Preservation of premetamorphic oxygen isotope ratios in granitic orthogneiss from the Adirondack Mountains, New York, USA

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doi: 10.1016/0016-7037(94)90247-X
Authors:Eiler, John M.; Valley, John W.
Author Affiliations:Primary:
University of Wisconsin, Department of Geology and Geopysics, Madison, WI, United States
Volume Title:Geochimica et Cosmochimica Acta
Source:Geochimica et Cosmochimica Acta, 58(24), p.5525-5535. Publisher: Pergamon, Oxford, International. ISSN: 0016-7037
Publication Date:1994
Note:In English. 79 refs.; illus., incl. 2 tables, geol. sketch map
Summary:Δ18O analyses are presented of 70 whole-rock samples of orthogneisses from the complexes of the Tuppe and Saranac sheets adjacent to the Marcy anorthosite and the Snowy Mt Dome. Additional samples included gabbros from the Oregon dome and granitic rocks for which there is no evidence of a genetic relation to the anorthosite-mangerite-charnockite-granite suite (AMCG) adjacent to the Marcy anorthosite. A correlation is found between Δ18O and major element composition within continuous mappable, meta-plutonic units, but not among non-consanguineous granitic rocks. Δ18O in mineral separates preserve high-T fractionations indicating closed-system retrograde exchange. The results indicate the role of assimilation in the magmatic evolution of granitic sheets related to anorthosite, the wide diversity of source Δ18O signatures in orthogneisses, and the preservation of these primary features through deep crustal granulite-facies metamorphism. The preservation of these features restricts models of granulite-facies metamorphism, prohibiting large amounts of pervasive fluids and large-scale isotopic equilibrium during deep crustal metamorphism. [R.K.H.]
Subjects:Gneisses; Granitic composition; Granulites; Grenvillian Orogeny; Isotope ratios; Isotopes; Mesoproterozoic; Metamorphic rocks; O-18/O-16; Orthogneiss; Ottawan Orogeny; Oxygen; Precambrian; Proterozoic; Stable isotopes; Upper Precambrian; Adirondack Mountains; Marcy Massif; New York; United States
Abstract Numbers:95M/3172
Record ID:1995036716
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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