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U-Th-Pb systematics of selected samples from Apollo 17, Boulder 1, Station 2

The Moon

By:
,
DOI: 10.1007/BF00569676

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Abstract

Nine U-Th-Pb whole-rock analyses of selected brecciated materials from sample 72215 and one analysis of a pigeonite basalt clast from 72275 are presented. Both samples are from Boulder 1, Apollo 17. These data supplement previous Boulder 1 U-Th-Pb analyses of samples 72275 and 72255. U and Th concentrations indicate that most of the samples contain a moderate to large KREEP component. Samples containing the least KREEP are a noritic clast (72255,49; Civet Cat clast) and an anorthositic clast (72275,117). Evidence for the migration of Pb from Pb-rich matrix material into relatively Pb-poor clasts is presented for two clasts. Most of the Boulder 1 data define a linear trend that intersects concordia at ??? 3.9 and 4.4 b.y. when plotted on a U-Pb concordia diagram. The presence of one anorthositic clast distinctly off this trend indicates that a simple two-stage U-Pb evolution history is inadequate to explain all the data. Accordingly physical significance is only attached to the lower concordia intercept age of 3.9-4.0 b.y. The older concordia intercept age of ??? 4.4 b.y. is interpreted to reflect an averaging of events both older and younger than 4.4 b.y. The data suggest that significant differentiation and/or metamorphism occurred ??? 4.2 b.y. ago. The age of this event, however, is not accurately defined by these data. ?? 1975 D. Reidel Publishing Company, Dordrecht-Holland.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
U-Th-Pb systematics of selected samples from Apollo 17, Boulder 1, Station 2
Series title:
The Moon
DOI:
10.1007/BF00569676
Volume
14
Issue:
3-4
Year Published:
1975
Language:
English
Publisher:
Kluwer Academic Publishers
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
The Moon
First page:
463
Last page:
471