Laboratory Stability Tests Applied to Devonian Lavas from Scotland

• Published in: Geophysical Journal International
• Main Author: Embleton, B. J. J.
• Format: Text
• Language: English
• Published: Oxford University Press 1968
• Subjects: Articles; North Pole
• Online Access: http://gji.oxfordjournals.org/cgi/content/short/16/3/239; https://doi.org/10.1111/j.1365-246X.1968.tb00220.x

The work was carried out primarily to check the validity of the Devonian geomagnetic field axis as determined by <cross-ref type="bib" refid="bib16">Stubbs (1958)</cross-ref> from measurements on uncleaned igneous samples. For this new survey, samples of six lava flows were collected from the Lorne Plateau (west Scotland) and ten flows were sampled from the Stonehaven-Montrose area and Tayside (east Scotland). Directions of magnetization were measured after treatment in successively applied a.c. magnetic fields up to a peak value of about 500 oersteds. Effects of heat treatment, up to 600 °C, on directions of magnetization are compared with the results of a.c. demagnetization. It was found that ten flows contained stable components of magnetization, the directions of which lay approximately along the geomagnetic field axis as found by Stubbs. A Devonian north pole position was thus computed as 121° E, 1° N. By consideration of subsequent geological events in connection with their possible effects on the primary magnetization and together with comparison of data from east and west Scotland, it is concluded that the stable magnetic remanence is primary and therefore Devonian in age.