HR: 14:55h
AN: V33G-06    [Abstracts]
TI: Hotspot-Ridge Interaction: Shaping the Geometry of Mid-Ocean Ridges
AU: * Mittelstaedt, E
EM: staggle@soest.hawaii.edu
AF: University of Hawaii Manoa, SOEST, Department of Geology and Geophysics, 1680 East West Road, Honolulu, HI 96822 United States
AU: Ito, G
EM: gito@hawaii.edu
AF: University of Hawaii Manoa, SOEST, Department of Geology and Geophysics, 1680 East West Road, Honolulu, HI 96822 United States
AB: Surface manifestations of hotspot-ridge interaction include geochemical anomalies, elevated ridge topography, negative gravity anomalies, off-axis volcanic lineaments, and ridge reorganization events. The last of these is expressed as either "captured" ridge segments due to asymmetric spreading, such as at the Galapagos, or as discrete jumps of the ridge axis toward the hotspot, such as at the Iceland, Tristan de Cuhna, Discovery, Shona, Louisville, Kerguelen, and Reunion hotspots. Mid-ocean ridge axis reorganizations through discrete jumps will cause variations in local volcanic patterns, lead to changes in overall plate shape and ridge axis morphology, and alter local mantle flow patterns. It has been proposed that discrete ridge jumps are a product of interaction between the lithosphere and a mantle plume. We examine this hypothesis using thin plate theory coupled with continuum damage mechanics to calculate the two-dimensional (plan-view) pattern of depth-integrated stresses in a plate of varying thickness with weakening due to volcanism at the ridge and above the plume center. Forces on the plate include plume shear, plate parallel gravitational forces due to buoyant uplift, and a prescribed velocity of plate motion along the edges of the model. We explore these forces and the effect of damage as mechanisms that may be required to predict ridge jumps.
DE: 8010 Fractures and faults
DE: 8159 Rheology--crust and lithosphere
DE: 8164 Stresses--crust and lithosphere
DE: 3035 Midocean ridge processes
DE: 3230 Numerical solutions
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting