Albian to Turonian agglutinated foraminiferal assemblages of the Lower Saxony Cretaceous sub-basins – implications for sequence stratigraphy and paleoenvironmental interpretation

Abstract

Abstract. Albian to Turonian carbonate deposits at three different locations of the Lower Saxony Cretaceous and thereby of the European mid-Cretaceous epeiric shelf sea were investigated for their fossil agglutinated foraminiferal fauna. In this study, 71 samples from two quarries and three drill cores were treated with formic acid, which enabled the study of agglutinated foraminiferal assemblages even in highly lithified limestones. In total, 114 species were determined and classified as belonging to nine morphogroups. In general, four agglutinated foraminiferal assemblages are distinguished: (1) an uppermost Albian–lowermost Cenomanian assemblage from the Wunstorf drill cores, with the dominant taxa Bathysiphon spp., Nothia spp., Psammosphaera fusca, Reophax subfusiformis, Bulbobaculites problematicus, Tritaxia tricarinata, Flourensina intermedia, Vialovella frankei, Arenobulimina truncata, and Voloshinoides advenus; (2) a Cenomanian assemblage from the Baddeckenstedt quarry and Wunstorf drill cores, with Ammolagena clavata, Tritaxia tricarinata, Vialovella frankei, Arenobulimina truncata, and Voloshinoides advenus; (3) an assemblage related to the Cenomanian–Turonian Boundary Event in Wunstorf and Söhlde dominated by Bulbobaculites problematicus; and (4) a Turonian assemblage in the Wunstorf and Söhlde sections with high numbers of Ammolagena contorta, Repmanina charoides, Bulbobaculites problematicus, Gerochammina stanislawi, and Spiroplectammina navarroana. The latest Albian–earliest Cenomanian assemblage consists of tubular, globular, and elongate foraminiferal morphogroups which are typical for the low- to mid-latitude slope biofacies. All other assemblages are composed of elongate foraminiferal morphogroups with additionally globular forms in the proximal settings of Baddeckenstedt and Söhlde or flattened planispiral and streptospiral forms in more distal settings of Wunstorf. For these assemblages, a new agglutinated foraminiferal biofacies named “mid-latitude shelf biofacies” is proposed herein. Changes in the relative abundance of different morphogroups can often be referred to single features of depositional sequences. Furthermore, classical macro-bioevents, which are often depositional-related, of the Lower Saxony Cretaceous seem to have a micro-bioevent or acme equivalent of the agglutinated foraminiferal fauna.

Agglutinated foraminifera from the Turonian–Coniacian boundary interval in Europe – paleoenvironmental remarks and stratigraphy

“…This species was previously reported to range from the Santonian to Eocene (Kaminski and Gradstein, 2005;Kaminski et al, 2011). This study extends the range of A. glabratus, while Besen et al (2021) already observed the species in the Cenomanian to Turonian from the Lower Saxony Basin. A. glabratus indicates bathyal settings (Kaminski and Gradstein, 2005).…”

“…3). Thus, recorded assemblages can be assigned to the mid-latitude shelf biofacies proposed by Besen et al (2021). The consistent occurrence of all morphogroups and the recorded diversities (Fig.…”

“…perplexus Zone at Bielefeld and in the M. labiatoidiformis Zone at Salzgitter-Salder. However, U. jankoi was observed to appear earlier in the middle Turonian in nearby sections: in Oerlinghausen (own observations by RMB) at about 15 km distance from the Ostwestfalendamm section and in Söhlde (Besen et al, 2021) at about 10 km distance from the Salzgitter-Salder section. The absence of this taxa in the basal metres of both studied sections is probably induced by the generally rare occurrence of U. jankoi in the German basins.…”

“…Specimens from this study are generally less robust than Ammobaculites agglutinans (d'Orbigny, 1846). Besen et al (2021) report this species from the Cenomanian to Turonian from the Lower Saxony Basin.…”

Siphopfenderina Gen. Nov. (Type-Species Arenobulimina Geyikensis Solak, 2022), a Primitive Pfenderinid Foraminifera From the Cretaceous of Neotethys

“…It is worth mentioning, that the genus Arenobulimina Cushman, 1927 is included in the suborder Ataxophragmiina Fursenko, 1958 displaying a "wall…(roughly, coarsely)…agglutinated typically with calcareous cement" (= non-canaliculate) (Kaminski, 2014, p. 102). Moreover, the genus Arenobulimina is recorded mostly from shales, as an inhabitant of open marine, deep water environments, contrary to the new taxon described herein (e.g., Reuss, 1845;Cushman, 1927;Gawor-Biedowa, 1969;Barnard & Banner, 1980;Frieg & Price, 1982;Hart et al, 1989;Besen et al, 2021). Hence, in accordance with the taxonomic relevance of a pseudokeriotheca as discussed previously, a new genus is introduced herein as Siphopfenderina gen. nov. with the new combination Siphopfenderina geyikensis (Solak, 2022).…”