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2 Acta Geologica Polonica

2 2004

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New advances in the stratigraphy and geochemistry of the German Turonian (Late Cretaceous) tephro- stratigraphic framework

Wiese F., Wood Ch. J., Wray D. S.

Acta Geologica Polonica

2004

Vol. 54, no. 4

657--671

The lowest of the five bentonites in the German Turonian tephrostratigraphic framework, T[C], can be correlated for the first time from the Rotplaner (red limestone) standard section in the Sohlde-Loges Quarry (Lower Saxony) to highly condensed, near-swell successions of the nearby Woltwiesche Quarry and the Hoppenstedt Quarry (Saxony-Anhalt). A second bentonite, T[C2], only recently recognised at Sohlde-Loges, is now identified at Woltwiesche and in the distal/expanded white limestone successions of the Salzgitter-Salder Quarry and the Floteberg road-cutting (both Lower Saxony). T[C2] can easily be located a short distance above a major lithofacies change (herein termed the Basal Upper Turonian Facies Turnover), making it an isochronous marker permitting correlation between condensed near-swell and expanded basinal sections. On this basis, a bentonite, previously identified as T[C] at Hoppenstedt must be re-assigned as T[C2].Examination of the major, trace, and rare-earth element (REE) data of all the five bentonites identified in Lower Saxony and Saxony-Anhalt shows that it is possible to discriminate between them to some extent. Bentonites TC[ ]and T[C2] are geochemically similar and separable from T[D], which is itself distinct from T[E] and T[F].

20 years of event stratigraphy in NW Germany; advances and open questions

Wiese F., Wood Ch. J., Kaplan U.

Acta Geologica Polonica

2004

Vol. 54, no. 4

639--656

The application of event stratigraphy in the Cenomanian to Lower Coniacian (Upper Cretaceous) Plńnerkalk Gruppe of northwestern Germany has advanced stratigraphic resolution considerably. For a short interval in the Upper Turonian, various genetically variable events (bioevents, tephroevents, stable isotope marker, eustatoevents) are reviewed and new data are partly added. In addition, the lateral litho and biofacies changes within individual events are discussed and provide a basis for a tentative high-resolution correlation between distal and proximal settings. The dense sequence of events permits a stratigraphic resolution of 50 - 100ky for some intervals. Beyond stratigraphic purposes, the alternation of fossil barren intervals with thin fossil beds still demands explanations. As taphonomic processes are considered to be play only a minor role, other explanations are required. It appears that trophic aspects and a calibration of planktic and benthic faunal assemblages may result in a better understanding of this biosedimentary system and its faunal characteristics.