Meteoritic Evidence for a Ceres-sized Water-rich Carbonaceous Chondrite Parent Asteroid
Carbonaceous chondrite meteorites record the earliest stages of Solar System geo-logical activities and provide insight into their parent bodies' histories. Some carbonaceous chondrites are volumetrically dominated by hydrated minerals, providing evidence for low temperature and pressure aqueou...
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Published in | Nature astronomy Vol. 2020; no. 4; pp. 350 - 355 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
England
Nature Publishing Group
01.04.2021
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Subjects | |
Online Access | Get full text |
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Summary: | Carbonaceous chondrite meteorites record the earliest stages of Solar System geo-logical activities and provide insight into their parent bodies' histories. Some carbonaceous chondrites are volumetrically dominated by hydrated minerals, providing evidence for low temperature and pressure aqueous alteration
. Others are dominated by anhydrous minerals and textures that indicate high temperature metamorphism in the absence of aqueous fluids
. Evidence of hydrous metamorphism at intermediate pressures and temperatures in carbonaceous chondrite parent bodies has been virtually absent. Here we show that an ungrouped, aqueously altered carbonaceous chondrite fragment (numbered 202) from the Almahata Sitta (AhS) meteorite contains an assemblage of minerals, including amphibole, that reflect fluid-assisted metamorphism at intermediate temperatures and pressures on the parent asteroid. Amphiboles are rare in carbonaceous chondrites, having only been identified previously as a trace component in Allende (CV3
) chondrules
. Formation of these minerals requires prolonged metamorphism in a large (~640-1800 km diameter), unknown asteroid. Because Allende and AhS 202 represent different asteroidal parent bodies, intermediate conditions may have been more widespread in the early Solar System than recognized from known carbonaceous chondrite meteorites, which are likely a biased sampling. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 VEH conducted and analyzed the spectral measurements, contributed to the scientific interpretation, and coordinated and wrote the manuscript. CAG conducted and analyzed SEM and EMPA measurements, performed the parent body size modeling, and contributed to the scientific interpretation of all data. AHT contributed to the metamorphic mineral assemblage modeling and textural interpretations. HCC contributed to the scientific interpretation of the observed EPMA, textural, and spectral results. MEZ conducted EMPA and TEM measurements and contributed to the scientific interpretation of those data. MHS provided the sample of AhS 202 from the University of Khartoum collection. Author Contributions |
ISSN: | 2397-3366 2397-3366 |
DOI: | 10.1038/s41550-020-01274-z |