The paleomagnetism of the permian red beds of Southwest Tanganyika

Abstract

Samples have been collected from twelve sites in red horizons of lower Permian (Ecca) age in southwest Tanganyika. Two directions of magnetization are observed, one steeply inclined with north-seeking poles down and the other with south-seeking poles down in the direction of the earth's present magnetic field. Specimens from all the sites were subjected to both alternating-field and thermal demagnetization. These laboratory studies show that the component which is north-seeking down with steep inclination is the stable direction of magnetization. It is suggested that the component aligned along the earth's present field is due to the growth of hematite (CRM) in this field. After treatment at temperatures of 300°C, specimens from nine of the twelve sites gave well-grouped directions of magnetization. On the assumption of a geocentric axial dipole field, the mean pole position is at 38.2°S, 64.9°E (A95 = 16°). This pole position places southern and eastern Africa in temperate or cold-temperate climatic zones, which is in accord with the available paleoclimatic evidence. The polarity (reversed) of the Ecca of southwest Tanganyika is in accord with all other Permian rocks that have previously been studied.