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 axes and another associated with recrystallized matrix showing subhorizontal calcite 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.