| mhorn | Дата: Saturday, 08.10.2011, 18:17 | Сообщение # 1 |
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| Mitta V.V., Zakharov V.A., Barskov I.S., Sel’tser V.B., Ivanov A.V. (2011) The Upper Bajocian–Lower Bathonian Boundary Section in the Outskirts of Saratov: Molluscan Characteristics and Biostratigraphy // Stratigraphy and Geological Correlation, Vol. 19, No. 5, P.502–514.
Pdf: http://rogov.zwz.ru/Mitta%20%20et%20al.,2011_bj-bt_en.pdf
The analysis of all available data on the structure of the Bajocian–Bathonian boundary section in the outskirts of Saratov (Sokur quarry) and the taxonomic composition of its ammonites, belemnites, and bivalves revealed a continuous succession of the Pseudocosmoceras michalskii (Upper Bajocian), Oraniceras besnosovi, and Arcticoceras ishmae (Lower Bathonian) zones. In connection with the critique by Meledina et al. (2009), correlation of Bajocian and Bathonian boundary strata of the Central Russia and Northern Siberia is discussed. The inconsistency of Siberian bivalve and belemnite assemblages with Central Russian ammonite zones is explained by heterochronous invasions of different molluscan groups. In my opinion (mhorn), at least partial correlation of the Ischmae zone with Lower Bathonian is unequivocal, but position of the upper boundary of this zone still remains questioned; moreover, uppermost horizon of the Ischmae zone now still known from the East Greenland only (fauna 17 after Callomon, 1993).
Middle Jurassic - Lower Cretaceous ammonites & aptychi
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