimentary record from NE German offshore wells and Scanian boreholes is compared with the seismic data. The Cambro-Silurian strata are composed mainly of quartzitic sandstones, shales and biomicritic limestones. The Silurian is dominated by grey, micaceous shale and micaceous siltstone deposited in a marginal basin. Upper Palaeozoic strata are merely encountered in the southernmost part of the investigated area. These include Zechstein strata. The Mesozoic deposits are dominated by a thick Cretaceous sequence of mainly limestones with interbedded sandstones.     

Studies of the motion of equatorial 630.0 nm airglow depletions

An all-sky-mapping filter photometeer has been used to study equatorial 630.0 nm nightglow intensity depletions. A generally eastward drift of the ～ 0m/sec. At times two airglow depletions moving at different velocities were observed simultaneously; in one case they merged. Simultaneous interferometric determinations of doppler shifts in the 630.0 nm line indicated that the velocity of the neutral atmosphere does not appear to be correlated with the drift of the airglow depletions. The results are compared with other observations.