Strontium isotope stratigraphy: Possible applications for age estimation and global correlation of Late Permian carbonates of the Pechishchi type section, Volga River

Abstract

In the present paper the 87 Sr/ 86 Sr values have been analysed for the Upper Kazanian regional stratotype section-Pechishchi and accompanied sections of Lower Kazanian and also Lower Permian. The section Pechishchi is unique section formed within the Kazanian palaeosea. It is characterized by three Noinsky's cycles of evaporitization of Kazanian palaeosea. The analysis of received data on 87 Sr/ 86 Sr shows that the highest ratios, characteristic of the Asselian, average at 0.70832. In the Artinskian, the 87 Sr/ 86 Sr ratios decrease to 0.70774. In the Kazanian, the strontium ratio is much lower: 0.70769 in the Early Kazanian and 0.70740 in the Late Kazanian. The position of received local data on global evolution 87 Sr/ 86 Sr curve, in common, is satisfactory. The discrepancies between local and global data observed at some points can be explained by the following: local features of the Permian deposition in the eastern part of the Russian Plate (the evaporitic trend and considerable isolation from the ocean); and problems with the chronostratigraphic positioning of the 87 Sr/ 86 Sr Phanerozoic evolution curve and local 87 Sr/ 86 Sr curves within the Permian. Multiple determinations of strontium isotope ratios in the Permian carbonates and the isotope dating of key samples would allow the revision of the Permian stratigraphic record. Strontium isotope stratigraphy offers an up-to-date and technologically advanced approach to the stratification and correlation of Permian sedimentary sections on both regional and global scales.

Permian strontium isotope stratigraphy

“…The Early-Middle Permian downwards trend of the marine 87 Sr/ 86 Sr curve has been used to improve age constraints in multiple localities: for example, Japan (Miura et al 2004), Russia (Nurgalieva et al 2007), Spitsbergen (Ehrenberg (Burke et al 1982;Denison et al 1994;Morante 1996;Korte et al 2006;Kani et al 2008Kani et al , 2013Wignall et al 2009;Shen et al 2010;Tierney 2010;Liu et al 2013). These low values are the lowest recorded for the entire Palaeozoic and very close to the Phanerozoic minimum at the Middle-Late Jurassic transition (Jones et al 1994;McArthur et al 2012), and therefore an important chemostratigraphic marker.…”

Earth Science Frontier at Urban Periphery: Geoheritage from the Vicinity of Kazan City, Russia

“…Two geological localities of the Verkhny Uslon District, namely Pechischi and Cheremushki, are well-known as highly important objects for the understanding of the Upper Kazanian (upper Roadian) and Urzhumian (Wordian) deposits of the eastern Russian Platform, as well as for the international stratigraphical correlation developments [33,41,[52][53][54][55][56][57][58]. Detailed stratigraphical, sedimentological, geochemical, paleontological, and palaeogeographical characteristics of these localities are available (see references above), and it would be unreasonable to repeat them.…”

“…Pechischi has outstanding scientific importance thanks to its value as a stratotype section, richness in fossils, and facies peculiarities. Cutting-edge research has already been conducted there [51,53,56], and there is significant potential for further developments (especially in regard to the global correlation of the Guadalupian Series). The educational importance is determined by the utility of the geosite for explaining a series of geological phenomena to earth science university students, and, in fact, the site is regularly exploited for such purposes by Kazan Federal University with its strong geoscience educational programs.…”