Abstract
Abstract The Forcarei Synform is a kilometric fold developed in the hinterland of the NW Iberian Variscan belt. A detailed analysis of the synform, based on quartz fabrics and kinematic markers, shows pervasively deformed rocks that have been continuously deformed during the last two main Variscan deformation phases (D 2 and D 3 ). Variscan D 2 minor structures related to the synform were formed under general non-coaxial flow and have a sub-horizontal maximum finite stretching toward the SSE. Later a coaxial D 3 produced a sub-vertical crenulation cleavage, and type 2 and 3 refolded folds figures at the meso- and micro-scale. Consequently, the strike of the foliations (S 2 and S 3 ) become sub-parallel and lineation (L 2 and L 3 ) are sub-horizontal. The geometry of the synform and the related structures can be interpreted in the context of D 3 . However the dominantly sinistral shear sense indicators, observed in both limbs of the synform (in map view), seem to be most probably developed during D 2 . A model is proposed involving the progressive clockwise rotation of a sub-horizontal shear, with general top-to-the-south sense, during the simultaneous development of shear zone and foliation in agreement with the kinematic indicators.
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