A geomagnetic event recorded in loess deposits of the Tönchesberg (Germany): identification of the Blake magnetic polarity episode

Abstract

High-resolution palaeomagnetic studies on a collection of nearly 350 specimens, taken from a 1.30 m thick section of an Upper Pleistocene loess profile from the Tönchesberg (Germany), are described. The Blake magnetic polarity episode is recorded in a layer above the partly eroded palaeosol of the Eemian interglacial. It is identified by its stratigraphic position and thermoluminescence data (≈90.0 - 110.0 kyr: Zöller, Conard & Hahn 1991; Frechen 1991, 1992). Magnetite and haematite contribute to the natural remanent magnetization (NRM). Directional behaviour during thermal and alternating-field cleaning suggests that magnetite carries a primary, (post-)depositional remanent magnetization (pDRM) and haematite a secondary, chemical remanent magnetization (CRM) of early diagenetic origin.