COSMOGENIC NUCLIDE DEPTH-PROFILES AND GEOCHEMICAL ANALYSIS OF MOUNTAIN REGOLITH AIMED AT QUANTIFYING RATES OF GLACIAL AND PERIGLACIAL EROSION

Clay minerals such as kaolinite and gibbsite in mountain regolith in present-day cold environments are often, without further age-constraint, interpreted as products of weathering in a warmer climate (e.g. Rea, 1996; Strømsøe, 2011). This reasoning has, in turn, been used to infer long residence times of the regolith and thereby slow development of landforms hosting these sediments.

Here we present five in-situ cosmogenic 10Be and 26Al depth-profiles from pits in regolith at a high-elevation low-relief summit in Reinheimen National Park in Norway, together with XRD and XRF measurements of the sediment.

We find that denudation in Reinheimen is fast enough to renew the regolith mantle several times during the Quaternary. Our observations furthermore do not support a simple relation between degree of weathering and cosmogenic nuclide concentrations of the sediment. We expect that these results could be representative of other high-elevation low-relief summits, which are a characteristic feature of many passive continental margins in cold regions.

References:

• Rea, B. R., Whalley, W. B., Rainey, M. M., & Gordon, J. E. (1996). Blockfields, old or new? Evidence and implications from some plateaus in northern Norway. Geomorphology, 15(2), 109-121.
• Strømsøe, J. R., & Paasche, Ø. (2011). Weathering patterns in high‐latitude regolith. Journal of Geophysical Research: Earth Surface, 116(F3).