Magnetic properties of the Bay of Islands ophiolite suite and implications for the magnetization of oceanic crust

Journal of Geophysical Research B: Solid Earth
By:  and 

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Abstract

Rock magnetic properties, opaque mineralogy, and degree of metamorphism were determined for 101 unoriented samples from the North Arm and Blow-Me-Down massifs of the Bay of Islands ophiolite complex, Newfoundland. The weathered and metamorphosed extrusive basalt samples have a weak, secondary magnetization arising from oxidation and exsolution of ilmenite of unknown origin. The initial magnetization of the underlying sheeted dike complex appears to have been destroyed by hydrothermal alteration soon after formation. The magnetic intensity of the gabbroic samples increases as the degree of alteration increases, with the highly altered upper metagabbros having an average intensity of 3×10−3 emu/c3. Because magnetization of the metagabbro samples is related to nonpervasive, variable alteration, these crustal units are unlikely to make a significant contribution to lineated magnetic anomalies. A compilation of our results and other studies suggests a model in which oceanic crust magnetization results from an upper extrusive basalt source layer, roughly 600 m thick, with no contribution from a deeper source layer recognizable from these Bay of Islands data.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Magnetic properties of the Bay of Islands ophiolite suite and implications for the magnetization of oceanic crust
Series title Journal of Geophysical Research B: Solid Earth
DOI 10.1029/JB089iB05p03291
Volume 89
Issue 5
Year Published 1984
Language English
Publisher American Geophysical Union
Contributing office(s) Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center
Description 18 p.
First page 3291
Last page 3308
Country Canada
State Newfoundland
Other Geospatial Bay of Islands
Online Only (Y/N) N
Additional Online Files (Y/N) N