Extreme warming of tropical waters during the Paleocene–Eocene Thermal Maximum

Aze, Tracy; Pearson, Paul Nicholas; Dickson, Alex; Badger, Marcus P. S.; Bown, Paul R.; Pancost, Richard D.; Gibbs, Samantha J.; Huber, Brian T.; Leng, Melanie J.; Coe, Angela L.; Cohen, A. S.; Foster, Gavin L.

doi:10.1130/g35637.1

Cited by 75 publications

(79 citation statements)

References 27 publications

(17 reference statements)

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“…These observations could be interpreted as supportive evidence for heat stress among planktic eukaryotes and possibly also land plants (Huber, 2008). Aze et al (2014) hypothesized that heat-stress effects may have played a role in Tanzania during the PETM as coccolithophores and foraminifera both decline in abundance, and although calcareous dinoflagellate cysts increase in relative abundance, these also remain at very low absolute abundances (Bown and Pearson, 2009). We surmise that heatstress effects during the PETM may not have been limited to the eastern equatorial Atlantic and western Indian Ocean, although it is difficult with the presently available data to disentangle the effects of dissolution, temperature, and other environmental stressors at all potentially affected sites.…”

Section: Global Tropical Heat Stress?mentioning

confidence: 57%

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

et al. 2018

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Abstract. 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 13 C-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 ‰ 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.

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Section: Global Tropical Heat Stress?mentioning

confidence: 57%

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

et al. 2018

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“…All complete sections below 2,500‐m paleodepth are marked by 100% dissolution (dark blue symbols in Figure ). Moreover, paleoshelf and paleoslope sites from Egypt, Italy, Nigeria, Spain, and Tanzania ranging from 100 to 1,500‐m paleo‐water‐depth, similar to or much deeper than the sites investigated on the Atlantic Coastal Plain, are also characterized by ~100% dissolution during part of the CIE (Alegret et al, ; Aze et al, ; Dupuis et al, ; Frieling et al, ; Giusberti et al, ; Lu et al, ; Schmitz et al, ; green symbols in Figure ). The LCI in Nigerian and Tanzanian sections has been attributed to temperatures during the height of the PETM that exceeded the tolerance of planktonic calcifiers (Aze et al, Frieling et al, , ).…”

Section: Discussionmentioning

confidence: 92%

Evidence for Shelf Acidification During the Onset of the Paleocene‐Eocene Thermal Maximum

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et al. 2018

Paleoceanog and Paleoclimatol

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A transect of paleoshelf cores from Maryland and New Jersey contains an ~0.19‐ to 1.61‐m‐thick interval with reduced percentages of carbonate during the onset of the Paleocene‐Eocene Thermal Maximum (PETM). Outer paleoshelf cores are barren of nannofossils and correspond to two minor disconformities. Middle paleoshelf cores contain a mixture of samples devoid of nannofossils and those with rare specimens characterized by significant dissolution (i.e., etching). The magnitude of the decrease in carbonate cannot be explained by dilution by clastic material or dissolution resulting from the oxidation of organic matter during early diagenesis. The observed preservation pattern implies a shoaling of the calcite compensation depth and lysocline to the middle shelf. This reduced carbonate interval is observed during the onset of the PETM on other continental margins raising the possibility that extreme shoaling of the calcite compensation depth and lysocline was a global signal, which is more significant than in previous estimates for the PETM. An alternative scenario is that shoaling was restricted to the northwest Atlantic, enhanced by regional and local factors (eutrophication from rivers and microbial activity associated with warming) that exacerbated the impact of acidification on the shelf.

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“…7). Elsewhere, temperature anomalies within the PETM range from +4-5 • C in low latitudes (Zachos et al, 2003;Aze et al, 2014) to +8 • C in high latitudes (Thomas et al, 2002;Frieling et al, 2014) and some low-latitude coastal sites (Zachos et al, 2006).…”

Section: Paleotemperaturementioning

confidence: 99%

The Paleocene–Eocene Thermal Maximum at DSDP Site 277, Campbell Plateau, southern Pacific Ocean

et al. 2015

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Abstract. Re-examination of sediment cores from Deep Sea Drilling Project (DSDP) Site 277 on the western margin of the Campbell Plateau (paleolatitude of ∼ 65 • S) has identified an intact Paleocene-Eocene (P-E) boundary overlain by a 34 cm thick record of the Paleocene-Eocene Thermal Maximum (PETM) within nannofossil chalk. The upper part of the PETM is truncated, either due to drilling disturbance or a sedimentary hiatus. An intact record of the onset of the PETM is indicated by a gradual decrease in δ 13 C values over 20 cm, followed by a 14 cm interval in which δ 13 C is 2 ‰ lighter than uppermost Paleocene values. After accounting for effects of diagenetic alteration, we use δ 18 O and Mg / Ca values from foraminiferal tests to determine that intermediate and surface waters warmed by ∼ 5-6 • at the onset of the PETM prior to the full development of the negative δ 13 C excursion. After this initial warming, sea temperatures were relatively stable through the PETM but declined abruptly across the horizon that truncates the event at this site. Mg / Ca analysis of foraminiferal tests indicates peak intermediate and surface water temperatures of ∼ 19 and ∼ 32 • C, respectively. These temperatures may be influenced by residual diagenetic factors and changes in ocean circulation, and surface water values may also be biased towards warm-season temperatures.

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Extreme warming of tropical waters during the Paleocene–Eocene Thermal Maximum

Cited by 75 publications

References 27 publications

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

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

Evidence for Shelf Acidification During the Onset of the Paleocene‐Eocene Thermal Maximum

The Paleocene–Eocene Thermal Maximum at DSDP Site 277, Campbell Plateau, southern Pacific Ocean

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