Alpine tectonics of Alentejo-Plasencia fault (Hesperian Massif)

Alentejo-Plasencia fault was active during the alpine compressional phases with a sinistral strike-slip movement in two main stages. The fault geometry was straight and no important bendings formed during Paleogene, when the maximum shortening direction was close to N-S or NNE-SSW. During Miocene (Middle Aragonian) and related to the Neocastellana tectonic phase, the Alentejo-Plasencia fault still moved as a sinistraI strike-slip due to a NW-SE compression, but the Extremadura sector of the fault curved and bends formed along the fault at certain points where important lithologic changes were present. Several restraining and releasing bends formed; these latter creating pull-apart basins, some of them filled with continental clastic sediments. Most of the fault displacement (about 3 Km.) seems to be related to the alpine tectonics. The small displacement compared with the fault length is coherent with its location on a co//s/ona/ area foreland