Condiciones de cristalización en granitoides variscos post-tectónicos de tipo I en el NO de Españael plutón de Porriño

  1. L. González-Menéndez 1
  2. G. Gallastegui 1
  3. A. Cuesta 2
  4. A. Rubio-Ordóñez 2
  5. P. Montero 3
  6. F. Bea 3
  1. 1 Instituto Geológico y Minero de España (IGME)
  2. 2 Universidad de Oviedo
    info

    Universidad de Oviedo

    Oviedo, España

    ROR https://ror.org/006gksa02

  3. 3 Universidad de Granada
    info

    Universidad de Granada

    Granada, España

    ROR https://ror.org/04njjy449

Montrer des affiliations +
Revue:
Geotemas (Madrid)

ISSN: 1576-5172

Année de publication: 2016

Titre de la publication: IX CONGRESO GEOLÓGICO DE ESPAÑA

Número: 16

Pages: 55-58

Type: Article

DIALNET GOOGLE SCHOLAR lock_openAccès ouvert editor

D'autres publications dans: Geotemas (Madrid)

Résumé

The crystallization sequence of post-tectonic I-type granitoids (NW Spain) is studied in the present work by phase equilibrium modeling (Rhyolite Melts, Thermocalc and Perple_x). The Porriño pluton from the SW of Galicia is chosen as representative for this investigation. This pluton is formed by a pink biotite granite, a grey biotite (± amphibole ± titanite) monzogranite and tonalitic-granodioritic enclaves (biotite + amphibole + titanite) included within the grey monzogranite. The intersection of the stability curve of titanite and the granite solidus at P ≥ 3 kbar is used to fix the crystallization models at P = 3.25 kbars. The comparison between the calculated crystallization and the petrography (modal counting) shows reasonable similarity for the Thermocalc and Perple_x models, whereas it is more problematic in the case of Rhyolite Melts (absence of biotite, amphibole, titanite, presence of subsolidus garnet and orthopyroxene). Thermocalc does not calculate amphibole while Perple_x does, but in very reduced amounts (≤ 0.25%) compared to the observed ones (≤ 1.5%). Experiments performed in similar rocks, though slightly more mafic, show similar crystallization sequences (biotite, amphibole, plagioclase). At higher temperatures these experiments reproduced clinopyroxene, observed in our PT models for the tonalitic-granodioritic enclaves and in some cases in the monzogranites.

La source de données: Dialnet