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    Axial high topography and partial melt in the crust and mantle beneath the western Galapagos Spreading Center

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    2008GC002100.pdf (1.647Mb)
    Date
    2008-12-04
    Author
    Blacic, Tanya M.  Concept link
    Ito, Garrett T.  Concept link
    Shah, Anjana K.  Concept link
    Canales, J. Pablo  Concept link
    Lin, Jian  Concept link
    Metadata
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    Citable URI
    https://hdl.handle.net/1912/3283
    As published
    https://doi.org/10.1029/2008GC002100
    DOI
    10.1029/2008GC002100
    Keyword
     Axial high; Galapagos Spreading Center; Partial melt; Lithospheric flexure 
    Abstract
    The hot spot-influenced western Galápagos Spreading Center (GSC) has an axial topographic high that reaches heights of ∼700 m relative to seafloor depth ∼25 km from the axis. We investigate the cause of the unusual size of the axial high using a model that determines the flexural response to loads resulting from the thermal and magmatic structure of the lithosphere. The thermal structure simulated is appropriate for large amounts of cooling by hydrothermal circulation, which tends to minimize the amount of partial melt needed to explain the axial topography. Nonetheless, results reveal that the large axial high near 92°W requires that either the crust below the magma lens contains >35% partial melt or that 20% melt is present in the lower crust and at least 3% in the mantle within a narrow column (<∼10 km wide) extending to depths of 45–65 km. Because melt fractions >35% in the crust are considered unreasonable, it is likely that much of the axial high region of the GSC is underlain by a narrow region of partially molten mantle of widths approaching those imaged seismically beneath the East Pacific Rise. A narrow zone of mantle upwelling and melting, driven largely by melt buoyancy, is a plausible explanation.
    Description
    Author Posting. © American Geophysical Union, 2008. 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 9 (2008): Q12005, doi:10.1029/2008GC002100.
    Collections
    • Geology and Geophysics (G&G)
    Suggested Citation
    Geochemistry Geophysics Geosystems 9 (2008): Q12005
     

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