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Global Seawater Redox Trends During The Late Devonian Mass Extinction Detected Using U Isotopes Of Marine Carbonates, David Allen White

Earth and Planetary Sciences ETDs

The Late Devonian extinction ranks as one of the ‘big five’ Phanerozoic extinctions affecting up to 80% of marine species and occurred during five distinct pulses spanning /or widespread marine anoxia. We test the marine anoxia hypothesis by analyzing uranium isotopes (δ²³⁸U) across a ~7 My interval of well-dated Upper Devonian marine carbonates from the Devil’s Gate Limestone in Nevada, USA.

The measured δ²³⁸U curve shows no co-variation with local anoxic facies, water-depth dependent facies changes, redox-sensitive metals, TOC, or diagnostic elemental ratios indicating the δ²³⁸U curve was not controlled by local depositional or …