EVIDENCE FOR A PRECOMPACTION EXPOSURE TO COSMIC RAYS IN A CHONDRULE FROM THE H6 CHONDRITE ALH76008 - SOLAR GAS RICH MATRIX
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dc.contributor.author | Polnau E. | |
dc.contributor.author | Eugster O. | |
dc.contributor.author | Krahenbuhl U. | |
dc.contributor.author | Marti K. | |
dc.date.accessioned | 2021-01-16T23:59:26Z | |
dc.date.available | 2021-01-16T23:59:26Z | |
dc.date.issued | 1999 | |
dc.identifier | https://elibrary.ru/item.asp?id=156991 | |
dc.identifier.citation | Geochimica et Cosmochimica Acta, 1999, 63, 6, 925-933 | |
dc.identifier.issn | 0016-7037 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/23248 | |
dc.description.abstract | We studied the cosmic-ray records of the H6 chondrite ALH76008 in a bulk sample, in a chondrule fragment, and in matrix material. The matrix was separated into olivine/pyroxene, plagioclase, and metal concentrates. For all samples He, Ne, and Ar isotopic measurements were performed. The cosmic-ray exposure age of the bulk chondrite is 1.72 +/- 0.11 Ma, whereas the 3He, 21Ne, and 38Ar ages of the chondrule exceed those of bulk material by 31%, 67%, and 55%, respectively. The radiation environment in the early solar system is ill defined, but for current production rates this translates into a precompaction exposure time of 0.90 Ma. Furthermore, the plagioclase (mainly anorthite) concentrate, representing a few percent of the total meteorite, contains solar-type noble gases that reveal differential irradiation of ALH76008 components. We observe a trapped ratio 20Ne/22Ne = 12.3 +/- 0.3, a value that is between those of solar wind and solar energetic particles. This is the first clear identification of differential irradiation conditions between a chondrule and the bulk chondrite; the short exposure age may favor the resolution of differential exposure histories. | |
dc.title | EVIDENCE FOR A PRECOMPACTION EXPOSURE TO COSMIC RAYS IN A CHONDRULE FROM THE H6 CHONDRITE ALH76008 - SOLAR GAS RICH MATRIX | |
dc.type | Статья |
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