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The Moho as a magnetic boundaryMagnetism in the crust and the upper mantle and magnetic results indicating that the seismic Moho is a magnetic boundary are considered. Mantle derived rocks - peridotites from St. Pauls rocks, dunite xenoliths from the Kaupulehu flow, and peridotite, dunite, and eclogite xenoliths from Roberts Victor and San Carlos diatremes - are weakly magnetic with saturation magnetization values from 0.013 emu/gm to less than 0.001 emu/gm which is equivalent to 0.01 to 0.001 wt% Fe304. Literature on the minerals in mantle xenoliths shows that metals and primary Fe304 are absent, and that complex Cr, Mg, Al, and Fe spinels are dominant. These spinels are non-magnetic at mantle temperatures, and the crust/mantle boundary can be specified as a magnetic mineralogy discontinuity. The new magnetic results indicate that the seismic Moho is a magnetic boundary, the source of magnetization is in the crust, and the maximum Curie isotherm depends on magnetic mineralogy and is located at depths which vary with the regional geothermal gradient.
Document ID
19790061863
Document Type
Reprint (Version printed in journal)
Authors
Wasilewski, P. J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Thomas, H. H. (NASA Goddard Space Flight Center Greenbelt, Md., United States)
Mayhew, M. A. (BTS, Inc. Seabrook, Md., United States)
Date Acquired
August 9, 2013
Publication Date
July 1, 1979
Publication Information
Publication: Geophysical Research Letters
Volume: 6
Subject Category
GEOPHYSICS
Distribution Limits
Public
Copyright
Other