Researchers have found an unexpected accumulation of the radioisotope beryllium-10 beneath the Pacific Ocean’s surface. This discovery, detailed in a study published in Nature Communications, suggests that these anomalies trace back to significant changes in ocean currents or cosmic ray interactions with the Earth’s atmosphere around 10 million years ago. Beryllium-10 is produced when oxygen and nitrogen atoms in the upper atmosphere interact with high-energy protons from space. The research aims to provide an independent time marker for ocean archives, improving the understanding of the planet’s geological history.
Unlike radiocarbon dating, which is limited to samples under 50,000 years old, beryllium-10 has a longer half-life of 1.4 million years, allowing scientists to date samples over 10 million years old. The researchers utilized accelerator mass spectrometry to study geological samples from the Pacific, finding nearly double the expected amount of beryllium-10 isotopes. They speculate this could be due to a significant reorganization of ocean currents or an astrophysical event, such as a supernova, that might have temporarily increased cosmic radiation around that time.
The team emphasizes the need for further measurements to determine whether these anomalies were caused by oceanic changes or cosmic events. They hope that additional studies in other oceans could reveal whether these findings represent a global phenomenon.
