Search results for "Nappe"

Transition from thin- to thick-skinned tectonics and consequences for nappe formation: Numerical simulations and applications to the Helvetic nappe s…

2015

Abstract We use two-dimensional numerical simulations to study the deformation style and the formation of nappes during the shortening of basement–cover systems with half-grabens. We perform simulations with only linear and power-law viscous rheology, and also thermo-mechanical simulations with viscoelastoplastic rheology and temperature-dependent viscosities. The accumulated, area-averaged strain is calculated for the sediments, es, and for the basement, eb, to quantify the deformation style. The results show that the transition from thin-skinned dominated (es/eb > 1) to thick-skinned dominated (es/eb ≤ 1) deformation is controlled by two effective viscosity ratios: the ratio of viscosity …

A crustal seismic profile across Sicily

2011

Abstract A crustal reflection seismic profile, more than 100 km long, was recorded across central Sicily, from the Tyrrhenian shore to the Sicily Channel, to understand the deep structures and the collision mechanisms between Europe and Africa and the subsequent geodynamic evolution. The profile was acquired using explosive sources and 240 active channels recorded by a Sercel 408-XL, 24 bits A/D converter, with a 12 km spread and a 24-fold coverage. The data were processed following a non-conventional procedure in order to preserve the relative amplitudes of the reflections and to better investigate the Sicily deep structures down to the Moho. The main highlighted structures are the dramati…

Solution-mass-transfer deformation adjacent to the Glarus Thrust, with implications for the tectonic evolution of the Alpine wedge in eastern Switzer…

2001

Abstract We have studied aspects of absolute finite strain of sandstones and the deformation history above and below the Glarus Thrust in eastern Switzerland. The dominant deformation mechanism is solution mass transfer (SMT), which resulted in the formation of a semi-penetrative cleavage. Our analysis indicates that the Verrucano and Melser sandstones, which lie above the thrust, were deformed coaxially, with pronounced contraction in a subvertical Z direction and minor extension in a subhorizontal X direction, trending at ∼200°. Most of the contraction in Z was balanced by mass-loss volume strains, averaging ∼36%. Below the Glarus Thrust, sandstones of the North Helvetic flysch have small…

Analyse cartographique de données pédologiques et hydrogéologiques appliquée à la gestion responsable de produits phytosanitaires

2014

BASF launched a Responsible Bentazone Management plan in 2011, in order to preserve water resources and sustain its bentazon based herbicide solutions. This molecule is commercialized by the company for several years and is found at concentrations above the standard for drinking water in about 1% of groundwater catchments in France. The action plan aims to reduce contamination situations with recommendations on the use of bentazone (dose, timing of application, restrictions on vulnerable soils on groundwater catchment areas) that complement the commercialization authorization. The study carried out during the internship focused on the diagnosis of a groundwater catchment area located in the…

An active bivergent rolling-hinge detachment system: Central Menderes metamorphic core complex in western Turkey.

2001

Two symmetrically arranged detachment systems delimit the central Menderes metamorphic core complex and define a bivergent continental breakaway zone in the Anatolide belt of western Turkey. Structural analysis and apatite fission-track thermochronology show that a large east-trending syncline within the Alpine nappe stack in the central part of the orogen is related to late Miocene-early Pliocene to recent core-complex formation. The syncline formed as a result of two opposite-facing rolling hinges in the footwalls of each of the two detachments. Back-rotation of the syncline limbs suggests that the detachments rotated from an initial dip of 50 degrees -60 degrees to a currently shallow or…

How does shear zone nucleate? An example from the Suretta nappe (Swiss Eastern Alps)

2016

In order to address the question of the processes involved during shear zone nucleation, we present a petro-structural analysis of millimetre-scale shear zones within the Roffna rhyolite (Suretta nappe, Eastern central Alps). Field and microscopic evidences show that ductile deformation is localized along discrete fractures that represent the initial stage of shear zone nucleation. During incipient brittle deformation, a syn-kinematic metamorphic assemblage of white mica + biotite + epidote + quartz precipitated at ca. 8.5 ± 1 kbar and 480 ± 50 °C that represent the metamorphic peak conditions of the nappe stacking in the continental accretionary wedge during Tertiary Alpine subduction. The…

L'eau sur le site d'Alésia : la contrainte hydrogéologique lors du siège de 52 av. J.-C.

2010

Mount Auxois, the theatre of operations during the siege of Alesia, was the object of a field study aimed at defining the area's natural hydraulic barriers. By combining archaeological and historical knowledge, the influence of this environment during a crisis situation such as that of 52 BC was evaluated. Quantification of the water available during the summer months, together with knowledge of the positions occupied by the opposing forces during the siege, provided more detailed information as to how the warring factions organised water supply and water management within their respective entrenchments.

L'eau et la société dans un milieu rural aride. De l'analyse vers la modélisation d'un système fragile et complexe

2008

Quelles que soient les causes du déficit hydrique dans le bassin versant du Souss, l’objectif visant la gestion des ressources en eau reste le même : préserver ces ressources pour la satisfaction des besoins à long terme. Ce bassin, qui s’étend sur une superficie de 16 200 km², est encadré par des reliefs volumineux ; le Haut-Atlas au Nord, l’Anti-Atlas au Sud, la jonction de ces deux chaînes précitées à l’Est et l’océan Atlantique à l’Ouest. Dans cet espace contrasté, l’aridité du climat et la sécheresse auxquelles s’ajoute l’irrégularité des précipitations, expliquent le recours fluctuant des usagers dans l’exploitation de la nappe phréatique. En effet, la demande en eau augmente surtout …

Quid iuris sub art. 428 c.p.p.

2008

Underplating-related finite-strain patterns in the Gran Paradiso massif, Western Alps, Italy: heterogeneous ductile strain superimposed on a nappe st…

2004

A finite-strain study in the central and northern Gran Paradiso massif of the Italian Western Alps has been carried out to elucidate whether ductile strain shows a relationship to nappe contacts and to shed light on the nature of the subhorizontal foliation typical of the gneiss nappes in the Alps. The R f /φ and Fry methods were used on feldspar porphyroclasts from 98 samples of the Gran Paradiso unit (upper tectonic unit of the Gran Paradiso massif) and 12 samples from the underlying Erfaulet unit (lower unit of the Gran Paradiso massif). Microstructures and thermobarometric data show that feldspar ductility at temperatures higher than c . 450 °C occurred only during high-pressure metamor…