Characterizing the evolution of Messinian Mediterranean-Atlantic exchange and deciphering their impact on global climate: A palynological and climate reconstruction approach

About This Grant

This project evaluates the importance of ocean gateways, the connection between two important bodies of water. Specifically, the movement of tectonic plates has caused the Gibraltar and other straits to close multiple times in Earth’s history, separating the Mediterranean Sea from the Atlantic Ocean. Because ocean circulation is density-driven, isolating the salty, dense Mediterranean waters from the Atlantic can influence global circulation as well as regional climate. This project uses palynology, or the study of microscopic fossils of pollen, spores, and dinoflagellate cysts preserved in sediment. Sediment cores were collected during an expedition at four sites on either side of the Atlantic-Mediterranean gateway. The species of pollen, spores, and dinoflagellates present in a sample correspond to what the air temperature (pollen, spores) and sea surface temperature (dinoflagellates) would have been at the time. By examining changes in species abundance over time, this project will uncover how the opening and closing of ocean gateways influences climate. The project will train three future palynologists: one undergraduate student and two graduate students. Training the next generation of U.S. palynologists is important as this specialized branch of science serves a key role in many important economic and intelligence fields, including forensic science, agriculture, and oil and gas exploration. The lead researcher will also collaborate with artist Rebecca Kamen to create “The Secret Tales of Pollen” exhibit. This exhibit will showcase sculptures and photography of various types of pollen and provide details about what these fossils teach us. The exhibit will be on display in Louisiana, but content will also be shared online. Here, art and science combine to boost public engagement in science and foster understanding of how fossils can be used to study Earth through geological time. Marine exchange between the Mediterranean and Atlantic occurred through relatively narrow paleo-gateways. Previous studies have proposed that changes at the paleo-straits impacted the evolution of thermohaline circulation at a global scale. The International Ocean Discovery Program (IODP) Expedition 401 recently recovered key expanded and continuous upper Miocene sediments on the Atlantic and Alboran Sea margins, on each side of the Gibraltar Strait. This research will entail high resolution palynological analyses of these cores between 8 and 4 million years ago to reconstruct water-mass and local environmental changes leading up to, during, and after the Messinian Salinity Crisis at four IODP Expedition 401 sites. Results will be used as input for two different climate reconstruction methods. Finally, microcharcoal particles will be used to quantify regional aridity and fire history. Reconstructing marine and terrestrial conditions across this interval is important as the way Earth systems currently distribute heat and salt in the world’s oceans were established during this timeframe. This proposal is part of a larger international and multidisciplinary investigation of how these local changes affect global-scale changes. The palynological reconstruction will be carried out by Louisiana State University undergraduate and graduate students. Palynological results will be shared with the general audience through a new art exhibit featuring pollen sculptures and photography. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.