Ediacarian fauna in the ancient strata of the Polar Urals

• Main Author: Leonid Fedorovich SHADRIN
• Format: Article
• Language: deu
• Published: Ural State Mining University 2019-06-01
• Series: Izvestiâ Uralʹskogo Gosudarstvennogo Gornogo Universiteta
• Subjects: Polar Urals; Precambrian; Ordovician; lilac quartzitic sandstones; Minisey and Manitanyrd formations; greenschist facies; Ediacarian fauna; stratigraphy; metamorphism.
• Online Access: http://www.iuggu.ru/en/2-19-4
• ISSN: 2307-2091; 2500-2414

The relevance of the work. The materials for the Third Interdepartmental Ural Stratigraphic Meeting noted that stratification of the pre-Paleozoic strata of the Urals and the separation of individual blocks is difficult due to the impossibility of using the biostratigraphic method with the same reliability as for the Paleozoic, as well as the absence of other objective criteria for stratigraphic stratification and correlation. And only units of the Upper Proterozoic (Vendian) are characterized by the corresponding complexes of stromatolites, oncolites, katagraphies, acritarch and microphytolites. The purpose of the work. During geological surveys of the 1960s in the Polar Urals, fossil finds were rare, and stratigraphic stratification of mappable strata often led to certain errors and misunderstandings when linking the boundaries and ages of the logged stratigraphic units at the junction of geological maps compiled by neighboring survey units. The question of the age of the purple quartzitic sandstones of the Minisey and Manitanyrd formations (seemingly devoid of organic remains), was not finally resolved. Results. The data presented in the paper about the discovery of an ancient fossil in the lilac quartzite sandstone of the Manitanyrd formation, similar in structure to the sea feathers that lived in the shallow sea environment during the era of the Vendian sedimentation, make it possible to carry out repeated gathering of palaeontological remnants in deposits of the Minisey and Manitanyrd formations. At present, the minisey and manitanyrd quartzitic sandstones date from the Ordovician, but, unlike Ordovician deposits, have a higher degree of metamorphism and are not yet paleontologically characterized. Despite the high degree of metamorphism, the Vendian fauna, according to M. A. Fedonkin (Priroda magazine, 1989), has been preserved due to several factors; he highlights conditions of giant sea shallows, which served as traps for living organisms during constant ebbs. The abundance of the benthic inhabitants and the high mobility of water contributed to the rapid burial of organic matter, especially during large storms. Conclusion. The discovery of the imprint of the Ediacian fauna of the quartzitic sandstones of the Manitanyrd formation in the region of the Paipudyn ridge in the Polar Urals gives hope for new finds, which will allow these ancient strata to acquire true geological age and exclude them from the Paleozoic formations.