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The discovery of an unusual spike in beryllium-10 levels in Pacific seafloor samples could be a breakthrough in geological dating, providing a new time marker for synchronizing the geological record.
Researchers from the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), the Dresden University of Technology (TUD) and the Australian National University (ANU) have discovered an unexpected increase in the concentration of beryllium-10, which could have occurred around 10 million years ago. Since traditional methods such as radiocarbon dating are limited to 50 years, alternative approaches are needed to analyze ancient events.
Beryllium-10 is a radioactive isotope that is formed by cosmic rays in the upper atmosphere and then falls to the Earth's surface in precipitation. With a half-life of 1,4 million years, this isotope is an important tracer in reconstructing past events, allowing researchers to trace Earth's history back up to 10 million years. Analyzing ferromanganese crusts that formed over millions of years, the team used accelerator mass spectrometry (AMS) to precisely measure the concentration of beryllium-10.
The results surprised scientists.
Repeated analysis of samples from different locations confirmed the existence of the anomaly, indicating a global or at least regional nature of this phenomenon.
Scientists have put forward two hypotheses for the causes of this surge in beryllium-10. The first is that changes in ocean circulation could have caused an uneven distribution of ??Be in different regions. “This could have led to ??Be being particularly concentrated in the Pacific Ocean,” explains Coll. An alternative version is related to astrophysical events, in particular a possible supernova explosion, which could have increased the level of cosmic radiation and contributed to an increase in the production of beryllium-10.
Further research is needed to confirm or refute these hypotheses.
If similar data are found worldwide, this would confirm the cosmic origin of the anomaly, while if it is limited to a specific region, an oceanographic factor would be a more likely explanation.
Whatever the reason, this discovery has significant potential for geochronology, as scientists strive to find global time markers that can reconcile geological archives such as ice cores and marine sediments.
This research opens new horizons in understanding the geological history of the Earth and could revolutionize the dating of ancient events. The results of the work are published in the journal Nature Communications..
