The Tarda Meteorite: A Window into the Formation of D-type Asteroids
International audience Dynamic models of solar system evolution suggest that D-type asteroids formed beyond Saturn's orbit and represent invaluable witnesses of the prevailing conditions in the outer solar system. Here, we report a comprehensive petrographic and isotopic characterization of the...
Published in: | The Astrophysical Journal Letters |
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Main Authors: | , , |
Other Authors: | , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
HAL CCSD
2021
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Subjects: | |
Online Access: | https://hal.archives-ouvertes.fr/hal-03368940 https://hal.archives-ouvertes.fr/hal-03368940/document https://hal.archives-ouvertes.fr/hal-03368940/file/Marrocchi-modified.pdf https://doi.org/10.3847/2041-8213/abfaa3 |
Summary: | International audience Dynamic models of solar system evolution suggest that D-type asteroids formed beyond Saturn's orbit and represent invaluable witnesses of the prevailing conditions in the outer solar system. Here, we report a comprehensive petrographic and isotopic characterization of the carbonaceous chondrite Tarda, a recent fall recovered in the Moroccan Sahara. We show that Tarda shares strong similarities with the D-type-derived chondrite Tagish Lake, implying that Tarda represents a rare sample of D-type asteroids. Both Tarda and Tagish Lake are characterized by the presence of rare 16 O-rich chondrules and chondrule fragments, high C/H ratios, and enrichments in deuterium, 15 N, and 13 C. By combining our results with literature data on carbonaceous chondrites related to C-type asteroids, we show that the outer solar system at that time was characterized by large-scale oxygen isotopic homogeneities in (i) the water-ice grains accreted by asteroids and (ii) the gas controlling the formation of FeO-poor chondrules. Conversely, the zone in which D-type asteroids accreted was significantly enriched in deuterium relative to the formation regions of C-type asteroids, features likely inherited from unprocessed, D-rich, molecular-cloud materials. |
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