The Cenomanian of Hoppenstedt, northern Germany a Subhercynian key section revisited
Wilmsen, Markus J.
Newsletters on Stratigraphy Volume 40 Number 3 (2004), p. 209 - 230
veröffentlicht: Dec 22, 2004
ArtNo. ESP026004003004, Preis: 29.00 €
The Cenomanian succession of the abandoned limestone quarry section of Hoppenstedt (Saxony Anhalt, northern Germany) was re-evaluated with respect to event and sequence stratigraphical key surfaces in order to place this Subhercynian Basin key section into the established integrated stratigraphic framework of the Cenomanian Stage. In the Lower Cenomanian Mantelliceras dixoni Zone, the 'sponge bed', 'the rib', the Schloenbachia/virgatus Event, the Orbirhyn - chia/Schloenbachia Event, the 'double limestone', and the Turrilites scheuchzerianus Event were recognized in a succession of marly marl-limestone rhythmites. Compared to the more distal eastern Lower Saxony Basin section of Baddeckenstedt, the Lower Cenomanian is considerably reduced in Hoppenstedt, related to lack of accommodation space during this interval. The Lower Cenomanian succession is erosionally truncated at the base of a prominent bioclastic limestone of Middle Cenomanian age which is lithologically similar to, and inferred to broadly correlate with, the Totternhoe Stone in England. This transgressive bed yielded in its upper part the belemnite Praeactinocamax primus (Arkhangelsky) together with Acanthoceras rhotomagense (Brongniart), indicating the primus Event of the Middle Cenomanian A. rhotomagense ammonite Zone. This correlation suggests a pronounced gap at the base of this bed, comprising the upper part of the upper Lower Cenomanian M. dixoni Zone and most of the lower Middle Cenomanian Cunningtoniceras inerme Zone. Upsection, a succession of marl-limestone rhythmites with large, three dimensional A. rhotomagense and Holaster subglobosus (Leske) capped by a minor erosion surface with Orbirhynchia mantelliana (J. de C. Sowerby ) indicates the middle A. rhotomagense Zone Mid-Cenomanian Event (MCE). The interval from the MCE upwards to the upper Middle Cenomanian Pycnodonte Event at Hoppenstedt is slightly expanded compared to Baddeckenstedt. From the Pycnodonte Event to the Upper Cenomanian 'Facies Change' at the boundary of the Calycoceras (Proeucalycoceras) guerangeri and the Metoicoceras geslinianum zones, the succession in Hoppenstedt is well comparable in facies and thickness to sections elsewhere in northern Germany, characterized by poorly fossiliferous, finegrained pelagic limestone ("Poor rhotomagense Limestones"). Cenomanian depositional sequences DS Ce III, DS Ce IV, and DS Ce V, capped by Cenomanian sequence boundaries SB Ce III (base of Totternhoe Stone-equivalent limestone), SB Ce IV (base of Pycnodonte Event), and SB Ce V (Facies Change), respectively, were recognized.