HR: 14:25h
AN: T43D-04    [Abstracts]
TI: The Important Roles of Oceanic Transform Faults in Hotspot-Ridge Interactions
AU: * Lin, J
EM: jlin@whoi.edu
AF: Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole Road, Woods Hole, MA 02543 United States
AU: Georgen, J E
EM: georgen@gly.fsu.edu
AF: Department of Geological Sciences, Florida State University, 311A Carraway, Tallahassee, FL 32306 United States
AU: Dick, H J
EM: hdick@whoi.edu
AF: Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole Road, Woods Hole, MA 02543 United States
AB: Transform faults are an essential component of the global seafloor spreading system and plate tectonics. In this study we review evidence, especially that recently obtained from the Southwest Indian Ocean, to further highlight the important roles that transform faults play in the dynamic interaction of hotspots with mid-ocean ridges: 1) When a mid-ocean ridge system migrates sufficiently close to a hotspot, the ridge geometry often undergoes dramatic reorganization so that the ridge axis is located where the lithosphere is weakest. Changes in the geometry of transform faults, together with ridge jumps, are the basic mode of such reorganization of ridge geometry. 2) Transform faults of large age offset are often observed to compartmentalize hotspot-influenced ridges into separate corridors of different average seafloor depth, as well as to limit the along-axis extent of hotspot influence, i.e., the "waist width". These effects are observed at ridges of all spreading rates, especially at the highly segmented ultraslow Southwest Indian Ridge. 3) Representing zones of weakness in the lithosphere, transform faults and the fracture zones have been found to be associated with the apparent track of some hotspots. For example, our recent survey near the Southwest Indian Ridge indicates that the Bouvet hotspot has "pierced" through the Shaka fracture zone to form a chain of seamounts that define a pseudo hotspot track. These and other lines of evidence testify to the important roles of oceanic transform faults in hotspot-ridge interactions and the creation and evolution of the oceanic lithosphere.
DE: 8121 Dynamics, convection currents and mantle plumes
DE: 3010 Gravity
DE: 3035 Midocean ridge processes
DE: 3040 Plate tectonics (8150, 8155, 8157, 8158)
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting