[June 19th 2023]3rd CO world Seminar

Third CO world Seminar

Presenter: Aradhna E. Tripati (UCLA)
Title: Frontiers of carbonate clumped isotope geochemistry as an applied tool in climatology and oceanography, within an inclusive science framework
Date: 6/19 (Mon) from:16:30 @MISHIMA Hall
The emergence of new proxies enables us to address fundamental questions about Earth’s climate evolution. A promising tool for the study of past conditions is the carbonate clumped isotope thermometer. In principle, this technique can provide a thermodynamically-based estimate of carbonate mineral formation temperature and a relatively assumption-free calculation of the oxygen isotopic composition of water. Over the past fifteen years, I have worked to develop its usability for paleoenvironmental, paleoclimatic, and paleoceanographic reconstructions. These efforts include studying the systematics of carbonate clumped isotopes in field-collected and cultured foraminifera and coccoliths and other archives including coral, mollusks, and lacustrine carbonates, measuring inorganic samples that are experimentally grown, and advancing theory. In this talk, I will summarize work we have done to improve measurement capabilities, advance this tool, and highlight several applications to reconstruct past temperatures.

Presenter:Robert Eagle (UCLA)
Title: Insights into the thermal physiology and trophic levels of extinct vertebrates from the chemistry of fossils: from dinosaurs to gigantic sharks
Date: 6/19 (Mon) from: 17:15 @MISHIMA Hall
13C-18O isotope ordering in carbonate groups in calcite, aragonite, and apatite is temperature-dependent and forms the basis of a tool for paleothermometry. Here I summarize our previous work showing that this isotope signature in teeth and eggshells reflects body temperatures of the organisms that produce them and report a new temperature calibration derived using shark and fish teeth. I show that there is potential to reconstruct the body temperatures of extinct organisms from measurements on well-preserved fossils. We have reported results from dinosaurs such as Camarasaurus and present new data on sharks such as Otodus megalodon, and in both cases we find body temperatures that are consistent with a degree of endothermy in both cases. In addition, I present data on the use of Zinc isotopes in tooth bioapatite and organic bound nitrogen to constrain the trophic position evolution of extinct sharks in the Otodus lineage