Middle Pleistocene (Saalian) lake outburst floods in the Münsterland Embayment (NW Germany): impacts and magnitudes

During the late Saalian Drenthe glaciation ice-damming of the Upper Weser Valley led to the formation of glacial Lake Weser. The lake drained catastrophically into the Münsterland Embayment as the western ice dam failed, releasing up to 110 km³ of water with a calculated peak discharge of 2.5 × 10⁵ m³/s to 1.3 × 10⁶ m³/s. Geographic information systems (GIS) and high-resolution digital elevation models (DEM) were used to map streamlined landforms and channel systems in front of lake overspills. Geological maps, 2450 boreholes and the DEM were integrated into the 3D modeling program GOCAD to reconstruct the distribution of flood-related deposits, palaeotopographic surfaces and the internal facies architecture of streamlined hills. The drainage pathways are characterized by the occurrence of deep plunge pools, channels, streamlined hills and 4 km long and 12 m deep V-shaped megaflutes. Plunge pools are deeply incised into Mesozoic basement rocks and occur in front of three major overspill channels. The plunge pools are up to 780 m long, 400 m wide and 35 m deep. Approximately 1–10.5 km downslope of the overspill channels fan shaped arrays of streamlined hills are developed, each covering an area of 60–130 km², indicating rapid flow expansion. The hills commonly have quadrilateral to elongated shapes and formed under submerged to partly submerged flow conditions, when the outburst flood entered a shallow lake in the Münsterland Embayment. Hills are up to 4300 m long, 1200 m wide, 11 m high and have characteristic average aspect ratios of 1:3.3. They are separated by shallow, anabranching channels in the outer zones and up to 30 m deep channels in the central zones. Hills partly display V-shaped chevron-like bedforms that have apices facing upslope, are 1.6–2.5 km long, 3–10 m high, 0.8–1.2 m from limb to limb, with limb separation angels of 20–35°. These bedforms are interpreted as mixed erosional depositional features. It is hypothesized that the post-Saalian landscape evolution of the Münsterland Embayment has considerably been influenced by catastrophic floods of glacial Lake Weser, creating large and deep valleys, which subsequently became the new site of river systems. The outburst floods probably followed the east-west-trending Saalian Rhine-Meuse river system eventually flowing into the North Sea, the Strait of Dover and the Bay of Biscay. It is speculated that the Hondsrug ice stream may have been enhanced or even triggered by the formation and outburst of glacial lakes in the study area.     

The sensitized photo-oxidation of n-pentadecane as a model for abiotic decomposition of aliphatic hydrocarbons in seawater

n-Pentadecane was photo-oxidized, as a surface film, on purified natural seawater under simulated environmental conditions with anthraquinone as sensitizer. Initial attack by hydrogen abstraction from carbon atoms within the chain is followed by reaction of the alkyl radicals thus generated with molecular oxygen. The stable reaction products identified by GC-MS strongly suggest that alkoxy radicals produced by cleavage of the peroxide bond are key intermediates in the decomposition of the original alkane. The alkoxy radicals stabilize themselves either as ketones by reaction with molecular oxygen which is transformed into HO₂ or, if μ-hydrogen atoms are available, by cyclic electron rearrangements similar to a Norrish type II photo-decomposition. The products of the electron rearrangements are 1-alkenes and daughter alkoxy radicals. The latter either yield methyl ketones and HO₂ radicals upon reaction with molecular oxygen or undergo further decomposition as long as γ-hydrogen atoms are available. The generation of acetone and HO₂ radicals, inferred by the proposed reaction mechanism as products of many such degradation sequences, offers a plausible explanation for their occurrence in seawater in addition to those already advanced.     

Untersuchung der Photolineationen und des bruchtektonischen Inventars im Raum Erbendorf (N-Bayern) mit besonderer Berücksichtigung der Gangvererzungen

Zusammenfassung Der Erbendorfer Raum wird durch den Schnittpunkt zweier wichtiger Grenzstörungszonen markiert. Die E-NE streichende »Erbendorfer Linie« trennt die moldanubische Region vom Saxothuringikum; die »Fränkische Linie« bildet die Grenze zwischen Grundgebirge und dem permomesozoischen Deckgebirge. Im Arbeitsgebiet stehen verschiedenartige Gesteine, wie Vulkanoklastika, Gneise, Granite und Klastite an. Ihr Bildungsalter reicht vom Oberproterozoikum bis in die Kreide. Auf engstem Raum finden sich in dieser Region und ihrer östlichen Fortsetzung auch strukturgebundene Vererzungen von Pb, Zn, Cu, BaSO₄ und U. Durch Analyse der Photolineationen und der Klufttektonik werden zwei tektonische Hauptphasen unterscheidbar: die Phase I ist durch ENE- bis E-gerichtete Strukturen gekennzeichnet. Sie steht mit der permo-karbonen Entwicklung des Erbendorfer Trogs in Zusammenhang. Im Gefolge dieser Einsenkung wurden die Pb-Zn-Gänge dieses Raumes angelegt. Die markanten NW- und NE-Richtungen repräsentieren das Inventar der Phase II und gehen auf Schervorgänge kretazisch bis tertiären Alters zurück. Sie laufen parallel dem Egertalgraben und der »Fränkischen Linie«.

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The Erbendorf area acts as a »tripple junction« in the sense of fault tectonic. The E to NE running »Erbendorf Line« which is taken to represent the boundary between the Moldanubian and the Saxothuringian Zone, is truncated by the deep-seated »Franconian Line« (NW-SE) which terminates the uplifted basement versus the Permo-Mesozoic foreland. To this area attention is not only called due to its variable lithologies (gneisses, greenstones, granites, volcaniclastic sediments, hard coal seams, etc.), different image (from upper Proterozoic through Cretaceous), but it merits also special attention for its fault-bounded Pb, Zn, Cu, BaSO₄, and U mineralizations, particularly in its eastern prolongation. With the help of photogeology and ground-follow-up analyses of fault systems the tectonic evolution of this region is studied in detail. Moreover, these investigations are aimed at constraining the age of formation of these vein-type mineralizations. Two major phases of block-faulting may be outlined in this »tectonic frontier area«. Stage I encompasses ENE- to NE-trending lineations; it is closely related to the subsidence of the Permo-Carboniferous Erbendorf Trough. As a direct result of this tensional faulting, the Pb-Zn veins of this area may be considered. Subsequently, shearing (stage II) took place along the NW-SE- and NE-SW directions. These movements are connected with faulting in the stress field of the prominent Eger Graben and the Franconian Line, both of which were active during Cretaceous and Tertiary times.

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Résumé La région d'Erbendorf est caractérisée par l'intersection de deux limites géologiques importantes: la ligne d'Erbendorf (»Erbendorfer Linie«), orientée ENE sépare les zones moldanubienne et saxothuringienne; la ligne franconique (»Fränkische Linie«) forme la frontière entre les roches du socle et la couverture permo-mésozoÏque. Cette région est remarquable par la grande variété lithologique (gneiss, roches vertes, granites, volcanoclastites, charbon, etc.), par l'éventail des âges (du ProtérozoÏque supérieur au Crétacé) et par la présence de minéralisations en Pb, Zn, Cu, BaSO₄ et U, liées à des failles, ces minéralisations s'étendant d'aillenrs plus à l'est. L'analyse des photo-linéaments et de la tectonique cassante permet de distinguer deux phases tectoniques importantes. La phase I est caractérisée par des structures de direction nord-est à est. Elle est en rapport avec l'affaissement permocarbonifère du bassin d'Erbendorf, à la suite duquel les filons à Pb-Zn se sont formés. La phase II est marquée par des directions nord-ouest et nordest, correspondant à des processus de cisaillement d'âge crétacé à tertiaire. Elles sont parallèles au graben d'Egertal et à la ligne franconique.

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Polarized electronic absorption spectra of colourless chalcocyanite,CuSO4, with a survey on crystal fields in Cu2+ minerals

Polarized electronic absorption spectra of colourless chalcocyanite, CuSO₄, have been measured using microscope-spectrometric techniques. The spectra are characterized by a structured and clearly polarized band system in the near-infrared spectral range with components centred at 11,720, 10,545, 9,100, and 7,320 cm^?1, which have been assigned to crystal field d–d transitions of Cu²⁺ cations in pseudo-tetragonally elongated CuO₆ polyhedra with point symmetry C _i ( \(\bar{1}\) ). The polarization behaviour is interpreted based on a D ₂(C ₂″) pseudo-symmetry. Crystal field calculations were performed for the actual triclinic point symmetry by applying the Superposition Model of crystal fields, as well as in terms of a ‘classic’ pseudo-tetragonal crystal field approach yielding the parameters Dq _(eq) = 910, Dt = 395, and Ds = 1,336 cm^?1, corresponding to a cubically averaged Dq _cub = 679 cm^?1. A comparative survey on crystal fields in Cu²⁺ minerals shows that the low overall crystal field strength in chalcocyanite, combined with a comparatively weak pseudo-tetragonal splitting of energy levels, is responsible for its unique colourless appearance among oxygen-based Cu²⁺ minerals. The weak crystal field in CuSO₄ can be related to the lower position of the SO₄ ^2? anion compared to, e.g. the H₂O molecule in the spectrochemical series of ligands.     

Interplay between scintillation and ionization in liquid xenon Dark Matter searches

We provide a new way of constraining the relative scintillation efficiency L_eff for liquid xenon. Using a simple estimate for the electronic and nuclear stopping powers together with an analysis of recombination processes we predict both the ionization and the scintillation yields. Using presently available data for the ionization yield, we can use the correlation between these two quantities to constrain L_eff from below. Moreover, we argue that more reliable data on the ionization yield would allow to verify our assumptions on the atomic cross sections and to predict the value of L_eff. We conclude that the relative scintillation efficiency should not decrease at low nuclear recoil energies, which has important consequences for the robustness of exclusion limits for low WIMP masses in liquid xenon Dark Matter searches.     

《香港、澳门和珠江三角洲——地理概述》书评

<正>Koon-kwai WONG(Ed·):Hong Kong,Macao and the Pearl River Delta:A Geographical Survey.Pp·386,Hong Kong(Hong Kong Educational Publishing Co.),E-mail:sales@hkep.com;2009.ISBN 978-988-200-475-7     

In situ identification of a CAI candidate in 81P/Wild 2 cometary dust by confocal high resolution synchrotron X-ray fluorescence

We detected additional CAI-like material in STARDUST mission samples of comet 81P/Wild 2. Two highly refractory cometary dust fragments were identified in the impact track 110 [C2012, 0, 110, 0, 0] by applying high resolution synchrotron induced confocal and conventional XRF analysis (HR SR-XRF). The use of a polycapillary lens in front of the detector for confocal spectroscopy dramatically improves the fidelity of particle measurements by removing contribution from the surrounding aerogel. The high spatial resolution (300 × 300 nm²; 300 × 1000 nm²) obtained allowed the detailed non-destructive in situ (trapped in aerogel) study of impacted grains at the sub-μm level.For the two largest particles of the track, the terminal particle and a second particle along the impact track, Ca concentration is up to 30 times higher than CI and Ti is enriched by a factor of 2 compared to CI. High resolution (HR) SR-XRF mapping also reveals that the highest concentrations of Ca, Ti, Fe (and Ni) measured within each grain belongs to different areas of the respective maps which indicate that the particles are composed of several chemically diverse mineral phases. This is in agreement with the finding of a complex phase assemblage of highly refractory minerals in the first ever detected Stardust mission CAI grain “Inti” of Track 25.Principle component analysis (PCA) is a powerful tool for extracting the dominant mineral components and was applied to the two grains indicating that regions in the terminal particle and the second particle are consistent with anorthite or grossite and gehlenite, monticellite or Dmitryivanovite (CaAl₂O₄), respectively.Our new findings demonstrate that the HR SR-XRF with confocal geometry and PCA analysis is capable of identifying CAI-like fragments without the need to extract particles from the aerogel matrix which is a time-consuming, complex and destructive process.Furthermore, the detection of new CAI-like fragments in the coma dust of comet 81P/Wild 2 strengthens the observation that strong mixing effects and, therefore, mass transport before or during comet formation must have occurred at least up to the region where Kuiper Belt comets formed (30 AU).     

Consumption-based GHG emission accounting: a UK case study

Global GHG emissions continue to rise, with nearly a quarter of it due to trade that is not currently captured within global climate policy. In the context of current trade patterns and limited global cooperation on climate change, the feasibility of consumption-based emissions accounting to contribute to a more comprehensive (national) policy framework in the UK is investigated. Consumption-based emissions results for the UK from a range of models are presented, their technical robustness is assessed, and their potential application in national climate policy is examined using examples of policies designed to reduce carbon leakage and to address high levels of consumption. It is shown that there is a need to include consumption-based emissions as a complementary indicator to the current approach of measuring territorial emissions. Methods are shown to be robust enough to measure progress on climate change and develop and inform mitigation policy. Finally, some suggestions are made for future policy-oriented research in the area of consumption-based accounting that will facilitate its application to policy.

Policy relevance

Emissions embodied in trade are rapidly increasing and there is thus a growing gap between production emissions and the emissions associated with consumption. This is a growing concern due to the absence of a global cap and significant variation in country-level mitigation ambitions. Robust measurements of consumption-based emissions are possible and provide new insights into policy options. This includes trade-related policy (e.g. border carbon adjustments) and domestic policies (e.g. resource efficiency strategies). As climate policy targets deepen, there is a need for a broad range of policy options in addition to production and technological solutions. Consumption-based emissions are complementary to production-based emissions inventories, which are still the most accurate estimate for aggregated emissions at the global level. However, without consumption-based approaches, territorial emissions alone will not provide a complete picture of progress in regional and national emissions reduction.     

Temperature-dependent leaching of chemical elements from mineral water bottle materials

It is well established that minute amounts of chemical elements will leach from bottle materials (glass or PET – polyethylene terephthalate) to water stored in such bottles. This study investigated whether leaching increases with storage temperature. For glass bottles this is clearly the case for a long list of elements: Ag, Al, As, B, Ba, Ca, Co, Cr, Cs, Cu, Fe, Ga, Ge, K, La, Li, Mg, Mo, Na, Ni, Pb, Rb, Sb, Se, Sn, Sr, Ti, U, V, W and Zr. However, for glass bottles drinking water maximum admissible concentration values as defined by European authorities are not exceeded even after 1 week of leaching at 80 °C. The critical temperature limit where leaching substantially increases for many elements appears to be 45 °C. For PET bottles, Sb is the only element where leaching is observed at all temperatures and again leaching strongly increases at 45 °C. For PET bottles Sb concentrations observed in water after 1 week storage at 80 °C reach almost four times the maximum admissible concentration values for drinking water but do not exceed the relevant higher limit for food (including water) packaged in PET.