Abstract
A considerable quantity of petromagnetic and palaeomagnetic measurements in the field has allowed us to obtain reliable palaeomagnetic results for such difficult and complex objects as ophiolites. Eifelian baked sediments, diabases (dyke contacts) and gabbros, and Tremadocian baked sediments were studied. Continuous thermocleaning, conglomerate and fold tests were applied. The palaeointensity was investigated by means of several palaeomagnetic methods: Wilson-Burakov, van Zijl-Shaw and Bagina-Petrova. The mean intensities of the geomagnetic fields are 7 and 16.5 μT, with mean palaeomagnetic pole positions of 9°N, 134°E and 6°S, 83°E, respectively. These data demonstrate that southern Urals (Mugodgary) was located near the northern margin of the East European plate during Ordovician-Devonian time. The allochthonous crustal oceanic plate was thrust upon the edge of the plate and deformed as late as the Permian. Changes in the polarity of the geomagnetic field are recorded in the succession of sheeted dykes, a direct corroboration of the Vine-Mathews hypothesis.
Published Version
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