100-1 Novel Chronostratigraphic Framework Resolves the Appearance of Macroscopic Animal Life in Newfoundland, Canada

Session: Snowballs, Unconformities, BIFs and Beyond: Navigating the Neoproterozoic Rock and Climate Records Using Geochronology

Presenting Author:

Authors:

Abstract:

The timing and tempo of animal evolution are questions of fundamental importance to understanding evolutionary controls and environmental constraints on the rise of large complex life. To answer these questions, we have been working in Ediacaran strata that contain Earth’s earliest animal ecosystems, exquisitely preserved as fossils in life position at Mistaken Point and Catalina Dome in Newfoundland, Canada. Understanding the relationship of these successions to each other, and to the Ediacaran timeline more broadly, has been difficult. First, although these rocks have been longstanding geochronological targets for high-precision U-Pb zircon dating because of their paleontological significance, published geochronological data from Mistaken Point have yielded inconsistent results, which we attribute to the geological complexity of these samples. Second, the canonical correlation of strata at Mistaken Point and Catalina Dome results in a systematic temporal offset of fossil occurrences between locations. We present a well-resolved Bayesian age model for Catalina Dome in order to clarify its temporal relationship to Mistaken Point. Our intensive geochronological workflow includes external backscattered electron imaging of grain surface morphology, cathodoluminescence imaging of internal zoning, and tandem measurement of U-Pb and trace elements via laser ablation prior to high-precision isotope dilution dating of these carefully screened and selected volcanic crystals. Our new ages document that the commonly accepted correlation of these locations is erroneous, obscuring environmental and evolutionary trends. These robust age constraints can now create a precise timeline capable of deconvolving causal relationships, quantifying rates of change, and placing local changes into a global context.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-7612

© Copyright 2025 The Geological Society of America (GSA), all rights reserved.