Project Details
Projekt
Oceanographic impact of the Paleocene-Eocene Thermal Maximum in the Southwest Indian Ocean
Subject Area
Geology
Term
since 2024
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 546924764
The modern continuing rise in atmospheric CO2 concentrations is a powerful incentive to improve our understanding of how the climate system operated in greenhouse periods of Earth history, particularly within intervals characterized by geologically rapid climate change. We propose to investigate the most severe short-lived greenhouse warming event of the past ~80 Myr, the Paleocene-Eocene Thermal Maximum (PETM), which abruptly initiated at ~56 Ma and persisted for ~170 kyr. During the PETM, Earth’s surface warmed by 4‒6C within only a few millennia as a result of a massive, rapid injection of carbon to the ocean‒atmosphere system. Due to associated deep-ocean acidification, many pelagic deep-water records are compromised by intense carbonate dissolution across the PETM, thereby preventing development of continuous histories of calcareous-walled plankton. Additionally, marine sedimentary records are affected by bioturbation and/or redistribution of sediments after deposition, thereby causing mixing of different ages of sedimentary components ‒ processes that can fundamentally confound records of short-lived events in the deep sea such as the PETM. We propose to tackle both of these problems through investigation of an extraordinary PETM sequence recently recovered by IODP Expedition 392 on the Agulhas Plateau, Southwest Indian Ocean. Due to relatively shallow water depths (~1500‒2000 m) at ~56 Ma, carbonate dissolution is much less severe at this site compared to other sites and, based on observed cyclic patterns of deposition, the sequence is exceptionally continuous. We will evaluate stable isotopic signatures across the event through state-of-the-art analysis of single shells of planktonic foraminifera. Since an individual planktonic foraminifera shell preserves an “instantaneous” signal from one specific point in time, pre-PETM and PETM shells can be unmixed by their diagnostic isotopic signatures. This approach will establish a robust and precise timeline for the onset of the carbon perturbation associated with the PETM at this site. With this framework in place, we will then: [1] assess changes in calcareous plankton assemblages integrating data from both zooplankton (planktonic foraminiferal) and phytoplankton (calcareous nannofossil) records, and [2] investigate variations in carbonate accumulation and associated lysocline dynamics across the PETM. Critically, we aim to test whether stable isotope signals and marine plankton communities in this region show perturbation immediately prior to the onset of the PETM CIE, the progression of changes during the event, and longer-lasting impacts during the recovery phase. This timely investigation will provide new insight into the deep-sea expression of the PETM and marine biotic change associated with the event. The results will also provide an essential framework for all follow-on studies of this exciting new record of the PETM.
DFG Programme
Infrastructure Priority Programmes
International Connection
USA
Co-Investigator
Dr. Thomas Westerhold
Cooperation Partners
Dr. Ashley Burkett; Dr. Brittany Hupp; Professor Dr. Donald E. Penman
