A Perspective from Earths Deep Mantle Krypton and Xenon on Evolution of Planetary Interiors
Abstract
The volatile elemental and isotopic compositions of planetary mantles is key to understand the processes that shaped the terrestrial planets and their atmospheres. Due to their very low reactivity and high volatility, noble gases are invaluable tracers of the cycling of volatiles on Earth and other terrestrial planets. In particular, the non-radiogenic isotopes of krypton (78Kr, 80Kr, 82Kr, 83Kr, 84Kr, 86Kr) and xenon (124Xe, 126Xe, 128Xe, 130Xe) provide direct evidence on the initial sources and redistribution of volatiles on planets (the rate of fission production of 83, 84, 86Kr is negligible in the Earths mantle). However, there is very limited, high precise data for the krypton and xenon compositions of Earths mantle sources, in particular for deep mantle plumes. Here we used a new methodology, that combined a recently developed protocol of gas accumulation, a protocol of heavy noble gas (Ar, Kr, Xe) separation and noble gas mass spectrometry with a Noblesse HR (Nu instruments), to obtain high precision measurements of the full suite of Kr and Xe isotopes from the deep mantle Galapagos and Iceland plumes. These two hotspots show among the most primitive helium, neon and tungsten isotopic compositions, indicative of relatively primitive, undegassed reservoirs, and thus providing primordial Kr and Xe composition of the Earths mantle. In this presentation, we will show the Kr and Xe isotopic compositions of these two hotspots. Building on these new results, we will introduce a new approach combining isotopic and elemental ratios to bring new insights on the distribution and cycling of volatiles through time, including the timing of volatile depletion in the Earths deep interior.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFMDI23A..05P