The post-collisional stabilization of thickened crust in the Southern Urals

The Urals are characterized by a depression of the Moho to a depth of 57 km. This structure is interpreted as a relic orogenic root, which has been conserved because no significant post-collisional processes occurred. However, there is evidence that voluminous post-collisional magmatism affected the lower crust. In this paper, we use thermal finite element models to quantify the influence of the post-collisional magmatism on the stabilization of the root. We show that at least 70% of the heat producing elements migrated in granitic melts from the lower crust to the upper crust. As a result the crustal heat flow reduced and the lithosphere could stabilize at a thickness of 180 km. Furthermore, we propose that a granulite metamorphic event during the thermal relaxation of the collision zone prevented the 57 km thick crust from delamination. These results strongly indicate that post-collisional processes were necessary for the stabilization of the Uralian crust and lithosphere.     

Petrography and geochemistry of target rocks and impactites from the Ilyinets Crater,Ukraine

Abstract— The ～400 Ma old Ilyinets impact structure was formed in the Precambrian basement of the Ukrainian Shield and is now mostly covered by Quaternary sediments. Various impact breccias and melts are exposed in its southern section. The crater is a complex structure with a central uplift that is surrounded by an annular deposit of breccias and melt rocks. In the annulus, brecciated basement rocks are overlain by up to 80 m of glass-poor suevitic breccia, which is overlain (and partly intercalated) by glass-rich suevite with a thickness of up to 130 m. Impact-melt rocks occur within and on top of the suevites—in some cases in the form of devitrified bomb-shaped impact-glass fragments. We have studied the petrographic and geochemical characteristics of 31, mostly shocked, target rock samples (granites, gneisses, and one amphibolite) obtained from drill cores within the structure, and impact breccias and melt rock samples from drill cores and surface exposures. Multiple sets of planar deformation features (PDFs) are common in quartz, potassium feldspar, and plagioclase of the shocked target rocks. The breccias comprise more or less devitrified impact melt with shocked clasts. The impact-melt rocks (“bombs”) show abundant vesicles and, in some cases, glass is still present as brownish patches and schlieren. All impact breccias (including the melt rocks) are strongly altered and have significantly elevated K contents and lower Na contents than the target rocks. The alteration could have occurred in an impact-induced hydrothermal system. The bomb-shaped melt rocks have lower Mg and Ca contents than other rock types at the crater. Compared to target rocks, only minor enrichments of siderophile element contents (e.g., Ni, Co, Ir) in impact-melt rocks were found.     

Continuous flow analysis of dissolved total phosphorus in seawater by UV-K2S2O8 online digestion method

Several methods for analysis of dissolved total phosphorus in seawater were reviewed. Discussions were focused on UV irradiation and persulphate oxidation methods which are the most popular dissolved organic phosphorus determination methods presently. The compounds used for the phosphorus recovery test were categorized into three groups according to their chemical structure. It was found that low power UV irradiation can decompose P-O-C or P-C bonds efficiently but may be inefficient for P-O-P bonds. Heating-bath in acid condition is useful for decomposing P-O-P bonds. Using the continuous flow analysis system (Auto-analyzer Ⅱ), UV digestion and heating-bath, series experiments were carried out based on the above analysis. Eleven model compounds were employed for the phosphorus recovery test and the factors influencing the decomposition efficiency of dissolved compounds containing phosphorus were clarified. Finally, the optimal design for determination of dissolved total phosphorus in seawater based on the routine continuous flow analysis system was presented. For the organic mono-phosphate, the recovery is more than 90% and a recovery of 33%～51% was obtained for inorganic or organic polyphosphates. Up to now, this is the highest decomposition efficiency for dissolved phosphorus based on the continuous flow analysis system.     

The Caledonian deformed ordovician of the Rügen area -sediment provenance and tectonic studies

Summary The Ordovician of the Rügen area shows no affinities with that of the adjacent regions of the East European Platform, situated immediately to the north (i.e. Bornholm and Skåne). By contrast, the detritus in the sandstones and greywackes points to an active continental margin in the southwest, along the southern border of the suspect Tornquist Ocean (i.e. northern Peri-Gondwana). Deformation features can be assigned to Caledonian tectonic events. The more than 3 km thick pile comprises a stacked wedge complex, which was emplaced against and onto the southwestern border of Baltica.     

Long-term measurements of surface ozone in the German Democratic Republic

The ozone concentration near the earth's surface has been measured at some stations in the GDR for more than 30 yr using the wet chemical method. Even at rural stations the ozone data show a significant linear increase by about 1–3% yr^–1. The ozone increase being stronger in summer than in winter is assumed to be due to photochemical ozone production from increasing anthropogenic emissions of trace gases that are transported over long distances. A weaker ozone increase by only about 0.2% per year was observed in the free troposphere (5.5 km) from balloon-soundings at Lindenberg within the period 1975–1984. If the ozone trends continue, the ozone concentration near the surface and its seasonal amplitude will have doubled around the turn of the century as compared to the mid-fifties.     

The lower atmosphere of the polar regions

Alfred Wegener initiated the study of the free polar atmosphere with more than 100 kite and tether balloon soundings to above 3000 m at Danmarkshavn, North Greenland, during 1906–09. From this beginning polar aerology advanced through a series of similar point studies to the first full upper air network during the IGY (1957/8). While its replacement by satellite remote sensing is gradually taking shape, the accumulated polar information has been thoroughly analyzed; a series of comprehensive accounts is referenced. The aspects singled out for this review are themes that would have been of special interest to Wegener — the surface energy balance and the polar inversion, the katabatic winds and snow drift, and the aerosols of the polar atmosphere.

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Zusammenfassung Alfred Wegener begann das Studium der freien Polaratmosphäre mit über 100 Drachen- und Fesselballonaufstiegen auf Höhen über 3000 m bei Danmarkshavn in Nordgrönland während der Jahre 1906–1909. Von diesem Anfang entwickelte sich die Polaraerologie durch eine Reihe ähnlicher Lokalstudien bis zum ersten vollständigen Beobachtungsnetz der freien Atmosphäre während des IGY (1956–8). Während des allmählichen Ersatzes dieses Systems durch Fernmessungen von Satelliten aus wurde die angesammelte Polarinformation gründlich analysiert; eine Reihe von umfassenden Berichten wird angeführt. Die hier behandelten Studien wären für Wegener von besonderem Interesse gewesen, da sie die Energiebilanz der Oberfläche und die Polarinversion, den katabatischen Wind und das Schneetreiben, und das Aerosol der Polaratmosphäre betreffen.

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Résumé C'est Alfred Wegener qui a commencé l'étude de l'atmosphère polaire par des sondages à l'aide de cerfs-volants et de ballons attachés jusqu'à une hauteur de 3000 m. à Danmarks-Havn au Groenland nord, de 1906 à 1909. Après ce début l'aérologie polaire se développa sur la base d'études locales jusqu'à l'établissement d'un premier réseau de stations d'observations pendant l'année géophysique internationale 1957–58. La recherche exposée ici aurait probablement intéressé Wegener car elle se rapporte à la balance énergétique de surface et à l'inversion polaire, aux vents katabatiques, à le chasse neige et aux aérosols de l'atmosphère polaire.

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Application of methane band-model parameters to the visible and near-infrared spectrum of Uranus

Laboratory band-model absorption coefficients of CH₄ are used to calculate the Uranus spectrum from 5400 to 10,400 Å. A good fit of both strong and weak bands for the Uranus spectrum over the entire wavelength interval is achieved for the first time. Three different atmospheric models are employed: a reflecting layer model, a homogeneous scattering layer model, and a clear atmosphere sandwiched between two scattering layers. The spectrum for the reflecting layer model exhibits serious discrepancies but shows that large amounts of CH₄ (5–10 km-am) are necessary to reproduce the Uranus spectrum. Both scattering models give reasonably good fits. The homogeneous model requires a particle scattering albedo $\text{(}\text{g}\text{?}\text{w}{}_{\mathrm{<mtext>p</mtext>}}\text{) ? 0.998}$ and an abundance per scattering mean free path $\text{(}\text{a}\text{?}\text{)}\text{of}\text{a}\text{?}\text{1}\text{km-am}$. The parameters derived from the sandwich layer model are: forsb the upper scattering layer a continuum single scattering albedo ($\text{g}\text{?}\text{w}{}_0$) of 0.995 and a scattering optical depth variable with wavelength consistent with Rayleigh scattering; for the clear layer they are a CH₄ abundance (a) of 2.2 km-am and an effective pressure (p) ? 0.1 atm; for the lower cloud deck a Lambert reflectivity (L) of 0.9 resulted. A severe depletion of CH₄ in the upper scattering layer is required. An enrichment of CH₄/H₂ over the solar ratio by a factor of 4–14 in the lower atmosphere is, however, indicated.     

Germane in the atmosphere of Jupiter

High-altitude spectra of Jupiter obtained from the Kuiper Airborne Observatory are analyzed for the presence of germane (GeH₄) in Jupiter's atmosphere. Comparison with laboratory spectra shows that the strong Q branch of the ν₃ band of germane at 2111 cm^?1 is prominent in the Jovian spectra. The abundance of germane in Jupiter's atmosphere is 0.006 (±0.003) cm-am corresponding to a mixing ratio of 0.6 ppb. This trace amount of germane is consistent with chemical equilibrium calculations if the germane present at ～1000°K is carried up by convection to the spectroscopically observable region at ～300°K.