Geochemical self-organization of olivine-grade contact metamorphosed chert nodules in dolomite marble, Kilchrist, Skye |
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| Authors: | M B HOLNESS |
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| Institution: | Department of Geology and Geophysics, University of Edinburgh, West Mains Road, Edinburgh EH9 3JW , UK (email:;) |
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| Abstract: | Chert nodules in dolostones in the aureole of the Tertiary Beinn an Dubhaich granite, Skye, have developed mm-scale concentric monomineralic bands of alternating calcite and olivine during breakdown of a diopside core by the reaction 3 Dol+Di=4 Cal+2Fo+2 CO2. A simple textural progression from thin (<1 cm) homogeneous olivine-calcite rims close to the olivine-in isograd, to total replacement of the diopside core by a ≤10 cm thick well-banded rim close to the carbonate-granite contact demonstrates the developmental stages of the patterning. Correlation of olivine grain size with band spacing, and a greater olivine grain size in banded compared with homogeneous rims support pattern development by post-nucleation geochemical self-organization. |
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| Keywords: | contact metamorphism self-organization siliceous dolostones |
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