Geologicheskii Vestnik

The paper presents the results of a paleomagnetic study of red-colored limestones of the Upper Riphean Katav Formation, as well as red-colored sandstones from the underlying and overlying Zilmerdak and Inzer Formations. If the primacy of the high-temperature component (HTC) of the Katav Formation magnetization, which was previously considered metachronous, is proved, this could become a good paleomagnetic reference point in the Neoproterozoic history of the Earth and would provide important information on the features of the behavior of the geomagnetic fi eld in the Late Precambrian. In total, more than 500 oriented samples from 4 sections were studied. Laboratory studies were carried out in accordance with the currently generally accepted methodology, including thermal demagnetization and component analysis of the selected directions of magnetization. In all sections, it was possible to identify bipolar HTC of magnetization, the fold and reversal tests for which are confi dently positive. The directions of magnetization in the Tolparovo and Karamaly sections are displaced approximately at 20° in declination relative to the directions in the Yuryuzan and Galyakberovo sections (as well as many other sections studied by the authors and other researchers). Perhaps this result is associated with tectonic movements. There is a regular shift in the mean direction of the HTC of magnetization upwards along the sections of Katav and Inzer Formations towards a decrease in inclination, which is a strong enough argument in favor of the primary magnetization of the Katav Formation rocks. In general, the results obtained confirm the point of view of V. Pavlov and I. Galle on the synchronism of Katav Formation limestones magnetization with its sedimentation time.

paleomagnetism, high temperature component of magnetization, Zijderveld diagram, Southern Urals, Upper Riphean, Katav Formation

• Cogné J.P. (2003) PaleoMac: A MacintoshTM application for treating paleomagnetic data and making plate reconstructions. Geochem. Geophys. Geosyst., 4(1), article 1007, doi:10.1029/2001GC000227.
• Enkin R.I. (1994) A computer program package for analysis and presentation of paleomagnetic data. Pacifi c Geoscience Centre. Geological Survey of Canada, 16 p.
• Komissarova R.A. (1970) Issledovanie drevnei namagnichennosti nekotorykh osadochnykh porod Yuzhnogo Urala v svyazi s problemoi metakhronnogo peremagnichivaniya. Dis. cand. fi z.-mat. nauk [Study of the ancient magnetization of some sedimentary rocks of the Southern Urals in connection with the problem of metachronous magnetization reversal. Cand. phys.-mat. sci. dis.]. Moscow, IFZ AN SSSR, 140 p. (In Russian).
• Kozlov V.I., Puchkov V.N., Krasnobaev A.A., Nekhorosheva A.G., Busharina S.V. (2011) Arshinian – new stratigraphic unit of Riphean in stratotypic sequences of the Southern Urals. Geologicheskii sbornik No. 9 IG UNC RAN [Geological collection No. 9 IG USC RAS] Ufa, DizainPoligrafServis Publ., 3-8. (In Russian).
• Pavlov V.E., Galle I. (2009) Katav limestones: a unique example of remagnetization or an ideal recorder of the Neoproterozoic geomagnetic fi eld? Fizika Zemli – Izvestiya. Physics of the Solid Earth, (1), 33-43. (In Russian).
• Puchkov V.N., Sergeeva N.D., Krasnobaev A.A. (2017) Stratigraphic scheme of the Riphean standard of the Southern Urals. Geologiya. Izvestiya Otdeleniya nauk o Zemle i prirodnykh resursov AN RB – Geology. Bulletin of the Department of Earth Sciences and Natural Resources of the Academy of Sciences of the Republic of Bashkortostan, (23), 3-26. (In Russian).
• Shipunov S.V. (1991) Paleomagnetism Katav Formation, Southern Urals. Fizika Zemli – Izvestiya. Physics of the Solid Earth, (5), 38-50. (In Russian).
• Shipunov S.V. (1993) Osnovy paleomagnitnogo analiza: Teoriya i praktika [Basics of paleomagnetic analysis: Theory and practice]. Moscow, Nauka Publ., 160 p. (proceedings GIN RAS, Issue 487) (In Russian).