Potassian Zirconium and Titanium Silicates and Strontian Cerian Perovskite in Lamproites from the Leucite Hills . Wyoming
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چکیده
The groundmass of lamproites from Middle Table Mountain, Leucite Hills, Wyoming, is characterized by the presence of potassium zirconium silicates and Sr{e-rich perovskite. Two intimately intergrown K-Z silicates of differing Ti content are recognizable by cathodoluminescence t chniques. Both are similar in composition to wadeite. Intergrown with these minerals is a phase having the composition of the Ti analog (K2TiSi3Oe) of wadeite (K2ZrSi3O9) that is considered to be a new mineral. Groundmass poikilitic perovskite is unusually rich in Sr (zt-7 wt.7o SrO) and rare-earth elements (5-12 wt.Vo Ce2O3) relative to perovskite occurring in other lamproites and kimberlites. The formation of this unusual suite of accessory minerals in the groundmass is considered to reflect the exfeme differentiation of this batch of lamproitic magma relative to other occurences of lamproite in the Irucite Hills.
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Isotopic analysis of mineral phases to unravel the origin of altered volcanic rocks: an example from the Leucite Hills lamproites
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