Caracterización mineral de zonas de falla ricas en minerales fibrosos de la arcillauna aproximación experimental y termodinámica

Resum

This thesis aims to identify the origin, thermodynamic stability and mechanical behaviour of fibrous clay minerals in fault zones. The results obtained suggest that the presence of fibrous clay minerals in fault zones can be a product of Mg-enrichment, catalysed by deformation and fluid circulation that promote mineral reactions and transformations. Hydration and volume changes as well as mineral reactions involving sepiolite were modelled using a thermodynamic approach that limits the stability of sepiolite to 325°C and is limited by the reaction sepiolite→talc+quartz+H2O. Furthermore, triaxial friction experiments established that fibrous clay minerals have higher frictional strength than their planar equivalents as a consequence of their different crystal structure. These result suggest that fibrous clay minerals can indeed be present and influence the distribution of seismogenic areas in Mg-rich fault systems.