Sm-Nd systematics of a tonalitic augen gneiss and its constituent minerals from northern Michigan

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doi: 10.1016/0016-7037(81)90148-4
Authors:Futa, K.
Author Affiliations:Primary:
U. S. Geol. Surv., Denver, CO 80225, United States
Volume Title:Geochimica et Cosmochimica Acta
Source:Geochimica et Cosmochimica Acta, 45(7), p.1245-1249. Publisher: Pergamon, Oxford, International. ISSN: 0016-7037
Publication Date:1981
Note:In English. 15 refs.; illus. incl. 2 tables
Summary:The Sm/Nd isotopic system was disturbed during metamorphism. Sm/Nd zircon ages are lower than the whole-rock Sm/Nd-model age. However, closely associated pairs of minerals (for example, sphene and biotite, or apatite and plagioclase) retain their apparent metamorphic ages. The Sm/Nd model age for the tonalitic augen gneiss of 3919 + or - 30 m.y. appears to reflect open-system behaviour during metamorphism. A mineralogically-different gneiss from the same location has a Sm/Nd model age 3520 + or - 70 m.y. The two whole-rocks differ in their Sm/Nd and Rb/Sr systematics and in their chondrite-normalized RE patterns. The whole-rock-normalized mineral RE patterns show the contribution of the major and trace minerals to the RE content of the whole rock. The trace minerals contain a significant amount of the total RE. [C.M.B.H.]
Subjects:Absolute age; Augen gneiss; Dates; Diorites; Geochronology; Gneisses; Igneous rocks; Marquette Range Supergroup; Metals; Metamorphic rocks; Metamorphism; Minor elements; Paleoproterozoic; Plutonic rocks; Precambrian; Proterozoic; Rare earths; Sm/Nd; Spectra; Tonalite; Upper Precambrian; X-ray fluorescence spectra; Gogebic County Michigan; Michigan; Michigan Upper Peninsula; United States; Watersmeet
Coordinates:N462800 N462800 E0891000 E0891000
Abstract Numbers:82M/2236
Record ID:1982056919
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom, Reference includes data from PASCAL, Institute de l'Information Scientifique et Technique
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