HR: 16:30h
AN: T22E-03    [PDF]
TI: Topographic Steady State in the Southern Alps of New Zealand
AU: * Herman, F
EM: frederic.herman@anu.edu.au
AF: australian national university, Research School of Earth Sciences, Canberra, ACT 0200 Australia
AU: Braun, J
EM: jean.braun@anu.edu.au
AF: australian national university, Research School of Earth Sciences, Canberra, ACT 0200 Australia
AB: Steady-states between erosional and tectonic processes occurring in continental collisions are important because these represent the stable states toward which the dynamic tectonic-erosion system evolves. Topographic steady-state has been illustrated by numerical models of landscape evolution but often relies on conditions such as invariant rock uplift rate, climate, lithology, etc. Alternatively, transient surface processes such as glacial erosion may prevent the development of a topographic steady-state. Horizontal tectonic advection may also avert achievement of a topographic steady-state. This concept can be easily understood by considering the following first-order one-dimensional equation governing landscape evolution: \begin{equation} \frac{\partial h}{\partial t} = u_{u}-u_{i}- v \frac{\partial h}{\partial x} \end{equation} where $h$ is elevation, $x$ horizontal distance, $u_{u}$ rock uplift rate, $u_{i}$ is incision rate (including diffusion of hillslope as well as incision of bedrock in fluvial channels) and $v$ horizontal velocity tectonic advection. A numerical solution of this equation is proposed to investigate which major regional mechanisms may or not permit to reach a topographic steady state. This solution is then coupled with a GIS analysis of a 50m DEM of the South Island in New Zealand, where a continental collision is occurring, to extract geomorphologic features across the orogen that can be explained in terms of the solution of the equation described above.
DE: 1815 Erosion and sedimentation
DE: 3210 Modeling
DE: 5470 Surface materials and properties
DE: 8102 Continental contractional orogenic belts
SC: Tectonophysics [T]
MN: 2003 Fall Meeting