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Partial melting beneath a Mid‐Atlantic Ridge Segment detected by teleseismic PKP delays
Author(s) -
Forsyth Donald W.
Publication year - 1996
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 - 10.1029/96gl00379
Subject(s) - geology , ridge , mid atlantic ridge , seismology , upwelling , crust , mid ocean ridge , mantle (geology) , partial melting , dike , seismometer , anomaly (physics) , oceanic crust , petrology , geophysics , tectonics , subduction , paleontology , oceanography , physics , condensed matter physics
An array of six ocean‐bottom seismometers deployed across a segment of the Mid‐Atlantic Ridge recorded PKP phases from four teleseismic earthquakes. After correcting for normal moveout and elevation differences, there is a systematic variation of anomalous travel time with distance from the ridge. Stations at the ridge‐axis are slowest. The average anomaly at a station 16 km from the axis is −0.36 s relative to the axial stations. Most of this anomaly is probably caused by the presence of partial melt beneath the ridge axis, perhaps concentrated primarily in the upper 30 km of the mantle. The rapid variation across‐axis suggests that the melt is either associated with a narrow zone of buoyant upwelling or a region of veins and dikes forming a narrow transport zone connecting a deep melt‐production region to the crust.