Geometría de cabalgamientos asociados a flancos normales de pliegues ( N de Biescas, Zona Surpirenaica)

Abstract

Paleogene rocks crop out in the South Pyrenean Zone as a flysch sequence of calcarenites and mudstones showing asymmetric south-verging chevron folds, with associated axial plane foliation. Thrust faults are generated at the long limbs of the chevron folds. They have duplex type geometry and, in particular, geometric features similar to those that characterize flexural slip duplexes. These show planar or gently curved roof and floor thrusts and the absence of ramp anticlines. The hanging-wall shows southwards sense of movement, which is in agreement with the vergence of other structures in the work area. Because pinnate joints related to thrusts planes cut clearly the axial plane foliation, thrusts are generated later than angular folds.