COMBINING A δ13CCARB CORRELATION ALGORITHM AND A REFINED RADIOMETRIC CHRONOLOGY TO ADVANCE PRECAMBRIAN (EDIACARAN) BASIN ANALYSIS (Invited Presentation)

Precambrian basin analysis commonly relies on a relative chronologic framework afforded by δ¹³C_carb chemostratigraphy. Inasmuch as excursions correlate globally and align unambiguously, δ¹³C_carb correlation allows workers to extrapolate absolute dates into sections lacking chronology to calibrate transformative biological and geochemical events. For many locations, however, extrapolated ages have primarily served as minimum or maximum age constraints on geological events. Here we present an effort to leverage existing δ¹³C_carb data and numerical tools to generate a better resolved chronology for the Ediacaran Period that can serve as a backbone to investigate the dates and rates of geo-, bio-, and geochemical events in globally distributed basins. We employed a dynamic programming (DP) algorithm to optimally align, in a least-squares sense (Hay et al., 2019), Ediacaran δ¹³C_carb chemostratigraphies with intercalated radioisotopic depositional age(s) (see compilation by Rooney et al., 2020). We utilized China δ¹³C_carb data (Jiang et al., 2007; Tahata et al., 2013) as the ‘target’ to align temporally calibrated sections (from NW Canada, Namibia, Oman, and Brazil). We adopted a Bayesian Markov chain Monte Carlo model (Schoene et al., 2019) to estimate depositional ages, with uncertainty, for every isotopic value of the composite δ¹³C_carb–age model. Next we constructed DP-based regional δ¹³C_carb composites of undated Ediacaran sections (Australia, Namibia, NW Canada, Oman, Siberia, and Mongolia), preferencing alignments closest to literature correlations. When aligning regional (undated) δ¹³C_carb composites to the ‘age composite’, we found multiple possibilities. Here we present both numerical and literature ‘preferred’ alignments for a subset of Ediacaran basins to discuss how each makes (testable) predictions for the time history of sedimentation at individual sections. This workflow can apply to other Precambrian (or Phanerozoic) geologic periods.