HR: 16:15h
AN: T32E-02    [PDF]
TI: Tectonic feedbacks in the Southern Andes arising from variations in the equilibrium line altitude
AU: * Tomkin, J H
EM: tomkin@geol.lsu.edu
AF: Louisiana State University, Dept. Geology and Geophysics, Baton Rouge, LA 70803-4101 United States
AU: Brandon, M T
EM: mark.brandon@yale.edu
AF: Yale University, Dept. Geology and Geophysics, New Haven, CT 06511 United States
AU: Reiners, P W
EM: peter.reiners@yale.edu
AF: Yale University, Dept. Geology and Geophysics, New Haven, CT 06511 United States
AB: There is considerable interest on the role of climate in controlling topography and local relief in tectonically active landscapes. Much of this discussion has focused on the role of fluvial erosion, but more recently the debate has turned to include glacial erosion as well, which is probably important in limiting the maximum elevation in convergent mountain belts such as the Andes, in which the summit regions are covered by significant amounts of alpine glaciers. We present a theoretical model that shows that the Andes presents a clear test case of quantifiable feedbacks between climate and tectonics. A convergent wedge model of Andean orogen development suggests that the lowering of the Equilibrium Line Altitude (ELA) since the Late Miocene may have lead to a lowering of the relief in the Southern Andes of around 1 km. Analytic calculations suggest that a lowering in relief of the ELA is capable of reducing the mass of the orogen by in excess of 30%. These estimates are supported by a numerical model of fluvial-glacial erosion at convergent orogens, with which we predict that the rate of tectonic rock uplift in the Southern Andes may have increased by more than 20% since the inception of the glacial cycles of the Quaternary, in response to increased erosion.
DE: 1625 Geomorphology and weathering (1824, 1886)
DE: 1645 Solid Earth
DE: 1827 Glaciology (1863)
DE: 8102 Continental contractional orogenic belts
DE: 9360 South America
SC: Tectonophysics [T]
MN: 2003 Fall Meeting