Strain removal within the Hercynian shear belt of central Brittany (western France): Methodology and tectonic implications

Abstract: Central Brittany comprises a major shear belt formed during the Hercynian Orogeny. In this paper, we present a model for the restoration f the belt, based on an exhaustive compilation ofavailable structural data. The model uses a geostatistical analy-sis of cleavage orientation data. The analysis shows that the eastern part of Central Brit-tany has been deformed by bulk dextral strike-slip, a feature that validates previous structural interpretations. It also provides explanations for: the strain patterns observed within and around the restored omain; the nature of domain boundaries and of associated kinematics; and the occurrence of local superimposed deformations. Central Brittany is bounded by the North Armor-ican Shear Zone (NASZ) to the north, and by the South Armorican Shear Zone (SASZ) to the south (Fig. 1). The SASZ (J6gouzo 1980) is one of the main tectonic features of the Hercynian belt of Western Europe that separates two domains of contrasted structural style and deformatio