‘High-temperature’ texture in naturally deformed Carrara marble from the Alpi Apuane, Italy

Abstract

From deformation experiments and numerical modelling, a large type variety of crystallographic preferred orientations (textures) are known for calcite. In contrast, naturally deformed samples usually show the ‘low-temperature (LT)’-texture type with only minor texture variations. The ‘high-temperature (HT)’-texture type is rarely described and mostly not very well defined. Based on neutron diffraction measurements and a quantitative texture analysis by means of the iterative series expansion method and the texture component model, this study gives evidence for the HT-texture type in a deformed marble from the Alpi Apuane in Italy. The microstructure of the sample shows elongated grains with long/short axis ratios of up to 10:1. The long axes of the grains are oriented parallel to the general direction of transport indicating prolate strain, but no shear sense. From the texture, a shear sense can be deduced that cannot be fully brought in line with the regional deformation and thermal history. The results indicate a larger texture variety of naturally deformed calcite rocks than generally assumed. This should stimulate further systematic texture studies for a better understanding of the texture forming mechanisms and the closely connected understanding of the kinematic significance of textures for the analysis of regional deformation histories.