| Reconstructing the evolution of Earth’s landscape is a key to understand its future evolution
and to identify the driving forces that shape Earth’s surface. Cosmogenic nuclide and
thermochronological methods are routinely used to quantify Earth surface processes over
102-104 yr and 106-107 yr, respectively (e.g. Lal 1991; Reiners and Ehlers 2005; von
Blanckenburg 2006). A comparison of the rates of surface processes derived from these
methods is, however, hampered by the large difference in their timescales. For instance, a
constant erosion rate of 0.1 mm/yr yield an apatite (U-Th)/He age of ~24 Ma and a 10Be age
of ~6 ka, respectively. Analytical methods that bridge this time gap are on the way, but are
not yet fully established (e.g. Herman et al. 2010). A ready to use alternative are river
profiles, which record the regional uplift history over 102-107 yr (e.g. Pritchard et al. 2009).
Changes in uplift are retained in knickzones that propagate with a distinct velocity upstream,
and therefore the time of an uplift event can be estimated. Here I present an integrative
inverse modelling approach to simultaneously reconstruct river profiles, model
thermochronological and cosmogenic nuclide data and to derive robust information about
landscape evolution over thousands to millions of years. An efficient inversion
routine is used to solve the forward problem and find the best uplift history and
erosional parameters that reproduce the observed data. I test the performance of the
algorithm by inverting a synthetic dataset and a dataset from the Sila massif (Italy).
Results show that even complicated uplift histories can be reliably retrieved by the
combined interpretation of river profiles, thermochronological and cosmogenic nuclide
data.
References
Gallagher, K., Brown, R. & Johnson, C. (1998): Fission track analysis and its applications
to geological problems. – Annu. Rev. Earth Planet., 26: 519-572.
Herman, F., Rhodes, E.J., Braun, J. & Heiniger, L. (2010): Uniform erosion rates and
relief amplitude during glacial cycles in the Southern Alps of New Zealand, as revealed from
OSL-thermochronology. – Earth Planet. Sci. Lett., 297: 183-189.
Lal, D. (1991): Cosmic ray labeling of erosion surfaces: in situ nuclide production rates
and erosion models. – Earth Planet. Sci. Lett. 104: 424-439.
Pritchard, D., Roberts, G.G., White, N.J. & Richardson, C.N. (2009): Uplift histories
from river profiles. – Geophys. Res. Lett., 36, L24301, doi:10.1029/2009GL040928.
Reiners, P.W. & Ehlers, T.A. (2005): Low-temperature Thermochronology: Techniques,
Interpretations, and Applications. – Rev. Mineral. Geochem., 58.
Von Blanckenburg, F. (2006): The control mechanisms of erosion and weathering at basin
scale from cosmogenic nuclides in river sediment. – Earth Planet. Sci. Lett., 242: 462-479. |