Crystallographic preferred orientations in eclogites – A review

Abstract

During the last decades, processes taking place in subduction zones have been a topic of extensive debate. There are many models on a tectonic scale, but knowledge of deformation at microscopic levels is essential for an understanding of the processes involved. Crystallographic preferred orientation (CPO) investigations of minerals in eclogites yield the possibility to study deformation in the crustal part of subducted oceanic lithosphere, as well as subducted continental units containing basic intrusions, which are frequently exhumed during continental collision. From CPO data of omphacite and garnet, as well as other constituent minerals in eclogites, conclusions on stress and strain at depth in currently active subduction zones can be drawn, as the pressure-temperature and strain path of the now exhumed rocks can be unraveled. This contribution provides an overview of CPO studies of eclogites concerning slip systems, deformation, strain and other possible CPO forming mechanisms in all major constituent mineral phases in eclogites and the implications of these microstructural data on subduction zone processes are discussed. Nevertheless, there are still many open questions and future research is essential.