Reassessment of the Salzgitter-Salder section as a potential stratotype for the Turonian–Coniacian boundary: stable carbon isotopes and cyclostratigraphy constrained by calcareous nannofossils and palynology

The Global Boundary Stratotype Section and Point (GSSP) for the base of the Coniacian Stage (Salzgitter-Salder, Germany) and its auxiliary sections (Słupia Nadbrzeżna, central Poland; Střeleč, Czech Republic; and El Rosario, NE Mexico)

“…A new approach -which required the selection of a main singlesection stratotype, supplemented by auxiliary sections to better define the range of variability associated with the boundary interval -was discussed during the Subcommission Meeting at the 10th International Symposium on the Cretaceous in Vienna in 2017. Furthermore, Silke Voigt presented an updated, high-resolution carbon isotope chemostratigraphy for Salzgitter-Salder and its possible correlation with Słupia Nadbrzeżna, which suggested that the hiatus at the base of the C. deformis erectus Zone (basal Coniacian) was much smaller than previously interpreted, or even non-existent -that is, the basal Coniacian in Salzgitter-Salder was continuous (Voigt et al, 2021). Finally, new inoceramid collections from the boundary interval showed that C. deformis erectus (Meek), the boundary marker, first appears slightly lower than previously documented (already in Bed 46 instead of Bed 47), which made the correlation to the Słupia Nadbrzeżna succession straightforward (here and in Voigt et al, 2021).…”

“…Furthermore, Silke Voigt presented an updated, high-resolution carbon isotope chemostratigraphy for Salzgitter-Salder and its possible correlation with Słupia Nadbrzeżna, which suggested that the hiatus at the base of the C. deformis erectus Zone (basal Coniacian) was much smaller than previously interpreted, or even non-existent -that is, the basal Coniacian in Salzgitter-Salder was continuous (Voigt et al, 2021). Finally, new inoceramid collections from the boundary interval showed that C. deformis erectus (Meek), the boundary marker, first appears slightly lower than previously documented (already in Bed 46 instead of Bed 47), which made the correlation to the Słupia Nadbrzeżna succession straightforward (here and in Voigt et al, 2021). With this new framework, no further obstacles existed to formally propose the Salzgitter-Salder quarry section as the GSSP of the Coniacian Stage.…”

“…The top of the newly revised Navigation Carbon Isotope Event (CIE) (Jarvis et al, 2006;Voigt et al, 2021), which extends from a horizon in the topmost M. scupini Zone to the C. waltersdorfensis waltersdorfensis Zone [spanning from Bed 42 (option 1) or Bed 39b (option 2) to the middle of Bed 46 in Salzgitter-Salder] is an excellent proxy for the base of the Coniacian Stage. Within the high-resolution carbon isotope chemostratigraphy of Salzgitter-Salder, the top of the Navigation CIE matches the old single-point definition of stage-boundary δ 13 C minimum proposed by Voigt and Hilbrecht (1997).…”

“…3-5), Wood et al (2004), and are summarized below. In addition, new observations by Čech (in Čech and Uličný, 2021), Voigt et al (2021) and Walaszczyk (unpublished) are included. The following beds yielded biostratigraphically significant macrofauna and bioevents (see also Fig.…”

“…The acme occurrence of C. w. waltersdorfensis in Bed 46 was previously interpreted as monospecific and referred to the waltersdorfensis II Event. However, this must be reinterpreted, as Bed 46 also contains the first C. deformis erectus (see Voigt et al, 2021). The subspecies erectus is the oldest chronosubspecies of the C. deformis lineage (see Walaszczyk and Wood, 1998;Walaszczyk and Cobban, 2000), which branched off from the waltersdorfensis lineage relatively early in the history of the Cremnoceramus clade.…”