The Last Pulse – dating the youngest deformation in the Alps with ESR thermochronometry
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 will be 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, will be used to model the exhumation of the footwalls through time. This will contribute significantly to fill the timescale gap between the present geophysical results and (million years ago) geological datasets, which have been produced in the 4D-MB SPP. 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 responded to the subduction polarity reversal.
If earthquakes partially reset the signal repeatedly with a certain intervall, the signal intensity will ultimately reach to steady-state level within a narrow range of periodic variation. This steady state level can be either expressed by an apparant age or fraction saturation, n/N; the latter has been used in luminescence and ESR thermochronology (e.g. Guralnik et al., 2015, King et al., 2016; 2020).