Zircon and allanite U-Pb ID-TIMS ages of vaugnerites from the Calzadilla pluton, Salamanca (Spain): dating mantle-derived magmatism and post-magmatic subsolidus overprint

Authors

  • F.J. LÓPEZ-MORO Departamento de Geología, Universidad de Salamanca 37008 Salamanca, Spain. Salamanca Ingenieros, S.L. 37118 Carbajosa de la Sagrada, Salamanca, Spain.
  • R.L. ROMER Deutsches GeoForschungsZentrum (GFZ) Telegrafenberg, 14473 Potsdam, Germany.
  • M. LÓPEZ-PLAZA Departamento de Geología, Universidad de Salamanca 37008 Salamanca, Spain.
  • M. GÓNZALEZ SÁNCHEZ nstituto de Recursos Naturales y Agrobiología de Salamanca (IRNASA-CSIC) Cordel de Merinas, 40-52, 37008 Salamanca, Spain.

Keywords:

Vaugnerite, Zircon, Allanite, U-Pb dating, Subsolidus overprint, Ledesma.

Abstract

Basic to intermediate high-K, high-Mg mantle-derived rocks occur throughout the Iberian Massif and are particularly important in the Tormes Dome, where vaugnerites form several stocks and small plutons. One of the largest and geochemically most variable among these plutons is the Calzadilla pluton in the Tormes Dome that crystallized at 318 ± 1.4Ma (Bashkirian; U-Pb TIMS zircon). This age reveals that the vaugnerite pluton was emplaced during the transition from late D2 extensional deformation to early D3 contractional deformation (319 to 317Ma). Large-scale extension in the area resulted, on one hand, in extensive anatexis in the crust due to quasiisothermal decompression and mica-dehydration melting and, on the other hand, in the upwelling of the mantle, which induced partial melting of the enriched domains in the lithospheric mantle. The driving reason why crustal and mantle melts were coeval is extension. The U-Pb ID-TIMS age of allanite is not related to the emplacement nor cooling of the Calzadilla vaugnerite, but it seems to be related to a younger subsolidus overprint ca. 275Ma that, in the scale of the Central Iberian Zone, corresponds to a period of hydrothermal alteration, including episyenite formation and tungsten mineralization.

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Published

2017-11-22

Issue

Section

Granites and Related Rocks. A tribute to Guillermo Corretgé