The Norumbega Fault Zone, Maine: a mid- to shallow-level crustal section within a transcurrent shear zone

Abstract

Studies of structure, metamorphism, and geochronology provide evidence that the Norumbega Fault Zone represents a transition from mid- to shallow crustal levels in a dextral, transcurrent shear zone within the northern Appalachian Orogen. A younging trend in 40Ar/39Ar cooling ages toward the northeast, together with the deformational fabrics and metamorphic features, are interpreted to represent exhumation of the southwestern section of the Norumbega Fault Zone from mid-crustal levels during the polyphase history of this transcurrent zone. The Norumbega Fault Zone may therefore serve as a model for deformational processes at mid- to shallow crustal levels in active strike-slip systems. -from Authors