Tiny fossils tell a long(ish) story

March 8, 2016
Figure 1 from Birch et al.: Changing ecology schematic of selected foraminiferal species for isotopic analysis across the Cretaceous-Paleogene (K-Pg) boundary.

The impact of an asteroid at the end of the Cretaceous caused mass extinctions in the oceans, as well as killing the dinosaurs on land. The carbon isotope difference between surface and seabed organisms (foraminifera) also collapsed due to these extinctions, suggesting that organic matter from surface waters did not reach the seafloor for up to 3 million years. However, seafloor organisms, which are dependent on food from surface waters, did not die off, suggesting some food must have reached the seabed.

In their open-access paper for Geology, Heather S. Birch and colleagues investigate this paradox by looking at carefully selected foraminiferal isotopes from a well-dated deep-sea core in the South Atlantic.

By taking into account the likely ecology of the foraminifera studied and whether any water mass changes were occurring at the time, they can better assess the record and transfer of organic matter to the seafloor. Birch and colleagues find that the flux of was reduced for a much shorter time (1.7 million instead of 3 million years). The authors note that ecology and water mass changes likely did have a small effect on the carbon isotope record, but they cannot explain the full reduction in carbon isotopes on their own.

Explore further: New digital seafloor map provides answers and more questions

More information: Partial collapse of the marine carbon pump after the Cretaceous-Paleogene boundary, Geology, geology.gsapubs.org/content/ea … 07/G37581.1.abstract

Related Stories

New digital seafloor map provides answers and more questions

August 10, 2015

Ocean sediments cover 70% of our planet's surface, forming the substrate for the largest ecosystem on Earth and its largest carbon reservoir—but the most recent map of seafloor geology was drawn by hand more than 40 years ...

Big data maps world's ocean floor

August 10, 2015

Scientists from the University of Sydney's School of Geosciences have led the creation of the world's first digital map of the seafloor's geology.

Recommended for you

Climate change made Harvey rainfall 15 percent more intense

December 14, 2017

A team of scientists from World Weather Attribution, including researchers from Rice University and other institutions in the United States and Europe, have found that human-caused climate change made the record rainfall ...

East Antarctic Ice Sheet has history of instability

December 13, 2017

The East Antarctic Ice Sheet locks away enough water to raise sea level an estimated 53 meters (174 feet), more than any other ice sheet on the planet. It's also thought to be among the most stable, not gaining or losing ...

Hydraulic fracturing negatively impacts infant health

December 13, 2017

From North Dakota to Ohio to Pennsylvania, hydraulic fracturing, also known as fracking, has transformed small towns into energy powerhouses. While some see the new energy boom as benefiting the local economy and decreasing ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.