LUNAR: The Last Pulse – dating the youngest deformation in the Alps with ESR thermochronometry

PIs: Valentina Argante, Sumiko Tsukamoto, Dave Tanner, Christian Brandes, Christoph v.Hagke

This project is a collaboration with LIAG, Hannover ( https://www.leibniz-liag.de/); It is part of the DFG funded Priority Program “Mountain Building Processes in 4-D” (http://www.spp-mountainbuilding.de/)

In this project, we perform ultralow temperature thermochronometry using quartz electron spin resonance (ESR) dating on four major faults in the Alps (the Simplon, Brenner, Salzachtal, and Giudicaria Faults) to estimate their Quaternary activity.  Samples are taken directly from fault core rocks, as well as indirectly across the fault, which allow us to examine whether there is recent thermal overprint on the fault core. Indirect ESR ages, together with new apatite and zircon (U-Th)/He and existing fission track ages, are used to model the exhumation of the footwalls through time. This will contribute to fill the timescale gap between the present geophysical results and (million years ago) geological datasets. Our study area covers the central-west, east, and southern parts the Alps and we will therefore be able to elucidate how the different parts of the orogen respond to the drivers of mountain building.

Outcrop of a brittle/ductile fault close to the locality of Visp, southern Switzerland (A), close to the Simplon Line (Tsukamoto et al., in prep). The outcrop contains a number of different fault rocks, see text. The insert shows a stereonet (equal area, lower hemisphere) of planes to the major slip surface. The slip surfaces are parallel to the major slip surface of the Simplon Line.