MICROSCALE AND MESOSCALE DEFORMATION STRUCTURES IN EXPERIMENTAL FAULTZONES

Kinematic structures of brittle, brittle-ductile and ductile shear zon es were developed in experimental simple shear deformation. Transparen t films of paraffin wax, with different initial fabrics, were progress ively deformed in a manually-driven, stage-mounted shear apparatus pro ducing heterogeneous simple shear (gamma = 0.36-2.64) at variable stra in rates of from 3.3 x 10(-5) to 4.08 x 10(-5) s(-1). En echelon fract ure arrays, compressive and tensile bridges, spaced cleavage, stylolit e-like cleavage and sigmoidal cleavage trails were developed in brittl e and brittle-ductile deformation. Structures produced in ductile expe riments were C'-S and CS fabrics, sigma-and delta-type asymmetric tail s, shear lenses and active folds of pre-existing and induced anisotrop y planes. The experiments offer insight into the microstructural proce sses involved, and demonstrate development of a progression of shear s tructures in a single, non-steady deformation.