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| Titel |
Erosion-driven uplift of the modern Central Alps |
| VerfasserIn |
J.-D. Champagnac, F. Schlunegger, K. Norton, F. von Blanckenburg, L. M. Abbühl, M. Schwab |
| 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 |
250020784
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| Zusammenfassung |
| We present a compilation of four sets of data of modern tectono-geomorphic processes in the
Central Alps of Switzerland that appear to suggest that rock uplift is a response to
climate-driven denudation in the absence of active convergence. These are (1) basin-averaged
Late Holocene denudation rates determined from cosmogenic nuclides and from suspended
river loads; these slightly exceed, but spatially mimic the pattern of rock uplift rates as
determined by geodetic leveling; (2) the geodetic reference point is also the geomorphic base
level with respect to erosion; we further present (3) a compilation of modern plate motion
velocities shows that the rotation pole of the Adriatic plate is located within the area,
hence the area is not under convergence; finally (4), we illustrate that the Central
Alps have acted as a closed system for Holocene sediment redistribution up to the
peri-Alpine lakes which have operated as a sink for the erosion products of the inner
Alps.
While a variety of hypotheses have been put forward to explain the Central Alpine uplift
(e.g. lithospheric forcing by convergence or mantle processes; ice melting) we show with a
numerical isostatic model that the correlation between erosion and crustal uplift rates reflects
a positive feedback between denudation and the associated isostatic response to unloading.
Therefore erosion does not passively respond to advection of crustal material as might be the
case in actively converging orogens. Other forces need to be considered to drive surface
erosion. We suggest that the geomorphic response of the Alpine topography to glacial
erosion and the resulting disequilibrium for modern channelized and associated
hillslope processes explains much of the pattern of modern denudation and hence rock
uplift. Therefore, in a non-convergent orogen such as the Central European Alps, the
observed vertical rock uplift is primarily a consequence of passive unloading due to
erosion.
REFERENCES:
Anderson, H. and Jackson, J., 1987. Active tectonics in the Adriatic region. Geophysical
Journal Royal Astronomical Society 91, 937–983.
Battaglia, M., Murray, M.H., Serpelloni, E. and Burgmann, R., 2004. The Adriatic region:
An independent microplate within the Africa-Eurasia collision zone. Geophysical Research
Letter 31, L09605, doi:10.1029/2004GL019723.
Calais, E., Nocquet, J., Jouanne, F. and Tardy, M., 2002. Current strain regime in the
Western Alps from continuous Global Positioning System measurements, 1996 – 2001.
Geology 30, 651-654.
Norton, K.P., von Blanckenburg, F., Schlunegger, F., Schwab, M. and Kubik,
P.W., 2008. Cosmogenic nuclide-based investigation of spatial erosion and hillslope
channel coupling in the transient foreland of the Swiss Alps. Geomorphology, 95,
474–486.
Wittmann, H., von Blanckenburg, F., Kruesmann, T., Norton, K.P., and Kubik, P., 2007.
The relation between rock uplift and denudation from cosmogenic nuclides in river sediment
in the Central Alps of Switzerland. Journal of Geophysical Research-Earth Surface 112,
doi:10.1029/2006JF000729. |
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