The Palaeomagnetism of some of the Hawaiian Islands

Abstract

Palaeomagnetic directions of igneous rocks from five of the main Hawaiian islands are analysed. After partial demagnetization and the climination of random sites, the directions are considered to be stable and isotropic and therefore are reliable indicators of the geomagnetic field in Hawaii during the last 5 million years. Both normal and reversed directions are found, which appear useful for stratigraphical correlation. The mean direction (357°+ 30°) is close to that of the axial dipole field in Hawaii. This is consistent with palaeomagnetic data from other rocks of the same age and suggests that there has been no rotation of the Hawaiian islands since their formation. The scatter of site directions about the mean direction allows an estimate to be made of the maximum magnitude of secular variation. This suggests that secular variation has not been abnormal in Hawaii when considered over the last 5 million years, although more detailed sampling is required to determine the detailed behaviour of secular changes. Copyright © 1965, Wiley Blackwell. All rights reserved