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Science 22 January 1993:
Vol. 259. no. 5094, pp. 499 - 503
DOI: 10.1126/science.259.5094.499
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Articles

Seismic Structure of the Southern East Pacific Rise

R. S. Detrick 1, A. J. Harding 2, G. M. Kent 1, J. A. Orcutt 2, J. C. Mutter 3, and P. Buhl 3

1 Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543
2 Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093
3 Lamont-Doherty Geological Observatory, Columbia University, Palisades, NY 10964

Seismic data from the ultrafast-spreading (150 to 162 millimeters per year) southern East Pacific Rise show that the rise axis is underlain by a thin (less than 200 meters thick) extrusive volcanic layer (seismic layer 2A) that thickens rapidly off axis. Also beneath the rise axis is a narrow (less than 1 kilometer wide) melt sill that is in some places less than 1000 meters below the sea floor. The small dimensions of this molten body indicate that magma chamber size does not depend strongly on spreading rate as predicted by many ridge-crest thermal models. However, the shallow depth of this body is consistent with an inverse correlation between magma chamber depth and spreading rate. These observations indicate that the paradigm of ridge crest magma chambers as small, sill-like, midcrustal bodies is applicable to a wide range of intermediate- and fast-spreading ridges.

Submitted on August 31, 1992
Accepted on November 20, 1992


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Drilling to Gabbro in Intact Ocean Crust.
D. S. Wilson, D. A. H. Teagle, J. C. Alt, N. R. Banerjee, S. Umino, S. Miyashita, G. D. Acton, R. Anma, S. R. Barr, A. Belghoul, et al. (2006)
Science 312, 1016-1020
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Off-Axis Crustal Thickness Across and Along the East Pacific Rise Within the MELT Area.
J. P. Canales, R. S. Detrick, S. Bazin, A. J. Harding, and J. A. Orcutt (1998)
Science 280, 1218-1221
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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)
Science 280, 1221-1224
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Magmatic segmentation of mid-ocean ridges: a review.
R. Batiza (1996)
Geological Society, London, Special Publications 118, 103-130
   Abstract »    PDF »
The response of ridge-crest hydrothermal systems to segmented, episodic magma supply.
R. M. Haymon (1996)
Geological Society, London, Special Publications 118, 157-168
   Abstract »    PDF »
The Effect of Magmatic Activity on Hydrothermal Venting Along the Superfast-Spreading East Pacific Rise.
T. Urabe, T. Urabe, E. T. Baker, J. Ishibashi, R. A. Feely, K. Marumo, G. J. Massoth, A. Maruyama, K. Shitashima, K. Okamura, et al. (1995)
Science 269, 1092-1095
   Abstract »    PDF »
Seismic Images of Active Magma Systems Beneath the East Pacific Rise Between 17{degrees}05' and 17{degrees}35'S.
J. C. Mutter, J. C. Mutter, S. M. Carbotte, W. Su, L. Xu, P. Buhl, R. S. Detrick, G. M. Kent, J. A. Orcutt, and A. J. Harding (1995)
Science 268, 391-395
   Abstract »    PDF »


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