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| Titel |
10Be erosion rates controlled by normal fault activity through incision and landslide occurrence |
| VerfasserIn |
Duna Roda-Boluda, Mitch D'Arcy, Alex Whittaker, Delia Gheorghiu, Angel Rodes |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250141392
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| Publikation (Nr.) |
 EGU/EGU2017-4899.pdf |
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| Zusammenfassung |
| Quantifying erosion rates, and how they compare to rock uplift rates, is fundamental for
understanding the evolution of relief and the associated sediment fluxes. The competing
effects of rock uplift and erosion are clearly captured by river incision and landsliding, but
linking these four important landscape processes remains a major challenge. We address
these questions using field data from southern Italy, and quantify the geomorphic response to
tectonic forcing. We present 15 new 10Be catchment-averaged erosion rates, collected
from catchments along five active normal faults with excellent slip rate constraints.
We find that erosion rates are strongly controlled by fault slip rates and that this
relationship is mediated by the degree of catchment incision and landslide activity. We
find that 10Be samples from low-relief, unincised areas above knickpoints yield
consistent erosion rates of ∼ 0.12 mm/yr, while samples collected below knickpoints
have erosion rates of ∼ 0.2 - 1.0 mm/yr. This comparison allows us to quantify the
impact that transient incisional response has on erosion rates. We demonstrate that in
this area incision is associated with frequent, shallow landsliding, and we show
that the volumes of landslides stored in the catchments are highly correlated with
10Be-derived sediment flux estimates, suggesting that landslides are likely to be a major
contributor to erosional fluxes. Despite widespread landsliding, CRN samples from the
studied catchments do provide reliable estimates of catchment-averaged erosion
rates, as these are consistent with fault throw patterns and rates. We suggest that
this is because landslides are frequent, small and shallow, and are stored on the
hillslopes for up to ∼ 103 yrs, representing the integrated record of landsliding
over several seismic cycles; and test this hypothesis using a numerical model of
landsliding and CRN dynamics. Our results show that adequate CRN mixing can
occur through runoff as landslides are stored on the hillslopes, as long as landslide
recurrence intervals are short, which is supported by the erosion rate magnitudes and
previous landslide studies in the area. This study contributes to our understanding of
erosion and sediment supply in tectonically-active areas, and offers novel insights
into the use of CRN to infer erosion rates in areas of intense landslide activity. |
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