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2 Acta Geologica Polonica

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Revision of the Upper Cretaceous ammonite fauna of the Bakony Mountains (Hungary)

Bodrogi I., Jazykova-Flidlider E.

Acta Geologica Polonica

2001

Vol. 51, nr 1

93-99

A revision of the ammonites from the Bakony Mountains (Hungary) based on collections of the Geological Institute of Hungary (MAFI) in Budapest, revealed the following sequence of faunas. The youngest Campanian ammonites from the South Bakony are three specimens of Pachydiscus (P.) praecolligatus COLLIGNON, 1955 from the Sumeg area; this is a typical Campanian species. Two specimens of former "Lower Maastrichtian Pachydiscus neubergicus (HAUER)" from Haraszt quarry have been re-determined as Early Campanian Eupachydiscus levyi (GROSSOUVRE, 1894). The fragmentary specimen of Mortoniceras sp. has been determined as Texanites (Texanites) sp. from the Upper Santonian. Two ammonite zones can be recognised for these sequences: Texanites sp. (Santonian) and Eupachydiscus levyi (Lower Campanian)

Biostratigraphy and correlation of the Turonian - Coniacian succession and the Turonian - Coniacian boundary problem in the Far East Russia based on ammonites and inoceramids

Zonova T., Jazykova-Flidlider E.

Acta Geologica Polonica

1998

Vol. 48, no. 4

483-494

The stratigraphy, ammonite and inoceramid content of the Turonian - Coniacian deposits of Far East Russia are presented. The evolution of North Pacific ammonites and inoceramids at the boundary of the two stages was studied and the levels of fundamental changes within the ammonite and inoceramid biota are recognized. The established palaeogeographic difference between the Sakhalin and the North-East region palaeobasins is reflected in the existence of two independent local zonal schemes. The main criteria of the Turonian-Coniacian stage boundary in the Far East of Russia were established on the basis of the two schemes. The Turonian/Coniacian (T/C) boundary is clearly marked by the change in the taxonomic diversity of the zonal inoceramid assemblages. It is defined at the base of the Inoceramus uwajimensis Zone. The appearance of the endemic ammonite species. Jimboiceras mihoense MATSUMOTO is the ammonite criterion for recognising the T/C stage boundary in Sakhalin. This is supported by occurrences of the cosmopolitan Coniacian genera Peroniceras and Forresteria.