Basin-scale reconstruction of euxinia and Late Devonian mass extinctions

Area of Science:

• Paleoceanography
• Geochemistry
• Paleontology

Background:

• The Devonian-Carboniferous transition was a period of significant environmental change, marked by shifts in ocean-atmosphere oxidation states.
• Factors influencing these changes include the proliferation of vascular land plants, glacioeustasy, eutrophication, and mass extinction events.

Purpose of the Study:

• To compile and analyze comprehensive geochemical data from the Bakken Shale to understand environmental dynamics during the Devonian-Carboniferous transition.
• To document the transgression of euxinic waters and their impact on Late Devonian extinction events.

Main Methods:

• Spatial and temporal compilation of geochemical data from 90 sediment cores.
• Analysis of geochemical proxies to reconstruct oceanographic conditions, specifically euxinia (presence of hydrogen sulfide).

Main Results:

• Detailed documentation of stepwise transgressions of toxic euxinic waters into shallow ocean environments.
• Correlation of these transgressions with a series of Late Devonian extinction events.

Conclusions:

• The expansion of shallow-water euxinia, driven by hydrogen sulfide toxicity, was a primary factor in Late Devonian mass extinctions.
• This finding suggests hydrogen sulfide toxicity is a key driver of biodiversity loss across the Phanerozoic.