Exhumation and erosion rates in the flat-topped Nock Mountains in the Eastern Alps constrained by low-temperature and cosmogenic 10Be data

Constraining rates of landscape evolution is a necessary pre-requisite for reconstructing the spatiotemporal evolution of the Earth´s surface. In our study, we present new zircon and apatite fission track and (U-Th)/He ages as well as catchment-wide 10Be-derived erosion rates to determine exhumation and erosion rates in the Nock Mountains, an elevated-low relief landscape in the Eastern Alps. Zircon fission track and zircon (U-Th)/He analyses yielded cooling ages of ~90 and ~80 Ma, respectively, which we interpret to reflect late Cretaceous cooling after Eoalpine metamorphism. Apatite fission track and (U-Th)/He ages are significant younger and range from ca. 35-28 Ma. Time-temperature history modelling of the thermochronological ages suggests enhanced cooling in the Eocene followed by thermal stagnation. Our results show that amount of erosion since ~35 Ma does not exceed 2-3 km and that average erosion rates did not significantly change. Assuming that rock exhumation occurred by erosion only, the long-term erosion rate is ~50-100 mm//kyr and therefore of similar magnitude as the short-term 10Be erosion rates that range from ~90-200 mm/kyr, despite the different timescales of the methods. Our data support the notion that the Nock Mountains represent an area of long-lasting stability although tectonic and glacial-interglacial cycles affected the Eastern Alps since ~35 Ma. (Poster)