The contemporary degassing rate of 40Ar from the solid Earth
Knowledge of the outgassing history of radiogenic 40Ar, derived over geologic time from the radioactive decay of 40K, contributes to our understanding of the geodynamic history of the planet and the origin of volatiles on Earth's surface. The 40Ar inventory of the atmosphere equals total 40Ar o...
| Published in: | Proceedings of the National Academy of Sciences |
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| Main Authors: | , , , , |
| Format: | Text |
| Language: | English |
| Published: |
National Academy of Sciences
2008
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| Subjects: | |
| Online Access: | http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2448820 http://www.ncbi.nlm.nih.gov/pubmed/18550816 https://doi.org/10.1073/pnas.0711679105 |
| Summary: | Knowledge of the outgassing history of radiogenic 40Ar, derived over geologic time from the radioactive decay of 40K, contributes to our understanding of the geodynamic history of the planet and the origin of volatiles on Earth's surface. The 40Ar inventory of the atmosphere equals total 40Ar outgassing during Earth history. Here, we report the current rate of 40Ar outgassing, accessed by measuring the Ar isotope composition of trapped gases in samples of the Vostok and Dome C deep ice cores dating back to almost 800 ka. The modern outgassing rate (1.1 ± 0.1 × 108 mol/yr) is in the range of values expected by summing outgassing from the continental crust and the upper mantle, as estimated from simple calculations and models. The measured outgassing rate is also of interest because it allows dating of air trapped in ancient ice core samples of unknown age, although uncertainties are large (±180 kyr for a single sample or ±11% of the calculated age, whichever is greater). |
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