Kaersutite megacrysts in the alkaline mafic dikes of the Panticosa pluton (Pyrenean Axial Zone, Spain): deep-origin xenocrysts

• Autores: Pablo Tierz López, Marceliano Lago San José, Carlos Galé Bornao, Enrique Arranz Yagüe, Teresa Ubide, Patricia Larrea, Tomás Sanz Serrano
• Localización: Geogaceta, ISSN 0213-683X, Nº. 52, 2012, págs. 139-142
• Idioma: inglés
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• Resumen

  • Megacrysts of kaersutite have been identified in several alkaline mafic dikes from the Panticosa pluton. They show strongly anhedral habits and resorption features, including Krs overgrowths and/or Cpx-Opq coronae. Chemically, the liquid in equilibrium with the megacryst cores is clearly different from the host alkaline dikes. In contrast, the liquid in equilibrium with Krs overgrowths and Cpx from the coronae agrees with the composition of some of the host alkaline dikes. According to the obtained results, Krs megacrysts must be considered xenocrysts. Therefore, their Middle Permian age (268 Ma) predates the emplacement of the alkaline dikes. The xenocrysts crystallised at about 30 km depth and were afterwards reequilibrated at lower depths.