Tracing the oxygen isotope composition of the upper Earth’s atmosphere using cosmic spherules

• Main Authors: Pack, Andreas, Höweling, Andres, Hezel, Dominik C., Stefanak, Maren T., Beck, Anne-Katrin., Peters, Stefan T. M., Sengupta, Sukanya, Herwartz, Daniel, Folco, Luigi
• Format: Text
• Language: English
• Published: Karlsruhe 2017
• Subjects: Antarc*; Antarctica
• Online Access: https://dx.doi.org/10.5445/ir/1000070814; https://publikationen.bibliothek.kit.edu/1000070814

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 O₂. Our data suggest that the Earth’s atmospheric O₂ is isotopically homogenous up to the thermosphere. This makes fossil I-type micrometeorites ideal proxies for ancient atmospheric CO₂ levels.