Collaborative Research: Stratigraphic, geochemical, and paleobiological tests of the co-evolution of multicellular life and environment in the late Ediacaran Period

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Stratigraphic, Geochemical, and Paleobiological Tests of the Co-Evolution of Multicellular Life and Environment in the Late Ediacaran Period Alan J. Kaufman, University of Maryland Shuhai Xiao, Virginia Polytechnic Institute and State University Dima Grazhdankin, Russian Academy of Sciences The PIs will undertake a basin-wide stratigraphic, geochemical, and paleobiological study of the carbonate-dominated Khatyspyt Formation in remote northern Siberia. Ediacaran fossils in this unit are remarkably preserved in fine-grained carbonates, promising a much enhanced anatomical and paleoecological view of Earths earliest animals. Insofar as the Ediacaran biota may have required abundant free oxygen to sustain metabolic activities, we hypothesize that their distribution may track environmental conditions, and propose tests of this linkage through high resolution time-series analyses of carbon and sulfur isotopes in multiple equivalent sections across the Khatyspyt depositional basin as well as other biological, elemental and isotopic indicators of redox conditions. The Khatyspyt Formation contains a wide range of unique carbonate-hosted Ediacaran organisms, as well as carbonaceous macrofossils, small shelly fossils, trace fossils and planktonic microfossils all in a single, 450-m-thick continuous succession cropping out along the Olenek, Khorbosuonka and Lena rivers. Results of the study should provide insights to the phenomenon of soft tissue preservation, increase the ecological resolution of the Ediacaran-Cambrian transition, and provide important constraints on the history of Earths earliest metazoans and the oceans in which they originated, diversified, and ultimately perished. The primary aim of this field and laboratory based proposal is to test whether the geologically brief Ediacaran experiment in complex multicellular life was controlled by the oxidation state of shallow marine environments. The proposed research will establish a new international collaboration with colleagues in Russia, and require two month-long field seasons above the Arctic Circle in northern Siberia. Graduate students from both U.S. institutions will accompany the PIs in the field, providing them with an enhanced learning experience that will promote both scientific and cultural exchange.