Shallow marine response and latitudinal variation across the Middle Eocene Climatic Optimum

Shallow marine environments are known to be incredibly important for biodiversity and the ocean’s chemical cycles. However, the current anthropogenic climate change means they are under threat (e.g. bleaching of coral reefs). Whilst researchers can and have cultured different shallow marine organisms in the laboratory under different temperatures and other climatic conditions, it is not possible to do this on a time scale that matches that of the natural world. We therefore must look to climate events in the geological past to better understand the impact that rapid climate change has on these environments.

The Middle Eocene Climatic Optimum (MECO) is one such prominent event. The MECO is a 500,000 year warming interval that occurred at ~40 million years ago, with elevated volcanic outgassing suggested as a possible causal mechanism. It is associated with up to a 6°C increase in sea surface temperatures and widespread ocean acidification. This rapid climate change induced shifts in biota and seasonality across low to high latitudes. However, despite their importance for the ocean, very few studies have addressed how the MECO impacted the shallow marine ecosystems.

In this project we will collect samples from sections in the Cap Bon Peninsula in Tunisia, which are known to contain the MECO interval. The region contains both deep ocean sediments and shallow platform carbonates which will allow us to correlate shallow marine biotic events to global stratigraphy. The presence of larger foraminifera and oyster fossils will also allow us to carry out seasonality studies using clumped isotopes from before, during and after the MECO – allowing us to examine the impact of the MECO on seasonality in detail. Analysis of volatile heavy metals will be used to determine if volcanism may have been a driving force behind the MECO. To examine the latitudinal variation in the response to the MECO we will compare these Tunisian results with Kysing-4 borehole from the North sea.

By combining palaeontological, geological and geochemical studies of these two key sites, we will be able to assess the extent and impact of the MECO on shallow marine ecosystems with implications for understanding their response to future warming scenarios.