Evidence for detrital remanent magnetization carried by hematite in Devonian red beds from Spitsbergen; palaeomagnetic implications

Abstract

Palaeomagnetic investigation of the Devonian red bed succession of Central Spitsbergen, the Wood Bay Formation, uncovered stable magnetic directions associated with blocking temperatures above 600°C. Rock magnetic properties are characterized by features commonly found in hematite-bearing red sandstones. The scattered directional distribution of stable magnetic components show large, non-systematic spatial variations hardly compatible with magnetic overprinting processes. Petrographic observations (Friend), suggest a detrital origin of the hematite granules present, probably derived from a lateritic source area. A depositional origin of magnetizations carried by hematite is also inferred from almost coinciding azimuthal distributions of remanent directions and maximum axis of susceptibility ellipsoids. Effects of the depositional environment upon the acquisition of DRM carried by hematite is discussed. Subjective pattern recognition of directional distributions from sampling areas on both sides of the Dicksonfjorden, enables a tentative stratigraphic correlation reflecting the presence of pre-Middle Carboniferous faulting downthrowing to the east. A clockwise post-Devonian rotation of the Central Spitsbergen (uncertain magnitude) is inferred from an estimate of the Devonian palaeomagnetic meridian.