Daniel Egli

Triassic metasediments in the internal Dinarides (Kopaonik area, southern Serbia): stratigraphy, paleogeographic and tectonic significance

Triassic metasediments in the internal Dinarides (Kopaonik area, southern Serbia): stratigraphy, paleogeographic and tectonic significance Strongly deformed and metamorphosed sediments in the Studenica Valley and Kopaonik area in southern Serbia expose the easternmost occurrences of Triassic sediments in the Dinarides. In these areas, Upper Paleozoic terrigenous sediments are overlain by Lower Triassic siliciclastics and limestones and by Anisian shallow-water carbonates. A pronounced facies change to hemipelagic and distal turbiditic, cherty metalimestones (Kopaonik Formation) testifies a Late Anisian drowning of the former shallow-water carbonate shelf. Sedimentation of the Kopaonik Formation was contemporaneous with shallow-water carbonate production on nearby carbonate platforms that were the source areas of diluted turbidity currents reaching the depositional area of this formation. The Kopaonik Formation was dated by conodont faunas as Late Anisian to Norian and possibly extends into the Early Jurassic. It is therefore considered an equivalent of the grey Hallstatt facies of the Eastern Alps, the Western Carpathians, and the Albanides-Hellenides. The coeval carbonate platforms were generally situated in more proximal areas of the Adriatic margin, whereas the distal margin was dominated by hemipelagic/pelagic and distal turbiditic sedimentation, facing the evolving Neotethys Ocean to the east. A similar arrangement of Triassic facies belts can be recognized all along the evolving Meliata-Maliac-Vardar branch of Neotethys, which is in line with a ‘one-ocean-hypothesis’ for the Dinarides: all the ophiolites presently located southwest of the Drina-Ivanjica and Kopaonik thrust sheets are derived from an area to the east, and the Drina-Ivanjica and Kopaonik units emerge in tectonic windows from below this ophiolite nappe. On the base of the Triassic facies distribution we see neither argument for an independent Dinaridic Ocean nor evidence for isolated terranes or blocks.

Some Hamiltonian models of friction II

In the present paper we consider the motion of a very heavy tracer particle in a medium of a very dense, non-interacting Bose gas. We prove that, in a certain mean-field limit, the tracer particle will be decelerated and come to rest somewhere in the medium. Friction is caused by emission of Cerenkov radiation of gapless modes into the gas. Mathematically, a system of semilinear integro-differential equations, introduced in Frohlich et al. [“Some hamiltonian models of friction,” J. Math. Phys. 52(8), 083508 (2011)10.1063/1.3619799], describing a tracer particle in a dispersive medium is investigated, and decay properties of the solution are proven. This work is an extension of Frohlich et al. [“Friction in a model of hamiltonian dynamics,” Commun. Math. Phys. 315(2), 401–444 (2012)10.1007/s00220-012-1564-2]; it is an extension because no weak coupling limit for the interaction between tracer particle and medium is assumed. The technical methods used are dispersive estimates and a contraction principle.

The role of precursory structures on Tertiary deformation in the Black Forest—Hegau region

Structural inheritance of preexisting crustal discontinuities is widely accepted to have played a crucial role during the Cenozoic tectonic evolution of the northern Alpine foreland. It is recognised as a process that can strongly influence local fault kinematics and strain patterns. The case study presented herein is dedicated to the tectonic analysis of the Freiburg–Bonndorf–Bodensee Fault Zone (FBBFZ) located at the external margin of the northern Alpine Molasse Basin and extending into the crystalline Black Forest Massif. The structure and kinematics of this crustal-scale fault zone are investigated by means of a regional analysis of locally mapped faults, kinematic analysis of outcrop-scale fractures and slip vector modelling. The exceptional possibility of analysing the fault zone exposed from basement to cover allowed for an evaluation of interaction between precursory structures and subsequent deformation features. The results of this study show that the crystalline basement structures exposed along the FBBFZ had a strong imprint on the map-scale fault pattern observable in the Mesozoic and Tertiary sequences. Kinematic analysis of outcrop-scale fracture systems in the latter units yields evidence for local multi-directional extension and strike-slip faulting during Miocene to recent times. While these observations may evoke the interpretation of a multistage palaeostress history along the FBBFZ, slip vector modelling of a very well exposed FBBFZ segment suggests that the various strain records can alternatively be explained by one single regional stress tensor and be related to superordinate deep-seated strike-slip deformation.

Anderson Localization Triggered by Spin Disorder—With an Application to EuxCa1−xB6

The phenomenon of Anderson localization is studied for a class of one-particle Schrödinger operators with random Zeeman interactions. These operators arise as follows: Static spins are placed randomly on the sites of a simple cubic lattice according to a site percolation process with density x and coupled to one another ferromagnetically. Scattering of an electron in a conduction band at these spins is described by a random Zeeman interaction term that originates from indirect exchange. It is shown rigorously that, for positive values of x below the percolation threshold, the spectrum of the one-electron Schrödinger operator near the band edges is dense pure-point, and the corresponding eigenfunctions are exponentially localized.Localization near the band edges persists in a weak external magnetic field, H, but disappears gradually, as H is increased. Our results lead us to predict the phenomenon of colossal (negative) magnetoresistance and the existence of a Mott transition, as H and/or x are increased.Our analysis is motivated directly by experimental results concerning the magnetic alloy EuxCa1−xB6.

Structural-permeability favorability in crystalline rocks and implications for groundwater flow paths: a case study from the Aar Massif (central Switzerland)

Groundwater flow in granitic bedrock is of major interest for underground projects such as radioactive waste disposal. It is generally accepted that granitic rocks of the upper crust are characterized as faulted low-porosity rocks showing fault-related permeability. In this study, the influence of existing faults on the present-day water flow in the Grimsel Test Site (Switzerland), an underground rock laboratory situated in granitoid rocks, was investigated by mapping water discharges. As a result, the link between water flow and faults considering slip-tendency analysis and fault intersections is evaluated. Water-conducting features were combined in a structural-permeability favorability map. Faults and dykes occur as three orientation groups, NE–SW, E–W, and NW–SE trending, all steeply dipping southwards with fault intersections also steeply plunging southwards. In total, 100 water discharges were mapped in summer 2014 and 85 in winter 2016, which are located along faults or fault intersections. A comparison of water discharges with structures showed that high-slip-tendency metabasic dykes and fault or dyke intersections represent the dominant flow paths. Further, it could be demonstrated that higher slip-tendency tends to lead to enhanced average hydraulic conductivity and therefore more constant water flow. Based on water fluxes, fault intersections are inferred to represent first-order locations of water percolation followed by high-slip-tendency metabasic dykes. The combination of all water-conducting features into a structural-permeability map results in covering all water discharges. Therefore, the structural-permeability favorability map can serve as suitable representation for constraining water inflow in fractured granitoid host rocks.RésuméL’écoulement des eaux souterraines dans le substratum granitique est d’un intérêt majeur pour les projets souterrains tels que le stockage des déchets radioactifs. Il est généralement admis que les roches granitiques de la croûte supérieure sont caractérisées comme des roches faillées de faible porosité montrant une conductivité hydraulique associée aux failles. Dans cette étude, l’influence des failles existantes sur l’écoulement actuel des eaux dans le site d’essai du Grimsel (Suisse), un laboratoire souterrain situé dans des roches granitoïdes, a été étudiée en cartographiant les sorties d’eau. Par conséquent, le lien entre l’écoulement d’eau et les failles en considérant l’analyse de tendance au glissement et les intersections des failles est évalué. Les caractéristiques conductrices vis-à-vis de l’eau ont été combinées dans une carte de la conductivité hydraulique structurale favorable. Les failles et les dykes se présentent selon trois groupes d’orientation, de tendance NE–SW, E–W, et NW–SE, tous avec un pendage fort vers le Sud avec des intersections de faille plongeant également de manière abrupte vers le Sud. Au total, ce sont 100 sites de sorties d’eau, localisés le long de failles ou d’intersection de failles qui ont été cartographiés à l’été 2014 et 85 à l’hiver 2016. Une comparaison des sorties d’eau avec les structures a montré que les dykes métabasiques à tendance élevée au glissement et les intersections de failles ou de dykes représentent les voies d’écoulement dominantes. De plus, on pourrait démontrer que la tendance au glissement la plus élevée tend à conduire à une augmentation de la conductivité hydraulique moyenne et donc à un écoulement d’eau plus constant D’après les flux d’eau, on déduit que les intersections des failles représentent des emplacements de premier ordre de percolation de l’eau, suivis des dykes métabasiques à tendance au glissement élevé. La combinaison de toutes les caractéristiques conductrices d’eau sur une carte de la conductivité hydraulique structurale permet de couvrir toutes les sorties d’eau. Par conséquent, la carte de conductivité structurale favorable peut servir de représentation appropriée pour limiter l’afflux d’eau dans les roches granitoïdes fracturées hôtes.ResumenEl flujo de agua subterránea en el basamento granítico es de gran interés para proyectos en el subsuelo, como la eliminación de desechos radiactivos. En general, se acepta que las rocas graníticas de la corteza superior se caracterizan por ser rocas de baja porosidad con fallas que muestran permeabilidad relacionada con el fallamiento. En este estudio, la influencia de las fallas existentes en el flujo real de agua en el sitio de ensayo de Grimsel (Suiza), un laboratorio del subsuelo situado en rocas granitoides, se investigó mediante el mapeo de las descargas de agua. Como resultado, se evalúa el vínculo entre el flujo de agua y las fallas considerando el análisis de tendencias de deslizamiento y las intersecciones de fallas. Las características de la conducción del agua se combinaron en un mapa de favorabilidad de la permeabilidad estructural. Las fallas y los diques ocurren como tres grupos de orientación, NE–SW, E–W y NW–SE, todos con fuertes pendientes hacia el sur con intersecciones de fallas que también se hunden hacia el sur. En total, se asignaron 100 descargas de agua en el verano de 2014 y 85 en el invierno de 2016, que se ubican a lo largo de fallas o intersecciones de fallas. Una comparación de las descargas de agua con las estructuras mostró que los diques metabásicos de alto deslizamiento y las intersecciones de fallas o diques representan las trayectorias de flujo dominantes. Además, podría demostrarse que una mayor tendencia al deslizamiento tiende a conducir a una mejor conductividad hidráulica promedio y, por lo tanto, a un flujo de agua más constante. Con base en los flujos de agua, las intersecciones de fallas se infieren para representar ubicaciones de primer orden de percolación de agua seguidas por diques metabásicos de tendencia de alto deslizamiento. La combinación de todas las características de conducción de agua en un mapa de permeabilidad estructural da como resultado cubrir todas las descargas de agua. Por lo tanto, el mapa de favorabilidad de la permeabilidad estructural puede servir como una representación adecuada para restringir el ingreso de flujo de agua en las rocas granitoides fracturadas.摘要花岗岩基岩中的地下水水流是地下项目诸如放射性废物处理项目中主要关注的问题。普遍公认的是,上层地壳的花岗岩特征一般都是断裂的低孔隙岩石,其渗透性显示出与断层相关。在本研究中,在(瑞士)一个位于花岗岩岩石中的地下岩石实验室,即Grimsel试验场,通过绘制水排泄图研究了现有断层对目前水流的影响。因此,还评估了鉴于滑动趋势分析的水流和断层之间的联系以及断层交叉点。在结构性渗透性有利度图中,综合了导水特征。断层和岩脉以三个方向组出现:NE–SW、E–W和NW–SE走向,所有都是向南陡然倾斜,并且断层交叉点也是向南陡然俯冲。总共2014年夏季绘制了100次水排泄,2016年冬季绘制了85次的水排泄,所有这些水排泄都位于沿断层或者沿断层交叉点的地方。水排泄与结构的比较显示,高度滑动趋势的变质基性岩脉和断层或岩脉交叉点为主要水流通道。此外,可以证明,较高的滑动趋势易于导致平均水力传导率增大,因此,使水流更加恒定。根据水通量,推测了断层交叉点,以展示水渗透的一级位置,水渗透之后为高度滑动趋势的变质基性岩脉。把所有导水特征融入结构性渗透性图中就会覆盖所有的水排泄。因此,结构性渗透性有力度图可作为约束断裂花岗岩水流入的合适表现形式。ResumoO fluxo de águas subterrâneas em embasamento granítico é de grande interesse para projetos subterrâneos como disposição de rejeito radioativo. É comumente aceito que rochas graníticas da crosta superior são caracterizadas como rochas falhadas de baixa porosidade apresentando permeabilidade relacionada aos falhamentos. Neste estudo, a influência de falhas existentes no fluxo atual de águas no Local de Testes de Grimsel (Suíça), um laboratório subterrâneo situado em rochas graníticas, foi investigada mapeando-se as descargas de água. Como resultado, é avaliada a conexão entre o fluxo de água e o falhamento considerando a análise da tendência de deslizamento e intersecção das falhas. As feições condutoras de água foram combinadas em um mapa de favorabilidade da permeabilidade estrutural. Falhas e diques ocorrem em três grupos de orientações, direções NE–SO, E–O e NO–SE, todos com mergulho alto para sul, com intersecções de falhas também com alto ângulo de mergulho para sul. No total, 100 pontos de descarga de água foram mapeados no verão de 2014 e 85 pontos no inverno de 2016, os quais estão localizados ao longo das falhas ou intersecções de falhas. Uma comparação das descargas de água com as estruturas demonstrou que diques metabásicos com alta tendência de deslizamento e intersecção de falhas ou diques representam os fluxos preferenciais dominantes. Além disso, pode ser demonstrado que maiores tendências de deslizamento tendem a levar a uma maior média de condutividade hidráulica e assim a um fluxo de água mais constante. Com base nos fluxos de água, infere-se que as intersecções de falhas representam locais de primeira ordem para percolação de água, seguidas por diques metabásicos com alta tendência de deslizamento. A combinação de todas as feições condutoras de água em um mapa de permeabilidade estrutural resulta na cobertura de todas as descargas de água. Portanto, o mapa de favorabilidade da permeabilidade estrutural pode servir como uma representação adequada para restringir a entrada de água em granitóides fraturados como rochas hospedeiras.

Constraints from 40 Ar/39 Ar geochronology on the timing of Alpine shear zones in the Mont Blanc-Aiguilles Rouges region of the European Alps: GEOCHRONOLOGY OF ALPINE SHEAR ZONES

The Mont Blanc and Aiguilles Rouges massifs, which form part of the external crystalline massifs of the western European Alps, record a young and fast exhumation history, as established by an extensive low-temperature thermochronology and geochronology data set. Various kinematic and dynamic models for Oligocene to Neogene deformation and exhumation of the Aiguilles Rouges-Mont Blanc system have been proposed. However, the timing of deformation along major shear zones in and around the massifs, which is crucial to these models, is still controversial. Our new 40Ar/39Ar data from key deformation zones in the Mont Blanc area show that NW directed thrusting lasted from Oligocene to mid-Miocene times in the Mont Blanc massif before a NW-ward jump of the deformation front to below the Aiguilles Rouges massif, which led to updoming of the Aiguilles Rouges and Mont Blanc massifs. This deactivated the main NW verging shear zones and caused back-folding and back thrusting east of the Mont Blanc, as well as upward extrusion of the Aiguilles Rouges massif. Subsequently, there was a switch to more coaxial shortening between the Aiguilles Rouges and Mont Blanc massifs associated with strain partitioning and related dextral strike-slip deformation on the eastern side of the Mont Blanc massif.

Characterisation and Imaging of a Near-vertical Fault Zone in Crystaline Rock from Hydrophone VSP Data

Summary A shallow near-vertical hydrothermally active fault zone embedded in fractured crystalline rocks of the central Alps has been drilled and geophysically explored in view of its potential analogies to planned deep petrothermal reservoirs in the Alpine foreland. Hydrophone-based zero-offset vertical seismic profiling (VSP) data were found to be highly effective for detecting open fractures and determining seismic velocity changes due to deformation. Walk-away hydrophone VSP data were acquired with a 45-degree crooked-line survey geometry with respect to the borehole plane, which requires 3D processing methods for seismic imaging. For imaging purposes, a laterally changing velocity cube was generated from the ZVSP velocities and projected along the strike of the fault. The subsequent, pre-stack-depth-migration imaging has been successful in delineating vertical structures, the target fault core, and an as of yet unknown, and correspondingly enigmatic, sub-horizontal structural feature.