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The influence of ridge geometry at the ultraslow-spreading Southwest Indian Ridge (9⁰-25⁰E) : basalt composition sensitivity to variations in source and process

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dc.contributor.advisor Henry J.B. Dick. en_US
dc.contributor.author Standish, Jared Jeffrey en_US
dc.contributor.other Woods Hole Oceanographic Institution. en_US
dc.date.accessioned 2006-11-07T16:52:37Z
dc.date.available 2006-11-07T16:52:37Z
dc.date.copyright 2006 en_US
dc.date.issued 2006 en_US
dc.identifier.uri http://hdl.handle.net/1721.1/34665
dc.description Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2006. en_US
dc.description Includes bibliographical references. en_US
dc.description.abstract Between 90-25° E on the ultraslow-spreading Southwest Indian Ridge lie two sharply contrasting supersegments. One 630 km long supersegment erupts N-MORB that is progressively enriched in incompatible element concentrations from east to west. The second 400 km long supersegment contains three separate volcanic centers erupting E-MORB and connected by long amagmatic accretionary segments, where mantle is emplaced directly to the seafloor with only scattered N-MORB and E-MORB erupted. Rather than a major break in mantle composition at the discontinuity between the supersegments, this sharp contrast in geometry, physiography, and chemistry reflects "source" versus "process" dominated generation of basalt. Robust along-axis correlation of ridge characteristics (i.e. morphology, upwelling rate, lithospheric thickness), basalt chemistry, and crustal thickness (estimated from gravity) provides a unique opportunity to compare the influence of spreading geometry and rate on MORB generation. What had not been well established until now is the importance of melting processes rather than source at spreading rates < 20 mm/yr. en_US
dc.description.abstract (cont.) Along the orthogonally spreading supersegment (14 mm/yr) moderate degrees of partial melting effectively sample the bulk mantle source, while on the obliquely spreading supersegment (7-14 mm/yr) suppression of mantle melting to low degrees means that the bulk source is not uniformly sampled, and thus "process" rather than "source" dominates melt chemistry. en_US
dc.description.statementofresponsibility by Jared Jeffrey Standish. en_US
dc.format.extent 286 p. en_US
dc.format.extent 71489623 bytes
dc.format.extent 71488786 bytes
dc.format.mimetype application/pdf
dc.format.mimetype application/pdf
dc.language.iso eng en_US
dc.publisher Massachusetts Institute of Technology en_US
dc.rights M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. en_US
dc.rights.uri http://dspace.mit.edu/handle/1721.1/7582
dc.subject Joint Program in Oceanography. en_US
dc.subject Earth, Atmospheric, and Planetary Sciences. en_US
dc.subject Woods Hole Oceanographic Institution. en_US
dc.subject.lcsh Geochemistry en_US
dc.title The influence of ridge geometry at the ultraslow-spreading Southwest Indian Ridge (9⁰-25⁰E) : basalt composition sensitivity to variations in source and process en_US
dc.type Thesis en_US
dc.description.degree Ph.D. en_US
dc.contributor.department Joint Program in Oceanography. en_US
dc.contributor.department Massachusetts Institute of Technology. Dept. of Earth, Atmospheric, and Planetary Sciences. en_US
dc.contributor.department Woods Hole Oceanographic Institution. en_US
dc.identifier.oclc 71197031 en_US


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