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| Titel |
Constraining sediment fluxes and grain-size characteristics in tectonically-perturbed catchments. |
| VerfasserIn |
A. C. Whittaker, M. Attal, P. A. Allen |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250023488
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| Zusammenfassung |
| The depositional characteristics of any basin fill (the sink) are fundamentally a product of the
coupled system of sediment release from hinterland catchments (the source) and its evolution
during transport downstream. Changes to the tectonic boundary conditions governing the
dynamics of erosion in upland catchments will therefore exert a significant effect on the
nature and magnitude of sediment supply to neighbouring basins. While recent advances in
tectonic geomorphology demonstrate the generic coupling between tectonic uplift and
landscape denudation, there has been relatively little work to quantify the timing,
characteristics and locus of sediment release from tectonically-perturbed upland
catchments, and the way in which this signal subsequently evolves downstream within
the fluvial system. We address this challenge using (i) field data to evaluate the
characteristics and source areas of sediment exported from modern fluvial catchments
draining across active normal faults in the Central Apennines in Italy and (ii) the
CHILD landscape evolution model to investigate how the locus and volume of
sediment exported from such catchments evolves through time and with the degree
of tectonic perturbation. We demonstrate that catchments undergoing a transient
response to an increase in fault uplift rate at 0.8 Ma are associated with significant
volumetric export of material derived largely from an incised zone upstream of the fault,
producing bi-modal grain-size distributions with elevated D84values within the transient
reach. This response is substantially driven by input from coupled hill-slopes, and
we show the amplitude and timescale of the landscape response is modulated by
the degree of tectonic perturbation. Our results challenge the view the sediment is
sourced uniformly from tectonically active catchments, and demonstrate that transient
responses to tectonics control the locus, magnitude and calibre of sediment supply to
basins. More widely, this work offers new insights for geomorphologists seeking to
decode the interactions between hill-slopes, sediment flux and channel incision in
transient landscapes, and we provide a fresh perspective for sedimentologists trying
to predict proximal hanging-wall stratigraphy in normal fault bounded terrains. |
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