A càrrec de Emilio CASCIELLO (GDL - Institut de Ciències de la Terra Jaume Almera, CSIC)
Organitzat conjuntament CSIC-UB

Data: 26-04-2011
Hora: 12:00
Lloc: Sala d'actes de l'Institut Jaume Almera

Descripció: The transformation of water-rich smectite clay minerals into anhydrous illite is a common reaction in sedimentary basins. It is thought to be driven by temperature increase associated with increasing depth. However it was also observed in the gouge of large faults, and since it involves the release of bound water from smectite it is thought to have a potentially key control on hydrologic and mechanical processes at subduction complexes. In this work the distribution of smectite and illite within a large shear zone is analysed at scales varying from outcrop to sub millimetre. The heterogeneous distribution of illite and smectite within this shear zone was studied by integrating outcrop-scale observations with a peeling technique that allows microscope and SEM observation to be made over areas in excess of 60 cm2. The observed patterns of smectite illitization suggest that temperature is not the primary cause of the mineral transformation inside the fault.