Dating can be full of surprises. In the social kind, one can learn about all sorts of unexpected things about a potential partner. In the scientific type, sometimes strange, unexplained phenomena comes to light.
The latter was the case for a group of scientists, who found twice as much Beryllium-10 in the Pacific seabed then expected. This anomaly could shift our understanding of cosmic phenomenon that affect the Earth and also help recalibrate scientific dating techniques, they report in Nature Communications.
Mystery in the Pacific Ocean
Dominik Koll, a postdoctoral researcher with TUD Dresden University of Technology, was searching for signs of stardust in the ferromanganese crust at the bottom of the Pacific Ocean. Instead, he noticed an anomaly: an accumulation of twice as much Beryllium-10 (10Be) dating back 10 million years than expected.
The rare radioactive isotope produced by cosmic rays in the atmosphere, is used to date objects millions of years old, because its half-life is 1.4 million years. Radiocarbon, used for dating archeological objects, has a half-life of 5,730 years, making it only useful for objects up to 50,000 years old.
The double dose of Beryllium-10 was unexpected, because no such increase of the isotope over the last 10 million years has been detected anywhere else on Earth.
“To find such a pronounced increase of 10Be was truly unexpected,” says Koll. “Something exceptional must have happened at that time.”
Varying Theories
But what? Koll has two theories: It could be due to either a massive shift in ocean currents or an unknown astrophysical event. The current hypothesis is the low-hanging fruit.
“Changing ocean currents should be straightforward to prove or dismiss,” says Koll. “The absolute amount of 10Be on Earth would be constant, therefore, a redistribution would need to take place to produce an anomaly in the Pacific. Consequently, there would be a lack of 10Be somewhere on Earth and you should also be able to find samples where the anomaly is not present at all."
The cosmic ray theory would take more work to verify or dispute.
“A higher production rate of 10Be due to an enhanced cosmic ray flux (interstellar cloud collision or supernova) on the other side would be a global phenomenon which would be imprinted into all archives,” says Koll. “We definitely need more investigations of ferromanganese crusts and deep-ocean sediments that are 10 million years old."
Taking and analyzing samples from all over the Earth, dating back 10 million years, would be necessary to confirm or deny that hypothesis.
Synchronizing All Timescales
This anomaly brings up a broader scientific issues — the need to synchronize different archives such as ice cores, tree-rings, deep-ocean sediments, and ferromanganese crusts. Doing so would provide a more accurate picture of the climate of the past, earlier habitability on Earth, or changes in Earth’s ecosystem.
“Currently they are all independently dated and there are tremendous efforts to synch all timescales,” says Koll. “An independent time marker, present in all archives of the same age, is the key to synchronize datasets. This anomaly is our chance, if discovered in other archives, to have another time marker, but on a completely different timescale.”
Read More: Record 2-Mile-Long Ice Core Represents 1.2 Million Years of Earth’s Climate History
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
Nature Communications. A cosmogenic 10Be anomaly during the late Miocene as independent time marker for marine archives
Before joining Discover Magazine, Paul Smaglik spent over 20 years as a science journalist, specializing in U.S. life science policy and global scientific career issues. He began his career in newspapers, but switched to scientific magazines. His work has appeared in publications including Science News, Science, Nature, and Scientific American.
