Fluid heterogeneity during granulite facies metamorphism in the Adirondacks; stable isotope evidence

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Authors:Valley, J. W.; O'Neil, James R.
Author Affiliations:Primary:
Univ. Wis.-Madison, Dep. Geol. and Geophys., Madison, WI, United States
Other:
U. S. Geol. Surv., United States
Volume Title:Contributions to Mineralogy and Petrology
Source:Contributions to Mineralogy and Petrology, 85(2), p.158-173. Publisher: Springer International, Heidelberg-New York, International. ISSN: 0010-7999
Publication Date:1984
Note:In English. 65 refs.; illus. incl. anal.
Summary:The preservation of pre-metamorphic whole-rock O-isotope ratios in Adirondack metasediments shows that neither these rocks nor adjacent anorthosites and gneisses have been penetrated by large amounts of externally derived, hot CO2-H2O fluids during granulite-facies metamorphism. Available data suggest that these rocks were not an open system during metamorphism; fluid/rock ratios were often 0.0-0.1. Isotopic analyses of 3-4 coexisting minerals from Adirondack marbles shows that isotopic equilibrium was attained at the peak of granulite and upper amphibolite-facies metamorphism. Thus the isotopic compositions or metamorphic fluids can be inferred from analyses of carbonates and fluid budgets can be constructed. Isotopic exchange is seen across marble-anorthosite and marble-granite contacts only on the scale of a few m. Small (<5 m) marble xenoliths are in approximate exchange equilibrium with their hosts, but for larger xenoliths and layers of marble there is no evidence of exchange at distances >10 m from meta-igneous contacts. [R.A.H.]
Subjects:Carbon dioxide; Facies; Geochemistry; Granulite facies; Isotopes; Marbles; Metamorphic rocks; Metamorphism; Metasedimentary rocks; Migration of elements; O-18/O-16; Oxygen; Petrology; Stable isotopes; Water; Adirondack Mountains; New York; United States; Fluid homogeneity; Northeastern New York
Coordinates:N430000 N443000 W0650000 W0773000
Abstract Numbers:84M/4158
Record ID:1985042724
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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