Tracing the oxygen isotope composition of the upper Earth’s atmosphere using cosmic spherules
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...
Main Authors: | , , , , , , , , |
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Format: | Text |
Language: | English |
Published: |
Karlsruhe
2017
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Subjects: | |
Online Access: | https://dx.doi.org/10.5445/ir/1000070814 https://publikationen.bibliothek.kit.edu/1000070814 |
Summary: | 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. |
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