Amazonitic K-feldspar is characteristic of evolved granitic pegmatites of NYF (niobium-yttrium-fluorine) type, associated with A-type granite emplacement. In this work, I focus on four notable examples of such an association: (1) West Keivy, Kola Peninsula, Russia, (2) Saint-Ludger-de-Milot, Quebec, (3) Lac Sairs, Quebec, and (4) Morefield, Virginia. A fifth locality, the Broken Hill metamorphosed exhalative-type volcanogenic deposits in Australia, is an unusual type of amazonitic K-feldspar formed in an ore environment. A total of nineteen samples of amazonitic K-feldspar were characterized geochemically and mineralogically on the basis of X-ray diffraction, electron-microprobe and laser-ablation ICP-MS analyses. Lead, as an essential requirement for formation of the blue-green amazonitic color, has received particular attention. In every case, the analytical data show elevated amounts of Pb and rare alkalis, which strongly partition into the K-rich phase of the perthite intergrowth. Unusual micrometric grains, highly enriched in Pb, are found in cracks in the material from West Keivy. Some of the grains represent a new mineral species, a Pb-dominant feldspar. The presence of amazonitic K-feldspar in a granitic pegmatite is more than a curiosity. It can shed light on important petrogenetic issues such as metasomatic rejuvenation of crustal rocks prior to regional melting in a period of extension.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.101650 |
| Date | January 2006 |
| Creators | Sokolov, Maria, 1969- |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Earth and Planetary Sciences.) |
| Rights | © Maria Sokolov, 2006 |
| Relation | alephsysno: 002600010, proquestno: AAIMR32787, Theses scanned by UMI/ProQuest. |
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