HR: 0800h
AN: OS41D-0519    [Abstracts]
TI: Geomorphology of the Southern Gulf of California Seafloor
AU: * Eakins, B W
EM: beakins@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093-0205 United States
AU: Lonsdale, P F
EM: plonsdale@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093-0205 United States
AU: Fletcher, J M
EM: jfletche@cicese.mx
AF: CICESE, Km 107 Carretera Tijuana-Ensenada, Ensenada, BC 22860 Mexico
AU: Ledesma, J V
EM: ledesma@uabc.mx
AF: Universidad de Autonoma Baja California, Facultad de Ciencias Marinas Apdo. Postal 453, Ensenada, BC 22800 Mexico
AB: A Spring 2004 multibeam sonar survey defined the seafloor geomorphology of the southern part of Gulf of California and the intersection of the East Pacific Rise with the North American continent. Survey goals included mapping structural patterns formed during the rifting that opened the Gulf and identifying the spatial transition from continental rifting to seafloor spreading. Multibeam sonar imagery, augmented with archival data and a subaerial DEM of Mexico, illuminates the principal features of this boundary zone between obliquely diverging plates: (i) active and inactive oceanic risecrests within young oceanic basins that are rich in evidence for off-axis magmatic eruption and intrusion; (ii) transforms with pull-apart basins and transpressive ridges along shearing continental margins and within oceanic crust; (iii) orphaned blocks of continental crust detached from sheared and rifted continental margins; and (iv) young, still-extending continental margins dissected by submarine canyons that in many cases are deeply drowned river valleys. Many of the canyons are conduits for turbidity currents that feed deep-sea fans on oceanic and subsided continental crust, and channel sediment to spreading axes, thereby modifying the crustal accretion process. We present a series of detailed bathymetric and seafloor reflectivity maps of this MARGINS Rupturing Continental Lithosphere focus site illustrating geomorphologic features of the southern part of the Gulf, from Guaymas Basin to the Maria Magdalena Rise.
DE: 9350 North America
DE: 8109 Continental tectonics--extensional (0905)
DE: 3022 Marine sediments--processes and transport
DE: 3035 Midocean ridge processes
DE: 3045 Seafloor morphology and bottom photography
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting