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dc.contributor.authorBaines, A. Graham  Concept link
dc.contributor.authorCheadle, Michael J.  Concept link
dc.contributor.authorDick, Henry J. B.  Concept link
dc.contributor.authorScheirer, Allegra Hosford  Concept link
dc.contributor.authorJohn, Barbara E.  Concept link
dc.contributor.authorKusznir, Nick J.  Concept link
dc.contributor.authorMatsumoto, Takeshi  Concept link
dc.date.accessioned2007-09-06T19:04:04Z
dc.date.available2007-09-06T19:04:04Z
dc.date.issued2007-06-23
dc.identifier.citationGeochemistry Geophysics Geosystems 8 (2007): Q06022en
dc.identifier.urihttps://hdl.handle.net/1912/1790
dc.descriptionAuthor Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 8 (2007): Q06022, doi:10.1029/2006GC001559.en
dc.description.abstractFrom 55°45′E to 58°45′E and from 60°30′E to 62°00′E, the ultraslow-spreading Southwest Indian Ridge (SWIR) consists of magmatic spreading segments separated by oblique amagmatic spreading segments, transform faults, and nontransform discontinuities. Off-axis magnetic and multibeam bathymetric data permit investigation of the evolution of this part of the SWIR. Individual magmatic segments show varying magnitudes and directions of asymmetric spreading, which requires that the shape of the plate boundary has changed significantly over time. In particular, since 26 Ma the Atlantis II transform fault grew by 90 km to reach 199 km, while a 45-km-long transform fault at 56°30′E shrank to become an 11 km offset nontransform discontinuity. Conversely, an oblique amagmatic segment at the center of a first-order spreading segment shows little change in orientation with time. These changes are consistent with the clockwise rotation of two ~450-km-wide first-order spreading segments between the Gallieni and Melville transform faults (52–60°E) to become more orthogonal to spreading. We suggest that suborthogonal first-order spreading segments reflect a stable configuration for mid-ocean ridges that maximizes upwelling rates in the asthenospheric mantle and results in a hotter and weaker ridge-axis that can more easily accommodate seafloor spreading.en
dc.description.sponsorshipFunding for this work came from a JOI-Schlanger Fellowship to Baines and NSF grant 0352054 to Cheadle and John.en
dc.format.mimetypeapplication/pdf
dc.language.isoen_USen
dc.publisherAmerican Geophysical Unionen
dc.relation.urihttps://doi.org/10.1029/2006GC001559
dc.subjectSouthwest Indian Ridgeen
dc.subjectAtlantis II fracture zoneen
dc.subjectAsymmetric spreadingen
dc.subjectRidge segmentationen
dc.titleEvolution of the Southwest Indian Ridge from 55°45′E to 62°E : changes in plate-boundary geometry since 26 Maen
dc.typeArticleen
dc.identifier.doi10.1029/2006GC001559


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