HR: 08:05h
AN: T21B-01 INVITED     [PDF]
TI: Fault and Rift evolution - All Features Great and Small
AU: * King, G C
EM: king@ipgp.jussieu.fr
AF: Laboratoire de Tectonique, IPGP, 4 place Jussieu, Paris, 75252 France
AU: Manighetti, I
EM: manig@usc.edu
AF: Department of Geological Sciences, University of Southern California, Los Angeles, CA 90089-074 United States
AU: Sammis, C
EM: sammis@usc.edu
AF: Department of Geological Sciences, University of Southern California, Los Angeles, CA 90089-074 United States
AU: Tapponnier, P
EM: tappon@ipgp.jussieu.fr
AF: Laboratoire de Tectonique, IPGP, 4 place Jussieu, Paris, 75252 France
AU: Armijo, R
EM: armijo@ipgp.jussieu.fr
AF: Laboratoire de Tectonique, IPGP, 4 place Jussieu, Paris, 75252 France
AU: Bowman, D
EM: bowman@fullerton.edu
AF: Department of Geological Sciences, California State University, Fullerton, CA 92834-6850 United States
AB: It has been recognised for some time that oceanic ridges propagate and that the process involves the transfer and concentration of stored elastic energy to the site where new rift is being created. Together with flexure associated with volcano loading and subduction, the evidence that oceanic lithosphere has long-term elastic strength seems convincing. Data demonstrating long-term strength and propagation-like behaviour for continental lithosphere has taken longer to collect. For the Gulf of Aden and two major faults (the Altyn Tagh and North Anatolian faults) the evidence now appears to be convincing. Over periods of many millions of years these fault have evolved in a way most simply explained if the continental lithosphere, like that of the oceans, is elastic overall. However, while the propagation of continental faulting or rifting is similar to that observed in engineering materials, there are important differences. A central tenant of traditional fracture mechanics is that big cracks grow at the expense of smaller ones, which therefore are unimportant. This is not true for the Earth, as demonstrated by the scale distribution of faults and earthquakes. Damage or breakdown zones also appear to be larger than those in engineering materials and to scale with the length of the associated fault. Finally, unmodified concepts of Critical Stress Intensity Factor cannot applied to the evolution of faulting in the Earth. Recent studies of long-term fault growth sheds new light on this problem. The cumulative slip profiles of such faults appear to be triangular and can only be explained by the development of large damage zones off the main fault, that incorporate macro- rather than micro-scale fissuring. Such triangular faults or cracks cannot behave like elliptical (or modified elliptical) ones since the stress intensity factor at their tips is zero. Hence, large faults are not favored with respect to small ones, and in the absence of interactions, all faults are equally likely to extend. Although these faults do extend, this consists of a process of linkage. The highly irregular slip profiles of long-term faults is consistent with this view.
DE: 1744 Tectonophysics
DE: 7218 Lithosphere and upper mantle
DE: 8010 Fractures and faults
SC: Tectonophysics [T]
MN: 2003 Fall Meeting