Texture Asymmetries as Shear Sense Indicators in NaturallyDeformed Mono‐ and Polyphase Carbonate Rocks

Abstract

The microstructural and quantitative texture analyses of a naturally deformed calcite mylonite, a dolomite mylonite and a dolomitic calcite mylonite reveal different texture asymmetries for comparable deformation conditions. Calcite shows a c ‐axis maximum rotated against the shear sense with regard to the main shear plane. In contrast, the dolomite shows a c ‐axis maximum rotated with the shear sense. In accordance with the experimental and simulated textures from the literature, this difference proves e‐twinning and r‐slip for calcite and f‐twinning and c‐slip for dolomite as the main deformation mechanisms. The dolomitic calcite mylonite shows for both the calcite and the dolomite a c ‐axis maximum rotated against the shear sense. On account of the microstructure of this sample, the dolomite texture has been passively overtaken from the deformation texture of calcite during a late‐deformative dolomitization. The results significantly contribute to the interpretation that the sampled shear zone is a transpressive strike–slip fault.