Palæomagnetism in Some Norwegian Sparagmites and the Late Pre-Cambrian Ice Age

Abstract

PRE-PLEISTOCENE glacial deposits have been claimed from many ages and latitudes. Palæomagnetic studies of the Permian tillites in Australia¹ suggest that they were near the geomagnetic, and probably also the geographical pole. The late Pre-Cambrian (‘Eo-Cambrian’, Varangian, Sinian, etc.) tillites are of special interest for several reasons: (1) Widespread occurrences have been claimed² and many are well established, for example, in Australia, China, Greenland, Norway and Spitsbergen. (2) Their stratigraphical position suggests that all are referable to one major glacial period (with, however, interglacial or interstadial intervals). It is therefore a key horizon in international correlation below the fossiliferous Lower Cambrian. (3) The boulder beds usually suggest deposition from floating ice in an apparently continuous marine succession. (4) Palæomagnetic determinations of Palæozoic and late Pre-Cambrian rocks from Britain and America³ give pole positions which suggest that the Norwegian and Arctic tillites were deposited not far from the geomagnetic equator. The successions in which they occur show facies consistent with a near equatorial position.