Oceanic Anoxic Event 2 triggered by Kerguelen volcanism

Area of Science:

• Geochemistry
• Paleoclimatology
• Plate Tectonics

Background:

• Large Igneous Provinces (LIPs) are linked to global warming and carbon cycle disruptions, such as Oceanic Anoxic Event 2 (OAE2) and the Mid-Cenomanian Event (MCE).
• The precise volcanic source and trigger mechanism for these events remain debated, with previous hypotheses involving the Caribbean LIP or High Arctic LIP.

Purpose of the Study:

• To determine the timing of volcanic activity associated with OAE2 and MCE.
• To identify the provenance of sedimentary material during these events.
• To elucidate the role of volcanism in triggering OAE2 and MCE.

Main Methods:

• Analysis of sedimentary mercury (Hg) concentrations in the Mentelle Basin to pinpoint volcanic timing.
• Neodymium (Nd) and strontium (Sr) isotope analysis to establish sedimentary provenance.
• Comparison of Hg data with Northern Hemisphere records.

Main Results:

• Elevated sedimentary Hg concentrations in the Mentelle Basin, exceeding Northern Hemisphere levels, indicate Kerguelen LIP volcanic activity.
• A shift towards radiogenic Nd isotopes points to Kerguelen LIP plateau uplift preceding and during OAE2.
• Limited evidence suggests volcanism did not directly cause the MCE, but pulsed Hg spikes before and during OAE2 were significant.

Conclusions:

• Kerguelen LIP volcanism and associated plateau uplift were active leading up to and during OAE2.
• Volcanic emissions from the Kerguelen LIP played a crucial role in driving climate and carbon cycle changes, ultimately triggering OAE2.