HR: 0800h
AN: T41A-1169    [Abstracts]
TI: Relative Plate Motion Changes Observed in an Analog Freezing-Wax Model
AU: Blais, A
EM: ablais@sdt.univ-brest.fr
AF: UBO, IEUM, UMR 6538, Place Nicolas Copernic, Plouzane, 29280 France
AU: * Naar, D F
EM: naar@usf.edu
AF: University of South Florida, College of Marine Science 140 Seventh Avenue South, St. Petersburg, FL 33701 United States
AB: We investigate the tectonic processes related to changes in seafloor spreading velocity using an Oldenburg and Brune (1972; Nature) freezing-wax analog model, which simulates plate tectonic processes at a shorter time scale (minutes instead of millions of years). Using videotape, we run several experiments at 5, 10, 20, 30 and 40 degrees of relative plate motion direction change. Observing the resulting seafloor spreading geometry after a designed change in relative motion, provides insight for understanding the evolution of corresponding examples in the ocean basins, such as the fracture zone bends near magnetic anomaly 34 along the Kane fracture zone in the Atlantic, and near anomaly 20 along the Mendocino fracture zone in the Pacific and the La Boussole fracture zone in the Indian Ocean. In addition, we document the origin, evolution, and eventual extinction of wax microplates forming within the center of a transform fault strand, much in the same manner as proposed by Bird and Naar (1994; Geology) for the presently active Easter and Juan Fernandez microplates along the southern East Pacific Rise. Although the wax analog model has been shown to have geometric and kinematic scaling properties, it has been difficult to show dynamic scaling. Recent work at Cornell by Bowdenschatz and Katz (URL below) with a different kind of wax and analog model has succeeded replicating the ridge and rift morphology associated with fast and slow seafloor spreading. These recent advances suggest that the model is a viable tool in obtaining insight of the rigid and non-rigid processes that occur during reorganizations of divergent and transform plate boundaries.
UR: http://milou.msc.cornell.edu/waxtectonics.html
DE: 8194 Instruments and techniques
DE: 8155 Plate motions--general
DE: 8157 Plate motions--past (3040)
DE: 3035 Midocean ridge processes
DE: 3040 Plate tectonics (8150, 8155, 8157, 8158)
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting