Mantle flow and melting underneath oblique and ultraslow mid-ocean ridges
Montesi, Laurent G. J.
Behn, Mark D.
MetadataShow full item record
Mid-ocean ridge morphology correlates strongly with spreading rate. As the spreading rate decreases, conductive cooling becomes more important in controlling ridge thermal structure and the axial lithosphere thickens. At ultraslow spreading rates, the ridge axis becomes sufficiently cold that peridotite blocks are emplaced directly at the seafloor and volcanism is limited to localized volcanic centers widely spaced along the ridge axis. Some slow-spreading ridges adopt an ultraslow morphology when their axis is oblique to the spreading direction. We present an analytical solution for mantle flow beneath an oblique ridge and demonstrate that the thermal structure and crustal thickness are controlled by the effective spreading rate (product of the plate separation velocity and the cosine of obliquity). A global compilation of oblique ridges reveals that ultraslow morphology corresponds to effective half rates less than 6.5 mm/yr, resulting in lithosphere that is thicker than ~30 km. We conclude that the transition from slow to ultraslow spreading is not related to a change of melt productivity but rather in the efficiency of vertical melt extraction.
Author 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 Geophysical Research Letters 34 (2007): L24307, doi:10.1029/2007GL031067.
Showing items related by title, author, creator and subject.
Interactions between mantle plumes and mid-ocean ridges : constraints from geophysics, geochemistry, and geodynamical modeling Georgen, Jennifer E. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2001-09)This thesis studies interactions between mid-ocean ridges and mantle plumes using geophysics, geochemistry, and geodynamical modeling. Chapter 1 investigates the effects of the Marion and Bouvet hotspots on the ultra-slow ...
Magde, Laura S. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1997-03)The formation of new oceanic crust is the result of a complex geodynamic system in which mantle rises beneath spreading centers and undergoes decompression melting. The melt segregates from the matrix and is focused to ...
Ito, Garrett T.; Lin, Jian; Graham, David W. (American Geophysical Union, 2003-11-20)Hot spot–mid-ocean ridge interactions cause many of the largest structural and chemical anomalies in Earth's ocean basins. Correlated geophysical and geochemical anomalies are widely explained by mantle plumes that deliver ...