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Micron-scale D/H heterogeneity in chondrite matrices: A signature of the pristine solar system water?
| Title: | Micron-scale D/H heterogeneity in chondrite matrices: A signature of the pristine solar system water? |
| Authors: | Piani, Laurette Browse this author | | Robert, Francois Browse this author | | Remusat, Laurent Browse this author |
| Keywords: | chondrite | | solar system | | water | | organic matter | | hydrogen isotopes | | NanoSIMS |
| Issue Date: | 1-Apr-2015 |
| Publisher: | Elsevier |
| Journal Title: | Earth and Planetary Science Letters |
| Volume: | 415 |
| Start Page: | 154 |
| End Page: | 164 |
| Publisher DOI: | 10.1016/j.epsl.2015.01.039 |
| Abstract: | 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 x 10(-6) (delta D-SMOW = -40 to 10 600%). 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 (<= 9%) of its relative contribution to the D/H ratio of water in Oort cloud family comets is proposed. |
| Rights: | (C) 2015 Elsevier B.V. All rights reserved. |
| Type: | article (author version) |
| URI: | http://hdl.handle.net/2115/58560 |
| Appears in Collections: | 理学院・理学研究院 (Graduate School of Science / Faculty of Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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Submitter: PIANI Laurette
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