Results of Paleomagnetic Study of the Neoproterozoic Katav Formation (Southern Urals)

The Neoproterozoic Katav Formation, which is a part of the Ural stratotype section, was considered to be remagnetized in the Late Paleozoic for many years. If the primary magnetization of the rocks is proven, the magnetostratigraphic record found in the Katav Formation may become a good paleomagnetic benchmark in the Neoproterozoic history of the Earth and serve as a source of information about deep processes in the Earth and their evolution. In this work, the arguments in favor of the primacy of the high-temperature characteristic component of magnetization of the Neoproterozoic Katav Formation rocks, previously put forward by V.E. Pavlov and I. Galle, were verified and confirmed on more extensive and detailed material. New paleomagnetic data have been obtained for two sections of the Katav Formation in the Southern Urals near the town of Yuryuzan and the village of Galiakberovo, as well as the overlying Inzer Formation near the village of Galiakberovo. A detailed magnetostratigraphic section of the Katav Formation for the Yuryuzan section is presented. The analysis of the upper part of the section shows 39 polarity intervals within the 74.6 m thick strata. The new data confirmed the existence of a trend of displacement of paleomagnetic directions from bottom to top along the studied sections of the Katav Formation, directed towards the paleomagnetic direction of the overlying Inzer Formation. The total value of the displacement in the Katav Formation is consistent in sections located at a distance from each other, located in areas with slightly different geological history. A significant difference in the direction of the characteristic component of magnetization in the Katav Formation from the corresponding directions in the Inzer Formation was confirmed. Generalization of new and previously obtained data gives grounds to consider the primary characteristic component of magnetization of the Katav Formation deposits, previously considered to be remagnetized. The frequency estimates of the geomagnetic reversals revealed by the new data in the upper part of the Yuryuzan section using the results of our previously performed cyclostratigraphic analysis are 11–12 reversals per million years. Thus, the existence of another interval of geomagnetic field hyperactivity in the Neoproterozoic is confirmed.