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Inoceramids and inoceramid biostratigraphy of the Upper Campanian to basal Maastrichtian of the Middle Vistula River section, central Poland

Walaszczyk I.

Acta Geologica Polonica

2004

Vol. 54, no. 1

95-168

The revised geological log and the biostratigraphy of the Late Campanian and earliest Maastrichtian succession of the Middle Vistula River section, central Poland, are presented. The biostratigraphy is based on inoceramid fauna, basically newly collected. Eight inoceramid zones were distinguished, corresponding, in ammonite/belemnite terms, to an interval from the upper Bostrychoceras polyplocum Zone up to the traditional Belemnella occidentalis Zone. From bottom upwards these are zones of: Cataceramus subcompressus, "Inoceramus" tenuilineatus, Sphaeroceramus pertenuiformis, "Inoceramus" altus, "Inoceramus" inkermanaensis, Trochoceramus costaecus, "Inoceramus" redbirdensis, and of Endocostea typica. The inoceramid assemblages allow a precise correlation with critical sections in Europe, as well as trans-Atlantic correlation to the US Western Interior. The traditional base of the Maastrichtian falls at the base of the Trochoceramus costaecus Zone, whereas the 'Tercis basal Maastrichtian boundary' may fall as high as lower Belemnella sumensis Zone. Based on the correlation to the US Western Interior, a subdivision of the Upper Campanian into Middle and Upper substages is suggested. The boundary between the Middle and the Upper Campanian substages may be defined by the base of the "Inoceramus" tenuilineatus Zone, which in ammonite terms, corresponds to the base of the Didymoceras donezianum Zone (=top of the Bostrychoceras polyplocum Zone). Thirty one inoceramid species level taxa are described, of which "Inoceramus" smirnovi nom.nov. is a replacement name; 10 species are left in open nomenclature. Inoceramids of the Middle Vistula succession represent a uniform fauna characteristic of the whole Euramerican biogeographical region.