EGU23-8959, updated on 02 Jan 2024
EGU General Assembly 2023
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Geochemical records of environmental change in the central Western Interior Seaway during the Cenomanian–Turonian Oceanic Anoxic Event (OAE 2)

Lawrence Percival1, Niels van Helmond2, Guy Plint3, Nina Papadomanolaki4, Yue Gao1, Steven Goderis1, and Philippe Claeys1
Lawrence Percival et al.
  • 1Analytical Environmental and Geochemistry Group (AMGC), Vrije Universiteit Brussel, Brussels, Belgium
  • 2Department of Earth Sciences, Utrecht University, Utrecht, The Netherlands
  • 3Department of Earth Sciences, University of Western Ontario, London, Ontario, Canada
  • 4CRNS, Centre Européen de Recherche et D’enseignement de Geosciences de L’environnement (CEREGE), Aix-en-Provence, France

The Cenomanian–Turonian Oceanic Anoxic Event (OAE 2: 94 Ma) marked one of the most severe episodes of climate and environmental change during the Cretaceous Period. The primary feature of this interval was widespread marine anoxia/euxinia, leading to deposition of organic-rich, thinly-bedded, mudstones across the world’s oceans, which in turn caused a pronounced positive shift in δ13C of seawater that is recorded (and characterizes) OAE 2 strata worldwide. The event was also marked by climate warming (with superimposed cooling pulses), biotic stress, and terrestrial perturbations such as increased continental weathering. However, the majority of studied records of OAE 2 were deposited in deep-marine Atlantic and Tethyan settings or European epicontinental basins. Thus, the record of environmental change in other locations or environments is less clear.


The Western Interior Seaway (WIS) represented a marine corridor across North America that connected the Arctic and Atlantic marine realms. Thus, understanding the environmental and oceanographic changes in the WIS during OAE 2 is crucial to resolving the wider impact of the event across the global marine realm. Several previous works have focused on sites towards the southern end of the WIS (e.g., Pueblo, Iona Core). In this study, we present a new multi-proxy geochemical dataset from a site in the central–northern part of the Western Interior Seaway: Pratts Landing (western Alberta, Canada). Previous palynological studies have highlighted a southward migration of boreal dinoflagellates during the Plenus Cold Event midway through OAE 2, as well as increased input of terrestrial organic matter. Here, we correlate these data with information from redox, nutrient, and volcanic proxies, and compare the Pratts Landing record with other deep- and shallow-marine records of OAE 2 to gain a wider perspective over the environmental changes that operated in different settings during that time interval. This viewpoint is key for understanding the differences and complexities in how surface phenomena were disturbed during OAE 2, and interpreting geochemical records of different settings during that time interval.

How to cite: Percival, L., van Helmond, N., Plint, G., Papadomanolaki, N., Gao, Y., Goderis, S., and Claeys, P.: Geochemical records of environmental change in the central Western Interior Seaway during the Cenomanian–Turonian Oceanic Anoxic Event (OAE 2), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8959,, 2023.