Formation and temporal evolution of the Kalahari sub-cratonic lithospheric mantle: Constraints from Venetia xenoliths, South Africa

R.C. Hin, M.L.A. Morel, O. Nebel, P.R.D. Mason, W. van Westrenen, G.R. Davies

    Research output: Contribution to JournalArticleAcademicpeer-review

    Abstract

    The ~533 Ma Venetia Diamond Mine is located between the Kaapvaal and Zimbabwe Cratons and the study of selected xenoliths provides the opportunity to investigate the temporal evolution of the sub-continental lithospheric mantle (SCLM) underneath southern Africa, as well as the extent and potentially the timing and nature of the Si-enrichment that characterizes the Kaapvaal SCLM. Most peridotite xenoliths contain 15-25% orthopyroxene, confirming Si-enrichment of the Venetian SCLM. Mineral major element compositions for 36 peridotitic mantle xenoliths record less melt depletion than inclusions in Venetian diamonds (e.g., olivine Mg# 88.7-93.4; mode 92.5). Olivine Mg# suggest on average ~40% melt extraction and reconstructed whole rock HREE concentrations can be modelled by 20% fractional melting in the garnet stability field followed by ~10 to 13% in the spinel stability field. Calculated Nb/Sr and Ce/Yb ratios for melts in equilibrium with garnet and clinopyroxene suggest that the xenolith suite underwent metasomatism by both hydrous fluids and kimberlite/carbonatite-type melts. Garnet Nd (T
    Original languageEnglish
    Pages (from-to)1069-1082
    JournalLithos
    Volume112
    Issue number1
    DOIs
    Publication statusPublished - 2009

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