Carbonate Geochemistry

Reasearch Group Dr. Sierra Petersen

Research in the Carbonate Geochemistry Lab focuses on reconstructing past climate and ocean conditions across Earth history using geochemical tools such as clumped and stable isotopes of carbonate shell fossils and linking those changes in climate to changes in marine life. We have ongoing projects focusing on the Cretaceous, Pliocene, and Pleistocene. Using different sampling methods, we can looking at climate changes on the scale of millions of years down to seasons.

Many of our projects relate reconstructed climate changes to changes in the marine faunal records, applying techniques from palaeontology. For example, we study how climate change contributed to the well known Cretaceous-Paleogene mass extinction and the lesser known regional marine extinction event in the Plio-Pleistocene Western Atlantic. 

We also use the same isotopic tools to probe physiology of marine mollusks, past and present. Differences in the isotopic composition of the inner and outer layers of marine bivalves reflect body processes and precipitation mechanisms, which may respond to environmental stress or be linked to inherited traits. Isotopic sampling can also reveal the season of spawning for bivalves, which can shift with climate change in interesting ways. 

Finally, in order to best interpret reconstructed d18Osw values from the ancient ocean, we study variations in modern d18Osw in coastal regions. Sampling occurs from shore and from the Eugen Seibold.