Current challenges and future developments in magnetic fabric research

Magnetic fabrics are used extensively as proxies for mineral fabrics and to correct paleomagnetic data, and have been proposed to quantify pore fabrics. Today's understanding and interpretation of magnetic anisotropy benefits from decades of carefully observing anisotropic mineral and rock properties, establishing and testing empirical relationships between magnetic and mineral fabrics, and developing models to quantify aspects of anisotropy. Each advance was preceded by some puzzling observations, i.e., data that could not be explained based on the models available at the time, e.g., ‘oblique’ or ‘inverse’ fabrics, or lithology-dependent anisotropy-strain relationships. These observations led to numerous experimental and numerical techniques designed to characterize magnetic fabrics and determine their origin. Despite the successful application of magnetic fabrics in many structural and tectonic problems, there are still phenomena and measurements that cannot be explained based on today's magnetic fabric theory. With the purpose of fostering future development, I will touch on three main areas where I see challenges in magnetic fabric research: (1) Experimental characterization of magnetic anisotropy, including the non-uniqueness of reported tensors, and non-linearity; (2) anisotropy modelling and defining the carrier minerals and origin of the magnetic fabric; (3) selection of adequate (sets of) anisotropy tensors to correct paleomagnetic data. The description of the challenges presented here will hopefully help define directions for future research, inform those that are new to anisotropy, and advance our field.