Bayesian inversion of a CRN depth profile to infer Quaternary erosion of the northwestern Campine Plateau (NE Belgium)
The rate at which low-lying sandy areas in temperate regions, such as the Campine Plateau (NE Belgium), have been eroding during the Quaternary is a matter of debate. Current knowledge on the average pace of landscape evolution in the Campine area is largely based on geological inferences and mo...
Main Authors: | , , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2017-07-01
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Series: | Earth Surface Dynamics |
Online Access: | https://www.earth-surf-dynam.net/5/331/2017/esurf-5-331-2017.pdf |
Summary: | The rate at which low-lying sandy areas in temperate regions, such
as the Campine Plateau (NE Belgium), have been eroding during the Quaternary
is a matter of debate. Current knowledge on the average pace of landscape
evolution in the Campine area is largely based on geological inferences and
modern analogies. We performed a Bayesian inversion of an in situ-produced
<sup>10</sup>Be concentration depth profile to infer the average long-term erosion
rate together with two other parameters: the surface exposure age and the
inherited <sup>10</sup>Be concentration. Compared to the latest advances in
probabilistic inversion of cosmogenic radionuclide (CRN) data, our approach
has the following two innovative components: it (1) uses Markov chain Monte
Carlo (MCMC) sampling and (2) accounts (under certain assumptions) for the
contribution of model errors to posterior uncertainty. To investigate to what
extent our approach differs from the state of the art in practice, a
comparison against the Bayesian inversion method implemented in the
CRONUScalc program is made. Both approaches identify similar maximum a
posteriori (MAP) parameter values, but posterior parameter and predictive
uncertainty derived using the method taken in CRONUScalc is moderately
underestimated. A simple way for producing more consistent uncertainty
estimates with the CRONUScalc-like method in the presence of model errors is
therefore suggested. Our inferred erosion rate of 39 ± 8. 9 mm kyr<sup>−1</sup> (1<i>σ</i>)
is relatively large in comparison with landforms that erode under comparable
(paleo-)climates elsewhere in the world. We evaluate this value in the light
of the erodibility of the substrate and sudden base level lowering during the
Middle Pleistocene. A denser sampling scheme of a two-nuclide concentration
depth profile would allow for better inferred erosion rate resolution, and
including more uncertain parameters in the MCMC inversion. |
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ISSN: | 2196-6311 2196-632X |