Bridging the Gap Between Experimental and Natural Fabrics: Modeling Ice Stream Fabric Evolution and its Comparison With Ice‐Core Data

Fabrics, also known as textures or crystallographic preferred orientations, reveal information about the deformation history of the flow of polycrystalline materials, including glacial ice, olivine in the mantle, and feldspar and quartz in the crust. Ice fabrics can have an order‐of‐magnitude effect on the ease of flow in ice sheets. However, due to the choice of ice core drill site locations, the outputs of fabric models have mostly been compared to observations from the least dynamic regions of the ice sheet (ice divides). Recently, fabric data from an active ice stream have become available from ice cores drilled at the East Greenland Ice‐core Project (EGRIP). In this work, we present a novel approach that combines satellite‐derived velocity data with the fabric evolution model SpecCAF, a continuum model based on dominant dislocation creep. We directly compare model output to ice‐core observations from EGRIP, allowing us to examine the quantitative predictions of calibrated fabric models alongside those of active ice streams for the first time. As the model is calibrated against laboratory experiments, it provides a surrogate to compare the evolution of fabrics under laboratory and natural conditions. The predictions show good qualitative agreement with the observed fabric patterns and orientations, suggesting that a fabric between a girdle and horizontal maximum, orientated perpendicular to the flow direction, is the characteristic ice stream fabric. A discrepancy in fabric strength is attributed to the lower strain rates of ice sheets compared to laboratory experiments, revealing a significant strain‐rate dependence in the processes controlling fabric evolution. Plain Language Summary Most materials that comprise the solid Earth, including the ice sheets and the mantle, flow viscously over long timescales. A key control of this flow is the average orientation of the crystals which make up these materials. In ice, measurements of this average orientation have to date been limited to areas where the ice deforms very slowly. Recently, data from an ice stream—a fast‐flowing region in the ice sheet—have become available. In this work, we predict the alignment of ice crystals in an ice stream, using a model previously tested and validated in the laboratory. Since the model gives good predictions of the crystal alignment seen in the laboratory, it can be used to compare between laboratory results and ice sheets for the first time. We predict that the alignme