Magnetization and suitability for paleomagnetic field intensity measurements of selected samples from sites 332, 334, and 335 of Leg 37 DSDP

Abstract

The magnetic properties of 31 small samples from sites 332, 334, and 335 of Leg 37 DSDP were measured, and attempts were made to determine paleomagnetic field intensity. Values of paleointensity of 0.5 and 0.7 times the present field were obtained using one sample from site 332 and one from Site 335 respectively. All of the remaining samples proved unsuitable for paleointensity determinations owing to alteration on heating. This alteration is of two types: (1) destruction of maghemite, which reduces the magnetization of the samples, and (2) a process that markedly increases their thermal and saturation remanences and which may involve precipitation of new small magnetic grains out of glass. A 19 m thick layer at a depth of about 600 m in hole 332B, which appears to be a single unit on the basis of visual examination and chemical analysis of samples, contains a magnetic polarity transition. This may be due to a field reversal, or a partial reversal, while the unit was being implaced. Only samples from site 335 have a magnetization that can account for the surface anomaly by the remanence of the layers drilled.