Abstracts > Pige Nicolas

The Paleocene-Eocene transition displayed several greenhouse gas-induced hyperthermal events, the best known being the Paleocene-Eocene Thermal Maximum (PETM; -56 Ma). The abrupt associated changes in environmental conditions may have deeply impacted coccolithophores which remains constitute a major component of deep-sea sediments. These single-celled algae are major players of the carbon cycle since, they consume CO2 for photosynthesis, and produce calcite platelets named coccoliths. Knowing the dissolution dynamics of calcareous nannofossils throughout the water column is essential to produce realistic carbon budgets across hyperthermal events.

In this work, we analyze the ODP Site 1209 (North Pacific) to reconstruct accumulation fluxes of coccoliths reaching the ocean floor during the latest Paleocene to earliest Eocene. For this, we use a high-resolution record of extra-terrestrial 3He-derived sedimentation rates. We compared the obtained fluxes to different proxies of dissolution (planktonic foraminifera fragmentation and coarse fraction) to disentangle the preservation and CaCO3 accumulation (mainly represented by coccoliths) signals recorded in the studies strata.

Our findings challenge the widely accepted model previously proposed for hyperthermal events, assuming that the CaCO3 accumulation is mainly controlled by dissolution. Indeed, our results suggest that it exist a strong causal (?) relationship between CaCO3 accumulation and the temperature for most of the Late Paleocene hyperthermal events.