ALBERT

Description: Following the unanimous vote of the Executive Committee of International Union of Geological Sciences in October 2022, the Global boundary Stratotype Section and Point for the base of the Campanian Stage is confirmed as the magnetic polarity reversal from Chron 34n (top of the Long Cretaceous Normal Polarity–Chron) to Chron C33r at the 221.53 m level in the Bottaccione Gorge section at Gubbio, Umbria–Marche Basin, Italy. This event has been widely identified in oceanic settings and in widespread onshore outcrops. Sedimentation across the Santonian– Campanian boundary interval in the proposed GSSP appears to be continuous, supported by evidence from the carbon isotope record and complete micro– and nannofossil biostratigraphy. The succession comprises deep–water cherty limestones (mudstones and foraminiferal wackestones) which provide a detailed record of calcareous nannofossils and planktonic foraminifera and yields an excellent palaeomagnetic record. The high–resolution carbon isotope record, derived from bulk sediment, provides an important additional means of correlation to other regions.

Description: The Cretaceous provides us with an excellent case history of ocean-climate-biota system perturbations. Such perturbations occurred several times during the Cretaceous, such as oceanic anoxic events and the end-Cretaceous mass extinction, which have been the subject of an abundant literature. Other perturbations, such as the mid-Maastrichtian Event (MME) remain poorly understood. The MME was associated with global sea-level rise, changes in climate and deep-water circulation that were accompanied by biotic extinctions including ‘true inoceramids’ and the demise of the Caribbean-Tethyan rudist reef ecosystems. So far, the context and causes behind the MME remain poorly studied. We conducted high-resolution integrated biotic, petrological and geochemical studies in order to fill this knowledge gap. We studied, in particular, carbonate Nd and Os isotopes, whole-rock Hg, C and N content, C and N isotopes in organic matter, S isotopes in carbonate-associated sulfate, along with C and O isotopes in foraminifera from the European Chalk Sea: the Polanówka UW-1 core from Poland and the Stevns-1 core from Denmark. Our data showed that sea-level rise of ∼50–100 m lasted around ∼2 Ma and co-occurred with anomalously high mercury concentration in seawater. Along with previously published data, our results strongly suggest that the MME was driven by intense volcanic–tectonic activity, likely related to the production of vast oceanic plateaus (LIP, Large Igneous Province). The collapse of reef ecosystems could have been the consequence of LIP-related environmental stress factors, including climate warming, presumably caused by emission of greenhouse gases, modification of the oceanic circulation, oceanic acidification and/or toxic metal input. The disappearance of the foraminifer Stensioeina lineage on the European shelf was likely caused by the collapse of primary production triggered by sea-level rise and limited amount of nutrient input. Nd isotopes and foraminiferal assemblages attest for changes in sea-water circulation in the European Shelf and the increasing contribution of North Atlantic water masses

Description: The stratigraphy and palynology of the upper Santonian–lower Campanian (Uintacrinus socialis–Gonioteuthis quadrata zones) Newhaven Chalk are described for the Campanian auxiliary GSSP section at Seaford Head, England. A new high-resolution bulk-sediment carbonate carbon stable-isotope (δ13Ccarb) curve provides the basis to refine the carbon-isotope event (CIE) stratigraphy of the section. Results are compared to a complementary palynological study of a second Campanian auxiliary GSSP section (U. socialis–O. pilula zones) at Bocieniec, Poland. Palynological assemblages are dominated by organic-walled dinoflagellate cysts (dinocysts; 208 taxa) at both sites. A stratigraphic framework is established via review of published lithostratigraphic, macrofossil, foraminifera and calcareous nannofossil records from the study sites. Carbon isotope curves with 13 major named CIEs provide a basis for correlation of Seaford Head and Bocieniec to sections at: Trunch, England; Poigny, France; Lägerdorf, Germany; and the Campanian GSSP at Gubbio, Italy. Correlations are constrained by biostratigraphic records, including dinocyst events. The Late Santonian δ13C Event (LSE, previously termed the Santonian–Campanian Boundary Event, SCBE) provides a key correlation level between Boreal and Tethyan sections and enables the placement of base Campanian markers: extinction levels of the crinoid Marsupites and the planktonic foraminifera Dicarinella asymetrica; the first appearance of the calcareous nannofossil Aspidolithus parcus parcus; and the C34n/C33r magnetozone boundary (the primary Campanian marker), in both Boreal and Tethyan sections. A holostratigraphy for the Santonian–Campanian boundary interval that integrates CIEs, macrofossils, benthic and planktonic foraminifera, calcareous nannofossils, dinocysts and magnetostratigraphy is presented. Rhynchodiniopsis juneae sp. nov. is described.