T174 Precambrian Basin Analysis

Thursday, 29 October 2020
10:00 AM - 12:00 PM
Meeting Rooms

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

Paper number: T174-2
Program: Technical Sessions
Time: 10:05 AM – 10:10 AM

Authors

Abstract

Precambrian basin analysis commonly relies on a relative chronologic framework afforded by δ13Ccarb chemostratigraphy. Inasmuch as excursions correlate globally and align unambiguously, δ13Ccarb 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 δ13Ccarb 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 δ13Ccarb chemostratigraphies with intercalated radioisotopic depositional age(s) (see compilation by Rooney et al., 2020). We utilized China δ13Ccarb 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 δ13Ccarb–age model. Next we constructed DP-based regional δ13Ccarb composites of undated Ediacaran sections (Australia, Namibia, NW Canada, Oman, Siberia, and Mongolia), preferencing alignments closest to literature correlations. When aligning regional (undated) δ13Ccarb 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.

Geological Society of America Abstracts with Programs. Vol. 52, No. 6

doi: 10.1130/abs/2020AM-355524

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