Palynology and calcareous nannofossil biostratigraphy of the Turonian – Coniacian boundary: The proposed boundary stratotype at Salzgitter-Salder, Germany and its correlation in NW Europe

Abstract

Abstract New palynological and calcareous nannofossil records are presented for the Turonian–Coniacian boundary section at Salzgitter-Salder, Germany, the candidate Coniacian GSSP. The proposed base of the Coniacian Stage is the base of Bed 46, the first appearance datum level of Cremnoceramus deformis erectus, which is coincident with a δ13C minimum at the top of the Navigation carbon isotope event. Palynological assemblages are dominated by organic walled dinoflagellate cysts (dinocysts). Stratigraphic ranges, abundances, species richness, diversity, and assemblage composition data are reported for 137 dinocyst and 119 nannofossil taxa. Dinocyst assemblages are dominated by the peridinioid cyst Palaeohystrichophora infusorioides and the gonyaulacoid cysts of Spiniferites spp. Dinocyst records, events and zonations are assessed. An uppermost Turonian P. infusorioides abundance minimum occurs within the Navigation event, and a marked influx and acme of the taxon with other peridinioid cysts occurs in the lower Coniacian (the P. infusorioides Event). The highest occurrence of Cyclonephelium membraniphorum is recorded at the base of the Coniacian. Correlation of the P. infusorioides Event between Germany, Czech Republic and England is demonstrated. This event represents a productivity pulse, attributed to water-mass reorganisation accompanying early Coniacian eustatic sea-level rise. The nannofossils Biscutum constans, Kamptnerius magnificus and Zeugrhabdotus noeliae, potential cool water indicators, display maximum relative abundances immediately below and above the stage boundary. An increased abundance of Marthasterites furcatus characterises the lowest Coniacian, and a coeval but more extended acme of the species occurs elsewhere. Helicolithus turonicus has its highest occurrence in the lower Coniacian Cremnoceramus walterdorfensis hannovrensis Zone.