Palaeomagnetism of Upper Jurassic limestones from Southern Germany

Abstract

Flat-bedded, shallow water, marine limestones interlayered with marls are well exposed in Franconia and Swabia, Southern Germany. The Upper Jurassic sediments sampled have been dated in detail palaeontologically, and cover the interval from middle Lower Oxfordian to middle Lower Kimmeridgian. Bed by bed sampling of sections at 11 localities throughout a thickness of more than 130 m yielded about 400 samples (1100 specimens) for palaeomagnetic analysis. The NRM intensities appear to correlate with the clay content and averaged 2 x 10^–7 Gauss.  Progressive alternating field demagnetization of each specimen was used to isolate the direction of the characteristic remanence, whose mean intensity averaged 5 x 10^–8 Gauss. Only normally magnetized rocks are found in the lower part of the section, but distinct zones of normal and reversed polarity are found in the upper part (middle Lower Kimmeridgian) in both regions of investigation. The polarity sequence is tentatively correlated with the ocean floor Mesozoic magnetic anomaly sequence. The data yield a reliable estimate of a Late Jurassic palaeomagnetic pole position for stable Europe.

          ARK: https://n2t.net/ark:/88439/y044102

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