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Seismic gap beneath Logachev Seamount: Indicator for melt focusing at an ultraslow mid‐ocean ridge?
Author(s) -
Schlindwein Vera,
Demuth Andrea,
Geissler Wolfram H.,
Jokat Wilfried
Publication year - 2013
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/grl.50329
Subject(s) - geology , seamount , lithosphere , magmatism , ridge , mid ocean ridge , seafloor spreading , crust , ridge push , seismology , mantle (geology) , volcano , geophysics , seismometer , oceanic crust , magma chamber , tectonics , magma , paleontology , subduction
Ultraslow spreading mid‐ocean ridges have a low magma budget and melt is distributed unevenly along the ridge axis. There is little or no basaltic crust between isolated magmatic centers. The processes that focus melts to segments of robust magmatism are not yet understood. During a seismic survey of the ultraslow spreading Knipovich Ridge in the Norwegian‐Greenland Sea with ocean bottom seismometers, we discovered a seismic gap in the upper mantle beneath Logachev Seamount, where micro‐earthquakes clearly delineate a shallowing of the maximum depth of faulting. A topography of the lithosphere that allows melts to travel laterally along its base and rise in areas of thin lithosphere has been proposed as a possible mechanism to explain the focusing of melts at volcanic centers, but has never been confirmed observationally. Our results are the first geophysical evidence for an along‐axis variation of the lithospheric thickness at an ultraslow spreading ridge.