Evidence for changes in sea-surface circulation patterns and ~20° equatorward expansion of the Boreal bioprovince during a cold snap of Oceanic Anoxic Event 2 (Late Cretaceous)

Planktonic foraminifera document palaeoceanographic changes across the middle Cenomanian carbon-isotope excursion MCE 1: new evidence from the UK chalk

“…3). A similar interpretation was proposed to explain the planktonic foraminiferal assemblage changes and the occurrence of the Boreal macrofauna C. arlesiensis , O. seminudum and P. plenus in the PCE interval at Eastbourne (UK) (O’Connor et al 2019; Falzoni & Petrizzo, 2022).…”

“…According to the literature (see reviews in Petrizzo et al 2020 and Falzoni & Petrizzo, 2022), Rotalipora and Thalmanninella inhabited cold/deep layers of the water column close to the thermocline, although with some differences observed among species and through time. Rotaliporids found in pelagic settings of the Tethyan Realm have been interpreted as oligotrophic, and thus required a relatively thick and stratified upper water column to complete their life cycle.…”

“…According to the observed record we infer that M. portsdownensis had a meso-eutrophic life strategy, proliferated in cold water and is probably a Boreal species. However, further studies are needed to confirm the stratigraphic and geographical distribution of this species which has rarely been mentioned in the literature, and, as discussed in the Taxonomic remarks section further below, additional studies are required to investigate its possible synonymy with Muricohedbergella kyphoma , a species coinciding with the coldest episode (Falzoni & Petrizzo, 2022) of the late Cenomanian Plenus Cold Event (PCE).…”

“…Comparison between the planktonic foraminiferal assemblages during the cooling episodes within the MCE 1 and those occurring at the PCE reveals a similar composition, with dominance of taxa more adapted to cooler and relatively poorly stratified water masses ( Muricohedbergella , Praeglobotruncana , Dicarinella ). Additional evidence for a Boreal origin of these assemblages is provided by the occurrence of common M. portsdownensis at Folkestone and M. kyphoma at Eastbourne (Falzoni & Petrizzo, 2022). Regardless of the taxonomic assignments of these species (as explained in the Taxonomic remarks section further below), they are only observed in the levels containing Boreal macrofossils and are therefore interpreted as mesotrophic–eutrophic species that did not require a thermally stratified water column.…”

Biotic and Paleoceanographic Changes Across the Late Cretaceous Oceanic Anoxic Event 2 in the Southern High Latitudes (IODP Sites U1513 and U1516, SE Indian Ocean)

“…Planktonic foraminifera across the Cenomanian‐Turonian boundary interval studied in several low to mid latitude regions of the Tethyan Realm (e.g., England: Falzoni & Petrizzo, 2020; Keller et al., 2001; Paul et al., 1999; Austria: Gebhardt et al., 2010; Wagreich et al., 2008; Italy: Coccioni & Luciani, 2004, 2005; Luciani & Cobianchi, 1999; Scopelliti et al., 2004, 2008; SE France: Falzoni & Petrizzo, 2022; Falzoni, Petrizzo, Jenkyns, et al., 2016; Grosheny et al., 2006; Takashima et al., 2009; Spain: Lamolda et al., 1997; Tunisia and Algeria: Benadla et al., 2018; Caron et al., 2006; Grosheny et al., 2013; Nederbragt & Fiorentino, 1999; Reolid et al., 2015; Zaghbib‐Turki & Soua, 2013; Iran: Kalanat et al., 2016; Kalanat & Vaziri‐Moghaddam, 2019; Morocco: Aquit et al., 2013; Falzoni et al., 2018; Keller et al., 2008), of the central Atlantic Ocean (Nigeria: Gebhardt, 1997; Morocco: Jati et al., 2010; Mexico: Ifrim et al., 2011), of the Indian Ocean (Tibet: Bomou et al., 2013), of the Pacific Ocean (Japan: Hasegawa, 1999), and of the Western Interior Seaway (e.g., USA: Caron et al., 2006; Desmares et al., 2007; Elderbak & Leckie, 2016; Elderbak et al., 2014; Keller & Pardo, 2004; Canada: Dionne et al., 2016; Bryant et al., 2021) underwent a significant change.…”