Geologicheskii Vestnik

To test the assumption that an episode of magnetic eld “hyperactivity” existed near the Precambrian – Fanerozoic boundary, a repeated, more detailed, paleomagnetic sampling of the longest continuous section of the Ediacaran Zygan Formation studied previously in the Southern Urals, located along the new Makarovo – Kulgunino road, was performed. In general, paleomagnetic studies have conrmed and made it possible to substantially detail the results obtained earlier. The new data on the Zigan Formation validate the previously obtained paleopole. New results from a 74-m thick section of the red-rock Zigan Formation revealed more than 30 magnetic polarity reversals. Previous cyclostratigraphic analysis gave an estimate of 1.6 Ma for rock mass accumulation. The average reversal frequency is 18–20 R/Ma, and in some parts of the section, the frequency can reach 30 R/Ma or more. This reversal frequency is considered abnormally high, and the conclusion that there was a period of ‘hyperactivity’ of the magnetic eld at the end of the Ediacaran, 548.2 ± 7.6 Ma, can be considered as conrmed.

paleomagnetism, magnetostratigraphy, Southern Urals, Ediacaran, Zigan Formation

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