Proterozoic zircon from augen gneiss, Yukon-Tanana Upland, east-central Alaska

Geology
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Abstract

U-Th-Pb analyses of zircons from an ortho-augen gneiss body in the Yukon-Tanana Upland of east-central Alaska yield strong evidence for the presence of early Proterozoic material in this area. U-Pb data define a chord that intersects concordia at about 2,300 and 345 m.y. We consider two interpretations: (1) the protolith was intruded during the Proterozoic and was subsequently metamorphosed in the Paleozoic or, more likely, (2) the protolith was intruded in the Paleozoic and incorporated material of Proterozoic age. An Sm-Nd model age of about 1,900 m.y. on a whole-rock sample of augen gneiss is additional evidence for the presence of Proterozoic material in the gneiss. K-Ar and U-Th-Pb dating of mica and sphene, respectively, reveal that younger thermal events occurred at least as recently as 110 m.y. ago.

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Publication type Article
Publication Subtype Journal Article
Title Proterozoic zircon from augen gneiss, Yukon-Tanana Upland, east-central Alaska
Series title Geology
DOI 10.1130/0091-7613(1981)9<469:PZFAGY>2.0.CO;2
Volume 9
Issue 10
Year Published 1981
Language English
Publisher Geological Survey of America
Contributing office(s) Central Energy Resources Science Center, Central Mineral and Environmental Resources Science Center, Geology, Minerals, Energy, and Geophysics Science Center
Description 5 p.
First page 469
Last page 473
Country United States
State Alaska
Other Geospatial Yukon-Tanana Upland
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