Planktic Foraminiferal Response to the “Latest Danian Event” (62.15 Ma) on an almost Global Scale – results from Shatsky Rise, Walvis Ridge and Newfoundland

Abstract:

The marine ecosystem of the Paleocene was disturbed by several transient warming events. One of these is the Latest Danian Event (LDE aka “Top C27n Event”). In deep-sea records the LDE is usually characterized by two distinctive XRF Fe peaks, paralleled by a ~0.7 ‰ negative δ¹³C excursion (prev. publ.). Here we present new stable isotope and faunal datasets from planktic foraminifera representing three ocean basins: The Pacific is covered by ODP Site 1210, the South Atlantic by ODP Site 1262 and the North Atlantic by IODP Site U1407. We compare the generated datasets in aspects of biotic response (planktic foraminifera), carbonate preservation as well as δ¹⁸O and δ¹³C signals of surface, subsurface and benthic taxa covering a time span of 900 kyr around the event to figure out to what extent the LDE influenced oceans and biota.

At Site 1210 a drop in planktic and benthic δ¹⁸O record suggest a temperature rise of ~2.5°C within 100 ky which is on the same scale as the benthic δ¹⁸O shift at 1209 (prev. publ.) suggesting the LDE to be a further potential Paleocene hyperthermal. Multivariate statistics imply distinct faunal changes starting below the LDE. A different assemblage after the event was observed specifically in photosymbiont-bearing taxa including the disappearance of Praemurica spp. and the strong increase of Igorina albeari . Minor dissolution is considered to be present during the LDE according to enhanced test fragmentation and decreased CaCO₃ and planktic foraminifera test abundance. A rising δ¹³C gradient between surface and subsurface dwelling foraminifera suggests sudden increased stratification of the upper water column ~100 ky below the LDE, strongly enhanced during it and less but still high above it. This might include a shallower thermocline and be linked to the development of a deep-chlorophyll maximum.

Faunal assemblages of 1262 show a similar development with an overall higher abundance of subsurface dwellers. Multivariate statistisc hint towards a change of the community during and after the LDE in contrast to Site 1210. Benthic δ¹⁸O and δ¹³C reflect the two Fe peaks and imply a ~2.8°C bottom water warming. Bulk-rock δ¹³C trends of U1407 are comparable to the other sites, the CaCO3 record shows strong response to the event, but a distinct lithological expression of the LDE is not apparent.