Axial high topography and partial melt in the crust and mantle beneath the western Galapagos Spreading Center
Blacic, Tanya M.
Ito, Garrett T.
Shah, Anjana K.
Canales, J. Pablo
MetadataShow full item record
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.
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.
Suggested CitationArticle: Blacic, Tanya M., Ito, Garrett T., Shah, Anjana K., Canales, J. Pablo, Lin, Jian, "Axial high topography and partial melt in the crust and mantle beneath the western Galapagos Spreading Center", Geochemistry Geophysics Geosystems 9 (2008): Q12005, DOI:10.1029/2008GC002100, https://hdl.handle.net/1912/3283
Showing items related by title, author, creator and subject.
Constructing the crust along the Galapagos Spreading Center 91.3°–95.5°W : correlation of seismic layer 2A with axial magma lens and topographic characteristics Blacic, Tanya M.; Ito, Garrett T.; Canales, J. Pablo; Detrick, Robert S.; Sinton, John M. (American Geophysical Union, 2004-10-21)Multichannel seismic reflection data are used to infer crustal accretion processes along the intermediate spreading Galapagos Spreading Center. East of 92.5°W, we image a magma lens beneath the ridge axis that is relatively ...
Morphology and segmentation of the western Galápagos Spreading Center, 90.5°–98°W : plume-ridge interaction at an intermediate spreading ridge Sinton, John M.; Detrick, Robert S.; Canales, J. Pablo; Ito, Garrett T.; Behn, Mark D. (American Geophysical Union, 2003-12-13)Complete multibeam bathymetric coverage of the western Galápagos Spreading Center (GSC) between 90.5°W and 98°W reveals the fine-scale morphology, segmentation and influence of the Galápagos hot spot on this intermediate ...
Faulting and volcanism in the axial valley of the slow-spreading center of the Mariana back arc basin from Wadatsumi side-scan sonar images Deschamps, Anne; Fujiwara, Toshiya; Asada, Miho; Montesi, Laurent G. J.; Gente, Pascal (American Geophysical Union, 2005-05-13)We analyzed in detail the geology of the median valley floor of the Mariana Basin slow-spreading ridge using sea surface geophysical data and a high-resolution deep-tow side-scan sonar survey over one spreading segment. ...