by Robert Schreiber
Berlin, Germany (SPX) Jul 30, 2025
Scientists have found a new way to probe the composition of Earth's ancient atmosphere by studying fossilized cosmic dust. An international team led by the University of Gottingen, with collaborators from the Open University, University of Pisa, and Leibniz University Hannover, developed a technique to analyze micrometeorites - tiny metal-rich particles from space that have been preserved in Earth's rock layers for billions of years.
These particles, visible as shooting stars when they enter the atmosphere, melt on entry and form tiny spheres of iron and nickel oxides. The oxygen in these oxides originates from the atmosphere at the time of entry, effectively capturing a chemical fingerprint of ancient air. Their widespread deposition on Earth creates a vast, untapped archive of atmospheric data.
Researchers at Gottingen University's Geoscience Centre and Leibniz University Hannover refined a method to measure the oxygen and iron isotope compositions in these micrometeorites with unprecedented precision. These isotope ratios reveal the isotopic makeup of the ancient atmosphere and shed light on past global CO2 levels and photosynthetic activity.
The findings suggest that fossilized micrometeorites are a valuable new tool for climate scientists, complementing established methods for reconstructing past atmospheric conditions. "Our analyses show that intact micrometeorites can preserve reliable traces of isotopes over millions of years despite their microscopic size," said Dr Fabian Zahnow, former doctoral researcher at Gottingen University and now at Ruhr University Bochum. However, the team also found that soil and rock can alter micrometeorites after deposition, underscoring the need for detailed geochemical screening.
Research Report:Traces of the oxygen isotope composition of ancient air in fossilized cosmic dust.
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