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Shipboard Geophysical Indications of Asymmetry and Melt Production Beneath the East Pacific Rise Near the MELT Experiment

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Science  22 May 1998:
Vol. 280, Issue 5367, pp. 1221-1224
DOI: 10.1126/science.280.5367.1221

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Abstract

Near the Mantle Electromagnetic and Tomography (MELT) Experiment, seamounts form and off-axis lava flows occur in a zone that extends farther to the west of the East Pacific Rise than to the east, indicating a broad, asymmetric region of melt production. More seamounts, slower subsidence, and less dense mantle on the western flank suggest transport of hotter mantle toward the axis from the west. Variations in axial ridge shape, axial magma chamber continuity, off-axis volcanism, and apparent mantle density indicate that upwelling is probably faster and more melt is produced beneath 17°15′S than beneath 15°55′S. Recent volcanism occurs above mantle with the lowest seismic velocities.

  • * To whom correspondence should be addressed. E-mail: scheirer{at}emma.geo.brown.edu

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