HR: 10:40h
AN: V42B-02    [Abstracts]
TI: Propagating Rift Explanation for the V-Shaped Ridges South of Iceland
AU: * Hey, R N
EM: hey@soest.hawaii.edu
AF: University of Hawaii, 2525 Correa Rd., Honolulu, HI 96822, United States
AU: Martinez, F
EM: fernando@hawaii.edu
AF: University of Hawaii, 2525 Correa Rd., Honolulu, HI 96822, United States
AU: Hoskuldsson, A
EM: armh@hi.is
AF: University of Iceland, Sturlugata 7, Reykjavik, 101, Iceland
AU: Benediktsdottir, A
EM: asdis@hawaii.edu
AF: University of Hawaii, 2525 Correa Rd., Honolulu, HI 96822, United States
AU: Jonsson, P K
EM: palli_kolka@hotmail.com
AF: University of Iceland, Sturlugata 7, Reykjavik, 101, Iceland
AU: Lemmond, P
EM: peter@whoi.edu
AF: Woods Hole Oceanographic Institution, MS 22, Woods Hole, MA 02540, United States
AU: Favia, J
EM: favia@hawaii.edu
AF: University of Hawaii, 2525 Correa Rd., Honolulu, HI 96822, United States
AU: Frazer, B
EM: konane@mit.edu
AF: MIT, 77 Massachussetts Ave., Cambridge, MA 02139, United States
AU: Jones, L
EM: lkj@indiana.edu
AF: Indiana University, 111 N. Jefferson St., Bloomington, IN 47408, United States
AU: Joshi, P
EM: joshpr9@salem.edu
AF: Salem College, 601 S. Church St., Winston Salem, NC 27101, United States
AU: Mueller, T
EM: tinamahina@gmail.com
AF: Hawaii Baptist Academy, 2429 Pali Hwy., Honolulu, HI 96817, United States
AU: Thomas, J
EM: jess_gray04@yahoo.com
AF: College of the Siskiyous, 800 College Avenue, Weed, CA 96094, United States
AB: During June-July 2007 we surveyed the Reykjanes Ridge system south of Iceland to investigate the origin of the V-shaped ridges seen in both bathymetry and gravity, 1st identified by Vogt, and usually interpreted as evidence for pulsing Iceland plume material flowing down an axial conduit. However, there are 2 processes that can produce V-shaped wakes along ridges: flow down an existing axis, and rift propagation. Flow down the pipe models, whether of magma pulses (Vogt, 1971) or magma deficits (Hardarson et al., 1997), predict V-wakes symmetric about the axis, whereas the propagating rift model predicts asymmetries caused by the lithospheric transfer. Contrary to previous interpretations from south of 62 N which suggested simple and continuous ridge evolution, and symmetric V wakes consistent with flow down the pipe models, our survey between 62 N and Iceland found evidence for multiple ridge reorganizations caused by new rifts propagating south from Iceland, and asymmetric V wakes. The asymmetry is highest near Iceland but moderate even south of 62 N. Thus at least some of the V-shaped ridges are the pseudofault/failed rift wakes of propagating rifts which are breaking through the Eurasia plate and transferring lithosphere to the North America plate, rather than resulting from plume pulses flowing down the existing axis. A plume pulse model could still be valid, but only with the modification that the plume pulses drive propagating rifts ahead of them that provide new conduits for the extra plume magma. Alternatively, it might be possible for a steady-state plume interacting with a non-steady state ridge axis, rather than vice versa, to produce the observed pattern. Propagating rifts that periodically open more favorable conduits for the plume flow could conceivably produce V-shaped ridges even from a non-pulsing plume.
UR: http://www.soest.hawaii.edu/HIGP/Faculty/hey/rr2007/index.html
DE: 3035 Midocean ridge processes
DE: 8121 Dynamics: convection currents, and mantle plumes
DE: 8137 Hotspots, large igneous provinces, and flood basalt volcanism
DE: 8150 Plate boundary: general (3040)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting