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Abstract: Reconstructing Earth's Climate Dynamics at the Dawn of Animals

In the Bergmann Lab at MIT, we use a combination of approaches to reconstruct ancient climate conditions. Carbonate, phosphatic and siliciclastic rocks retain significant information about climatic conditions in Earth’s deep history in their sedimentological, petrographic and geochemical character. Determining absolute temperature ranges and seawater oxygen isotope (δ18O) fluctuations over geologic time is one crucial component of understanding Earth's long term climate history and the co-evolution of Earth and life. Carbonate clumped isotope thermometry (D47) of ancient carbonates and fossils has the potential to unravel competing effects on δ18O records. 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 micro-analytical screening techniques based on petrographic and chemical indicators of alteration. I will present results that utilize all of these strategies to assess the climate variability in the latest Precambrian and earliest Phanerozoic. Our results suggest critical differences between recent paleoclimate conditions and those of the deep past both in terms of the response of the climate system to external perturbations as well as the controls that govern the climate system's recovery to perturbations.

In the Bergmann Lab at MIT, we use a combination of approaches to reconstruct ancient climate conditions. Carbonate, phosphatic and siliciclastic rocks retain significant information about climatic conditions in Earth’s deep history in their sedimentological, petrographic and geochemical character. Determining absolute temperature ranges and seawater oxygen isotope (δ18O) fluctuations over geologic time is one crucial component of understanding Earth's long term climate history and the co-evolution of Earth and life. Carbonate clumped isotope thermometry (D47) of ancient carbonates and fossils has the potential to unravel competing effects on δ18O records. 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 micro-analytical screening techniques based on petrographic and chemical indicators of alteration. I will present results that utilize all of these strategies to assess the climate variability in the latest Precambrian and earliest Phanerozoic. Our results suggest critical differences between recent paleoclimate conditions and those of the deep past both in terms of the response of the climate system to external perturbations as well as the controls that govern the climate system's recovery to perturbations.

Distinguished Lecturer

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