Tropical Atlantic climate and ecosystem regime shifts during the Paleocene-Eocene Thermal Maximum

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doi: 10.5194/cp-14-39-2018
Author(s): Frieling, Joost; Reichart, Gert-Jan; Middelburg, Jack J.; Röhl, Ursula; Westerhold, Thomas; Bohaty, Steven M.; Sluijs, Appy
Author Affiliation(s): Primary:
Utrecht University, Laboratory of Palaeobotany and Palynology, Utrecht, Netherlands
Nederlands Instituut voor Zeeonderzoek, Netherlands
University of Bremen, Germany
University of Southampton, United Kingdom
Volume Title: Climate of the Past
Source: Climate of the Past, 14(1), p.39-55. Publisher: Copernicus, Katlenburg-Lindau, International. ISSN: 1814-9324
Note: In English. 120 refs.; illus., incl. 1 table, sketch map
Summary: The Paleocene-Eocene Thermal Maximum (PETM, 56 Ma) was a phase of rapid global warming associated with massive carbon input into the ocean-atmosphere system from a 13C-depleted reservoir. Many midlatitude and high-latitude sections have been studied and document changes in salinity, hydrology and sedimentation, deoxygenation, biotic overturning, and migrations, but detailed records from tropical regions are lacking. Here, we study the PETM at Ocean Drilling Program (ODP) Site 959 in the equatorial Atlantic using a range of organic and inorganic proxies and couple these with dinoflagellate cyst (dinocyst) assemblage analysis. The PETM at Site 959 was previously found to be marked by a ∼ 3.8 ppm negative carbon isotope excursion (CIE) and a ∼ 4 °C surface ocean warming from the uppermost Paleocene to peak PETM, of which ∼ 1 °C occurs before the onset of the CIE. We record upper Paleocene dinocyst assemblages that are similar to PETM assemblages as found in extratropical regions, confirming poleward migrations of ecosystems during the PETM. The early stages of the PETM are marked by a typical acme of the tropical genus Apectodinium, which reaches abundances of up to 95 %. Subsequently, dinocyst abundances diminish greatly, as do carbonate and pyritized silicate microfossils. The combined paleoenvironmental information from Site 959 and a close-by shelf site in Nigeria implies the general absence of eukaryotic surface-dwelling microplankton during peak PETM warmth in the eastern equatorial Atlantic, most likely caused by heat stress. We hypothesize, based on a literature survey, that heat stress might have reduced calcification in more tropical regions, potentially contributing to reduced deep sea carbonate accumulation rates, and, by buffering acidification, also to biological carbonate compensation of the injected carbon during the PETM. Crucially, abundant organic benthic foraminiferal linings imply sustained export production, likely driven by prokaryotes. In sharp contrast, the recovery of the CIE yields rapid (<<10 kyr) fluctuations in the abundance of several dinocyst groups, suggesting extreme ecosystem and environmental variability.
Year of Publication: 2018
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Africa; Apectodinium; Assemblages; Atlantic Ocean; Bottom water; Carbonates; Caribbean Sea; Cenozoic; Chemical composition; Climate; Climate change; Colombian Basin; Concentration; Cores; Cyclic processes; Demerara Rise; Depositional environment; Dinoflagellata; Dissolved oxygen; East Pacific; Ecosystems; Emission spectra; Equatorial Atlantic; Equatorial Pacific; Eukaryotes; Global; ICP mass spectra; Leg 143; Leg 159; Leg 165; Leg 198; Leg 199; Leg 207; Magnetic properties; Magnetic susceptibility; Marine environment; Mass spectra; Microfossils; Mid-Pacific Mountains; Nicaragua Rise; Nigeria; North Atlantic; North Pacific; Northeast Pacific; Northwest Atlantic; Northwest Pacific; ODP Site 1001; ODP Site 1209; ODP Site 1215; ODP Site 1220; ODP Site 1221; ODP Site 1260; ODP Site 865; ODP Site 959; ODP Site 999; Ocean Drilling Program; Oxygen; Pacific Ocean; Paleocene; Paleocene-Eocene Thermal Maximum; Paleoclimatology; Paleoecology; Paleogene; Paleomagnetism; Palynomorphs; Sea-level changes; Sediments; Shatsky Rise; Shelf environment; Solutes; Spectra; Temperature; Tertiary; Tropical environment; Upper Paleocene; Variations; West Africa; West Atlantic; West Pacific; X-ray fluorescence spectra
Coordinates: N033740 N033740 W0024408 W0024408
Record ID: 2018027986
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Copernicus Gesellschaft, Katlenburg-Lindau, Germany