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Devonian dikes from north central Newfoundland: A radiometric‐paleomagnetic study
Author(s) -
Reynolds P. H.,
Murthy G. S.
Publication year - 1983
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/gl010i006p00432
Subject(s) - dike , geology , paleomagnetism , devonian , radiometric dating , earth's magnetic field , magnetite , seismology , paleontology , geochemistry , magnetic field , physics , quantum mechanics
40 Ar/ 39 Ar age spectra have been obtained for biotites and hornblendes representing a suite of diabase dikes from the northern part of Newfoundland’s Gander Zone. A primary apparent age of 375 ± 10 Ma is suggested, a value probably very close to the age of intrusion. A number of the age spectra are discordant; this perhaps results from a disturbing ‘event’ ∼180 Ma ago. Magnetic analysis of the dike swarm has yielded four paleopoles; three of these magnetizations appear to be carried by multi‐domain magnetite, the other by hematite. If the magnetite magnetizations are primary, they possibly reflect a period of aberrant geomagnetic field behaviour at about the time given above. On the other hand, if the hematite magnetization is primary, the data can be interpreted in terms of the displaced terrain model of Kent and Opdyke. However, our data imply that the relative southern displacement of Acadia in the Devonian may be smaller than these authors have suggested.