A new model for the formation of a spaced crenulation (shear band) cleavage in the Dalradian rocks of the Tay Nappe, SW Highlands, Scotland

摘要: Abstract The main conclusion of this study is that non-coaxial strain acting parallel to a flat-lying D 1 spaced cleavage was responsible for the formation 2 crenulation (shear band) in Dalradian rocks Neoproterozoic-Lower Ordovician age SW Highlands, Scotland. cm-dm-scale microlithons are asymmetric; have geometrically distinctive nose and tail; show thickened central portion resulting from back-rotation constituent microlithons. current terminology used describe cleavages reviewed updated. Aided by exceptional 3D exposures, it shown how embryonic flexural-slip folds developed into comprising fold-pair domains wrapped anastomosing seams. bulk partitioned low-strain separated zones high strain. This new model provides template determining sense shear both situations ductile, higher where other indicators, such as folds, give ambiguous results. Analogous structures include tectonic lozenges zones, duplexes. Disputes over direction during emplacement Tay Nappe, apparently intractable conflict between minor fold asymmetry sense, appear be resolved.