Thermal stress on the biosphere during the extreme warmth of the
Paleocene–Eocene Thermal Maximum (PETM) was most severe at low
latitudes, with sea surface temperatures at some localities exceeding
the 35
The Paleocene–Eocene Thermal Maximum (PETM) was a period of global
warming associated with ocean acidification, an intensified
hydrological cycle, a reduction in marine dissolved oxygen
concentrations, eustatic sea level rise, and major ecological shifts
(e.g., Zachos et al., 2003; Gingerich 2006; Dickson et al., 2014;
Sluijs et al., 2008; Carmichael et al., 2017). Recent age estimates
place the PETM at approximately 55.93–55.71
Paleocene–Eocene Thermal Maximum (55.8
International Ocean Discovery Program–International Continental
Scientific Drilling Program (IODP–ICDP) Site M0077 is located on the peak
ring of the Chicxulub impact crater in the Yucatán Peninsula,
Mexico (Fig. 1) (Morgan et al., 2017). The crater was a marine
basin in the Paleogene, with mainly pelagic and outer-platform
sediment deposition (Lefticariu et al., 2006). Immediately after
impact, some of the rim may have been subaerially emergent (Morgan
et al., 1997) but if so would have been quickly eroded. During the
PETM, only isolated areas of the crater rim may have been emergent,
given the existence of an embayment into the crater to the north and
northeast (Gulick et al., 2008). Although PETM records from the Gulf
of Mexico are scarce, another site in the Chicxulub crater, the
Yaxcopoil-1 (Yax-1) core, contains a PETM section identified by a
negative carbon isotope excursion, deposited during a period of
maximum flooding (Whalen et al., 2013) (Fig. 1). The PETM has also
been identified on the Mississippi paleo-shelf (Fig. 1), where evidence
indicates increased TEX
Quantitative palynological abundances are expressed in terms of
specimens per gram using a
IODP–ICDP drilling at Site M0077 recovered Paleocene to early Eocene
post-impact sedimentary rocks between 617.33 and 505.70
Stratigraphic column of Site M0077. Palynological concentrations
(CC) are given as specimens per gram.
The PETM interval (607.27–607.06
Bioturbation is absent to minimal in the PETM, with rare
Total organic carbon (TOC) is low above and below the PETM (Fig. 2),
with high concentrations (
TEX
Nannofossil abundances decrease through the PETM section and become
rare in the post-PETM section. Foraminifera at Site M0077 are abundant
in the upper Paleocene section but are absent to very rare in the PETM
section, with evidence of reworking. Dinosteranes, biomarkers
associated with dinoflagellates (e.g., Summons et al., 1987), have
relatively high concentrations in the upper Paleocene and lower PETM
section, with decreased abundance in the PETM and post-PETM
sections. Organic-walled microfossils are absent to rare in the
Paleocene. Dinoflagellate cyst concentrations peak at
607.26
As described earlier, the PETM section in the Site M0077 core is
bracketed by unconformities and incomplete, with the onset and
recovery missing, and only part of the PETM section is preserved. The
fine-grained nature and lack of sedimentary structures indicating
current deposition indicate that the PETM interval recovered was
deposited in relatively deep, quiet water with sediments largely
settling from suspension. The laminated black shale points toward low
oxygen conditions. However, the trace fossil assemblage implies that
anoxia and/or euxinia were likely intermittent. Water depths for Site
M0077 during most of the Paleocene were on the order of
600–700
The PETM age of the shale interval at Site M0077
(607.27–607.06
SSTs were estimated using the relative abundance of thaumarchaeotal
isoGDGTs. Here we used the TEX
TEX
Several lines of evidence indicate increased terrestrial input during
the PETM, including increased concentrations of terrestrial
palynomorphs, increased D
The relative abundance of the clay mineral palygorskite increases through the PETM section. Higher abundances of palygorskite in other PETM sediments have been interpreted as evidence for increased aridity (Carmichael et al., 2017), as palygorskite commonly forms in coastal marine environments in which continental alkaline waters are concentrated by evaporation (Bolle and Adatte, 2001). At Site M0077, the palygorskite may have originally formed in hypersaline lagoonal environments similar to other Eocene–Oligocene palygorskite deposits in the Yucatán Peninsula (de Pablo Galán, 1996). The increase in the relative abundance of palygorskite through the PETM section may therefore be the result of increased fluvial transport of sediments to Site M0077 from lagoonal environments to the south rather than the result of increased aridity.
The near absence of bioturbation in the PETM section, with preserved
sedimentary lamination and high TOC, is consistent with bottom water
anoxia through much of the PETM, and sulfur bacteria biomarkers are
indicative of photic zone euxinia (e.g., Summons and Powell, 1987;
Grice et al., 2005; Sluijs et al., 2014) in the earlier PETM
record. Depleted
In the Paleocene interval at Site M0077, carbonate deposition
dominates and palynomorphs are nearly absent, probably due to poor
preservation of organic material (Lowery et al., 2018, 2020). Low
values of TOC
A notable acme of fungal spores occurs in the middle part of the
PETM. This acme is dominated by aff.
The PETM pollen and plant spore assemblage is broadly similar to later
Ypresian assemblages observed higher in the core, with angiosperm
pollen dominant, particularly reticulate tricolpate–tricolporate
pollen of unknown lower botanical affinity (e.g.,
The PETM in the Chicxulub impact crater was a time of extremely high
SSTs (
All data and supplementary methods are included in the Supplement.
The supplement related to this article is available online at:
IODP–ICDP Expedition 364 Scientists: Joanna Morgan (Department of Earth Science and Engineering, Imperial College London, UK), Sean P. S. Gulick (Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78712, USA; Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78712, USA), Claire Mellett (British Geological Survey, The Lyell Center, UK), Johanna Lofi (CNRS, Aix-Marseille Univ, IRD, Coll France; INRAE, CEREGE, Aix-en-Provence, France), Elise Chenot (GeoRessources, Université de Lorraine, CNRS, France), Gail Christeson (Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78712, USA), Phillippe Clayes (Analytical, Environmental, and Geo-Chemistry, Vrije Universiteit Brussel, Belgium), Charles Cockell (Center for Astrobiology, School of Physics and Astronomy, University of Edinburgh, UK), Marco Coolen (Department of Chemistry, Western Australian Organic and Isotope Geochemistry Centre (WA-OIGC), Curtin University, Australia), Ludovic Ferrière (Natural History Museum, Austria), Catalina Gebhardt (Alfred Wegener Institute Helmholtz Centre of Polar and Marine Research, Germany), Kazuhisa Goto (International Research Institute of Disaster Science, Tohoku University, Japan), Heather Jones (Department of Geosciences, Pennsylvania State University, University Park, PA 16801, USA), David Kring (Lunar and Planetary Institute, Houston, TX 77058, USA), Christopher Lowery (Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, TX 78712, USA), Rubén Ocampo-Torres (Groupe de Physico-Chimie de l'Atmosphère, L'Institut de chimie et procédés pour l'énergie, l'environnement et la santé (ICPEES), France), Ligia Perez-Cruz (Instituto de Geofísica, Universidad Nacional Autónoma De México, Mexico), Annemarie E. Pickersgill (School of Geographical and Earth Sciences, University of Glasgow, UK), Michael Poelchau (Department of Geology, University of Freiburg, Germany), Auriol Rae (Department of Earth Science and Engineering, Imperial College London, UK), Cornelia Rasmussen (Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, USA), Mario Rebolledo-Vieyra (Unidad de Ciencias del Agua, Centro de Investigación Científica de Yucatán, A.C., Mexico), Ulrich Riller (Institut für Geologie, Universität Hamburg, Germany), Honami Sato (Japan Agency for Marine-Earth Science and Technology, Japan), Jan Smit (Faculty of Earth and Life Sciences FALW, Vrije Universiteit Amsterdam, Netherlands), Sonia Tikoo (Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ 08854, USA), Naotaka Tomioka (Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Japan), Michael Whalen (Department of Geosciences, University of Alaska Fairbanks, Fairbanks, AK 99775, USA), Axel Wittmann (LeRoy Eyring Center for Solid State Science, Arizona State University, AZ 85281, USA), Kosei Yamaguchi (Department of Chemistry, Toho University, Japan), Long Xiao (School of Earth Sciences, Planetary Science Institute, China University of Geosciences (Wuhan), China), William Zylberman (CNRS, L'Institut de recherche pour le développement, Coll France, Aix Marseille University, France).
VS led the writing and organization of the paper. VS, SW, NBNO, and JMKO'K analyzed the terrestrial palynology. JV analyzed the dinoflagellate assemblages. KG, BS, ThB, and LS provided biomarker data and interpretation. MTW provided carbon and nitrogen isotopes and sedimentological evaluation of the core. KO'M provided additional isotope and geochemical data. IA, JAA, and CML researched the foraminiferal assemblages. EC provided clay mineralogy data. HJ provided nannofossil data. FJRT provided ichnological data. JG and FD provided magnetic data. SPSG, TiB, JL, JM, and other co-authors assisted with conceptualization and writing of the paper.
The authors declare that they have no conflict of interest.
This research used samples and data provided by the International Ocean Discovery Program (IODP). Thanks to Roger E. Summons and Xingqian Cui (MIT, US) for MRM analyses. This is University of Texas Institute for Geophysics contribution no. 3676 and Center for Planetary Systems Habitability contribution no. 0013.
This research has been supported by the CENEX (Center for Excellence in Palynology) Endowed Chair Fund, a scholarship from Louisiana State University, a 2018 James M. and Thomas J. M. Schopf Award Student Research Grant from the Paleontological Society, an ARC-Discovery grant (DP180100982) from the Australian Research Council (ARC), a postgraduate award from Curtin University, IODP-France, the Research Foundation 100 Flanders (FWO grant 12Z6618N), NERC grant NE/P005217/1, and National Science Foundation OCE grants 14-50528, 1737199, 1736951, and 1737351.
This paper was edited by Alberto Reyes and reviewed by C. Jaramillo and Kate Littler.