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The H2O component of sheared mantle peridotites from the Kaapvaal craton: evidence for hydrous deformation with implications for the stability of cratons

Sheared peridotite xenoliths entrained by kimberlites provide snapshots of metasomatism and deformation within the cratonic mantle. Here, we present H2O concentrations of nominally anhydrous minerals (olivine, orthopyroxene and clinopyroxene) in 18 low-, moderate- and high-T sheared peridotites from...

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Hauptverfasser: Heckel, Catharina (Verfasst von) , Withers, Anthony C. (Verfasst von) , Woodland, Alan B. (Verfasst von) , Gibson, Sally A. (Verfasst von) , Ludwig, Thomas (Verfasst von)
Dokumenttyp: Article (Journal)
Sprache:Englisch
Veröffentlicht: 24 January 2026
In: Contributions to mineralogy and petrology
Year: 2026, Jahrgang: 181, Heft: 2, Pages: 1-22
ISSN:1432-0967
DOI:10.1007/s00410-025-02295-5
Online-Zugang:Verlag, kostenfrei, Volltext: https://doi.org/10.1007/s00410-025-02295-5
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Verfasserangaben:Catharina Heckel, Anthony C. Withers, Alan B. Woodland, Sally A. Gibson, Thomas Ludwig
Beschreibung
Zusammenfassung:Sheared peridotite xenoliths entrained by kimberlites provide snapshots of metasomatism and deformation within the cratonic mantle. Here, we present H2O concentrations of nominally anhydrous minerals (olivine, orthopyroxene and clinopyroxene) in 18 low-, moderate- and high-T sheared peridotites from the Kimberley and northern Lesotho kimberlite cluster (Kaapvaal craton). H2O contents range from < 1-80 µg/g (olivine), 70-310 µg/g (orthopyroxene) and 120-300 µg/g (clinopyroxene), implying hydration through metasomatism. Core to rim heterogeneities in H2O concentrations indicate that ortho- and clinopyroxene cores preserve an older metasomatic/deformation event in the lithospheric mantle while olivine cores record the youngest metasomatic event. The latter must have happened immediately prior to xenolith entrainment and transport to the surface. Calculated H2O contents for the metasomatic agents range from 1 to 3 wt% H2O. We speculate that highly-reactive hydrous (proto-)kimberlitic melts caused oxidizing metasomatism that triggered deformation prior potentially enhanced craton destabilization as well as the local resorption of diamonds.
Beschreibung:Im Text ist "2" tiefgestellt
Gesehen am 15.04.2026
Beschreibung:Online Resource
ISSN:1432-0967
DOI:10.1007/s00410-025-02295-5

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