256-7 Exploring the Signal of Late Devonian Anoxia Through Space and Time

Session: Life and Environments Through Time and Space: Multi-Record Approaches to Stratigraphic Paleobiology, Part I

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Marine anoxia has been linked with important events in the history of life including the Late Devonian mass extinctions. Trace fossils are an important indicator of bottom water oxygen stress and have revealed that dysoxic and anoxic conditions were widespread, often fluctuating rapidly, through much of the Late Devonian in Laurentian epeiric basins. Additional proxies, including organic-walled microfossils, trace metal concentrations, stable isotope records, biomarker signals, and pyrite framboid populations can provide a fuller picture of conditions from the sediment water interface up through the water column. The combination of these proxies through the Late Devonian in the Appalachian Basin reveals variable signals that suggest different drivers for repeated anoxic events and correlative biotic turnovers through time. While these proxies are widely used as indicators of anoxia, it is important to evaluate their utility in other geographic regions, especially beyond the well-studied black shales deposited in epicratonic seaways. In order to fully explore the appropriate application of redox proxies, these metrics are applied globally in different depositional and tectonic settings to explore the signal of anoxia through the Late Devonian. Comparing these proxies exposes examples incongruent records of marine oxygen levels: different proxies indicating dissimilar relative oxygen levels. This ongoing research emphasizes the need for a multiproxy approach for understanding ancient oceanographic dynamics and careful selection of specific redox proxies for reconstructing the causes and consequences of anoxia in the geologic past.

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

doi: 10.1130/abs/2025AM-6440

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