Open AccessThe Palaeomagnetism of the Umkondo Lavas, Eastern Southern Rhodesia
Author(s) -
McElhinny M. W.
Publication year - 1966
Publication title -
geophysical journal of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0016-8009
DOI - 10.1111/j.1365-246x.1966.tb03065.x
Subject(s) - paleomagnetism , geology , earth's magnetic field , secular variation , dispersion (optics) , geomagnetic pole , demagnetizing field , geophysics , seismology , magnetization , geochemistry , magnetic field , physics , quantum mechanics , optics
Summary The mean direction of magnetization of samples collected from nine sites in the Umkondo lavas shows no significant difference from that of the Umkondo dolerites after demagnetization in alternating magnetic fields. This supports the contention of geologists that the dolerites are the intrusive phase of the lavas. The lavas exhibit considerably greater dispersion than the dolerites and it seems possible that the sampling of the latter may have been insufficient to average out secular variation. The combined data for the lavas and the dolerites gives an estimate of the angular dispersion of the geomagnetic field in Umkondo times which is in good agreement with that calculated for the present field.