A recent discovery deep beneath the Pacific Ocean has intrigued scientists worldwide. According to a study published in the journal Nature Communications, researchers found an unexpected surge of the radioactive isotope beryllium-10 in ocean floor sediments dating back approximately 10 million years. The concentration of beryllium-10 did not decrease as expected beyond a certain point in time; instead, they found an anomalous increase, indicating a radioactive "pulse" during that period.
"We came across an anomaly that had not been discovered until now," said Dr. Dominik Koll from Helmholtz-Zentrum Dresden-Rossendorf in Germany, the lead author of the study. He explained that his team found an accumulation of beryllium-10 in geological samples from the depths of the Pacific Ocean, almost double their previous estimates, suggesting a global phenomenon.
Beryllium-10 is continuously produced by cosmic rays interacting with Earth's atmosphere. It is incorporated into ferromanganese crusts on the ocean floor at a steady rate, contributing to the extremely slow development of these deep, metal-rich layers. The age of these crusts can be determined by radiometric dating using beryllium-10, which serves as a natural stopwatch due to its steady decay rate.
The research team hopes the discovery could serve as an independent time marker to refine geological datasets. "This beryllium anomaly has the potential to serve as such a marker," Dr. Koll said, according to 20 Minutos. If similar peaks are found worldwide, it would allow researchers to synchronize different records by aligning them with the same unexpected increase 10 million years ago.
Scientists are investigating possible explanations for this accumulation of beryllium-10, considering two main scenarios: changes in ocean currents and astronomical events. In one scenario, the unusual radioactive accumulation could have been caused by a sudden and drastic change in ocean circulation around Antarctica 10 to 12 million years ago.
Alternatively, Earth could have briefly lost its protective solar shield, known as the heliosphere, after passing through a dense interstellar cloud. This would have exposed the planet to increased cosmic ray flux, leading to an elevated global beryllium-10 production rate. "Only new measurements can indicate whether the beryllium anomaly was caused by changes in ocean currents or has astrophysical reasons," Dr. Koll explained in a statement, according to Futurism.
The research team examined samples from several areas of the Pacific Ocean, confirming that all showed the same anomalous increase. Analysis from locations nearly 3,000 kilometers apart confirmed the same anomaly. This suggests that the anomaly may spread throughout the Pacific Ocean and potentially across the entire planet.
To determine which hypothesis is correct, researchers plan to analyze more samples from all major oceans and both hemispheres. "That is why we plan to analyze more samples in the future and hope that other research groups will do the same," Dr. Koll continued.
Ferromanganese crusts, which grow slowly over extremely long time scales, exist in every ocean on Earth and can preserve the chemical composition of the ocean for millions of years. Researchers can use the decay rate of beryllium-10 into boron, which has a half-life of 1.4 million years, as a natural stopwatch to discern the age and history of rocks and sediments.
"Only time can tell whether the anomalous radioactive region beneath the ocean is a local or global phenomenon," the scientists noted.
This article was written in collaboration with generative AI company Alchemiq