TWO POPULATIONS OF CARBONATE IN ALH84001: GEOCHEMICAL EVIDENCE FOR DISCRIMINATION AND GENESIS
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dc.contributor.author | Eiler J.M. | |
dc.contributor.author | Valley J.W. | |
dc.contributor.author | Graham C.M. | |
dc.contributor.author | Fournelle J. | |
dc.date.accessioned | 2021-04-16T04:39:53Z | |
dc.date.available | 2021-04-16T04:39:53Z | |
dc.date.issued | 2002 | |
dc.identifier | https://www.elibrary.ru/item.asp?id=919334 | |
dc.identifier.citation | Geochimica et Cosmochimica Acta, 2002, 66, 7, 1285-1303 | |
dc.identifier.issn | 0016-7037 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/27873 | |
dc.description.abstract | We present major and trace-element, oxygen isotope, textural, and structural data for carbonates and related phases in the SNC meteorite ALH84001. These data document the existence of at least two distinct carbonate populations: one composed of finely zoned, chemically and isotopically heterogeneous concretions of magnesio-siderite with distinct white magnesite rims, and a second composed of relatively homogeneous, isotopically and compositionally simple domains of ankeritic carbonate and intimately intergrown glass and fine-grained pyroxene. We suggest on the basis of textural evidence and geochemical systematics that the first population consists of low-temperature aqueous precipitates, and the second is produced by shock melting of the first. Values of δ18O and Sr/Ca ratios are correlated with one another in magnesio-siderite concretions; the trend formed by these data is consistent with the predicted relationship for inorganic precipitation of carbonate from a solution of constant composition between temperatures of ~190°C (for concretion cores) to 20°C (for magnesite-rich concretion rims). Given the assumptions inherent in this temperature estimate, the aqueous fluid parental to carbonate concretions is constrained to have a δ18O of -5%% VSMOW (significantly mass fractionated compared with expected juvenile martian volatiles) and minor-element abundances broadly similar to terrestrial seawater. | |
dc.title | TWO POPULATIONS OF CARBONATE IN ALH84001: GEOCHEMICAL EVIDENCE FOR DISCRIMINATION AND GENESIS | |
dc.type | Статья |
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