Late Paleozoic Remagnetization on the Western Slope of the Southern Urals: Age and Geotectonic Implications

Abstract

The paper presents the results of paleomagnetic studies on numerous intrusive bodies of the Bashkirian megazone – a major tectonic zone of the Southern Urals. More than 70 intrusions in different parts of the Bashkirian megazone (in the northern, central and southern part of the structure) were sampled. The studied intrusions have Riphean age, however, like a significant part of the rocks of the Southern Urals, these intrusive bodies were remagnetized during the Late Paleozoic collision within the Urals fold belt. This article will discuss the secondary Late Paleozoic component of natural remanence magnetization. According to the paleomagnetic data obtained, the secondary Late Paleozoic component in most of the Bashkirian megazone is post-fold, i.e. formed after the completion of the main phase of fold deformations in the Southern Urals. A comparison of paleomagnetic directions obtained from intrusions in different parts of the Bashkirian megazone showed that there did not significant movements of individual parts of the Bashkirian megazone relative to each other after the formation of the Late Paleozoic component. The Late Paleozoic remanence component yielded a paleomagnetic pole of Plong = 171.6°, Plat = 39.9°, α95 = 5.9°, N = 6 from 6 areas (38 sites) in the Bashkirian megazone. The obtained pole is statistically indistinguishable from the mean of 15 poles for Stable Europe with ages of 280–301 million years. Thus, the secondary Late Paleozoic component in the Bashkirian megazone formed approximately 280–301 million years ago, after which the Bashkirian megazone did not experience any relative motions with respect to the East European craton.