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| Titel |
Warming, euxinia and sea level rise during the Paleocene–Eocene Thermal Maximum on the Gulf Coastal Plain: implications for ocean oxygenation and nutrient cycling |
| VerfasserIn |
A. Sluijs, L. van Roij, G. J. Harrington, S. Schouten, J. A. Sessa, L. J. LeVay, G.-J. Reichart, C. P. Slomp |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 10, no. 4 ; Nr. 10, no. 4 (2014-07-25), S.1421-1439 |
| Datensatznummer |
250117020
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| Publikation (Nr.) |
 copernicus.org/cp-10-1421-2014.pdf |
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| Zusammenfassung |
The Paleocene–Eocene Thermal Maximum (PETM, ~ 56 Ma) was a
~ 200 kyr episode of global warming, associated with massive
injections of 13C-depleted carbon into the ocean–atmosphere system.
Although climate change during the PETM is relatively well constrained,
effects on marine oxygen concentrations and nutrient cycling remain largely
unclear. We identify the PETM in a sediment core from the US margin of the
Gulf of Mexico. Biomarker-based paleotemperature proxies (methylation of
branched tetraether–cyclization of branched tetraether (MBT–CBT) and
TEX86) indicate that continental air and sea surface temperatures
warmed from 27–29 to ~ 35 °C, although
variations in the relative abundances of terrestrial and marine biomarkers
may have influenced these estimates. Vegetation changes, as recorded from
pollen assemblages, support this warming.
The PETM is bracketed by two unconformities. It overlies Paleocene silt- and
mudstones and is rich in angular (thus in situ produced; autochthonous) glauconite
grains, which indicate sedimentary condensation. A drop in the relative
abundance of terrestrial organic matter and changes in the dinoflagellate
cyst assemblages suggest that rising sea level shifted the deposition of terrigenous
material landward. This is consistent with previous findings of eustatic sea
level rise during the PETM. Regionally, the attribution of the
glauconite-rich unit to the PETM implicates the dating of a primate fossil,
argued to represent the oldest North American specimen on record.
The biomarker isorenieratene within the PETM indicates that euxinic photic
zone conditions developed, likely seasonally, along the Gulf Coastal Plain.
A global data compilation indicates that O2 concentrations dropped in
all ocean basins in response to warming, hydrological change, and carbon
cycle feedbacks. This culminated in (seasonal) anoxia along many continental
margins, analogous to modern trends. Seafloor deoxygenation and widespread
(seasonal) anoxia likely caused phosphorus regeneration from suboxic and
anoxic sediments. We argue that this fueled shelf eutrophication, as widely
recorded from microfossil studies, increasing organic carbon burial along
many continental margins as a negative feedback to carbon input and global
warming. If properly quantified with future work, the PETM offers the
opportunity to assess the biogeochemical effects of enhanced phosphorus
regeneration, as well as the timescales on which this feedback operates in
view of modern and future ocean deoxygenation. |
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