Solution slip and separations on strike-slip fault zones: theory and application to the Mattinata Fault, Italy.

We present a set of relationships to determine the component of slip and separations generated by the cleavage-controlled volume contraction in strike-slip fault zones. The fault walls can translate toward each other along the (cleavage-normal) axis of maximum shortening as rock is dissolved by pressure solution along patterned cleavage surfaces within strike-slip fault zones. The fault zone shortening produces an 'apparent slip' and possible separations of reference stratigraphic surfaces across the fault zone. Solution related slip and separations can differ in magnitude and have either the same or the opposite sense. These discrepancies depend upon the amount of fault zone shortening and upon the angles between the fault and the shortening axis, and between the fault and the reference stratigraphic surface. Separations can be considerable at any scales even for very low amounts of fault zone thinning. Apparent slip can be appreciable for large amounts of fault zone thinning and/or high fault-to-cleavage incidence angles. With the proper geometrical conversions, the relationships here presented can apply to any fault type.