| Jonathan Chen, the study's lead author, examines foraminifera fossils under a microscope. Photo Credit: Northwestern University |
Scientific Frontline: Extended "At a Glance" Summary: Cretaceous Planktic Foraminifera Extinction
The Core Concept: A 113-million-year-old mass extinction event of marine planktic foraminifera was driven by severe ocean acidification caused by massive volcanic carbon dioxide emissions. Microscopic fossil evidence confirms that acidic surface waters dramatically reduced the ability of these organisms to build calcium carbonate shells.
Key Distinction/Mechanism: By measuring calcium isotope ratios within individual microfossils, researchers differentiated between the severe calcification stress experienced by surface-dwelling plankton and the milder impact on deep-sea benthic organisms, proving that atmospheric carbon dioxide acidified surface waters before reaching the ocean floor.
Origin/History: During the Early Cretaceous period, specifically at the Aptian-Albian boundary, the massive Kerguelen Plateau volcanic province erupted in the southern Indian Ocean, spewing vast quantities of carbon dioxide into the atmosphere.
Major Frameworks/Components:
- Isotope Geochemistry: The use of calcium isotope ratios as a geochemical proxy to measure historical biocalcification rates and physiological stress in shell-building organisms.
- Carbon Sequestration: The role of foraminifera in the natural carbon cycle, locking away carbon within external, solid calcium carbonate shells.
- Volcanic Forcing: The mechanism by which large igneous provinces, such as the Kerguelen Plateau, emit atmospheric carbon dioxide that subsequently dissolves into surface seawater and lowers its pH.
- Biocalcification: The biological process by which marine organisms construct shells from carbonate ions, a process significantly hindered by increased seawater acidity.


.png)




.jpg)

.jpg)


.jpg)
.png)