Planktic foraminiferal response to an early Paleocene transient warming event and biostratigraphic implications

Abstract

The Latest Danian Event (LDE, ~ 62.2 Ma) is characterized by global changes in the carbon cycle as indicated by two negative δ13C excursions of up to ~ 1‰. These δ13C shifts are accompanied by a 2–3 °C warming of both surface and deep waters based on benthic and planktic foraminiferal δ18O measurements, and the LDE has, thus, been considered as a so-called hyperthermal event. The event lasted for 200 kyr and has been identified in various ocean basins and shallow marine settings. Here, we present a compilation of data from three deep-sea cores covering the Pacific, North and South Atlantic oceans as well as a southern Tethyan shelf section to document the response of planktic foraminifera assemblages to ocean warming. In all studied successions, we observe the disappearance of the planktic foraminifer genus Praemurica on a global scale that took place close to the onset of the LDE. Moreover, on the long run, praemuricids were contemporaneously replaced by morozovellids. Both the decline of Praemurica and a temperature increase started between 200 and 260 kyr before the LDE onset and were punctuated by the LDE itself. In this paper, we propose two mechanisms that have controlled the environmental changes associated with this event, (1) increased activity of the North Atlantic Igneous Province acting on long time-scales, and (2) changes of orbital parameters resulting in insolation changes on shorter time-scales.In contrast to a proposed muted benthic foraminiferal response, the planktic community has been substantially impacted by the LDE as indicated by changes in planktic foraminifera faunas and calcareous nannofossils. Finally, our quantitative and conventional approaches identifying stratigraphically important planktic foraminifera datum levels justify a revision of the upper Danian to lower Selandian planktic foraminifera biozonation.

Multiproxy analyses of paleoenvironmental and paleoceanographic changes during the Danian-Selandian in East Central Sinai: An integrated stable isotope and planktic foraminiferal data

“…The studied section occurs 5 km west away from El Themed village in East Central Sinai (29 °46′39.11″N and 34 °15′52.00″E; Figure 1A). In the present study, Morozovella, Acarinina, and Igorina are considered as warm water genera, whereas cool water taxa include Parasubbotina and Subbotina; the keeled genera include Morozovella and Igorina (Speijer, 2003;Guasti, 2005;Bornemann et al, 2009;Bornemann et al, 2021). Additionally, the planktic foraminifera species are also categorized based on their depth habitat, as corroborated by isotopic studies (Table 1 and references therein).…”

“…The Pα-P1b zones (64.97-62.9 Ma; Interval 1; samples 3-8) are characterized by the dominance of thermocline dweller Eoglobigerina (36%: consisting of E. eobulloides, E. edita and E. simplicissima) (Figures 3, 7). The thermocline dwellers inhabit the deeper segments of the water column (e.g., thermocline), indicating the presence of a deeper thermocline, reduced stratification and/or eutrophic conditions (Bornemann et al, 2021) (see Table 1 for species habitat categorization). The other dominant taxa, Praemurica (20.4%: Pr.…”

“…taurica and Pr. pseudoinconstans) prefers cooler waters (Guasti, 2005 and references therein); globally, the genus is well-documented to have disappeared just before the advent of the warm hypothermal Lower Danian Event (LDE: Berggren and Norris, 1997;Olsson et al, 1999;Jehle et al, 2015;Bornemann et al, 2021) (Figure 7). Cool surface waters are also supported by the presence of Chiloguembelina (C. morsei; 3.3%), Globanomalina (G. archeocompressa and G. planocompressa) and Subbotina (S. triloculinoides and S. trivialis; 7%) (see Boersma and Premoli Silva, 1983;Shackleton, 1985;Pearson et al, 1993;Van Eijden, 1995;Kelly et al, 1996;Lu et al, 1998;Quillévéré and Norris, 2003;Guasti, 2005) (Figure 7).…”

“…Parasubbotina and Subbotina (59%) are considered cool surface water species and deep thermocline dwellers, suggesting enhanced and stable water column stratification and meso-to oligotrophic conditions (Boersma and Premoli Silva, 1983;Boersma and Premoli Silva, 1991;Pearson et al, 1993;Norris, Frontiers in Earth Science frontiersin.org 1996; Berggren and Norris, 1997) (Figure 7). However, Bornemann et al (2021) considered them as mesotrophic, subsurface taxa; lower δ 13 C values throughout the interval also suggests increased productivity. In the present study, during the LDE hypothermal event, both Parasubbotina and Subbotina decreased dramatically, suggesting their preference for cooler mesotrophic waters (see also Guasti, 2005 and references therein); low δ 13 C values throughout the interval also supports mesotrophic conditions (Figure 7).…”

“…Globally, also, the LDE is characterized by a prominent negative δ 13 C excursion in different marine settings like the southern Tethyan shelf (Egypt; Bornemann et al, 2009), the northern Tethys (Bjala, Bulgaria;Dinarès-Turell et al, 2012), the eastern North Atlantic (Zumaia, Spain;Dinarès-Turell et al, 2010), and the Pacific Ocean (Westerhold et al, 2011; see also Bornemann et al, 2021). As with other Paleogene hyperthermals (such as the PETM), the negative δ 13 C excursion has been attributed to the addition of huge amounts of δ 13 C depleted carbon to the ocean and atmosphere.…”