Mesoscopic fault array of the northern Umbrian Appennine fold belt, Italy: geometry of conjugate shear by pressure-solution slip.

The strata of the N Umbrian Apennine fold belt are cut by an array of mesoscopic faults that generally display strike- or oblique-slip offset. The unusual orientation pattern of mesoscopic faults of the study area may indicate that the mechanics of initiating faults in rocks undergoing pressure-solution deformation is different from that in rocks undergoing purely brittle deformation. Alternatively, the fault pattern may indicate that the faults represent slip on pre-existing fractures. If this latter situation is true, the geometry of the fault array may merely reflect the geometry of the pre-existing joint array.-from Authors