Fast long-term denudation rate of steep alpine headwalls inferred from cosmogenic 36Cl depth profiles

Mair, David; Lechmann, Alessandro; Yesilyurt, Serdar; Tikhomirov, Dmitry; Delunel, Romain; Vockenhuber, Christof; Akçar, Naki; Schlunegger, Fritz (2019). Fast long-term denudation rate of steep alpine headwalls inferred from cosmogenic 36Cl depth profiles. Scientific Reports, 9(1), p. 11023. Nature Publishing Group 10.1038/s41598-019-46969-0

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Quantifications of in-situ denudation rates on vertical headwalls, averaged over millennia, have been thwarted because of inaccessibility. Here, we benefit from a tunnel crossing a large and vertical headwall in the European Alps (Eiger), where we measured concentrations of in-situ cosmogenic 36Cl along five depth profiles linking the tunnel with the headwall surface. Isotopic concentrations of 36Cl are low in surface samples, but high at depth relative to expectance for their position. The results of Monte-Carlo modelling attribute this pattern to inherited nuclides, young minimum exposure ages and to fast average denudation rates during the last exposure. These rates are consistently high across the Eiger and range from 45 ± 9 cm kyr−1 to 356 ± 137 cm kyr−1 (1σ) for the last centuries to millennia. These high rates together with the large inheritance point to a mechanism where denudation has been accomplished by frequent, cm-scale rock fall paired with chemical dissolution of limestone.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences

UniBE Contributor:

Mair, David; Lechmann, Alessandro; Yesilyurt, Serdar; Delunel, Romain; Akçar, Naki and Schlunegger, Fritz

Subjects:

500 Science > 550 Earth sciences & geology
500 Science > 530 Physics

ISSN:

2045-2322

Publisher:

Nature Publishing Group

Language:

English

Submitter:

Fritz Schlunegger

Date Deposited:

06 Aug 2019 13:37

Last Modified:

22 Oct 2019 22:57

Publisher DOI:

10.1038/s41598-019-46969-0

PubMed ID:

31363133

BORIS DOI:

10.7892/boris.132290

URI:

https://boris.unibe.ch/id/eprint/132290

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