Actividad volcánica explosiva de tipo peleano en el umbral de Siliqua, sector oriental del valle del Cixerri, Oligoceno del Suroeste de la isla de Cerdeña, Italia
- Autores: Domingo Gimeno Torrente, A. Assorgia, K. Balogh, N. Díaz, Martina Francesca Marongiu, R. Rizzo, F.A. Secchi, L. Lecca
- Localización: Geotemas (Madrid), ISSN 1576-5172, Nº. 1, 3, 2000 (Ejemplar dedicado a: V Congreso Geológico de España (Alicante, 10-14 julio 2000)), págs. 321-324
- Idioma: español
- Enlaces
-
Resumen
This paper provides evidence o f pelean block and ash pyroclastic deposits related to the 28 m.y.
andesitic domes o f the Siliqua threshold, central-southwestern Sardinia island, Italy. After a detailed mapping survey a complete petrographic, geochemical and geochronological study has been done over a set o f 31 samples, including massive lava bodies and pelean clast. The pelean deposits are characterized by prevalence o f unvesiculated lava clasts over crystal (Plg-Amph-Bt rich), scarcity o f absence o f juvenile clasts, crude reverse gradding and decimetric to meter size o f blocks. The clasts are petrographically similar to the dome samples, with a prevalence o f holocrystalline coarse-grained porphyries over holocrystalline panhypidiomorhic pig-rich microgranular to granular rocks that constitutes most o f the andesitic domes. Geological mapping and characterization o f volcanic lithofacies allows individualization o f explosive vents.An origin to explosivity related to gravitative unstable growth o f subaerial domes, mixing o f magmas or sismic-induced collapse o f domes is prospected taking into account the current state o f knowledge.
