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The present work is a first comprehensive study of the trace-element composition and zoning in clinopyroxene- and amphibole-group minerals from carbonatites, incorporating samples from 14 localities worldwide (Afrikanda, Aley, Alnö, Blue River, Eden Lake, Huayangchuan, Murun, Oka, Ozernaya Varaka, Ozernyi, Paint Lake, Pinghe, Prairie Lake, Turiy Mys). The new electron-microprobe data presented here...
Bebedourite is a cumulate rock composed of variable but roughly equant amounts of diopside, apatite, magnetite, phlogopite, and a Ca–Ti phase (mostly perovskite, more rarely titanite and/or Ti-garnet). Other minerals may be modally important, such as olivine and K-feldspar in the least and most evolved members of the bebedourite series, respectively. The magmatic evolution in bebedourites is accompanied...
The Tchivira carbonatites contain several pyrochlore generations. Rare pyrochlore crystals, close to the fluorcalciopyrochlore end member composition, occur as primary magmatic crystals and are replaced due to subsolidus hydrothermal processes. These produced leaching of Na in the A position, balanced by F removal from the Y position. Interaction of oxydizing hydrothermal fluids with carbonatites...
U–Pb and Th–Pb ages of zircons from seven meta-carbonatite and three meta-alkaline rock samples provide evidence for three distinct episodes of carbonatite and alkaline magmatism in the southern Canadian Cordillera spanning a period of ~460Ma. The earliest, Neoproterozoic event occurred at ~800–700Ma and coincides with the postulated initial break-up of Rodinia. The second, previously undocumented,...
Peperites in the Limagne graben (French Massif Central) have been interpreted up to now as phreatomagmatic eruptions involving fragmentation of sedimentary rocks during magma–water interaction. We report about the possible magmatic origin of the carbonates involved in the peperites from Gergovie and Pileyre localities. In these two volcanic deposits, carbonates are manly dolomitic in composition,...
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