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2 Acta Geologica Polonica

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The Aucellina biostratigraphy of the Upper Albian (Early Cretaceous) of the Kirchrode I cored borehole, Hannover-Kirchrode, northern Germany

Wood C. J.

Acta Geologica Polonica

2016

Vol. 66, no. 4

695--708

The Aucellina biostratigraphy of the Upper Albian Kirchrode Marls Member succession in the Kirchrode I (1/91) cored borehole is described and the fauna illustrated. The borehole commenced at an unknown depth below the Early Cenomanian marls of the Bemerode Member, but higher beds of the Kirchrode Marls and the basal beds of the Bemerode Member were exposed in the Mittellandkanal and its Stichkanal extension at Misburg. The borehole and surface exposures permit a virtually complete Late Albian succession of Aucellina species to be observed. Published Aucellina range data from the borehole are reassessed and it is suggested that the lower part of the recorded range is based partly on misidentifications of fragments of thin-shelled bivalves such as Syncyclonema and Amussium. Aucellina appears in the borehole succession within the upper part of the Callihoplites auritus ammonite Subzone (Mortoniceras inflatum Zone) and continues to the top of the borehole succession within the Preaeschloenbachia briacensis ammonite Subzone (Stoliczkaia spp. Zone). Aucellina from higher in the briacensis Subzone collected from the Misburg Mittellandkanal section are also discussed and illustrated. There is some evidence that Aucellina occurs typically at levels in the borehole containing predominantly Boreal European Province ammonites, supporting the general inference that Aucellina lived in cooler northern waters. In contrast, Aucellina is poorly represented in intervals with Tethyan ammonites and thin-shelled inoceramids (e.g. the Mortoniceras (Durnovarites) perinflatum Subzone, Stoliczkaia spp. Zone). The briacensis Subzone, with an admixture of Tethyan (Stoliczkaia) and Boreal ammonites contains a distinctive, taxonomically highly diverse Aucellina assemblage. Relevant taxonomic research on European Late Albian and Early Cenomanian Aucellina faunas is reviewed. The Late Albian Aucellina succession in the borehole differs from that established from partially correlative successions in England.

Silicified sea life – Macrofauna and palaeoecology of the Neuburg Kieselerde Member (Cenomanian to Lower Turonian Wellheim Formation, Bavaria, southern Germany)

Schneider S., Jäger M., Kroh A., Mitterer A., Niebuhr B., Vodrážka R., Wilmsen M., Wood C. J., Zágoršek K.

Acta Geologica Polonica

2013

Vol. 63, no. 4

555--610

With approximately 100 species, the invertebrate macrofauna of the Neuburg Kieselerde Member of the Wellheim Formation (Bavaria, southern Germany) is probably the most diverse fossil assemblage of the Danubian Cretaceous Group. Occurring as erosional relicts in post-depositional karst depressions, both the Cretaceous sediments and fossils have been silicified during diagenesis. The Neuburg Kieselerde Member, safely dated as Early Cenomanian to Early Turonian based on inoceramid bivalve biostratigraphy and sequence stratigraphy, preserves a predominantly soft-bottom community, which, however, is biased due to near-complete early diagenetic loss of aragonitic shells. The community is dominated by epifaunal and semi-infaunal bivalves as well as sponges that settled on various (bio-) clasts, and may widely be split into an early bivalve-echinoid assemblage and a succeeding sponge-brachiopod assemblage. In addition to these groups we document ichnofauna, polychaete tubes, nautilids and bryozoans. The fauna provides evidence of a shallow to moderately deep, calm, fully marine environment, which is interpreted as a largescale embayment herein. The fauna of the Neuburg Kieselerde Member is regarded as an important archive of lower Upper Cretaceous sea-life in the surroundings of the Mid-European Island.