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

December 31, 1981

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.

Publication Year 1981
Title Proterozoic zircon from augen gneiss, Yukon-Tanana Upland, east-central Alaska
DOI 10.1130/0091-7613(1981)9<469:PZFAGY>2.0.CO;2
Authors John N. Aleinikoff, Cynthia Dusel-Bacon, Helen L. Foster, Kiyoto Futa
Publication Type Article
Publication Subtype Journal Article
Series Title Geology
Index ID 70186542
Record Source USGS Publications Warehouse
USGS Organization Central Energy Resources Science Center; Central Mineral and Environmental Resources Science Center; Geology, Minerals, Energy, and Geophysics Science Center