RUSSIAN JOURNAL OF EARTH SCIENCES VOL. 9, ES1002, doi:10.2205/2007ES000221, 2007

Conclusions

[44]  1. The strontium isotope ratios recorded in the Pechishchi section clearly indicate the position of the studied Permian deposits on the global curve within the generally accepted time scale. The ambiguities existing at some points are associated with equivocal solutions to chronostratigraphic problems of the Permian system and with the local sedimentation features.

[45]  2. The zonation of 87Sr/86Sr isotope ratios corresponds to the stratification pattern. The Lower Permian is characterised by increased strontium ratios and the Kazanian by reduced ones.

[46]  3. The above variations of the isotope ratio are caused by the interaction between land and sea on the one side and between local basins and the ocean on the other.

[47]  4. The obtained isotope data permit the identification of at least three evolutionary types of sedimentation basins in the Volga-Kama region.

[48]  Type 1: an Early Permian basin that was apparently a vast, shallow-water, carbonate platform under the active influence of the ocean and climatic changes, such as global glacial processes and local non-glacial evaporation. The 87Sr/86Sr ratios are well correlated with the corresponding strontium ratios on the global curve for the ocean and clearly indicate the marine genesis of these deposits.

[49]  Type 2: an Early Kazanian basin with 87Sr/86Sr ratios generally corresponding to the globally reduced 87Sr/86Sr ratios in the oceanic water at that time.

[50]  Type 3: a Late Kazanian basin, in which the strontium isotope ratio is expectedly low but higher than on the global curve, which can be explained by the local features of the Upper Permian deposition in the eastern part of the Russian Plate (the evaporitic trend and considerable isolation from the ocean) and by the problems of chronostratigraphic positioning of the Phanerozoic 87Sr/86Sr curve and local 87Sr/86Sr curves for the Permian.

[51]  5. Multiple determinations of strontium isotope ratios in the Permian carbonates and the absolute 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.


RJES

Citation: Nurgalieva, N. G., V. A. Ponomarchuk, and D. K. Nurgaliev (2007), Strontium isotope stratigraphy: Possible applications for age estimation and global correlation of Late Permian carbonates of the Pechishchi type section, Volga River, Russ. J. Earth Sci., 9, ES1002, doi:10.2205/2007ES000221.

Copyright 2007 by the Russian Journal of Earth Sciences

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