GSA Connects 2021 in Portland, Oregon

Paper No. 87-5
Presentation Time: 9:00 AM-1:00 PM


MEYER, Fran1, ESSACK, Zahra1, JOST, Adam B.1, STRAUSS, Justin2 and BERGMANN, Kristin D.1, (1)Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, (2)Department of Earth Sciences, Dartmouth College, Hanover, NH 03755

The Bitter Springs Anomaly (BSA; ca. 810-800 Ma) is the first major negative carbon isotope excursion observed in the Neoproterozoic record. Studies have hypothesized ocean euxinia during the BSA, followed by rising oxygen levels and increased eukaryotic diversification, but the driving mechanism of the excursion is still unclear. One of the best-preserved carbonate sequences of the BSA is located on the Svalbard archipelago, a region that bolsters important sedimentary rock records from the Proterozoic to Phanerozoic. Carbonate clumped isotopes (Δ47) record the carbonate precipitation temperature and can thus be used with the mineral ẟ18O to derive fluid ẟ18O. If the primary Δ47 signature has been altered, this method can also provide a better understanding of diagenetic processes. This method has not been used on carbonate records from the BSA, and could potentially provide a tool to understand the negative ẟ13C excursion or the diagenetic history of varied locations and lithofacies from Svalbard carbonates deposited during this interval. In this study, we seek to provide a more robust geochemical record for the BSA by adding carbonate ẟ13C, ẟ18O, and Δ47-temperature data from Svalbard in attempt to constrain BSA conditions, or alternatively, the diagenetic history of Svalbard. Samples were collected in northwestern Nordaustlandet from the Roaldtoppen locality and in northeastern Spitsbergen, from the Geerbukta and Dracoisen localities. We analyzed 458 (190 from Roaldtoppen, 199 from Geerbukta, and 69 from Dracoisen) new ẟ13C and ẟ18O values from Svalbard before, during, and after the BSA. In addition, we produced 22 clumped carbonate isotope temperature estimates: five values from Roaldtoppen (87-158 °C), eight from Geerbukta (59-80 °C), and nine from Dracoisen (51-140 °C). These new data demonstrate the local variation of clumped temperatures from samples roughly the same age. This indicates a varied diagenetic and solid state reordering history, with samples from Spitsbergen being less affected. We also aim to demonstrate differences among carbonate lithofacies due to their relative susceptibility to alteration.