Titaniferous phlogopites from the leucite lamproites of the West Kimberley area,Western Australia |
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| Authors: | Roger H Mitchell |
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| Institution: | (1) Department of Geology, Lakehead University, Thunder Bay, P7B 5E1, Ontario, Canada |
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| Abstract: | Phlogopites in the wolgidites, fitzroyites and cedricites (leucite lamproites) of the West Kimberley area range in composition from titaniferous phlogopite to titaniferous tetraferriphlogopite. Two distinct compositional trends are present. In wolgidites micas are characterized by strong total iron enrichment, moderate Al and Mg depletion and little enrichment in tetrahedral ferric iron. Micas in fitzroyites and cedricites are characterized by strong depletion in Al and strong enrichment in tetrahedral ferric iron at approximately constant Mg contents. Individual centers of fitzroyite intrusion are characterized by distinct mica TiO2 contents. The phlogopite compositional trends at low pressures are very different to those of kimberlite micas. An origin of these lamproites involving differentiation of a kimberlitic magma is considered unlikely. |
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