40AR/39AR DATING OF APOLLO 12 REGOLITH: IMPLICATIONS FOR THE AGE OF COPERNICUS AND THE SOURCE OF NONMARE MATERIALS
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dc.contributor.author | Barra F. | |
dc.contributor.author | Swindle T.D. | |
dc.contributor.author | Korotev R.L. | |
dc.contributor.author | Jolliff B.L. | |
dc.contributor.author | Zeigler R.A. | |
dc.contributor.author | Olson E. | |
dc.date.accessioned | 2024-04-20T09:00:46Z | |
dc.date.available | 2024-04-20T09:00:46Z | |
dc.date.issued | 2006 | |
dc.identifier | https://elibrary.ru/item.asp?id=12091574 | |
dc.identifier.citation | Geochimica et Cosmochimica Acta, 2006, 70, 24, 6016-6031 | |
dc.identifier.issn | 0016-7037 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/43720 | |
dc.description.abstract | Twenty-one 2-4 mm rock samples from the Apollo 12 regolith were analyzed by the 40Ar/39Ar geochronological technique in order to further constrain the age and source of nonmare materials at the Apollo 12 site. Among the samples analyzed are: 2 felsites, 11 KREEP breccias, 4 mare-basalt-bearing KREEP breccias, 2 alkali anorthosites, 1 olivine-bearing impact-melt breccia, and 1 high-Th mare basalt. Most samples show some degree of degassing at 700-800 Ma, with minimum formation ages that range from 1.0 to 3.1 Ga. We estimate that this degassing event occurred at 782 ? 21 Ma and may have been caused by the Copernicus impact event, either by providing degassed material or by causing heating at the Apollo 12 site. 40Ar/39Ar dating of two alkali anorthosite clasts yielded ages of 3.256 ? 0.022 Ga and 3.107 ? 0.058 Ga. We interpret these ages as the crystallization age of the rock and they represent the youngest age so far determined for a lunar anorthosite. The origin of these alkali anorthosite fragments is probably related to differentiation of shallow intrusives. Later impacts could have dispersed this material by lateral mixing or vertical mixing. | |
dc.subject | ANORTHOSITE | |
dc.subject | ARGON-ARGON DATING | |
dc.subject | GEOCHRONOLOGY | |
dc.subject | LUNAR SOIL | |
dc.subject | MARE BASALT | |
dc.subject | REGOLITH | |
dc.title | 40AR/39AR DATING OF APOLLO 12 REGOLITH: IMPLICATIONS FOR THE AGE OF COPERNICUS AND THE SOURCE OF NONMARE MATERIALS | |
dc.type | Статья | |
dc.identifier.doi | 10.1016/j.gca.2006.09.013 |
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