Resumen de 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
Domingo Gimeno Torrente, A. Assorgia, K. Balogh, N. Díaz, Martina Francesca Marongiu, R. Rizzo, F.A. Secchi, L. Lecca
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.
