Disequilibrium features in experimentally shocked mixtures of olivine plus silica glass powders

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Authors:Schaal, R. B.
Author Affiliations:Primary:
1335 First Street, Gilroy, CA 95020, United States
Volume Title:Contributions to Mineralogy and Petrology
Source:Contributions to Mineralogy and Petrology, 81(1), p.39-47. Publisher: Springer International, Heidelberg-New York, International. ISSN: 0010-7999
Publication Date:1982
Note:In English. 29 refs.; illus. incl. 8 anal., 2 tables
Summary:Shock-recovery experiments (17) were performed on powder 1:2 mixtures of olivine (Fo92) and pure vitreous silica; powders of <45 mu m grain size were shocked by impact of projectiles which created pressures of 6.2-64.2 kbar. Melt chemistry is bimodal in each sample: colourless melts are 99.9% SiO2; pale to dark green melts range 47-64% SiO2 and represent a progressive mixture of olivine melt (41% SiO2) with silica glass melt (in the enstatite compositional range). Chemical disequilibrium is thus shown by the creation of these olivine-normative melts from a quartz-normative starting composition, and by the chemical heterogeneity in the melts. Petrographic disequilibrium is shown in cataclastic textures and in thermal effects showing non-uniform granular melting; this disequilibrium is caused by an irregular P distribution resulting from the rapid collapse of pore spaces. [R.A.H.]
Subjects:Chain silicates; Enstatite; Equilibrium; Experimental studies; Fabric; Glasses; High pressure; Igneous rocks; Impactites; Major elements; Metamorphic rocks; Metamorphism; Nesosilicates; Olivine; Olivine group; Orthopyroxene; Orthosilicates; Petrology; Pressure; Pyroxene group; Shock metamorphism; Silicates; Synthetic materials; Volcanic rocks; Africa; Egypt; Indian Ocean; North Africa; Red Sea
Coordinates:N234000 N234000 E0360800 E0360800
Abstract Numbers:83M/1477
Record ID:1985080254
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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