Abrupt global-ocean anoxia during the Late Ordovician–early Silurian detected using uranium isotopes of marine carbonates

2018/05/21 by Rick Bartlett, Maya Elrick, James R. Wheeley +3 · 2 citations
Earth and Planetary Sciences · #Acritarch #Anoxic waters #Cenozoic #Deglaciation #Earth science #Extinction event #Geochemistry and Elemental Analysis #Geology #Geology and Paleoclimatology Research #Glacial period #Oceanography #Ordovician #Paleontology #Paleontology and Stratigraphy of Fossils #Phanerozoic

paper · pdf · doi:10.1073/pnas.1802438115

openalex publication_date 2018/05/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/25

Abstract

C positive excursion, but lasted longer indicating that controls on the C budget were partially decoupled from global-ocean redox trends. U cycle modeling suggests that there was a ∼15% increase in anoxic seafloor area and ∼80% of seawater U was sequestered into anoxic sediments during the HOAE. Unlike other ocean anoxic events (OAE), the HOAE occurred during peak and waning icehouse conditions rather than during greenhouse climates. We interpret that anoxia was driven by global cooling, which reorganized thermohaline circulation, decreased deep-ocean ventilation, enhanced nutrient fluxes, stimulated productivity, which lead to expanded oxygen minimum zones.

Citations

• Multispecies stable isotopes of benthic foraminifers reveal past changes of organic matter decomposition and deepwater oxygenation in the Arabian Sea
• Geochemistry of oceanic anoxic events
• The Late Ordovician Mass Extinction
• Do all mass extinctions represent an ecological crisis? Evidence from the Late Ordovician
• Epipelagic chitinozoan biotopes map a steep latitudinal temperature gradient for earliest Late Ordovician seas: Implications for a cooling Late Ordovician climate
• A Cenozoic-style scenario for the end-Ordovician glaciation
• Large perturbations of the carbon and sulfur cycle associated with the Late Ordovician mass extinction in South China
• Dynamic sulfur and carbon cycling through the end-Ordovician extinction revealed by paired sulfate–pyrite δ34S
• A sulfidic driver for the end-Ordovician mass extinction
• Climate change and the selective signature of the Late Ordovician mass extinction
• End Ordovician extinctions: A coincidence of causes
• Environmental changes in the Late Ordovician-early Silurian: Review and new insights from black shales and nitrogen isotopes
• Disentangling the record of diagenesis, local redox conditions, and global seawater chemistry during the latest Ordovician glaciation

Cited by

• Marine redox variability from Baltica during extinction events in the latest Ordovician–early Silurian
• Late Ordovician mass extinction [wikipedia]

Related

• Geochemistry of oceanic anoxic events
• The climatic significance of Late Ordovician‐early Silurian black shales
• A nutrient control on expanded anoxia and global cooling during the Late Ordovician mass extinction
• Environmental changes in the Late Ordovician-early Silurian: Review and new insights from black shales and nitrogen isotopes
• Exploring the mechanisms of Devonian oceanic anoxia: impact of ocean dynamics, palaeogeography, and orbital forcing