Examining erosion in New Zealand over millennial timescales using in-situ 10Be and 14C
- 1GFZ Potsdam, Geomorphology, Potsdam, Germany (firstname.lastname@example.org)
- 2ETH Zurich, Zurich, Switzerland
- 3University of California Berkeley, Berkeley, United States
- 4University of Potsdam, Potsdam, Germany
Landslides are the major erosional process in many orogens, and one of the most sensitive erosional process to tectonic and climatic perturbations. However, it remains extremely difficult to constrain long-term or past rates of landslide activity, and hence their contribution to long-term landscape evolution and catchment sediment fluxes, because the physical records of landsliding are often removed in <102 yrs. Here, we use the in-situ 10Be and in-situ 14C concentrations of recent landslide deposits and catchments from the Fiordland and the Southern Alps of New Zealand to: (a) estimate landslide frequencies over 103-104 yr timescales, which we compare against landslide inventories mapped from air photos (<102 yrs) to estimate changes in landslide activity, (b) quantify catchment-averaged erosion rates, and landslide’s contribution to those erosional fluxes, and (c) test whether paired 14C-10Be measurements can be used to trace erosional depth-provenance and identify transient erosion rate changes. We show that 10Be concentrations on landslide deposits can be used to estimate landslide recurrence intervals and frequency over 103 yr timescales, and that 14C/10Be ratios reflect the depth-provenance of sediment, and possibly transient changes in erosion rates. The comparison of our 10Be-based long-term landslide frequencies with short-term published inventories suggests that landslide frequencies have increased towards the present by up to an order of magnitude. We compare sediment fluxes inferred from these long- and short-term landslide inventories with sediment flux estimates derived from 10Be catchment-averaged erosion rates, which allows us to examine fluctuations in erosion rate estimates from 101 to 103 yrs timescales.
How to cite: Roda-Boluda, D., Schilgen, T., Lupker, M., Hella, W., Jeff, P., Stefanie, T., and Aaron, B.: Examining erosion in New Zealand over millennial timescales using in-situ 10Be and 14C , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9309, https://doi.org/10.5194/egusphere-egu2020-9309, 2020