Oxygen isotope diffusion and zoning in diopside; the importance of water fugacity during cooling

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doi: 10.1016/S0016-7037(98)00120-3
Authors:Edwards, Katrina J.; Valley, John W.
Author Affiliations:Primary:
University of Wisconsin, Department of Geology and Geophysics, Madison, WI, United States
Volume Title:Geochimica et Cosmochimica Acta
Source:Geochimica et Cosmochimica Acta, 62(13), p.2265-2277. Publisher: Pergamon, Oxford, International. ISSN: 0016-7037
Publication Date:1998
Note:In English. 46 refs.; illus., incl. 9 tables, sketch map
Summary:The results are presented of cold cathode luminescence, reflected differential interference contrast, optical microscopy, SEM and X-ray composition mapping to evaluate processes other than diffusion that might alter the oxygen isotopic composition of eight samples of diopside separated from marbles of New York State, USA. δ 18O analyses are presented of bulk (whole-mineral) diopsides; there is a positive correlation between decreasing bulk δ 18O with decreasing grain size for some, but not all samples. Variations in O isotope ratios between grains of different sizes are related to peak T, cooling rate and water fugacity during cooling. The results indicate that in slowly cooled high-grade metamorphic terrains, water fugacity can vary between rocks during cooling, and water fugacity is the most important constraint on the degree of O isotope retrograde exchange. [R.K.H.]
Sections:Geochemistry
Subsections:Minerals and ores
Subjects:Cathodoluminescence; Chain silicates; Clinopyroxene; Cooling; Diffusion; Diopside; Experimental studies; Facies; Fugacity; Geochemistry; Grain size; Granulite facies; Inclusions; Ion probe data; Isotope ratios; Isotopes; Marbles; Mass spectra; Metamorphic rocks; Metamorphism; O-18/O-16; Oxygen; Phase equilibria; Pyroxene group; Retrograde metamorphism; SEM data; Silicates; Spectra; Stable isotopes; Thermal history; Water; X-ray data; Xenoliths; Adirondack Mountains; Essex County New York; New York; Saint Lawrence County New York; United States; Cascade Slide; Mount Marcy Quadrangle
Abstract Numbers:99M/1700
Record ID:1998056501
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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