Das Überleiten von variscischer zu saxonischer Tektonik am nordwestlichen Thüringer Walde

Zusammenfassung Im Thüringer Walde sind zwischen Oberrotliegendem und Zechstein Bewegungen orogener Art nachweisbar. Die Diskordanz der noch zur variscischen Ära gehörenden Mosbacher Phase (nach Ort und Bach Mosbach) umfaßt auch vorzechsteinzeitliche Verwerfungen. Die bisher als primär angesehenen Grenzen der Oberrotliegendverbreitung sind infolge dieser sekundären Beeinflussung somit nicht mehr sicher festzulegen. Doch dürften die Störungen von mosbacher Alter hauptsächlich die unterpermischen Beckenränder betroffen haben. Am Nordrande des Thüringer Waldes ist die jüngere saxonische Tektonik einem solchen vorzechsteinzeitlichen Bruch gefolgt. Über der alten Narbe, die Gebiete grundsätzlich verschiedenen Baues trennt, entstand ein verwickelt gebauter — erst gezerrter, dann gepreßter — Grabenzug. Nach regionalen. Bohrergebnissen ist zu vermuten, daß auch benachbarte Gräben (z. B. Netra—Eisenach) auf einer solchen alten Naht zwischen hochliegendem Grundgebirge einerseits, permischem Beckenareal andererseits entstanden sind. Für spätere Zeiten mag sich die Hoffnung ergeben, daß aus dem saxonischen Bau einmal gewisse Rückschlüsse auf die Struktur des Untergrundes möglich werden könnten.     

Luminescence dating of lacustrine sediments from Tangra Yumco (southern Tibetan Plateau) using post‐IR IRSL signals from polymineral grains

Radiocarbon dating of bulk organic matter is the most commonly used method for establishing chronologies of lake sediments for palaeoclimate reconstructions on the Tibetan Plateau. However, this method is likely to be problematic because the dated material often suffers from old carbon contamination. Recently, advances in luminescence‐based chronological techniques have provided new options for dating lacustrine sediments. In the current study, we tested for the first time the applicability of a new post‐IR IRSL (pIRIR) measurement protocol for dating fine‐grained polymineral material from a deep‐lake sediment core from the central part of Tangra Yumco, on the southern Tibetan Plateau. Our results show that: (i) radioactive disequilibria in the uranium decay chain were observed in the studied lake sediments, and thus taken into account for dose rate calculation by using a dynamic modelling approach; (ii) the suitability and robustness of the pIRIR protocol measured at 150°C (pIRIR₁₅₀) for our samples are confirmed by a set of luminescence characteristic tests as well as the agreement with an independent age control; (iii) turbidite deposition partly caused an insufficient resetting of luminescence signals and thus apparent overestimation in luminescence dating; (iv) compared with the luminescence‐based age‐depth model, the ¹⁴C ages of bulk organic matter from the studied core generally yielded an age difference of ～2 ka, which is attributed to hardwater reservoir effects in Tangra Yumco. This study highlights the need for multi‐dating approaches of lake sedimentary archives on the Tibetan Plateau.     

Earth's free core nutation determined using C032 superconducting gravimeter at station Wuhan/China

The long series tidal gravity observations from 1997 to 2002 recorded with C032 superconducting gravimeter (SG) at station Wuhan/China are used in order to study the Earth's geodynamics. The tidal gravity parameters are determined precisely using Eterna software package after careful data pre-processing. The Earth's free core nutation (FCN) resonant parameters (eigenperiods, quality factors and resonant strengths) are determined accurately. The results show the determined eigenperiod to be 431.0 sidereal days with an accuracy of ±1.81%, the quality factor is a negative one as of −7002, and the resonance strength can be explained by the elastic property of the Earth's mantle. The discrepancy of the eigenperiods when using various ocean models can amount to ±1.8%. The 30 sidereal days difference between the determined eigenperiod in this paper and the one in theoretical computation given by Wahr and Bergen can be explained by the real dynamic ellipticity of the Earth's liquid core, i.e., it is about 5% larger than the one under the hydrostatic equilibrium assumption.     

Beitrag zur Tektonik archaischer Sedimente im Barberton-Bergland (Transvaal-Südafrika)

Zusammenfassung Die Serien des Swaziland-Systems im Gebiet der Montrose Farm (25 km südwestlich von Barberton) zeigen ähnliche Deformationen wie die wesentlich jüngeren Serien des Moodies-Systems. Strukturbestimmende Störungen mit Versetzungsbeträgen von mehr als 1000 m sind in wesentlich stärkerem Maße vorhanden als bisher angenommen. Das zu beobachtende spröde bis plastische Verhalten von gebändertem Hornstein wird auf unterschiedlichen SiO₂-Gel-Gehalt zur Zeit der Deformation zurückgeführt. Eine Gliederung der orogenetischen Ereignisse für einen Teil der Swaziland-Geosynklinale wird gegeben.

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In the Montrose Farm area (25 km SW of Barberton) Series of the Swaziland System show similar deformations as the essentially younger series of the Moodies System. Thrustfaults with desplacements of more than 1000 m are developed more often than formerly assumed. The brittle to plastic behaviour of banded cherts is due to a different content of gelic SiO₂ during deformation. A possible development of a part of the Swaziland geosyncline is given.

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Résumé Dans les séries du système Swaziland dans la région de Montrose Farm (à 25 km sud-ouest de Barberton) il y a des déformations analogues aux séries beaucoup plus jeunes du Système Moodie. Des Failles avec des déplacements de plus de 1000 m se trouvent plus souvent qu'on n'avait supposé jusqu'à présent. La conduite mobile à solide du silex zoné s'explique par le différent contenu de Gel de SiO₂ au movement de la déformation. Les événements de la période orogénétique seront exposés pour une partie du Swaziland géosynclinal.

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Swaziland Montroes (25 - ). , Moodies. Swaziland.

     

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.     

Beach cusp morphodynamics

Detailed measurements of three-dimensional beach cusp morphology were made on a steep gradient, low energy, microtidal beach in Perth, Western Australia. During the field campaign a variety of wave conditions and tidal ranges were experienced, and these differing hydrodynamic conditions were reflected in a consistent pattern of morphological changes to the beach cusp system. A useful parameter to delineate between trends of cusp destruction and re-formation appeared to be the surf similarity parameter ξ = tan β/√I₀/L₀, where H₀ is offshore wave height, L₀ is deep water wave length and tan β is beach gradient. For ξ < 1·2 the beach cusps were planed off, whereas cusp morphology was enhanced when ξ > 1·2. A small storm was experienced at the start of the field campaign period and resulted in considerable erosion of the beach face. The cusp morphology across the lower beachface was destroyed, but a subtle remnant of the pre-storm cusp morphology was preserved on the upper beachface. When cusps reformed after the storm, under the influence of declining wave conditions, they appeared at the same location and with the same dimensions as the pre-storm cusp morphology. Hence, it is considered that the cusp re-formation was controlled more by the antecedent morphology than the hydrodynamic conditions. This indicates that positive feedback between swash hydrodynamics and beachface morphology, necessary to form beach cusps, does not require a large variation in relief. © 1997 John Wiley & Sons, Ltd.     

Oil seepage and carbonate formation: A case study from the southern Gulf of Mexico

Oil seeps from the southern Gulf of Mexico can be regarded as natural laboratories where the effect of crude oil seepage on chemosynthesis‐based communities and carbonate precipitation can be studied. During R/V Meteor cruise 114 the seep sites UNAM (Universidad Nacional Autónoma de México) Ridge, Mictlan Knoll and Tsanyao Yang Knoll (Bay of Campeche, southern Gulf of Mexico) were investigated and sampled for authigenic carbonate deposits containing large amounts of liquid oil and solid asphalt. The δ¹³C values of individual carbonate phases including: (i) microcrystalline matrix aragonite and calcite; (ii) grey, cryptocrystalline to microcrystalline aragonite; and (iii) clear, fibrous aragonite cement, are between ?30‰ and ?20‰, agreeing with oil as the primary carbon source. Raman spectra reveal that residual heavy oils from all sites are immature and most likely originate from the same reservoir. Geochemical batch modelling using the software code PHREEQC demonstrates how sulphate‐driven oxidation of oil‐derived low‐molecular to high‐molecular weight hydrocarbons affects carbonate saturation state, and shows that the oxidation state of carbon in hydrocarbon compounds and oxidation rates of hydrocarbons control carbonate saturation and precipitation at oil seeps. Phase‐specific trace and rare earth element contents of microcrystalline aragonite and calcite, grey cryptocrystalline aragonite and clear aragonite were determined, revealing enrichment in light rare earth elements for grey aragonite. By comparing trace element patterns of carbonates with those of associated oils, it becomes apparent that liquid hydrocarbons constitute an additional source of trace metals to sedimentary pore waters. This work not only demonstrates that the microbial degradation of oil at seeps may result in the precipitation of carbonate minerals, it also elucidates that trace metal inventories of seep carbonates archive diagnostic elemental patterns, which can be assigned to the presence of heavy hydrocarbons in interstitial pore waters.     

Die Sturmfluten vom 9. und 10. Februar 1949 an der deutschen Nordseeküste

Zusammenfassung Es wird der Verlauf des Wasserstandes am 9. und 10. Februar 1949 an der deutschen Nordseeküste an Hand von Pegelaufzeichnungen mehrerer Orte verfolgt. Die zugehörige Wetterlage wird mittels besonderer, zeitlich engabständiger Wetterkarten für die Deutsche Bucht untersucht. Aus der Wetterentwicklung ist der ungewöhnliche Verlauf der Sturmfluten zu erklären. Sie wurden durch das Sturmfeld eines Tiefdrucktroges hervorgerufen, das sich an der nordfriesischen Küste besonders stark auswirken konnte, weil die zugehörige Zyklone im entscheidenden Entwicklungsstadium der Sturmflut am 9. Februar nördlich von Sylt nahezu stationär die Deutsche Bucht nach Norden hin absperrte. Die Wasserstandsaufzeichnungen von Husum und Hamburg, die besonders betrachtet werden, zeigen, da das meteorologische Geschehen den Gezeitenablauf völlig überdecken und Höchst wasserstände unabhängig von diesem erzeugen kann.

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The storm surges of February 9th and 10th, 1949 on the German coast of the North Sea

Summary By the aid of tide gauge records the development of the water level on the German coast of the North Sea on February 9th and 10th, 1949, is discussed. Special weather charts for the German Bight for short intervals are plotted in order to elucidate this unusual development of the tide. Its chief cause was the stormfield of a trough of low pressure whose greatest effect was on the coast of North Friesland, because on February 9 th, at the decisive stage of the tide wave, the storm centre was almost stationary off the Island of Sylt, blocking the outflow of water from the German Bight towards the north. Inspection of the tide curves of Husum and Hamburg demonstrates that the effect of air pressure and wind can mask the normal tides and produce maximum heights independently of the the tidal curve.

     

Statistical Relational Learning of Grammar Rules for 3D Building Reconstruction

The automatic interpretation of 3D point clouds for building reconstruction is a challenging task. The interpretation process requires highly structured models representing semantics. Formal grammars can describe structures as well as the parameters of buildings and their parts. We propose a novel approach for the automatic learning of weighted attributed context‐free grammar rules for 3D building reconstruction, supporting the laborious manual design of rules. We separate structure from parameter learning. Specific Support Vector Machines (SVMs) are used to generate a weighted context‐free grammar and predict structured outputs such as parse trees. The grammar is extended by parameters and constraints, which are learned based on a statistical relational learning method using Markov Logic Networks (MLNs). MLNs enforce the topological and geometric constraints. MLNs address uncertainty explicitly and provide probabilistic inference. They are able to deal with partial observations caused by occlusions. Uncertain projective geometry is used to deal with the uncertainty of the observations. Learning is based on a large building database covering different building styles and façade structures. In particular, a treebank that has been derived from the database is employed for structure learning.