A major mid-crustal decollement of the Paleozoic convergent margin of western Gondwana: The Guacha Corral shear zone, Argentina

摘要

The Guacha Corral shear zone (GCSZ) is one of the most significant and widest thrusts in the western Gondwana margin of Argentina. It is 10-16 km wide and thrusts 525-515 Ma forearc migmatites of the Pampean Orogeny eastwards onto greenschist fades rocks metamorphosed at 460-450 Ma during the Famatinian Orogeny. It is divided into two sections. At the highest structural levels, the shear zone is >7.5 km wide and records high-T, amphibolite facies deformation. At lower structural levels, this is overprinted by a >2.5 km-wide, low-T, greenschist fades shear zone. The two are separated by a transitional zone where overprinting relationships are preserved. Motion in the two sections had the same kinematics.