Emission features in the solar corona after the perihelion passage of Comet 1979 XI

On the coronograph spectrophotographic records taken on 31.372 UT, August 1979, some faint emission features were found which can be ascribed to Siii and Niii. These emissions were obviously a transient phenomena which were detected only 10 hr after the supposed fall of Comet 1979 XI in the Sun's photosphere. It cannot be excluded that the appearance of Si and Ni lines was triggered by the evaporation of dust particles with a high abundance of heavier elements in the solar corona. This assumption is also supported by intensity distribution of the Fex coronal line around the Sun's limb. The maximum coincide with the position angle of the projected path of the comet.     

Some consequences of meteoroid impacts on Saturn's rings

High-velocity impacts of interplanetary meteoroids on Saturn's rings are discussed. It is shown that the neutral gas emitted by impact vaporization may be responsible, to a large part, for the observed neutral ring atmosphere. Both the predicted neutral gas injection rate and the gas temperature (or kinetic energy) are compatible with the measurements (see Broadfoot, A. L., B. R. Sandel, D. E. Shemansky, J. B. Holberg, G. R. Smith, D. F. Strobel, J. C. McConnell, S. Kumar, D. M. Hunten, S. K. Atreya, T. M. Dohnahne, H. W. Moos, J. L. Bertaux, J. E. Blamont, R. B. Pomphrey, and S. Linik, Science212, 206–211, 1981). Heavy ejecta particles produce a particulate ring “halo”. The physical properties of this halo are calculated, and it appears to be identical with the tenous particle population discussed by Baum and Kreidl (1982). Erosion of Saturn's ring particles, the resulting mass balance, and regolith formation are estimated. This provides some constraints on surface properties and optical albedo.     

A geological and geotechnical investigation of the settlement area of Zümrüt Building (Konya, Turkey) which caused 92 fatalities due to its collapse

This study examines the local geological conditions and soil structure as possible causes of the collapse of the Zümrüt Building 2 February 2004. This catastrophe resulted in 92 fatalities and 35 injuries. This study also examines other views which claim weak soil structure, elastic and consolidation settlement of soil and excessive groundwater extraction as well as subsidence resulting from the underground silt erosion as possible factors. Zümrüt Building was constructed on normally consolidated, low plasticity clay. The underground water table was 30 m in depth. The internal friction angle of soil was 8°–30°, its cohesion was between 34 and 127 kN/m² and standard penetration test numbers varied between 11 and 50. The underground water level beneath Zümrüt Building had risen 4.5 m since its construction. Therefore the claim that subsidence resulting from the decrease of underground water level contributed to the collapse is incorrect. Secondly the settlement, resulting from the filling up of the pores created by the silt receding with the underground water, was 4.4 mm in total, and attributing this as the primary cause of the collapse is also incorrect. Soil properties, in situ and laboratory test results showed that the existing and/or expected settlement and the differential ground settlement in the Zümrüt building vicinity had the potential to cause structural damage. The tensile stresses caused by differential settlements recorded here are thought to be an indicator, but not the main cause contributing to the collapse of the building. The Zümrüt Building collapse was due to several compounding mistakes during the construction phase. These were geotechnical and other project faults and the use of low quality construction materials. The resulting catastrophe caused 92 fatalities, 35 injuries and a material loss of approximately US$7 million.     

Georadiochemical evidence to weathering of mining residues of the Mansfeld mining district,Germany

Mining heaps are used as archives for the investigation of weathering processes. Aim of this work was to investigate the different weathering behavior of heap materials derived from Kupferschiefer mining with respect to environmental hazard. For this purpose, Kupferschiefer and slag material of two heaps of different age were examined regarding to the radionuclide distribution and geochemical composition. By measuring of the local dose rate, performing digital autoradiography and gamma spectrometry the radiological load of the heaps and the heap materials was determined. The geochemical characterization of the samples was performed by XRF, ICP–OES and ICP–MS. The results show a clear higher radionuclide load of the younger slag heap. A depletion of chalcophile and lithophile elements in the older slag was determined. Apart from a homogeneous radionuclide distribution, considerable radionuclide enrichments in fossil fragments could be proven. The results reveal a different weathering behavior of slag material in comparison to the Kupferschiefer depending on the chemical binding of the elements on organic and inorganic species. Natural organic matter as well as apatite in Kupferschiefer act as retention barrier for some metals.     

Anthropogenic affects on lake sedimentation process: a case study from Lake Sapanca, NW Turkey

Lake Sapanca in NW Turkey is a fault originated freshwater basin fed by seasonally variable flows of 15 streams. Considerations of lake–river interaction, supported by statistical measures of 47 bottom samples, suggest that sediment transport and deposition within the lake is controlled by two types of human constructed structures in addition to natural factors: (1) the dykes constructed in the front of streams, which feed the lake by strong flows, to prevent the filling of lakebed by coarse-grained sediments; (2) the constructed regulator on the outflowing Çarksuyu stream results in a higher sedimentation rate of clay-sized material on the NE corner of the lake, which is extraordinary in the shelf environment.     

The Ca-Eskola component in eclogitic clinopyroxene as a function of pressure, temperature and bulk composition: an experimental study to 15 GPa with possible implications for the formation of oriented SiO2-inclusions in omphacite

Experiments have been conducted in the P-T range 2.5–15 GPa and 850–1,500°C using bulk compositions in the systems SiO₂–TiO₂–Al₂O₃–Fe₂O₃–FeO–MnO–MgO–CaO–Na₂O–K₂O–P₂O₅ and SiO₂–TiO₂–Al₂O₃–MgO–CaO–Na₂O to investigate the Ca-Eskola (CaEs Ca_0.5□_0.5AlSi₂O₆) content of clinopyroxene in eclogitic assemblages containing garnet + clinopyroxene + SiO₂ ± TiO₂ ± kyanite as a function of P, T, and bulk composition. The results show that CaEs_ss in clinopyroxene increases with increasing T and is strongly bulk composition dependent whereby high CaEs-contents are favoured by bulk compositions with high normative anorthite and low diopside contents. In this study, a maximum of 18 mol% CaEs_ss was found at 6 GPa and 1,350°C in a kyanite-eclogite assemblage garnet + clinopyroxene + kyanite + rutile + coesite. By comparison, no significant increase in CaEs_ss with increasing P could be observed. If the formation of oriented SiO₂-rods frequently observed in eclogititc clinopyroxenes is due to the retrogressive breakdown of a CaEs-component then these textures are a cooling rather than a decompression phenomenon and are most likely to be found in kyanite-bearing eclogites cooled from temperatures ≥750°C. The presence of clinopyroxene with approx. 4 mol% CaEs_ss in an experiment conducted at 2.5 GPa/850°C confirms earlier suggestions based on field data that vacancy-rich clinopyroxenes are not necessarily restricted to ultrahigh pressure metamorphic conditions. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

National flood discharge mapping in Austria

This article presents the approach and the results of a study in which 30, 100 and 200 year return period flood discharges were estimated for 26,000 km of Austrian streams. Three guiding principles were adopted: combination of automatic methods and manual assessments by hydrologists to allow speedy processing and account for the local hydrological situation; combination of various sources of information including flood peak samples, rainfall data, runoff coefficients and historical flood data; and involvement of the Hydrographic Services to increase the accuracy and enhance the acceptance of results. The flood discharges for ungauged catchments were estimated by the Top-kriging approach with manual adjustment to the local flood characteristics. The adopted combination approach proved to be very efficient both in terms of the project time required and in terms of the accuracy and acceptability of the estimated flood discharges of given return periods.     

The role of the volatile phase for REE and Y fractionation in low-silica carbonate magmas: implications from natural carbonatites, Namibia

Summary Two bimodal carbonatite complexes in Namibia of Cretaceous age are explored as to the presence and composition of a coexisting carbonatitic fluid. The Kalkfeld and Ondurakorume complexes contain both Ca- and Mg/Fe-carbonatites, composed of calcite alone or calcite with ferroan dolomite, fluorapatite and strontianite. The major element evolution in the bulk rocks from s?vites to beforsites is due to crystallization of calcite and fluorapatite. All carbonatites show a negative Y anomaly in normalised REE plots. Fractionation is accompanied by successively lower HREE contents between Tb and Yb, expressed by the ratios Nd/Ho and Ho/Lu. The evolution of this downward-facing hump goes along with decreasing Y contents in bulk rocks and minerals. All this requires an additional phase coexisting with the carbonate liquid during fractionation. Comparison between the bulk rocks and the expelled fluid shows that the latter had preferentially accumulated the HREE and Y. Further evidence for this process are hydrothermal, HREE, Y-rich fluorites in other carbonatite complexes which reflect the composition of the expelled fluid. The high strength of fluoride complexes suggests that fluoride complexing in the carbonatitic fluid is the process responsible for extracting HREE and Y from the carbonatite magma, leaving fractionated carbonatite rocks depleted in these elements. The geochemical evolution of carbonatite magmas along fractionation has therefore to be considered in a melt-mineral-fluid system. Correspondence: B. Bühn, Instituto de Geociências, Universidade de Brasilia, Campus Universitário Darcy Ribeiro, Brasilia 70910-900, Brazil