Vegetation response to exceptional global warmth during Oceanic Anoxic Event 2.

Area of Science:

• Paleoclimatology
• Paleobotany
• Marine Geology

Background:

• The Cenomanian-Turonian Oceanic Anoxic Event (OAE2) around 94.5 million years ago was a period of global marine anoxia and significant biotic change, coinciding with extreme warmth in the Phanerozoic.
• Limited data exists on how continental ecosystems responded to this greenhouse warming event.

Purpose of the Study:

• To investigate the response of continental vegetation to the OAE2 greenhouse episode.
• To reconstruct terrestrial climate and vegetation dynamics during OAE2 using palynological data.

Main Methods:

• Analysis of a terrestrial palynological record from an expanded OAE2 section in the Southern Provençal Basin, France.
• Integration of marine-derived temperature data (TEX₈₆) to correlate terrestrial and marine conditions.

Main Results:

• Despite peak temperatures reaching 38°C, continental vegetation remained diverse and adapted to warm conditions.
• A cooling phase within OAE2, the Plenus Cold Event (PCE), triggered a shift towards open, savanna-type vegetation dominated by angiosperms, replacing conifer forests.
• The PCE also coincided with the initial radiation of early Normapolles-type pollen, a key angiosperm group.

Conclusions:

• Continental ecosystems demonstrated resilience and adaptability to extreme warming during OAE2.
• The Plenus Cold Event induced significant, albeit transient, shifts in terrestrial vegetation, favoring angiosperm diversification.