GSA Connects 2021 in Portland, Oregon

Paper No. 76-5
Presentation Time: 9:00 AM


MILLIKIN, Alexie1, STRAUSS, Justin2, HALVERSON, Galen P.3, BERGMANN, Kristin D.4, TOSCA, Nicholas J.5 and ROONEY, Alan1, (1)Department of Earth & Planetary Sciences, Yale University, 210 Whitney Ave., New Haven, CT 06511, (2)Department of Earth Sciences, Dartmouth College, Hanover, NH 03755, (3)Department of Earth and Planetary Sciences, McGill University, Montreal, QC H3A 0E8, Canada, (4)Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, (5)Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, United Kingdom

The Tonian-Ediacaran lower and middle Hecla Hoek succession of Svalbard, Norway represents one of the most complete and well preserved Neoproterozoic sedimentary successions worldwide. With diverse fossil assemblages, an extensive carbonate δ13C record, and sedimentary evidence for two distinct Cryogenian glaciations, this succession has the potential to yield profound insights into the Neoproterozoic Earth system; however, at present there are no radiometric age constraints for these strata. Current correlation schemes across northeastern Svalbard, as well as to Neoproterozoic successions globally, rely upon litho- and chemostratigraphic records.

Here we present the first direct radiometric age constraints from the Hecla Hoek succession. Two new Re-Os ages and initial Os values tightly constrain the age of Neoproterozoic glaciation in Svalbard and provide insight into pre- and post-glacial weathering regimes. An age from the Russøya Member (Elbobreen Formation) facilitates correlation of the negative carbon isotope excursion recorded therein with the pre-glacial Islay anomaly of the Callison Lake Formation (Windermere Supergroup) in Northwest Canada and the Didikama and Matheos formations (Tambien Group) in Ethiopia. Vase-shaped microfossils from this same member can now also be allied to global records with pre-Cryogenian biostratigraphic significance. These results solidify global chemo- and biostratigraphic correlations for the late Tonian Period and lay the groundwork for assessing the synchroneity of biogeochemical cycle perturbations during this interval. In addition, these new age constraints provide a unique opportunity to construct a temporally-calibrated geochemical, biological, and geological framework to assess the timing and triggers of early eukaryotic evolution and the most extreme climatic changes in Earth history.