Tracing the oxygen isotope composition of the upper Earth's atmosphere using cosmic spherules.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 28569769.
- Also identified by DOI 10.1038/ncomms15702 and PMC identifier 5461487.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Molten I-type cosmic spherules formed by heating, oxidation and melting of extraterrestrial Fe,Ni metal alloys. The entire oxygen in these spherules sources from the atmosphere. Therefore, I-type cosmic spherules are suitable tracers for the isotopic composition of the upper atmosphere at altitudes between 80 and 115 km. Here we present data on I-type cosmic spherules collected in Antarctica. Their composition is compared with the composition of tropospheric O<sub>2</sub>. Our data suggest that the Earth's atmospheric O<sub>2</sub> is isotopically homogenous up to the thermosphere. This makes fossil I-type micrometeorites ideal proxies for ancient atmospheric CO<sub>2</sub> levels.