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dc.contributor.authorDowman, E
dc.contributor.authorWall, F
dc.contributor.authorJeffries, T
dc.contributor.authorTreloar, P
dc.contributor.authorCarter, A
dc.contributor.authorRankin, A
dc.date.accessioned2017-08-01T07:50:57Z
dc.date.issued2017-07-27
dc.description.abstractMineralogical assemblages are fundamental to the interpretation of geological processes. Zircon is an integral petrographic component of the mineral assemblages present in fenites (rocks formed by alkaline metasomatism) associated with the 136 Ma-aged Chilwa Island carbonatite complex, Malawi. Zircon exhibits contrasting characteristics and properties across the fenite aureole that surrounds the carbonatite stock. It shows intense grain dissolution and subsequent replacement by pyrochlore in the more intensely metasomatised ‘high-grade’ fenite of the innermost part of the aureole. By contrast, relict zircon crystals form the nucleus for the development of apatite-ilmenite-REE mineral assemblages in less altered zones. These changes in zircon properties are considered to be evidence of the diverse nature of fluids that metasomatised the Chilwa Islands fenite aureole. Although zircon is a principal component of the fenite mineral assemblages, when dated by LA-ICP-MS techniques it was found to predate the other minerals present in the mineral assemblages and thus, the age of carbonatite intrusion, by over 380 Ma. Instead of co-crystallising with the assemblage, zircon is therefore interpreted as providing a focus around which the minerals in the fenite assemblage formed. This implies that caution is needed both in the interpretation of Zr mobility in metasomatic assemblages, and also in attributing a zircon age to the assemblage as a whole in such sequences.en_GB
dc.identifier.citationAvailable online 27 July 2017en_GB
dc.identifier.doi10.1016/j.gr.2017.07.008
dc.identifier.urihttp://hdl.handle.net/10871/28734
dc.language.isoenen_GB
dc.publisherElsevieren_GB
dc.rights.embargoreasonPublisher policyen_GB
dc.subjectzirconen_GB
dc.subjectgeochronologyen_GB
dc.subjectfeniteen_GB
dc.subjectmetasomatismen_GB
dc.subjectcarbonatiteen_GB
dc.titleGranitoid zircon forms the nucleus for minerals precipitated by carbonatite-derived metasomatic fluids at Chilwa Island, Malawien_GB
dc.typeArticleen_GB
dc.identifier.issn1342-937X
dc.descriptionThis is the author's accepted manuscripten_GB
dc.descriptionThe final version is available from Elsevier via the DOI in this recorden_GB
dc.identifier.eissn1878-0571
dc.identifier.journalGondwana Researchen_GB


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