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Space Science & Astrobiology Division – Special Seminar Series

Title: Neoproterozoic records of environmental extremes from the onset of the Sturtian Snowball Earth glaciation — Tyler Mackey Agouron Postdoctoral , Fellow in the Massachusetts Institute of Technology Department of Earth, Atmospheric and Planetary Sciences —

Abstract: Carbonate strata from NE Svalbard provide a window into changing depositional environments through Neoproterozoic climate perturbations including the Sturtian and Marinoan Snowball Earth events (~720–635 Ma). These sedimentary successions are also coincident with global records for the ecological expansion of complex life. Comparison of carbonate clumped isotope values (∆47­) in specific petrographic textures and their association with organic matter preservation provides a test for post-depositional alteration. Stratigraphic variability in dolomite ∆47­ values could reflect preferential alteration of specific textures or changes in temperature associated with dolomite precipitation. Carbonate strata have also been resedimented as clasts in Sturtian diamictites, and comparison of clasts to underlying stratigraphy and diamictite carbonate matrix provides a test for the source and timing of stratigraphic variations in ∆47­ values. Regional variability in clumped isotope temperatures correspond to independent records of organic matter maturity. Together, these data indicate that at least some component of the ∆47 signal reflects differences temperature of dolomite precipitation between pre- and syn-glacial settings and that strata may preserve primary biomarkers from this pivotal period in Earth history.

Point of contact: darlene.lim@nasa.gov



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