HR: 1340h
AN: T33B-1353    [Abstracts]
TI: Lava Dome Formation Along a Superfast Overlapping Spreading Center, 28-32 S on the East Pacific Rise
AU: * Howell, J K
EM: jkhowell@ncsu.edu
AF: Department of Marine, Earth and Atmospheric Sciences, North Carolina State University, Campus Box 8208, Raleigh, NC 27695, United States
AU: Bohnenstiehl, D R
EM: drbohnen@ncsu.edu
AF: Department of Marine, Earth and Atmospheric Sciences, North Carolina State University, Campus Box 8208, Raleigh, NC 27695, United States
AU: Hey, R N
EM: hey@soest.hawaii.edu
AF: Hawaii Institute of Geophysics and Planetology, School of Ocean and Earth Science and Technology, University of Hawaii, 2525 Correa Road, Honolulu, HI 96822, United States
AB: Deep-towed DSL-120 bathymetric data reveal the pattern of axial lava dome formation along a superfast spreading portion of the southern East Pacific Rise (EPR). The data span the overlapping limbs of the giant (~120 km offset) propagator system near 30 S. Domes are identified using a closed-contour algorithm, with auto- detections manually edited to account for the bathymetric gaps associated with the sonar system's nadir region and topographic shadowing. Along non-overlapping portions of the rift system with a full spreading rate of ~150 mm/yr, lava domes are rare and exhibit low relief relative to those imaged in equivalent datasets along the 17-19 S portions of the EPR [White et al., 2000 JGR]. As the axial depth increases and spreading rate decreases along the overlapping portion of the rift, the density of lava domes increases abruptly. Similarly, near-bottom photographic data show that pillow lava morphologies are restricted to these overlapping sections of the ridge crest. Both observations are consistent with the eruption of lower effusion rate lavas near the ends of these first- order segments. The occurrence of higher lava dome density near the ends of finer-scale segments, however, is less evident from our observations.
UR: http://web.mac.com/drbohnen/iWeb/MG_NCSU/Welcome.html
DE: 3000 MARINE GEOLOGY AND GEOPHYSICS
DE: 3035 Midocean ridge processes
DE: 8416 Mid-oceanic ridge processes (1032, 3614)
DE: 8427 Subaqueous volcanism
DE: 8429 Lava rheology and morphology
SC: Tectonophysics [T]
MN: 2007 Fall Meeting