Late Pleistocene loess‐palaeosol sequences in the Vojvodina region,north Serbia

Late Pleistocene loess‐palaeosol sequences are widespread in the Vojvodina region, with thicknesses reaching a maximum of about 20 m. Our investigations include more than 40 of these loess sections. Geochronology of the last glacial loess‐palaeosol sequences, based on luminescence dating and amino acid racemisation, provides correlations between Upper Pleistocene loess‐palaeosol sediments in Vojvodina and comparable deposits at other European localities. Sedimentary logs of magnetic susceptibility, grain‐size measurements and carbonate content, combined with malacological evidence, indicate two main relatively cold and arid phases during the last glacial period, related to intensive accumulation of loess units L1L1 and L1L2, as well as many brief episodes of dry and windy climatic conditions, suggesting a possible relationship with cold events recorded in the North Atlantic region. Generally, late Pleistocene climate in the region was dry and relatively warm, compared with glacial period sites in central Europe, and was characterised by sharp differences between glacial and interglacial modes. New data and interpretations presented in this study emphasise the significance of loess‐palaeosol sequences in Vojvodina for the reconstruction of the temporal and spatial evolution of late Pleistocene palaeoclimate in this part of Europe. Copyright © 2007 John Wiley & Sons, Ltd.     

Projections of global warming-induced impacts on winter storm losses in the German private household sector

We present projections of winter storm-induced insured losses in the German residential building sector for the 21st century. With this aim, two structurally most independent downscaling methods and one hybrid downscaling method are applied to a 3-member ensemble of ECHAM5/MPI-OM1 A1B scenario simulations. One method uses dynamical downscaling of intense winter storm events in the global model, and a transfer function to relate regional wind speeds to losses. The second method is based on a reshuffling of present day weather situations and sequences taking into account the change of their frequencies according to the linear temperature trends of the global runs. The third method uses statistical-dynamical downscaling, considering frequency changes of the occurrence of storm-prone weather patterns, and translation into loss by using empirical statistical distributions. The A1B scenario ensemble was downscaled by all three methods until 2070, and by the (statistical-) dynamical methods until 2100. Furthermore, all methods assume a constant statistical relationship between meteorology and insured losses and no developments other than climate change, such as in constructions or claims management. The study utilizes data provided by the German Insurance Association encompassing 24 years and with district-scale resolution. Compared to 1971–2000, the downscaling methods indicate an increase of 10-year return values (i.e. loss ratios per return period) of 6–35 % for 2011–2040, of 20–30 % for 2041–2070, and of 40–55 % for 2071–2100, respectively. Convolving various sources of uncertainty in one confidence statement (data-, loss model-, storm realization-, and Pareto fit-uncertainty), the return-level confidence interval for a return period of 15 years expands by more than a factor of two. Finally, we suggest how practitioners can deal with alternative scenarios or possible natural excursions of observed losses.     

Calculation of uncertainties of U-Pb isotope data

Equations are derived for the estimation of errors and error correlations for various types of U-Pb isotope data, taking into account ion-beam instabilities, run-to-run variability in mass-discrimination, uncertainties in Pb and U concentrations, and uncertainties in initial-Pb and blank-Pb amount and isotopic composition. Equations are also given for the calculation of concordia intercept errors.     

Neue Gesichtspunkte zur Entstehung des Planetensystems

Ohne Zusammenfassung

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New views on the origin of the planetary system

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Nouveaux aperçus sur l'origine du système planétaire

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Vortrag anläßlich der 61. Jahrestagung der Geologischen Vereinigung 1971 in München.     

The low-boron contest: minimising surface contamination and analysing boron concentrations at the ng/g-level by secondary ion mass spectrometry

Summary In-situ analyses of boron using secondary ion mass spectrometry (SIMS) is impeded by surface contamination of the analysed samples. We analysed 40 different natural and synthetic silicate materials, including meteoritic and mantle minerals, in order to find a material with an extremely low boron content that allows us to quantify the level of contamination. Different cleaning procedures were tested, and it was shown that using an ultrasonic cleaner with ultrapure water to clean the sample and setting the imaged field of the ion probe smaller than the primary beam spot reduces the boron contamination level to <2ng/g at a total analysis time of 12min (pre-sputtering: 400s).Herasil 102, a pure synthetic SiO₂ glass manufactured by Heraeus Quarzglas GmbH, Germany, was found to contain 1ng/g boron, and therefore we recommend this glass as a sample to test the contamination level of boron in SIMS analyses.Results for lithium show that analysis of this element is also influenced by contamination, but the contamination levels are much lower than those for boron.     

Der RÜckwärtseinschnitt auf der Kugel und die Funkortung bei weit entfernten Sendern

Zusammenfassung In der folgenden Arbeit wird vorausgesetzt, daß man die geographischen Koordinaten dreier SenderA, B, C kennt und eine stereographische Karte mit einem der Sender, z. B.C, als Kartenpol zur VerfÜgung hat. Die wahre N-Richtung braucht man nicht zu kennen. Vom unbekannten StandortS aus werden durch Funkpeilung die sphärischen WinkelC S A= undC S B= gemessen. Es wird gezeigt, wie man in der stereographischen Karte rein geometrisch und mathematisch streng die beiden zu und gehörigen (den Pothenotschen Kreisen der Ebene entsprechenden) Standkurven in ihrem ganzen Verlauf zeichnen kann. Einer der Schnittpunkte dieser beiden Kurven ist der gesuchte StandortS; seine geographischen Koordinaten werden der stereographischen Karte entnommen. Welcher der acht Schnittpunkte der richtige ist, ergibt sich aus dem gegißten Besteck. — Über die Ausgestaltung dieses Verfahrens zu einem Hilfsmittel der praktischen Navigation wird später gesprochen werden.

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Resection on the sphere and radio direction finding with the aid of long-distance wireless stations

Summary The following paper proceeds from the supposition that the co-ordinates of three wireless transmittersA,B, C are known and that a stereographic map is available having as pole the transmitterC, i. e. one of the three transmitters. The true northern direction needs not to be known. The spheric anglesC S A= andC S B= are measured by radio direction finding from the unknown positionS. It is explained how to plot — in a purely geometrical and rigorously mathematical way on a stereographic map — the entire path of the two radio position curves belonging to and and corresponding with the Pothenot circles on the plane. One of the eight points of intersection of the two radio position curves is the required fixS; its geographical co-ordinates are taken from the stereographic map; which of the intersection points is the right one will be found by the aid of the result of dead reckoning.In a later paper it will be explained how to develop this method to a practical aid in navigation.

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Le recoupement sur la sphère et la radiogoniométrie à l' aide d' émetteurs à grande portée

Résumé Le travail suivant part de la supposition que les coordonnées géographiques de trois émetteursA, B, C soient connues et que l'on dispose d'une carte stéréographique dont l'émetteurC, c.à.d. un des trois émetteurs, soit le pÔle. Il n'est pas nécessaire de connaÎtre le Nord vrai. On mesure les deux angles sphériquesC S A= etC S B= par radiogoniométrie à partir du point inconnuS. En se servant d'une méthode purement géométrique et rigoureusement mathématique on montre de quelle manière on peut porter sur la carte stéréographique tout le cours des deux »courbes de position« associées aux angles et et correspondant aux cercles de Pothenot en planimétrie. Un des huit points d'intersection de ces deux »courbes de position« est la position cherchéeS; on tire ses coordonnées géographiques de la carte stéréographique. Celui des huit points d'intersection qui se confond avec le point estimé indiquera la position correcte.L'extension de cette méthode à une aide de navigation sera l'objet d'un futur travail.

     

Li abundances in eclogite minerals: a clue to a crustal or mantle origin?

The mineral phases of 33 eclogite and garnet clinopyroxenite samples from various tectonic settings were analysed for Li by secondary ion mass spectrometry (SIMS). In all samples, Li is preferentially incorporated into clinopyroxene (0.4 to 80 µg/g), whereas co-existing garnet contains only minor amounts of Li (0.01 to 3.7 µg/g). When present, glaucophane shows Li abundances which are similar to those of clinopyroxene, but phengite contains significantly less Li than clinopyroxene. Additional phases, such as amphibole, quartz, clinozoisite and kyanite, have low Li concentrations (<1 µg/g). No correlation is apparent between the Li contents and major-element compositions of clinopyroxene or garnet. On the basis of both measured Li concentrations in clinopyroxene and estimated Li abundances in the whole rocks, the investigated samples can be subdivided into high-Li and low-Li groups. These groups coincide with the mode of origin of the rocks. Metabasaltic (metagabbroic) eclogites from high-pressure terranes belong to the high-Li group whereas, except for one eclogite, all kimberlite- and basanite-hosted xenoliths have low Li contents. Samples from eclogites and garnet clinopyroxenites associated with orogenic peridotites fall into both groups. It is suggested that the high-Li eclogites originated from basaltic oceanic crust whereby the notable Li enrichment of some samples was probably caused by low-temperature hydrothermal alteration prior to subduction. Furthermore, the low-Li eclogites and garnet clinopyroxenites may represent high-pressure cumulates from mafic melts percolating through the mantle.     

Beitrag zur Frage des Gleichgewichtes im System Düne-Strand-Vorstrand an der Ostseeküste

Zusammenfassung Faziesstudien an Abrasions-, Anlandungs- und stabilen Küsten der Ostsee lassen erkennen, daß der Zustand eines Küstenabschnittes abhängig ist von dem Verhältnis zwischen den Kornverteilungen des Vorstrandes, Strandes und der Düne. Zur Charakteristik der litoralen Sedimente wird der große Viertelgewichtsdurchmesser (Q₇₅) herangezogen, der sich aus der Summenkurve der Sandanteile ergibt. Die Kiese werden vernachlässigt, da sie anderen Transport-bedingungen unterliegen. Stabile Küsten, deren verschiedene Faziesbereiche sich im Gleichgewicht befinden, sind gekennzeichnet durch Zustandsquotienten Q₇₅-Strand/Q₇₅-Vorstrand>1 und Q₇₅-Strand/Q₇₅-Düne=1-1,4. Anlandungsküsten zeigen stets Werte zwischen 1,0 und 1,4, Abrasionsküsten Quotienten <1. Die Ermittlung des Zustandsquotienten erweist sich als eine einfache Methode zur Kennzeichnung stabiler und unstabiler Küstenbereiche der Ostsee.     

Formation and evolution of carbonate chimneys at the Lost City Hydrothermal Field

The Lost City Hydrothermal Field at 30°N, near the Mid-Atlantic Ridge, is an off-axis, moderate temperature, high-pH (9-10.8), serpentinite-hosted vent system. The field is hosted on ∼1.5 Ma crust, near the summit of the Atlantis Massif. Within the field, actively venting carbonate chimneys tower up to 60 m above the seafloor, making them the tallest vent structures known. The chemistry of the chimneys and vent fluids is controlled by serpentinization reactions between seawater and underlying peridotite. Mixing of <40-91 °C calcium-rich vent fluids with seawater results in the precipitation of variable mixtures of aragonite, calcite, and brucite. The resultant deposits range from tall, graceful pinnacles to fragile flanges and delicate precipitates that grow outward from fissures in the bedrock. In this study, mineralogy, petrographic analyses, major and trace element concentrations, and Sr isotopic compositions are used to propose a model for the growth and chemical evolution of carbonate chimneys in a serpentinite-hosted environment. Our results show that nascent chimneys are characterized by a porous, interlacing network of aragonite, and brucite minerals that form extremely fragile structures. The chemistry of these young deposits is characterized by ∼10 wt% Ca and up to 27 wt% Mg, extremely low trace metal concentrations, and ⁸⁷Sr/⁸⁶Sr isotope ratios near 0.70760. During aging of the chimneys, progressive reactions with seawater result in the dissolution of brucite, the conversion of aragonite to calcite, and infilling of pore spaces with calcite. The oldest chimneys are dominated by calcite, with bulk rock values of up to 36 wt% Ca and <1 wt% Mg. These older structures contain higher concentrations of trace metals (e.g., Mn and Ti), and have Sr isotope ratios near seawater values (0.70908). Exposed ultramafic rocks are prevalent along the Mid-Atlantic, Arctic, and Indian Ocean ridge networks and it is likely that other Lost City-type systems exist.