Size-related stable isotope changes in planktic foraminifera across the “Latest Danian Event” (ODP Site 1262, Walvis Ridge)

The Latest Danian Event (LDE, ∼62.15 Ma) represents a transient carbon cycle perturbation on a global scale similar to the Paleocene-Eocene Thermal Maximum, but of a much lower magnitude. This event took place during a time interval that is characterized by major changes in the calcareous plankton communities like the appearance and diversification of the fasciculithid nannolith group and the establishment of dinoflagellate photosymbiosis within the Praemurica/Morozovella planktic foraminifera. Size-related isotope changes (d13C, d18O) of planktic foraminifera might indicate changes in the depth habitat of foraminifera with ontogeny. An increase in d13C with size may point to the existence of (dinoflagellate) photosymbionts, and are often used to identify photosymbiosis in extinct foraminifera. Size fraction data on middle Paleocene taxa are generally rare and only poorly constrained concerning their stratigraphic age. Here we present detailed isotopic data from seven samples across the LDE of seven taxa including the asymbiotic Parasubbotina variospira and various symbiont-bearing taxa of the Praemurica, Morozovella and Igorina lineages that provide new insights into the life style of these taxa. Moreover, we intend to test if photosymbiotic activity changes occur during the LDE.status: publishe

Paleoceanographic changes across the Latest Danian Event in the South Atlantic Ocean and planktic foraminiferal response

A number of short warming events occurred during Paleocene and Eocene, of which the "Paleocene-Eocene Thermal Maximum" (PETM, 56 Ma) is the most severe and most investigated event. The less known "Latest Danian Event" (LDE) at 62.2 Ma represents a 200 ky-lasting warming phase, superimposed on a long-term cooling trend after the Early Paleocene. South Atlantic ODP Site 1262 data, covering ~1 myr, indicate a warming of the entire water column by 1.5-2.6°C, accompanying a prominent negative carbon isotope excursion (~0.9-1.1 ‰) and a long-term re-organization of the planktic foraminiferal fauna associated with the LDE. This study unravels a different paleoceanographic evolution of the upper ocean structure compared to results from Pacific ODP Site 1210. Unlike the Pacific, the Atlantic site lacks an apparent change of stratification as well as an overall dominance of thermocline dwelling planktic foraminifera species and a low abundance of surface dwelling photosymbiotic foraminifera. Within the LDE, indications for a slightly enhanced stratification of the upper water column and transient warming was indicated when surface dwelling planktic foraminifera became temporarily more abundant. The long-term evolution in planktic foraminifera with the disappearance of Praemurica at the LDE onset and a contemporaneous rise in Morozovella is similar to the trends reported from Shatsky Rise ODP Site 1210

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

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.Deutsche ForschungsgemeinschaftKU Leuven http://dx.doi.org/10.13039/501100004040Projekt DEA

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

<jats:title>Abstract</jats:title><jats:p>The Latest Danian Event (LDE, ~ 62.2 Ma) is characterized by global changes in the carbon cycle as indicated by two negative δ<jats:sup>13</jats:sup>C excursions of up to ~ 1‰. These δ<jats:sup>13</jats:sup>C shifts are accompanied by a 2–3 °C warming of both surface and deep waters based on benthic and planktic foraminiferal δ<jats:sup>18</jats:sup>O 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 <jats:italic>Praemurica</jats:italic> 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 <jats:italic>Praemurica</jats:italic> 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.</jats:p><jats:p>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.</jats:p&gt