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Abstract

The Cretaceous–Paleogene boundary (∼66 million years ago) represents the most recent mass extinction event when an estimated 75% of all species became extinct, including all non-avian dinosaurs. Here we focus on the stable carbon isotope (δ13C) analysis of coal and coaly sediments across the terrestrial K/Pg boundary from 10 sites, between 42 and 64°N, USA and Canada. Our δ13C data set shows a statistically significant positive correlation with paleolatitude that we interpret as a consequence of our lower latitude sites being relatively warmer and more humid than our higher latitude sites. Temporally, our data indicates that the K/Pg boundary event is represented by a unique carbon isotope shift that can be readily separated from background excursions through the latest Maastrichtian and earliest Paleogene. This excursion reaches a minimum several centimeters above the K/Pg boundary. Published geochronological constraints on our data suggest the observed carbon isotope excursion at the K/Pg boundary lasted between 10 and 36 kyr and possibly outlasted the fall-out of material injected into the atmosphere by bolide impact. Such a short duration for the K/Pg negative excursion contrasts with some marine records and in this respect may be more related to shallow marine or neritic zone responses to global sea-level and/or climatic change resulting in shorter-lived localized or regional water column deoxygenation. Notably, a short duration negative excursion at the K/Pg is compatible with events associated with the Chicxulub impact.

Publication Date

2026-07-11

Publication Title

Paleoceanography and Paleoclimatology

Volume

41

Issue

7

ISSN

2572-4517

Acceptance Date

2026-06-25

Deposit Date

2026-08-05

Funding

Natural Environment Research Council. Grant Number: NE/S002324/1

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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