Zhao, Chen and Lodders, Katharina and Bloom, Hannah and Chen, Heng and Tian, Zhen and Pető, Mária (2020) Potassium isotopic compositions of enstatite meteorites. METEORITICS & PLANETARY SCIENCE, 55 (6). pp. 1404-1417. ISSN 1086-9379
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Abstract
Enstatite chondrites and aubrites are meteorites that show the closest independent and mass-dependent isotopic fractionations. Due to the analytical challenges to obtain high-precision K isotopic compositions in the past, potential differences in K isotopic compositions between enstatite meteorites and the Earth remained uncertain. We report the first high-precision K isotopic compositions of eight enstatite chondrites and four aubrites and find that there is a significant variation of K isotopic compositions among enstatite meteorites (from -2.34‰ to -0.18‰). However, K isotopic compositions of nearly all enstatite meteorites scatter around the bulk silicate earth (BSE) value. The average K isotopic composition of the eight enstatite chondrites (-0.47 ± 0.57‰) is indistinguishable from the BSE value (-0.48 ± 0.03‰), thus further corroborating the isotopic similarity between Earth's building blocks and enstatite meteorite precursors. We found no correlation of K isotopic compositions with the chemical groups, petrological types, shock degrees, and terrestrial weathering conditions; however, the variation of K isotopes among enstatite meteorite can be attributed to the parent-body processing. Our sample of the main-group aubrite MIL 13004 is exceptional and has an extremely light K isotopic composition (δ41K = -2.34 ± 0.12‰). We attribute this unique K isotopic feature to the presence of abundant djerfisherite inclusions in our sample because this K-bearing sulfide mineral is predicted to be enriched in 39K during equilibrium exchange with silicates.
Item Type: | Article |
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Uncontrolled Keywords: | Astrophysics - Earth and Planetary Astrophysics; |
Subjects: | Q Science / természettudomány > QB Astronomy, Astrophysics / csillagászat, asztrofizika |
SWORD Depositor: | MTMT SWORD |
Depositing User: | MTMT SWORD |
Date Deposited: | 09 Feb 2023 10:16 |
Last Modified: | 09 Feb 2023 10:16 |
URI: | http://real.mtak.hu/id/eprint/158582 |
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