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Late Cenomanian.Turonian (Cretaceous) ammonites from Wadi Qena, central Eastern Desert, Egypt : taxonomy, biostratigraphy and palaeobiogeographic implications

Nagm E., Wilmsen M.

Acta Geologica Polonica

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2012

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Vol. 62, no. 1

63-89

EN

In Egypt, marine Upper Cenomanian.Turonian strata are well exposed in the Eastern Desert. The southernmost outcrops are located in the central part of Wadi Qena, where the lower Upper Cretaceous is represented by the fossiliferous Galala and Umm Omeiyid formations. From these strata, numerous ammonites have been collected bed-by-bed and 13 taxa have been identified, which are systematically described herein. Four of them (Euomphaloceras costatum, Vascoceras globosum globosum, Thomasites gongilensis and Pseudotissotia nigeriensis) are recorded from Egypt for the first time. The ammonite ranges are used for a biostratigraphic zonation of the lower Upper Cretaceous succession in the northern and central part of Wadi Qena: the Upper Cenomanian.Lower Turonian has been subdivided into five biozones (including a new upper Lower Turonian biozone based on the occurrence of Pseudotissotia nigeriensis), and one biozone has been recognized in the Upper Turonian. Palaeobiogeographically, the ammonite assemblage has a Tethyan character. During the Early Turonian, influences of the Vascoceratid Province were predominant with strong affinities to typical Nigerian faunas. This shows the significance of faunal exchange between Egypt and Central and West Africa via the Trans-Saharan Seaway. Compared to contemporaneous ammonoid faunas from the northern part of the Eastern Desert, Boreal influences are much less obvious in Wadi Qena. Thus, the present study greatly enhances the knowledge of the Late Cretaceous palaeobiogeography and biostratigraphy of Egypt and adjacent areas.

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Cenomanian Acanthoceratoidea (Cretaceous Ammonoidea) from the Koppeh Dagh, NE Iran : taxonomy and stratigraphic implications

Mosavinia A., Wilmsen M.

Acta Geologica Polonica

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2011

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Vol. 61, no. 2

175-192

EN

Seven species of the acanthoceratoidean genera Forbesiceras Kossmat, 1897, Mantelliceras Hyatt, 1903, Acanthoceras Neumayr, 1875 and Cunningtoniceras Collignon, 1937 are described and illustrated from the upper (i.e., Cenomanian) part of the Aitamir Formation of the Koppeh Dagh, northeast Iran. The mantelliceratines were collected from Lower Cenomanian silty shales while the rest of the fauna stems from lower Middle Cenomanian glauconitic sandstones in the upper part of the formation. The ammonite association allows recognition of the lower Lower Cenomanian Mantelliceras mantelli and the lower Middle Cenomanian Acanthoceras rhotomagense zones. The upper Lower Cenomanian M. dixoni Zone is not proven by its index but is most likely represented by a unit of fossil-poor shales intercalated between the two above-mentioned zones. The lowermost Middle Cenomanian Cunningtoniceras inerme Zone, however, is potentially at least partly missing due to a major sea-level fall and lowstand in the latest Early to earliest Middle Cenomanian. A preliminary sequence stratigraphic interpretation of the successions suggests the presence of Lower Cenomanian sequence boundaries Sb Ce 1-3. The Aitamir Formation is truncated along a major regional unconformity at the base of the overlying Abderaz Formation (Turonian.Coniacian). The Upper Cenomanian and most likely also (parts of) the Lower Turonian are missing. This major unconformity has a tectonic origin as it deviates from the eustatic sea-level trend which was very high at this time. Furthermore, contemporaneous tectonic unconformities are also known from Central Iran and may have their origins in rotational movements of the Central-East Iranian Microcontinent.

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Latest Campanian to Early Maastrichtian (Cretaceous) nautiloids from the white chalk of Kronsmoor, northern Germany

Wilmsen M., Esser K. J.

Acta Geologica Polonica

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2004

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Vol. 54, no. 4

489-498

EN

A well preserved and stratigraphically tightly constrained nautiloid fauna consisting of two species is described from the uppermost Campanian to Lower Maastrichtian white chalk section of Kronsmoor, northern Germany. Cymatoceras patens (KNER, 1848) occurs rather frequently in the Kronsmoor section; one specimen is from the Upper Campanian Micraster grimmensis/Cardiaster granulosus Zone, one from the upper Belemnella pseudobtusa to lowermost Belemnella obtusa Zone. The bulk of the material (nine specimens) is from the Early Maastrichtian B. obtusa and Belemnella sumensis zones. The species is known from the Upper Campanian to Lower Maastrichtian of northern Germany, The Netherlands, Poland, the Ukraine, and possibly Denmark. Cymatoceras loricatum (SCHLUTER, 1876) occurs in Kronsmoor (four specimens) in an interval comprising the Early Maastrichtian upper B. obtusa to B. sumensis zones.The species was hitherto only recorded from the uppermost Lower and Upper Campanian of Westphalia and Lower Saxony, Germany. Both species appear to be restricted to the Central European Subprovince of the temperate North European Province (Boreal Realm).