Recognizing salt-tectonics and the need for re-assessing strike-slip displacements in the Northern Calcareous Alps: Implications for lateral orogenic extrusion

Salt tectonics has only been recently recognized as a significant element in the evolution of the Northern Calcareous Alps (NCA), along their entire length. Specific to the central NCA, a number of sedimentary growth wedges (implying Triassic salt-related syn-sedimentary deformation) and other evidence for Triassic salt tectonics have been recognized along two of the main Neogene strike-slip corridors of the central NCA: along the KLT (Königssee-Lammertal-Traunsee) fault and along the Ennstal segment of the SEMP (Salzach–Ennstal–Mariazell–Puchberg) fault. Similar features indicating Triassic salt tectonics have been documented along the Wolfgangsee corridor. Salt structures are typically characterized by the absence or condensation of stratigraphy above them. This explains why the Neogene strike-slip features are so consistently associated to the outcrop of “deep” (old) units of the NCA stratigraphy. Recycling and tectonic of overprinting of zones of weakness is a usual feature, and it is therefore unsurprising that strike-slip of the NCA thrust sheets during Neogene lateral extrusion concentrated on previously existing salt structures. More surprising is the fact that, if Neogene strike-slip faults follow the trace of previous salt structures, this implies that the genesis of the rhomboidal map pattern of Neogene strike-slip corridors is actually inherited from a Triassic salt tectonics framework. This in turn implies that far from being a Neogene feature, the offsets of geological elements observed along the strike-slip corridors is, at least partially, Triassic in origin. An immediate conclusion is that estimates provided to date on the magnitudes of displacement for the central NCA Neogene strike-slip system require a revision. Likewise, the nature of the SEMP and its splays as purely Neogene structures (at least in their shallowest portion across the NCA stratigraphy) is questionable. This contribution does not raise questions about the documented kinematics of the Neogene strike-slip system, which is solidly researched, but merely seeks to provide new insights that can help re-assess the actual role of strike-slip along the key strike-slip elements of the central NCA

Introduction: geodynamic evolution of the Zagros

This special issue of Geological Magazine presents a collection of 17 papers dealing with different aspects of the Zagros orogen. Many, though not all, of these contributions were presented as part of a highly successful session devoted to the geodynamic evolution of the Zagros belt at the European Geosciences Union General Assembly 2010 in Vienna (Austria). The aim of this gathering was to assemble a broad group of Earth scientists interested in the Zagros orogen to discuss and disseminate new results and ideas efficiently. This volume presents a collection of some of the diverse research that is currently being carried out in the Zagros. We believe that these studies contribute to the understanding of the geodynamic evolution of the Zagros Mountains in particular, but in addition to orogenic processes in genera

The Minimized Power Geometric model: An analytical mixing model for calculating polyphase rock viscosities consistent with experimental data

International audienceHere we introduce the Minimized Power Geometric (MPG) model which predicts the viscosity of any polyphase rocks deformed during ductile flow. The volumetric fractions and power law parameters of the constituting phases are the only model inputs required. The model is based on a minimization of the mechanical power dissipated in the rock during deformation. In contrast to existing mixing models based on minimization, we use the Lagrange multipliers method and constraints of strain rate and stress geometric averaging. This allows us to determine analytical expressions for the polyphase rock viscosity, its power law parameters, and the partitioning of strain rate and stress between the phases. The power law bulk behavior is a consequence of our model and not an assumption. Comparison of model results with 15 published experimental data sets on two-phase aggregates shows that the MPG model reproduces accurately both experimental viscosities and creep parameters, even where large viscosity contrasts are present. In detail, the ratio between experimental and MPG-predicted viscosities averages 1.6. Deviations from the experimental values are likely to be due to microstructural processes (strain localization and coeval other deformation mechanisms) that are neglected by the model. Existing models that are not based on geometric averaging show a poorer fit with the experimental data. As long as the limitations of the mixing models are kept in mind, the MPG model offers great potential for applications in structural geology and numerical modeling

Displacement–length scaling of brittle faults in ductile shear

AbstractWithin a low-grade ductile shear zone, we investigated exceptionally well exposed brittle faults, which accumulated antithetic slip and rotated into the shearing direction. The foliation planes of the mylonitic host rock intersect the faults approximately at their centre and exhibit ductile reverse drag. Three types of brittle faults can be distinguished: (i) Faults developing on pre-existing K-feldspar/mica veins that are oblique to the shear direction. These faults have triclinic flanking structures. (ii) Wing cracks opening as mode I fractures at the tips of the triclinic flanking structures, perpendicular to the shear direction. These cracks are reactivated as faults with antithetic shear, extend from the parent K-feldspar/mica veins and form a complex linked flanking structure system. (iii) Joints forming perpendicular to the shearing direction are deformed to form monoclinic flanking structures. Triclinic and monoclinic flanking structures record elliptical displacement–distance profiles with steep displacement gradients at the fault tips by ductile flow in the host rocks, resulting in reverse drag of the foliation planes. These structures record one of the greatest maximum displacement/length ratios reported from natural fault structures. These exceptionally high ratios can be explained by localized antithetic displacement along brittle slip surfaces, which did not propagate during their rotation during surrounding ductile flow

Structural investigations of the W termination of the ‘Schneeberg Zug’ — Austroalpine Unit, Southern Tyrol: Results from a crustal scale shear zone

The Austroalpine microplate traces the Alpine collision event between the Africa-related southern Alpine realm and the European continent. The southern margin of this microplate, the basement to the north of Meran (including Texel unit and Schneeberg Zug) is characterized by regional eo-Alpine high-pressure metamorphism (Hoinkes & Thöni, 1987). PT conditions decrease from SE (Texel unit) to the pre-alpine basement in the NW. The HP Rocks were exhumed within a ca. 15km broad SW-NE-striking, NWdipping high strain zone (Sölva et al. 2001). The high-pressure Texel crystalline is tectonically underlain by the Campo unit in the south and overlain by the Ötztal-Stubai Basement in the north(west). The Schneeberg Zug forms an up to 5km thick shear zone at its base, representing the study area. It shows normal-sense kinematics and separates pre-Alpine basement rocks in the hanging wall from high-pressure rocks in the footwall, the Texel unit. These were emplaced on top of pre-Alpine basement rocks (Campo unit) by an eo-Alpine ductile thrust. Lithologically the western termination of the Schneeberg Zug comprises characteristic garnet micaschists, marble layers, amphibolites, quartzites, hornblende-garben-schists and calcschists. These lithologies are called Bunte Serie (Mauracher, 1981) and differ from the polyphase adjacent Texel unit and the polymetamorphic basement rocks in the hanging wall due to their lithological content and their monometamorphic evolution. Petrological and geochronological investigations on the eastern continuation of these characteristic metapelitic rocks evidence the time of garnet growth during D1 close to the Cretaceous pressure peak. Sm-Nd isochron data of these continuously zoned garnets yielded crystallization ages between 90 and 95 Ma. Preliminary structural investigations yielded four major deformation events: D1 produced a compositional layering and a mylonitic foliation; generally this ductile deformation in the northwestern portion of the Schneeberg Zug is characterized by contemporaneous shearing and folding forming isoclinal folds with axes oriented parallel to the NW–SE plunging stretching lineation. Deformation stage D2 formed tight folds with steep NW to WSW plunging axes and NW to W dipping axial planes, which refold the D1 related structures. Deformation stage D3 is characterized by a crenulation with NW-plunging axes and NW-dipping axial planes. Lower greenschist-facies shear-zones dipping to the W and with shear sense top to W– WNW represent the last ductile event. They crosscut the older structural inventory. Brittle deformation evidences normal faulting reactivating the NW dipping main foliation as well as related dextral strike slip movement. Geochronological data and structural investigations indicate a continuous eo- Alpine tectono-metamorphic evolution, which started at high grade conditions homogenously distributed over the whole shear zone. With decreasing temperature conditions the deformation progressively partitioned into distinct shear zones.conferenc

Simulating Bilingual Aphasia Rehabilitation: Evidence from a computational model

Current research on bilingual aphasia has only begun to inform us about optimal rehabilitation but the literature is sparse in terms of interpreting the nature of naming impairments in bilingual aphasia. The goal of the present study is to build a model that can simulate language impairments and rehabilitation in patients with bilingual aphasia. Specifically, the model takes into account Age of Acquisition (AoA) and pre-stroke language use in the two languages. This model is subsequently lesioned at specific sites and then rehabilitated in one language (e.g., either English or Spanish) and the extent of cross language transfer is examined

Rehabilitation and cross-language transfer in bilingual aphasia: towards a computational model

Uli Grasemann and Risto Miikkukainen are with the Department of Computer Science, The University of Texas at Austin, Austin, TX 78712, USA -- Chaleece Sandberg and Swathi Kiran are with the Department of Speech, Language and Hearing Sciences, Boston University, Boston, MA 02215, USABilingual aphasia, defined as a loss of one or both languages in bilingual individuals that results from left hemisphere damage, is of increasing interest worldwide because more than half of the world’s population is bilingual. Despite the importance of this topic in an increasingly bilingual world, disparities in diagnosis and treatment of bilingual aphasia continue to exist. Current research on this topic lacks specific recommendations on which languages should be trained in a bilingual aphasic individual and to what extent cross-language transfer occurs subsequent to rehabilitation. Factors contributing to the paucity of research in this area relate to the multitude of possible language combinations in a bilingual individual, the relative competency of the two languages of the bilingual individual, and the effect of focal brain damage on bilingual language representation. It is, however, unfeasible to examine these issues clinically without undertaking a large scale longitudinal study in this population. As a potential solution to this problem, we are currently developing a computational model that will make a systematic examination of cross-language transfer subsequent to rehabilitation possible. The model is an extended version of DISLEX, a simulation of lexical access in humans based on self-organizing maps. For the present work, the model was extended to simulate a bilingual language system in which language representations can vary by age of acquisition and relative proficiency. The model can be lesioned systematically in different ways to simulate the damage leading to bilingual aphasia. Subsequent training using only one of the model’s two languages will then be performed to simulate treatment in aphasic individuals, and will make it possible to examine how age of acquisition, level of pre-morbid language proficiency, and post-morbid language performance influence the nature and degree of cross-language transfer. Here we report on the progress of the project so far. An outline of the model is given, including its implementation as well as its theoretical underpinnings in light of recent empirical evidence. The methods and input data used to train the model and to simulate treatment and clinical tests are described. First findings are presented that demonstrate that the model is able to match the available data on individual patients before the onset of aphasia. Starting with such models of individual patients, possible effects of lesions to the model and their ability to simulate post-morbid language performance are then discussed. Finally, we discuss how the model could in the future complement clinical research in determining the best approach to treating aphasia in bilingual patients, possibly in a way that is tailored to individual patients.Computer [email protected]

2,2´-Methylenverbrückte Bispiperidine : Darstellung und Eigenschaften neuartiger Ligandensysteme

Die Arbeit beschreibt Synthesewege zu 2,2’-Methylenverbrückten Piperidinen sowie die Trennung der anfallenden Stereoisomeren und die Darstellung verschiedener Derivate dieser Verbindungsklasse. Mit dem Einsatz als neuartige Liganden sowie der möglichen Verwendung als beta-turn-Peptidomimetika werden mögliche Anwendungen dieser Verbindungsklassen beschrieben

Detection and analysis of morphotectonic features utilizing satellite remote sensing and GIS: An example in SW Jordan

This study investigates the dominant orientations of morphological features and the relationship between these trends and the spatial orientation of tectonic structures in SW Jordan. Landsat 8 and hill-shaded images, constructed from 30 m-resolution ASTER-GDEM data, were used for automatically extracting and mapping geological lineaments. The ASTER-GDEM was further utilized to automatically identify and extract drainage network. Morphological features were analyzed by means of azimuth frequency and length density distributions. Tectonic controls on the land surface were evaluated using longitudinal profiles of many westerly flowing streams. The profiles were taken directly across the northerly trending faults within a strong topographic transition between the low-gradient uplands and the deeply incised mountain front on the east side of the Dead Sea Fault Zone. Streams of the area are widely divergent, and show numerous anomalies along their profiles when they transect faults and lineaments. Five types of drainage patterns were identified: dendritic, parallel, rectangular, trellis, and modified dendritic/trellis. Interpretation and analysis of the lineaments indicate the presence of four main lineament populations that trend ~ E–W, ~ N–S, NE–SW, and NW–SE. Azimuthal distribution analysis of both the measured structures and drainage channels shows similar trends, except for very few differences in the prevailing directions. The similarity in orientation of lineaments, drainage system, and subsurface structural trends highlights the degree of control exerted by underlying structure on the surface geomorphological features. Faults and lineaments serve as a preferential conduit for surface running waters. The extracted lineaments were divided into five populations based on the main age of host rocks outcropping in the study area to obtain information about the temporal evolution of the lineament trends through geologic time. A general consistency in lineament trends over the different lithological units was observed, most probably because repeated reactivation of tectonism along preexisting deep structural discontinuities which are apparently crustal weakness zones. The reactivation along such inherited discontinuities under the present-day stress field is the most probable explanation of the complicated pattern and style of present-day landscape features in SW Jordan

Modeling bilingualism as a dynamic phenomenon in healthy and neurologically affected speakers across the lifespan: A Commentary on “Computational Modeling of Bilingual Language Learning: Current Models and Future Directions”

In their review article, Li and Xu offered an insightful overview of the contributions and limitations of computational models of bilingual language learning and processing to our current understanding of the bilingual mind. They further proposed joining cross-disciplinary efforts toward building a computational account that links cognitive theory and neurobiological accounts of bilingualism as part of their suggested future research agenda. We agree with Li and Xu’s suggestions and further propose that (a) the scope of computational models of bilingual language learning and processing should be expanded to include other perspectives: language learning context, maintenance, and decay of linguistic competence and bilingual language breakdown and that (b) existing modeling efforts already work toward addressing these areas, answering the proposed desiderata for good computational models