Geothermal evolution of the Astrakhan Arch region of the Pricaspian basin

The Astrakhan Arch region contains one of the largest sub-salt structures of the Pricaspian basin, where perspectives for hydrocarbon generation and accumulation in the Devonian to Carboniferous deposits are considered to be high. The paper addresses the problem of structural and geothermal evolution of the region deformed by salt movements. Initially, we developed a model of the regional structural evolution along a geological profile using the volume-balancing and back-stripping methods and geological constraints on the sedimentation, erosion, and paleo-water depths. Then we developed geothermal models (along the study profile) associated with the regional structural evolution. The models were constrained by the temperatures measured in four deep boreholes along the profile. We show that the present temperatures and heat flux are influenced by the presence of salt diapirs. Since the Early Carboniferous and till Middle Permian times, the temperatures predicted by the models vary significantly due to the regional transgression and the presence of seawater. The temperature of Devonian–Carboniferous carbonates increases since the Late Permian (time of post-salt deposition) and attains its maximum values in the SW-part of the profile. If the model assumptions concerning the constant vertical and zero lateral heat fluxes are valid, we can conclude that hydrocarbons are most likely to be generated in the SW-part of the region for the post-Early Permian time.     

Numerical investigation of soil plugging inside open-ended piles with respect to the installation method

The development of a soil plug inside an open-ended pile with respect to the installation method is examined using numerical simulations. In this paper, the penetration process of an open-ended tubular pile with diameter D = 61 cm into granular soil is investigated. The aim is to achieve a better understanding of the mechanisms of soil plugging inside open-ended piles with respect to the installation method. As an example, the horizontal stress distribution inside the tubular pile after installation shows significant increase depending on the installation method. The numerical results are compared to experimental data.     

Seismic rupture during the 1960 Great Chile and the 2010 Maule earthquakes limited by a giant Pleistocene submarine slope failure

Determining factors that limit coseismic rupture is important to evaluate the hazard of powerful subduction zone earthquakes such as the 2011 Tohoku‐Oki event (Mw = 9.0). In 1960 (Mw = 9.5) and 2010 (Mw = 8.8), Chile was hit by such powerful earthquakes, the boundary of which was the site of a giant submarine slope failure with chaotic debris subducted to seismogenic zone depth. Here, a continuous décollement is absent, whereas away from the slope failure, a continuous décollement is seismically imaged. We infer that underthrusting of inhomogeneous slide deposits prevents the development of a décollement, and thus the formation of a thin continuous slip zone necessary for earthquake rupture propagation. Thus, coseismic rupture during the 1960 and 2010 earthquakes seems to be limited by underthrusted upper plate mass‐wasting deposits. More generally, our results suggest that upper plate dynamics and resulting surface processes can play a key role for determining rupture size of subduction zone earthquakes.     

Die Quadalquivirstörung

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Influence of pile installation on adjacent structures

Pile installation leads to significant changes in the main state variables of the surrounding soil. In addition, the installation process may have an influence on adjacent or intersecting structures such as pile grillages. In this paper, three‐dimensional numerical analyses are presented to investigate the effects of pile driving with open or closed cross‐sections on the surrounding soil and on adjacent structures. Two different installation methods are used: quasi‐static pile jacking and vibratory pile driving. The numerical models are evaluated and verified using data from field tests performed in situ during the construction of the quay wall at the container terminal CT4 in Bremerhaven. Two case studies are presented to characterize the main influence factors for additional loading on adjacent structures due to pile installation. Finally, a parametric study is conducted showing the influence of the installation method, pile cross‐section and distance of a pile from an existing structure on the additional loading for this structure. Copyright © 2009 John Wiley & Sons, Ltd.     

Frequency and intensity of high-altitude floods over the last 3.5 ka in northwestern French Alps (Lake Anterne)

In central Western Europe, several studies have shown that colder Holocene periods, such as the Little Ice Age, also correspond to wet periods. However, in mountain areas which are highly sensitive to erosion processes and where precipitation events can be localized, past evolution of hydrological activity might be more complicated. To assess these past hydrological changes, a paleolimnological approach was applied on a 13.4-m-long sediment core taken in alpine Lake Anterne (2063 m asl) and representing the last 3.5 ka. Lake sedimentation is mainly composed of flood deposits triggered by precipitation events. Sedimentological and geochemical analyses show that floods were more frequent during cold periods while high-intensity flood events occurred preferentially during warmer periods. In mild temperature conditions, both flood patterns are present. This underlines the complex relationship between flood hazards and climatic change in mountain areas. During the warmer and/or dryer times of the end of Iron Age and the Roman Period, both the frequency and intensity of floods increased. This is interpreted as an effect of human-induced clearing for grazing activities and reveals that anthropogenic interferences must be taken into account when reconstructing climatic signals from natural archives.     

Bacterial consortium and axenic cultures isolated from activated sewage sludge for biodegradation of imidazolium-based ionic liquid

Extensive research and increasing number of potential industrial applications made ionic liquids (ILs) important materials in design of new, cleaner technologies. Together with the technological applicability, the environmental fate of these chemicals is considered and significant efforts are being made in designing strategies to mitigate their potential negative impacts. Many ILs are proven to be poorly biodegradable and relatively toxic. Bioaugmentation is known as one of the ways of enhancing the microbial capacity to degrade xenobiotics by addition of specialized strains. The aim of current work was to select microbial species that could be used for bioaugmentation in order to enhance biodegradation of ILs in the environment. We subjected activated sewage sludge to the selective pressure of 1-methyl-3-octylimidazolium chloride ([OMIM][Cl]) and isolated nine strains of bacteria which were able to prevail in these conditions. Subsequently, we utilized axenic cultures (pure cultures) of these bacteria as well as mixed consortium to degrade this IL. In addition, we performed growth inhibition tests and found that bacteria were able to grow in 2 mM, but not in 20 mM solutions of [OMIM][Cl]. The biodegradation conducted by the isolated consortium was higher than conducted by the activated sewage sludge when normalized by the cell density, which indicates that the isolated strains seem specifically suited to degrade the IL.     

Die Formen der Kantenkiesel

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Stratigraphie und Tektonik des Hochlandes von Costa-Rica

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Physical properties of rocks from the upper part of the Yaxcopoil‐1 drill hole,Chicxulub crater

Abstract— Physical properties were determined in a first step on post‐impact tertiary limestones from the depth interval of 404–666 m of the Yaxcopoil‐1 (Yax‐1) scientific well, drilled in the Chicxulub impact crater (Mexico). Thermal conductivity, thermal diffusivity, density, and porosity were measured on 120 dry and water‐saturated rocks with a core sampling interval of 2–2.5 m. Nondestructive, non‐contact optical scanning technology was used for thermal property measurements including thermal anisotropy and inhomogeneity. Supplementary petrophysical properties (acoustic velocities, formation resisitivity factor, internal surface, and hydraulic permeability) were determined on a selected subgroup of representative samples to derive correlations with the densely measured parameters, establishing estimated depth logs to provide calibration values for the interpretation of geophysical data. Significant short‐ and long‐scale variations of porosity (1–37%) turned out to be the dominant factor influencing thermal, acoustic, and hydraulic properties of this post impact limestone formation. Correspondingly, large variations of thermal conductivity, thermal diffusivity, acoustic velocities, and hydraulic permeability were found. These variations of physical properties allow us to subdivide the formation into several zones. A combination of experimental data on thermal conductivity for dry and water‐saturated rocks and a theoretical model of effective thermal conductivity for heterogeneous media have been used to calculate thermal conductivity of mineral skeleton and pore aspect ratio for every core under study. The results on thermal parameters are the necessary basis for the determination of heat flow density, demonstrating the necessity of dense sampling in the case of inhomogeneous rock formations.