HR: 0830h
AN: T31E-0888    [PDF]
TI: Seismic imaging of the continent-ocean transition in the southern Gulf of California
AU: * Brown, H E
EM: hbrown@uwyo.edu
AF: University of Wyoming, Department of Geology and Geophysics, Laramie, Wy 82071 United States
AU: Paramo, P
EM: paramo@uwyo.edu
AF: University of Wyoming, Department of Geology and Geophysics, Laramie, Wy 82071 United States
AU: Holbrook, W S
EM: steveh@uwyo.edu
AF: University of Wyoming, Department of Geology and Geophysics, Laramie, Wy 82071 United States
AU: Lizarralde, D
EM: danl@eas.gatech.edu
AF: Georgia Tech, School of Earth and Atmospheric Science, Atlanta, GA 30332 United States
AU: Kent, G
EM: gkent@ucsd.edu
AF: Scripps Institute of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093 United States
AU: Harding, A
EM: aharding@ucsd.edu
AF: Scripps Institute of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093 United States
AU: Gonzalez, A
EM: juaneu@cicese.mx
AF: CICESE, Km. 107 Carretera Tijuana, Ensenada, 2732 Mexico
AU: Fletcher, J
EM: jfletche@cicese.mx
AF: CICESE, Km. 107 Carretera Tijuana, Ensenada, 2732 Mexico
AU: Umhoefer, P
EM: paul.umhoefer@nau.edu
AF: Northern Arizona University, Dept of Geology P O Box 4099, Flagstaff, AZ 86011 United States
AU: Axen, G
EM: gaxen@ess.ucla.edu
AF: UCLA, Department of Earth and Space Sciences, Los Angeles, CA 90095 United States
AB: We present seismic reflection images and a preliminary velocity model of the crust at the mouth of the Gulf of California. The Gulf of California is a unique place to study rifting because the transition from rifted continental margin to oceanic crust to conjugate rifted margin occurs within a fairly short distance, making segments easy to recognize. In the fall of 2002, multi-channel seismic (MCS) data were collected along an ~550 km northwest southeast trending transect from the southern tip of the Baja peninsula over the East Pacific Rise to mainland Mexico. In addition, thirty-six ocean bottom seismometers (OBS) were deployed at ~10 km spacing along the transect to collect wide-angle seismic data. Our goals are 1) to examine the relationships between extensional style, lithospheric composition, and rheology, and 2) to determine whether the Gulf of California margins are volcanic or non-volcanic. MCS images show oceanic crust that lacks seaward dipping reflectors or voluminous extrusives, indicating a non-volcanic rifted margin in the southernmost Gulf of California. Preliminary velocity models of the northwestern margin show an abrupt transition from a 25-km-thick continental crust to an oceanic crust of normal thickness.
DE: 0935 Seismic methods (3025)
DE: 1724 Ocean sciences
DE: 1734 Seismology
SC: Tectonophysics [T]
MN: 2003 Fall Meeting