Influence of melt induced mechanical anisotropy on the magnetic fabrics and rheology of deforming migmatites, Central Vosges, France
Abstract
In the Central Vosges (France), we describe and model the structural relationships existing between orthogneiss domains and their surrounding viscous migmatites. These domains show a structural and anisotropy of magnetic susceptibility (AMS) zonation associated with an increasing amount of melt from the core to their margins.
A pre-extension oblate to plane strain fabric is preserved in the core of the orthogneiss domains where the granite veins were emplaced along a dilated mechanical anisotropy. This systematic fabric and structural succession is due to contrasting rheological evolution between orthogneiss and metasedimentary migmatites during progressive melting and continuously evolving degree of mechanical anisotropy in the stronger orthogneiss.
Numerical modeling confirms the role of the relationship between initial mechanical anisotropy and superimposed deformation overprints on finite AMS fabrics in migmatites.