Project

deformation; exhumation; fluid-rock interaction; seismic faulting; Helvetic nappes; European Alps

Lead
Lay summary
This project aims to establish the geometry, kinematics, mechanisms and relative and absolute timing of ductile-brittle deformation related to extension/transtension and exhumation in the Rawil Depression (central Helvetic Alps), within the footwall of the Rhône-Simplon fault zone. The nappe stack in the Rawil Depression between the Aar and Mont Blanc massifs is overprinted by dominantly dextral transtensional faults developed or reactivated during the Neogene (i.e. < 24 Ma). This area shows the evolution, during exhumation, of fault systems from partially ductile to brittle conditions. However, the interplay between extension and exhumation in the Rawil Depression is still not well understood, especially with regard to the pressure (depth) - temperature - time history and the source and composition of fluids involved. The project will develop a 4D model of deformation and exhumation for the Rawil Depression from Neogene to recent times. In following this aim, it will also consider the importance of re-activation of precursor structures, such as syn-sedimentary faults, on the overall tectonic architecture, as well as the mechanism of transtensional oblique-slip fault development and the influence of fluid-rock interaction during brittle-ductile deformation. The exhumed fossil faults can also act as models for currently active faults at depth in this most seismically disturbed region of Switzerland.

Direct link to Lay Summary

Last update: 21.02.2013

Number	Title	Start	Funding scheme

This project aims to establish the geometry, kinematics, mechanism(s) and (relative and absolute) timing of ductile-brittle deformation related to extension/transtension and exhumation in the Rawil Depression (central Helvetic Alps), within the footwall of the Rhône-Simplon fault zone. The nappe stack in the Rawil Depression between the Aar and Mont Blanc massifs is overprinted by dominantly dextral transtensional faults developed or reactivated during the Neogene. This area shows the evolution, during exhumation, of fault systems from partially ductile to brittle conditions. However, the interplay between extension and exhumation in the Rawil Depression is still not well understood, especially with regard to the P (depth)-T-t history and the source and composition of fluids involved. The project will develop a 4D model of deformation and exhumation for the Rawil Depression from Neogene to recent times. In following this aim, it will also consider the importance of re-activation of precursor structures, such as syn-sedimentary faults, on the overall tectonic architecture, as well as the mechanism of transtensional oblique-slip fault development and the influence of fluid-rock interaction during brittle-ductile deformation. The exhumed fossil faults can also act as models for currently active faults at depth in this most seismically disturbed region of Switzerland.