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U-Th-Pb systematics of zircon inclusions in rock-forming minerals: A study of armoring against isotopic loss using the Sherman Granite of Colorado-Wyoming, USA

Contributions to Mineralogy and Petrology

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DOI: 10.1007/BF00371194

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Abstract

Zircon inclusions were separated from the five major rock-forming minerals of the Sherman Granite of southern Wyoming, in order to evaluate the degree of discordance as a possible function of host minerals. U-Th-Pb isotopic ratios were determined for two size fractions of zircon inclusions from each mineral, plus five size fractions from the bulk rock. Isotopic data from the inclusions have more than double the spread of data on a discordia obtained from the bulk sample, thereby yielding better-resolved concordia intercepts. However, isotopic ratios and morphologic characteristics indicate that the Pb/U systematics are complicated by inherited radiogenic lead. Although the data array cannot unequivocally be explained by the armoring process, the proposed methodology has succeeded in identifying groups of zircon with different isotopic characteristics. As such, this technique can be used to decipher complex geologic/isotopic histories and may be a useful addition to routine zircon geochronology. ?? 1983 Springer-Verlag.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
U-Th-Pb systematics of zircon inclusions in rock-forming minerals: A study of armoring against isotopic loss using the Sherman Granite of Colorado-Wyoming, USA
Series title:
Contributions to Mineralogy and Petrology
DOI:
10.1007/BF00371194
Volume
83
Issue:
3-4
Year Published:
1983
Language:
English
Publisher location:
Springer-Verlag
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
259
Last page:
269
Number of Pages:
11