Zirconium-bearing accessory minerals in UK Paleogene granites: textural, compositional, and paragenetic relationships
<p>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 <span class="inline-fo...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2021-09-01
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| Series: | European Journal of Mineralogy |
| Online Access: | https://ejm.copernicus.org/articles/33/537/2021/ejm-33-537-2021.pdf |
| Summary: | <p>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 <span class="inline-formula">+</span> 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<span class="inline-formula">+</span>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.</p> |
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| ISSN: | 0935-1221 1617-4011 |