Magnetic field hyperactivity during the early Neoproterozoic: A paleomagnetic and cyclostratigraphic study of the Katav Formation,southern Urals,Russia |
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| Institution: | 1. Institute of Geology — Subdivision of the Ufa Federal Research Centre of the Russian Academy of Sciences (IG UFRC RAS), Russia;2. Geological Institute, Russian Academy of Sciences, Moscow, Russia;3. Department of Earth and Planetary Sciences, Neil Opdyke Paleomagnetic Laboratory, University of Florida, Gainesville, FL 32611, United States |
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| Abstract: | We present a detailed magnetostratigraphic and cyclostratigraphic profile through the Riphean (Tonian) Katav Formation in the southern Urals. The study confirms the primary nature of the magnetization in these rocks. The cyclostratigraphic study identified several orbital periods including the 405 ka long eccentricity. This allows us to quantify the reversal frequency in the Katav and our estimates range of 7–12 reversals per million years. Based on our study, we identify an interval of magnetic field reversal hyperactivity in the Neoproterozoic interval. Age estimates for the Katav are contentious and range somewhere between 800 Ma and 900 Ma based on carbonate Pb-Pb ages and stable isotope correlations. The paleomagnetic poles obtained in this study of the Katav (and overlying Inzer) Formation do not fit anywhere on the Baltica apparent polar wander path between 1100 Ma and 900 Ma. Furthermore, they lie 90° away from the 900 Ma segment of the path. We tentatively estimate their age to be closer to 800 Ma and perhaps confirm a previously hypothesized pulse of rapid true polar wander between 825 Ma and 790 Ma. |
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| Keywords: | Magnetostratigraphy Cyclostratigraphy Hyperactive reversal True polar wander Tonian |
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