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Van Tuyl Lecture: Kristin Bergmann, Massachusetts Institute of Technology
October 18 @ 4:00 pm - 5:00 pm
Kristin Bergmann, Massachusetts Institute of Technology
241 Berthoud Hall, 4PM
Topic: Carbonates before Skeletons and the PreCambrian World
Abstract: Carbonate and phosphatic rocks retain significant information about climatic conditions in Earth’s deep history. Determining how temperature and seawater oxygen isotope (δ18O) fluctuations influenced carbonate and phosphatic δ18O records over geologic time, therefore, is crucial for understanding the coupled evolutions of Earth’s climate and biota. Carbonate clumped isotope thermometry (D47) of ancient carbonates and fossils has the potential to unravel these competing effects. However, diagenetic effects must be considered using strategies of analysis of two or more co-existing minerals (i.e. calcite, dolomite and apatite), comparisons between co-existing fabrics (i.e. late-stage cements vs. primary shells), and screening based on textural and chemical indicators of recrystallization. Interpretations should take advantage of independent constraints on burial and thermal history. Creating a robust record of climate requires multi-section high-resolution comparisons through δ18O excursions, and comparing similar materials globally across space and time. We will present results that utilize all of these strategies to assess the climate variability in the latest Precambrian and Phanerozoic.