2015/02/14 by Laurette Piani, F. Robert, François Robert +2 · 66 citations
Chemistry · Physics and Astronomy · #Analytical Chemistry (journal) #Astro and Planetary Science #Astrobiology #Astrophysics and Star Formation Studies #Carbonaceous chondrite #Chemistry #Chondrite #Environmental chemistry #Formation and evolution of the Solar System #Geochemistry #Geology #Isotope #Isotope fractionation #Meteorite #Mineralogy #Ordinary chondrite #Organic matter #Parent body #Physics #Stellar, planetary, and galactic studies #astro-ph.EP
paper · pdf · doi:10.1016/j.epsl.2015.01.039
published in Earth and Planetary Science Letters 415, 154-164 (Elsevier BV) · 40 pages, 8 figures, 2 tables, one supplement
openalex publication_date 2015/02/14 · arxiv created 2016/09/28 · arxiv updated 2016/09/29 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Organic matter and hydrous silicates are intimately mixed in the matrix of chondrites and in-situ determination of their individual D/H ratios is therefore challenging. Nevertheless, the D/H ratio of each pure component in this mixture should yield a comprehensible signature of the origin and evolution of water and organic matter in our solar system. We measured hydrogen isotope ratios of organic and hydrous silicates in the matrices of two carbonaceous chondrites (Orgueil CI1 and Renazzo CR2) and one unequilibrated ordinary chondrite (Semarkona, LL3.0). A novel protocol was adopted, involving NanoSIMS imaging of H isotopes of monoatomatic (H-) and molecular (OH-) secondary ions collected at the same location. This allowed the most enriched component with respect to D to be identified in the mixture. Using this protocol, we found that in carbonaceous chondrites the isotopically homogeneous hydrous silicates are mixed with D-rich organic matter. The opposite was observed in Semarkona. Hydrous silicates in Semarkona display highly heterogeneous D/H ratios, ranging from 150 to 1800 × 10-6 (δDSMOW = -40 to 10,600 permil). Organic matter in Semarkona does not show such large isotopic variations. This suggests limited isotopic exchange between the two phases during aqueous alteration. Our study greatly expands the range of water isotopic values measured so far in solar system objects. This D-rich water reservoir was sampled by the LL ordinary chondrite parent body and an estimate (up to 9 %) of its relative contribution to the D/H ratio of water in Oort cloud family comets is proposed.