174-6 Palaeoecological response to Earth System changes across the Cenomanian – Turonian boundary in the UK Chalk Sea

Session: Environmental Instability During Greenhouse Periods: Impact on Terrestrial and Marine Ecosystems

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The Cenomanian-Turonian boundary interval (Late Cretaceous ~93.9 myrs ago) coincides with a dramatic period of environmental change. This includes the global carbon cycle perturbation of Oceanic Anoxic Event 2 (OAE-2), rapid changes in seawater oxygenation and temperature on both a local and global scale (e.g., the ‘Plenus Cold Event’ and early Turonian thermal maximum), as well as sea level and productivity fluctuations. Despite a wealth of proxy and geological data, the effects of these events on the diversity and functional ecology of marine ecosystems remain uncertain. The Chalk Group of the United Kingdom provides a complete and abundantly fossiliferous record across this interval within the Anglo-Paris Basin, and is currently the focus of the ChaSE (Chalk Sea Ecosystems) project. Using extensive macrofossil collections from the expanded Cenomanian-Turonian marine sedimentary sequence exposed at Eastbourne (East Sussex, United Kingdom) held at the Natural History Museum, London as well as new quantitative field and geochemical proxy data, we document several intervals across the broad C-T boundary interval where the marine macrofauna in the UK Chalk Sea underwent significant changes in both taxonomic and functional diversity. We demonstrate how these data are related to and driven by each of the environmental changes outlined above, and how they provide important evidence for the complex regional response, and resilience, of marine ecosystems to Earth System perturbations in the greenhouse world of the Late Cretaceous.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-8718

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