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Alvin magnetic survey of zero‐age crust: CoAxial Segment Eruption, Juan de Fuca Ridge 1993
Author(s) -
Tivey Maurice A.,
Johnson H. Paul
Publication year - 1995
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 - 10.1029/94gl02081
Subject(s) - dike , geology , magnetic anomaly , lava , extrusive , crust , ridge , seismology , geophysics , magma , anomaly (physics) , volcano , petrology , paleontology , physics , condensed matter physics
Magnetic profiles obtained by deep submersible ALVIN across a newly erupted lava flow on the Juan de Fuca Ridge (JDFR) show strong magnetic anomaly fields (>20,000 nT) and high crustal magnetization (>50 A/m contrast) relative to the surrounding older lavas. These results are consistent with previous ideas that extrusive crust is initially highly magnetized. Within the high amplitude magnetic anomaly over the center of the flow, there is a clearly defined deep, “notch‐like” magnetic low. This notch may indicate thermal demagnetization associated with a subsurface feeder dike, weakly magnetized intrusives or altered extrusive rock. If the former mechanism is active, the notch should disappear with time as the dike cools.