Abstract

The fabric of the ice-thrust argillaceous bedrock from a shear zone was studied in hand specimens, under a polarizing microscope and a scanning electron microscope. The fabric included principal displacement shears, Riedel shears, conjugate sets of particle alignments, cutans, lithorelics, and aggregations which dense cores of randomly oriented groups of clay platelets wrapped by an external layer of oriented clay particles in a turbostatic arrangement. In addition, the bedrock has been disturbed by permafrost, cycles of loading and unloading, and weathering, causing the magnitude of deformation to vary within the ice-thrust shear zone.The fabric of the ice-thrust shear zone is similar to that of shear zones formed by tectonic activity and by laboratory shear tests, suggesting that all these shear zones were formed under conditions of similar kinematic restraint.

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