Blar i forfatter "Shaikh, Azhar M."

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    • Evolution of ultrapotassic volcanism on the Kaapvaal craton: deepening the orangeite versus lamproite debate 

      Tappe, Sebastian; Shaikh, Azhar M.; Wilson, Allan H.; Stracke, Andreas (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-08-02)
      Orangeites are a significant source of diamonds, yet ambiguity surrounds their status among groups of mantle-derived potassic rocks. This study reports mineralogical and geochemical data for a c. 140 Ma orangeite dyke swarm that intersects the Bushveld Complex on the Kaapvaal craton in South Africa. The dykes comprise distinctive petrographic varieties that are linked principally by olivine ...

    • Origins of olivine in Earth’s youngest kimberlite: Igwisi Hills volcanoes, Tanzania craton 

      Shaikh, Azhar M.; Tappe, Sebastian; Bussweiler, Yannick; Vollmer, Christian; Brown, Richard J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-07-31)
      Monomineralic millimeter-sized olivine nodules are common in kimberlites worldwide. It is generally thought that such ‘dunitic nodules’ originate from the base of the cratonic lithosphere and that their formation marks the onset of deep-rooted kimberlite magmatic plumbing systems. However, thermobarometric constraints to support such a model have been lacking thus far. This study focuses on the ...

    • Redox state of the Dharwar craton root as inferred from eclogite and peridotite sourced mantle cargo, with implications for kimberlite and lamproite magma formation 

      Shaikh, Azhar M.; Bussweiler, Yannick; Viljoen, Fanus; Bolhar, Robert; Ravi, S.; Hezel, Dominik C.; Ueckermann, Henriëtte; Tappe, Sebastian (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-11-16)
      Despite over 400 occurrences of kimberlites and related rocks in India, mantle-derived xenoliths are known only from a few occurrences. This paucity of mantle-derived xenoliths in Indian kimberlites has hampered investigations of the subcontinental lithospheric mantle (SCLM). Using a valuable selection of the rare xenolith inventory, we here report Fe<sup>3+</sup>/ΣFe measurements for garnets using ...