L tectonites

The most common external kinematic framework that can form L tectonites involves simultaneous transport-perpendicular shortening in two directions. Hence, large domains of L>S and L tectonites are a common feature of orogen-parallel elongation. In every case, external variations in boundary conditions and/or internal variations in structural setting and rheology localize constriction to form L tectonites. External boundary conditions are important in density-driven vertical tectonics. Elsewhere, internal variations in structural setting and rheology are more important. The most common are the formation of L tectonites in fold hinge zones and in compositionally homogeneous rocks while heterogeneous rocks accommodate constriction by folding.