Permo-Carboniferous (Kiaman) palaeointensity results from the western Bohemian Massif, Germany

Abstract

Thellier palaeointensity analyses were carried out on samples from three quartz porphyry intrusions located within the western part of the Bohemian Massif close to the German-Czech Republic border. These intrusives have been dated at 280-275 Ma, which places them in the main part of the Permo-Carboniferous (Kiaman) Reversed Superchron (P-CRS). This age is consistent with the mean characteristic remanence direction calculated at D/I = 204°/ - 1°, giving a VGP at 36°N, 341°E. Palaeointensity values range from 6.6 μT to 22.1 μT, with a mean value of 12.0±1.3 μT, which has a corresponding VDM value of (3.0±1.2) × 1022 A m2. This suggests that the geomagnetic field strength recorded by the quartz porphyries is only 37 per cent of the current value, supporting recent studies that report a field strength of between 25 and 40 per cent of the present-day value during the P-CRS.