Open AccessTopography associated with crustal flow in continental collisions, with application to Tibet
Author(s) -
Bendick R.,
McKenzie D.,
Etienne J.
Publication year - 2008
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.2008.03890.x
Subject(s) - geology , lithosphere , dimensionless quantity , crust , viscosity , flow (mathematics) , isostasy , collision , geodesy , continental collision , position (finance) , geophysics , amplitude , deformation (meteorology) , geometry , seismology , mechanics , tectonics , physics , oceanography , computer security , mathematics , finance , quantum mechanics , computer science , economics
SUMMARY Collision between an undeformable indenter and a viscous region generates isostatically compensated topography by solid‐state flow. We model this process numerically, using a finite element scheme. The slope, amplitude and symmetry of the topographic signal depend on the indenter size and the Argand number of the viscous region, a dimensionless ratio of gravitational body forces to viscous forces. When applied to convergent continental settings, these scaling rules provide estimates of the position of an indenter at depth and the mechanical properties of the viscous region, especially effective viscosity. In Tibet, forward modelling suggests that some elevated, low relief topography within the northern plateau may be attributed to lower crustal flow, stimulated by a crustal indenter, possibly Indian lithosphere. The best‐fit model constrains the northernmost limit of this indenter to 33.7°N and the maximum effective viscosity of Eurasian middle and lower crust to 1 × 10 20 ± 0.3 × 10 20 Pa s.