Zirconium-bearing accessory minerals in UK Paleogene granites: Textural, compositional, and paragenetic relationships

Harvey E. Belkin; Ray MacDonald

doi:10.5194/ejm-33-537-2021

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Zirconium-bearing accessory minerals in UK Paleogene granites: Textural, compositional, and paragenetic relationships

Harvey E. Belkin·Ray MacDonald

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Abstract

The mineral occurrences, parageneses, textures, and compositions of Zr-bearing accessory minerals in a suite of UK Paleogene granites from Scotland and Northern Ireland are described. Baddeleyite, zirconolite, and zircon, in that sequence, formed in hornblende + biotite granites (type 1) and hedenbergite–fayalite granites (type 2). The peralkaline microgranite (type 3) of Ailsa Craig contains zircon, dalyite, a eudialyte-group mineral, a fibrous phase which is possibly lemoynite, and Zr-bearing aegirine. Hydrothermal zircon is also present in all three granite types and documents the transition from a silicate-melt environment to an incompatible element-rich aqueous-dominated fluid. No textures indicative of inherited zircon were observed. The minerals crystallized in stages from magmatic through late-magmatic to hydrothermal. The zirconolite and eudialyte-group mineral are notably Y + REE-rich (REE signifies rare earth element). The crystallization sequence of the minerals may have been related to the activities of Si and Ca, to melt peralkalinity, and to local disequilibrium.

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European Journal of Mineralogy Article

Source-reported bounding extent: 54.061864482791236° to 57.27175687671797° latitude; -7.259167863003029° to -4.371029936775869° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Harvey E. Belkin, Ray MacDonald. 2021-09-23. Zirconium-bearing accessory minerals in UK Paleogene granites: Textural, compositional, and paragenetic relationships. https://doi.org/10.5194/ejm-33-537-2021

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