The relationship between deformation and metamorphism in the Canigou Massif, Pyrenees: a case study

Abstract

Previous interpretations of the structure of the Canigou massif have related the development of the regional foliation to tectonic emplacement of the Canigou orthogneisses within the Infracaradocian sediments (Guitard 1970, Casas 1978,Lagarde 1978). Re-investigation of the structural evolution of the massif has shown that the regional foliation (S3) is preceded by the development of a pervasive S1 foliation and localized large-scale D2 folding. D2 folds affect the contact between the Canigou orthogneisses and underlying metasediments, indicating that the orthogneisses were emplaced within the sedimentary sequence prior to the development of the regional foliation. S3 is a subhorizontal crenulation foliation subparallel to S0-S1, except locally where D2 folding results in a more discordant relationship. Regional doming of S3 is associated with post-D3 folding and mylonite development. Porphyroblast-matrix microtextural relationships indicate that the peak of Hercynian low-P-high-T regional metamorphism is synchronous with progressive development of S3. Complex Si/Se geometries indicate that deformation was inhomogeneous on a small scale.