Publication Date:
2019-07-16
Description:
Ultraslow spreadingmid-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.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
