An Upper Carboniferous-Lower Permian (280 Ma) palaeomagnetic pole from the western margin of the Bohemian Massif

Autor: Heinrich Soffel, F. Harzer
Rok vydání: 1991
Předmět:
Zdroj: Geophysical Journal International. 105:547-551
ISSN: 1365-246X
0956-540X
Popis: SUMMARY In the area of the drill site of the German Continental Deep Drilling Project KTJ3 on the western margin of the Bohemian Massif 15 sites of Uppermost Carboniferous to Lowermost Permian rocks (quartz porphyries, granites and a siltstone, geographic mean coordinates: 12"E, 49.8"N) have been studied in order to obtain a reliable pole position for this time interval. The investigated rocks are syngenetic or only slightly younger than the youngest granites of the Fichtelgebirge for which a K/Ar and Rb/Sr age of 280 Ma has been determined by Besang ef al. (1976). While four sites (quartz porphyries) showed too weak intensities of the natural remanent magnetization NRM, the results of two sites with otherwise good rock magnetic properties had to be discarded because of uncertain tectonic position in a shear zone. The remaining nine sites have all reversed polarity as expected for a remanence age within the reversed Kiaman interval and a mean pole position at 165.9"E, 42.3"N with N = 9, R = 8.8776, A,, = 6.4". This is in good agreement with the mean Upper Carboniferous-Lower Permian European pole position of Stable Europe according to Irving & Irving (1982) and of the Bohemian Massif (Krs 1968). Rock magnetic investigations revealed that the ChRM of the siltstone is due to primary magnetite, while the mostly single-component characteristic remanent magnetization ChRM of the magmatic rocks is carried by primary magnetite and by primary haematite produced by syngenetic high-temperature oxidation of primary magnetite.
Databáze: OpenAIRE
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