HR: 0800h
AN: T51A-0436 INVITED [Abstracts]
TI: Predictions of Fault Spacing at the Scale of the Lithosphere From Analytical, Numerical, and Analogue
Studies
AU: * Montesi, L G
EM: montesi@whoi.edu
AF: Woods Hole Oceanographic Institution, Dpt. Geology and Geophysics, Woods Hole, MA 02543
United States
AU: Behn, M D
EM: mbehn@whoi.edu
AF: Woods Hole Oceanographic Institution, Dpt. Geology and Geophysics, Woods Hole, MA 02543
United States
AU: Corti, G
EM: cortigi@steno.geo.unifi.it
AF: CNR-IGG, Section of Florence, Via La Pira, 4, Florence, 50030
Italy
AB:
The location of individual faults is influenced by various local phenomena such as deformation history and heterogeneity in
the deforming rock masses. Nevertheless, large-scale instabilities attempt to impose a deformation length scale or wavelength
on the deforming rocks. At the scale of the lithosphere, one such instability that has been recognized for many years is the
buckling/necking instability. This instability occurs in lithosphere models containing vertical strength contrasts and
undergoing horizontal shortening or extension. Stress heterogeneities due to the buckling/necking instability can influence
fault distribution. More recently, it has been found that if the rheology of a layer obeys a strain-rate weakening law, a
superposed faulting instability develops, immediately producing a network of regularly-spaced faults. The fault spacing
expected from the faulting instability is smaller than for necking-controlled faulting. Hence, in field studies it is
ambiguous how to interpret structures that display a characteristic fault spacing. Focusing on tensile environments, we will
compare the expected spacing that arises from the faulting and necking instabilities to the fault patterns obtained in
numerical and analogue models of extension in an idealized layered structure.
DE: 8005 Folds and folding
DE: 8010 Fractures and faults
DE: 8120 Dynamics of lithosphere and mantle--general
DE: 3220 Nonlinear dynamics
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting