Publication Date:
2022-05-26
Description:
Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 113 (2008): B03307, doi:10.1029/2007JB005113.
Description:
Multichannel reflection and coincident wide-angle seismic data collected during the 2002 Premier Experiment, Sea of Cortez, Addressing the Development of Oblique Rifting (PESCADOR) experiment provide the most detailed seismic structure to date of the southern Gulf of California. Multichannel seismic (MCS) data were recorded with a 6-km-long streamer, 480-channel, aboard the R/V Maurice Ewing, and wide-angle data was recorded by 19 instruments spaced every ∼12 km along the transect. The MCS and wide-angle data reveal the seismic structure across the continent-ocean transition of the rifted margin. Typical continental and oceanic crust are separated by a ∼75-km-wide zone of extended continental crust dominated by block-faulted basement. Little lateral variation in crustal thicknesses and seismic velocities is observed in the oceanic crust, suggesting a constant rate of magmatic productivity since seafloor spreading began. Oceanic crustal thickness and mean crustal velocities suggest normal mantle temperature (1300°C) and passive mantle upwelling at the early stages of seafloor spreading. The crustal thickness, width of extended continental crust, and predicted temperature conditions all indicate a narrow rift mode of extension. On the basis of upper and lower crust stretching factors, an excess of lower crust was found in the extended continental crust. Total extension along transect 5W is estimated to be ∼35 km. Following crustal extension, new oceanic crust ∼6.4-km-thick was formed at a rate of ∼48 mm a−1 to accommodate plate separation.
Description:
This work was supported by the National Science Foundation
MARGINS program, grant OCE-0112152.
Keywords:
Rifting
;
Seismic
;
Wide-angle
;
Refractions
Repository Name:
Woods Hole Open Access Server
Type:
Article
Format:
application/pdf
Format:
text/plain
Format:
image/jpeg
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