Hot carbonates deep within the Chicxulub impact structure

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Abstract

Constraining the thermodynamic conditions within an impact structure during and after hypervelocity impacts is extremely challenging due to the transient thermal regimes. This work uses carbonate clumped-isotope thermometry to reconstruct absolute temperatures of impact lithologies within and close to the ∼66 Myr old Chicxulub crater (Yucatán, México). We present stable oxygen (δ18O), carbon (δ13C), and clumped-isotope (Δ47) data for carbonate-bearing impact breccias, impact melt rock, and target lithologies from four drill cores on a transect through the Chicxulub structure from the northern peak ring to the southern proximal ejecta blanket. Clumped isotope-derived temperatures (T(Δ47)) are consistently higher than maximum Late Cretaceous sea surface temperatures (35.5°C), except in the case of Paleogene limestones and melt-poor impact breccias outside of the crater, confirming the influence of burial diagenesis and a widespread and long-lived hydrothermal system. The melt-poor breccia unit outside the crater is overlain by melt-rich impact breccia yielding a much higher T(Δ47) of 111 ± 10°C (1 standard error [SE]), which likely traces the thermal processing of carbonate material during ejection. Finally, T(Δ47) up to 327 ± 33°C (1 SE) is determined for the lower suevite and impact melt rock intervals within the crater. The highest temperatures are related to distinct petrological features associated with decarbonation and rapid back-reaction, in which highly reactive CaO recombines with impact-released CO2 to form secondary CaCO3 phases. These observations have important climatic implications for the Cretaceous–Paleogene mass extinction event, as current numerical models likely overestimate the release of CO2 from the Chicxulub impact event.
Original languageEnglish
Article numberpgad414
Pages (from-to)1-14
Number of pages14
JournalPNAS Nexus
Volume3
Issue number1
DOIs
Publication statusPublished - 1 Jan 2024

Bibliographical note

Funding Information:
This research is financially supported by the Belgian Federal Science Policy (BELSPO) project Chicxulub and the Research Foundation—Flanders (FWO; Fonds Wetenschappelijk Onderzoek) project G0A6517N to P.C. P.K. is supported by FWO PhD fellowship 11E6621N. P.C. and S.G. thank the Excellence of Science project “ET-HoME” and the VUB Strategic Research Program for support, as well as the FWO—Hercules Program for financing the μXRF and SIRMS instrument at the VUB.

Funding Information:
Bart Lippens and Priya Laha (VUB) are thanked for sample preparation and assistance with SEM-EDS analyses, and David Verstraten (VUB) for assistance with the SIRMS instrument. The authors are grateful to David Burtt (Stony Brook University) for providing the Rayleigh model outputs used in Fig. . This project was supported by data and samples from International Ocean Discovery Program (IODP)–International Continental Scientific Drilling Program (ICDP) Expedition 364. We would like to thank the associate editor and two anonymous reviewers for their constructive suggestions which improved the quality of this paper.

Publisher Copyright:
© The Author(s) 2024. Published by Oxford University Press on behalf of NAR Cancer.

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