Geochemical and palynological sea-level proxies in hemipelagic sediments: A critical assessment from the Upper Cretaceous of the Czech Republic

摘要: Geochemical and palynological records are presented for an expanded Turonian–Coniacian hemipelagic succession in the central Bohemian Cretaceous Basin. A high-resolution stratigraphic framework is provided by biostratigraphy organic carbon stable-isotope (δ13Corg) chemostratigraphy. short-term (100 kyr) sea-level curve has been derived from transgressive/regressive maxima / shore-proximity data established basin-wide sediment geometries. The viability of geochemical parameters as potential proxies tested against this independently record. Elemental chemostratigraphy demonstrated to offer a reliable means identifying medium- long-term (0.4–2.4 Myr) trends. Manganese associated with periods high sea level, troughs intervals low level. Falling Mn contents accompany regression rising values transgression. Major transgressive events medium-term change marked sharp increases Ti/Al ratios, but cycles not consistently identified. Long-term δ13Corg variation dinoflagellate cyst species richness positively correlated show similarities curve. Baseline trends have cycle duration close 2.4 Myr long-eccentricity cycle. Dinocyst closely follows changes dinocyst diversity coincident most flooding events. Periods rapid rise caused influx more diverse ‘outer shelf’ assemblage into study area, together addition shallower water species, some which may transported basin hypopycnal flows. Changes proportion abundance peridinioid cysts (principally Palaeohystrichophora infusorioides) were controlled principally changing nutrient levels. Proximity always consistent independent model. This exemplifies need understand all factors influencing elemental before making simplistic level interpretations.