Multiply exsolved clinopyroxene megacrysts from the Frank Smith Mine, Cape Province, South Africa

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doi: 10.1016/0024-4937(83)90036-1
Authors:Clarke, D. B.; Pe-Piper, Georgia S.
Author Affiliations:Primary:
Dalhousie Univ., Dep. Geol., Halifax, NS, Canada
Volume Title:Lithos (Oslo)
Source:Lithos (Oslo), 16(1), p.75-84. Publisher: Elsevier, Amsterdam, International. ISSN: 0024-4937
Publication Date:1983
Note:In English. 31 refs.; illus. incl. 2 tables
Summary:The clinopyroxene megacrysts from the Frank Smith kimberlite show multiple exsolution of garnet, orthopyroxene and oxide phases. In one of the megacrysts the lamellar texture has partly recrystallized to a granular one. The chemical compositions of the exsolved phases are similar to those of discrete nodules and of granular pyroxenites found in the same kimberlite. Conditions of formation of the original homogeneous clinopyroxene solid solution are estimated to be approx 1500°C and 37 kbar, whereas the re-equilibration conditions are closer to 900°C and 35 kbar. The megacrysts may have belonged to the Karroo age magmatism which predated kimberlite activity and have been brought to the surface as accidental xenocrysts by the Frank Smith kimberlite. [G.R.]
Subjects:Chain silicates; Chemical composition; Clinopyroxene; Exsolution; Igneous rocks; Kimberlite; Megacrysts; Minerals; Petrography; Petrology; Pressure; Pyroxene group; Silicates; Temperature; Ultramafic composition; Africa; Cape Province region; South Africa; Southern Africa; Cape Province South Africa; Frank Smith Mine
Abstract Numbers:83M/4949
Record ID:1986020194
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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