Scientists detect unexpected radioactive material surge beneath ocean

An international team of scientists has uncovered an unexpected and significant spike in the radioactive isotope beryllium-10 (¹⁰Be) embedded in ocean floor sediments nearly three miles beneath the Central Pacific. The discovery, reported by Earth.com, reveals a dense band of ¹⁰Be dating back about 10 million years, with concentrations raising the normal background levels by roughly 73 percent.

Led by Dr. Dominik Koll of the Australian National University and Helmholtz-Zentrum Dresden-Rossendorf, the researchers analyzed ferromanganese crust samples retrieved from sites thousands of miles apart. Their findings confirm that this ¹⁰Be anomaly persisted for approximately 1.4 million years and represents a unique event within the last 15 million years of geological records.

Beryllium-10 forms in the upper atmosphere when cosmic rays collide with nitrogen and oxygen atoms, eventually settling into the ocean through rain and snow. Its slow radioactive decay—with a half-life of 1.39 million years—makes ¹⁰Be a powerful tool for dating marine sediments and understanding Earth's environmental history.

The research team suggests that the spike coincides with significant climatic and oceanographic changes during the Late Miocene epoch. During this period, the Antarctic Circumpolar Current (ACC) strengthened as ocean gateways near Australia and South America widened, drastically reshaping global ocean circulation. This shift likely caused ¹⁰Be-rich southern waters to flood the central Pacific, resulting in the elevated isotope levels found in the sediment layers.

The study also dismisses earlier hypotheses attributing the spike to Antarctic meltwater pulses or sudden increases in cosmic ray production due to solar or geomagnetic fluctuations. Instead, the data indicate that changes in deep-water circulation played a central role in delivering and concentrating ¹⁰Be on the seafloor.

Future investigations aim to refine the timing and extent of this event by examining low-sedimentation mud cores in the South Pacific, which offer higher temporal resolution. Scientists are also analyzing another isotope, manganese-53 (⁵³Mn), to cross-validate the findings.

If corroborated globally, this ¹⁰Be layer could serve as a “golden spike” marker, helping geologists synchronize marine sediment records worldwide and enhancing models of Miocene climate evolution. Oceanographers would gain critical insights into the development of the ACC—a key driver of the Earth’s icehouse climate—while astrophysicists might better understand past cosmic events impacting our planet.

As Earth.com highlights, this thin ribbon of radioactive beryllium in the Pacific Ocean not only chronicles shifts in Earth’s climate but also connects terrestrial geology to the broader cosmic environment, revealing the ocean floor as a remarkable cosmic diary etched in radioactive ink.

By Vugar Khalilov