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Science 22 May 1998:
Vol. 280. no. 5367, pp. 1218 - 1221
DOI: 10.1126/science.280.5367.1218
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Reports

Off-Axis Crustal Thickness Across and Along the East Pacific Rise Within the MELT Area

J. Pablo Canales, * Robert S. Detrick, Sara Bazin, Alistair J. Harding, John A. Orcutt

Wide-angle seismic data along the Mantle Electromagnetic and Tomography (MELT) arrays show that the thickness of 0.5- to 1.5-million-year-old crust of the Nazca Plate is not resolvably different from that of the Pacific Plate, despite an asymmetry in depth and gravity across this portion of the East Pacific Rise. Crustal thickness on similarly aged crust on the Nazca plate near a magmatically robust part of the East Pacific Rise at 17°15'S is slightly thinner (5.1 to 5.7 kilometers) than at the 15°55'S overlapping spreading center (5.8 to 6.3 kilometers). This small north-south off-axis crustal thickness difference may reflect along-axis temporal variations in magma supply, whereas the across-axis asymmetry in depth and gravity must be caused by density variations in the underlying mantle.

J. P. Canales and R. S. Detrick, Department of Geology and Geophysics, Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, MA 02543, USA.
S. Bazin, A. J. Harding, J. A. Orcutt, Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093-0225, USA.
*   To whom correspondence should be addressed. E-mail: juan{at}sienna.whoi.edu

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
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Imaging the Deep Seismic Structure Beneath a Mid-Ocean Ridge: The MELT Experiment.
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Shipboard Geophysical Indications of Asymmetry and Melt Production Beneath the East Pacific Rise Near the MELT Experiment.
D. S. Scheirer, D. W. Forsyth, M. Cormier, and K. C. Macdonald (1998)
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