PRELIMINARY-RESULTS AND RELIABILITY OF PALEOINTENSITY STUDIES ON HISTORICAL AND C-14 DATED HAWAIIAN LAVAS

Palaeointensity determinations, using Coe's version of the Thellier method, for 7 flows on Hawaii are used to illustrate some of the problems in palaeointensity determinations by this method. It is shown that the linearity of NRM-TRM is not an adequate criterion for acceptance, but that it is very powerful when combined with the PTRM test. Examples are given of the effect of chemical changes during heating, viscous remanence and the use of low field susceptibility measurements. The importance of multiple determinations from different samples from the same site is also demonstrated. The within site dispersion is some 10% although it is hoped to reduce this to 3%.