AMS data and EBSD maps of small scale marble shear zone - Estremoz, Portugal

We studied two structural profiles across subvertical thin shear zone in marble from quarry in Estremoz (Portugal) to clarify a relationship between AMS and strain in natural rocks. The mesoscopic fabric can be described as changing from the subhorizontal coarse-grained foliation towards the ∼2cm-wide shear zone center with subvertical fine-grained foliation. In microstructure, the shear zone records dynamic recrystallization of calcite aggregate which resulted in development of porphyroclastic microstructure with increasing proportion of fine-grained recrystallized matrix towards the shear zone center. Two distinct crystallographic preferred orientations of calcite were recorded. One related with porphyroclasts, characterized by subvertical orientation of calcite <c> axes and another associated with recrystallized matrix showing subhorizontal calcite <c> axes orientation. The majority of the rock mass is diamagnetic, corresponding well with the thermomagnetic curves, with local paramagnetic accumulations in form of thin bands.