Green garnets from the Newlands kimberlite,Cape Province,South Africa |
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| Authors: | DB Clarke DA Carswell |
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| Institution: | Department of Geology, Dalhousie University, Halifax, N.S. Canada;Department of Geology, University of Sheffield, Sheffield Great Britain |
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| Abstract: | Six crystals of green, uvarovite-rich garnet from the Newlands kimberlite have been analysed. The range of Cr2O3 is 10.04–14.04% and CaO is 19.18–25.94% (wt.), and thus they are similar to garnets found in only one other kimberlite province, namely Yakutia. By combining data from both the Russian and South African occurrences, four models are considered for the formation of such garnets. The model which best accounts for the available chemical data, and mode of occurrence, involves formation of the uvarovitic garnets during subsolidus recrystallization of spinel wehrlitic cumulates, which themselves had been produced by a fractionating magma at a depth of about 200–250 km. |
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