Experimentally determined compositions of diopside-jadeite pyroxene in equilibrium with albite and quartz at 1200-1350°C and 15-34 kbar

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doi: 10.1016/0016-7037(85)90178-4
Authors:Gasparik, Tibor
Author Affiliations:Primary:
State Univ. N.Y., Dep. Earth and Space Sci., Stony Brook, NY, United States
Volume Title:Geochimica et Cosmochimica Acta
Source:Geochimica et Cosmochimica Acta, 49(3), p.865-870. Publisher: Pergamon, Oxford, International. ISSN: 0016-7037
Publication Date:1985
Note:In English. 19 refs.; illus. incl. 2 tables
Summary:Equilibrium compositions of diopside-jadeite pyroxene coexisting with albite and quartz were experimentally determined at 25 different P-T conditions, using the electron microprobe. The new data and 600°C data provided the following mixing properties of the diopside (Di)-jadeite (Jd) solid solution (J,K): Gxs = XJdXDi(12 600 - 9.45T + (12 600 - 7.6T)(XJd - XDi) - (21 400 - 16.2T)(XJd - XDi)2). The Di-Jd solution is close to ideal above 1000°C but immiscible below 565°C. The Di-Jd solvus is slightly asymmetric with the crest at composition Di42.4Jd57.6. Excess enthalpy is positive but smaller than indicated by the enthalpy of solution measurements. Disorder in the Di-Jd solution is significantly smaller than complete disorder implied by the ionic two-site model. (Author's abstract) [C.M.B.H.]
Subjects:Albite; Chain silicates; Chemical composition; Clinopyroxene; Coexisting minerals; Diopside; Enthalpy; Entropy; Feldspar group; Framework silicates; Jadeite; Miscibility gap; Order-disorder; P-T conditions; Phase equilibria; Plagioclase; Pyroxene group; Quartz; Silica minerals; Silicates; Space groups; Stability; Transformations; Unit cell
Abstract Numbers:86M/0541
Record ID:1985049631
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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