The hydrogen isotopic composition and content of the ureilite parent body: constraints from new ungrouped achondrites
Abstract
Evidence for SiO2-rich melts on the ureilite parent body (UPB) stems from feldspathic clasts within polymict ureilites and has been additionally preserved and recorded in rare fragments of the Almahata Sitta meteorite suite, which originated from the asteroid 2008 TC3. These unique fragments demonstrated that ancient crust-forming volcanism on small planetary bodies was not simply restricted to basaltic lithologies. Two recent Northwest Africa finds (NWA) 15,820 and NWA 16789 expand the known quantity of SiO2-rich material from the UPB, allowing for a more representative investigation into the chemical and isotopic variations among these unique lithologies. Here, we measured the H abundance and isotopic composition (δD) of NWA 15820 and NWA 16789 to evaluate the bulk UPB water content, resulting in a revised minimum bulk water content of 13 µg/g H2O. Furthermore, we report the δD of water in the UPB. While the D/H ratio of late-stage phosphates and glass is highly fractionated as a result of magmatic degassing, nominally anhydrous silicate pyroxene better records the original δD of the UPB. In particular, the pyroxene within NWA 16789 records a δD value of 83 ± 79‰, which we infer is the best estimate for the original δD of water in the UPB.
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BibTeX
@article{riderstokes2026hydrogen,
title = {{The hydrogen isotopic composition and content of the ureilite parent body: constraints from new ungrouped achondrites}},
author = {B.G. Rider-Stokes and A. Stephant and M. Nottingham and J. Gamblin and E. Füri and S.S. Russell and X. Zhao and M. Anand and M.J. Whitehouse and M.M. Grady},
journal = {Geochimica et Cosmochimica Acta},
year = {2026},
month = sep,
doi = {10.1016/j.gca.2026.07.047},
url = {https://hal.science/hal-05719020v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - The hydrogen isotopic composition and content of the ureilite parent body: constraints from new ungrouped achondrites
AU - B.G. Rider-Stokes
AU - A. Stephant
AU - M. Nottingham
AU - J. Gamblin
AU - E. Füri
AU - S.S. Russell
AU - X. Zhao
AU - M. Anand
AU - M.J. Whitehouse
AU - M.M. Grady
PY - 2026
DA - 2026/09/01
JO - Geochimica et Cosmochimica Acta
DO - 10.1016/j.gca.2026.07.047
UR - https://hal.science/hal-05719020v1
AB - Evidence for SiO2-rich melts on the ureilite parent body (UPB) stems from feldspathic clasts within polymict ureilites and has been additionally preserved and recorded in rare fragments of the Almahata Sitta meteorite suite, which originated from the asteroid 2008 TC3. These unique fragments demonstrated that ancient crust-forming volcanism on small planetary bodies was not simply restricted to basaltic lithologies. Two recent Northwest Africa finds (NWA) 15,820 and NWA 16789 expand the known quantity of SiO2-rich material from the UPB, allowing for a more representative investigation into the chemical and isotopic variations among these unique lithologies. Here, we measured the H abundance and isotopic composition (δD) of NWA 15820 and NWA 16789 to evaluate the bulk UPB water content, resulting in a revised minimum bulk water content of 13 µg/g H2O. Furthermore, we report the δD of water in the UPB. While the D/H ratio of late-stage phosphates and glass is highly fractionated as a result of magmatic degassing, nominally anhydrous silicate pyroxene better records the original δD of the UPB. In particular, the pyroxene within NWA 16789 records a δD value of 83 ± 79‰, which we infer is the best estimate for the original δD of water in the UPB.
SN - 0016-7037
SN - 1872-9533
ER -