STRUCTURAL ZONATION AS A RESULT OF INHOMOGENEOUS NONCOAXIAL DEFORMATION AND ITS CONTROL ON SYNTECTONIC INTRUSIONS - AN EXAMPLE FROM THE CAP-DE-CREUS AREA, EASTERN PYRENEES

The Hercynian structure in the Pyrenees is characterized by the overpr inting of several deformational events, each one associated with spati al changes in tectonic style. The variations in tectonic style depend on the lithological setting and on the tectonic regime, both changing in space and time. However, structural zonations also arise from inhom ogeneity of deformation during one event. The studied area in the Cap de Creus is an example of the transition from low strain domains, wher e an earlier foliation is slightly folded, to a high strain domain, wh ere tight or isoclinal folding caused the transposition of the earlier foliation. This structural inhomogeneity was developed from progressi ve deformation involving the generation of minor S-shaped folds and a major shear zone-like structure consisting on an open Z-bend. Both str uctures display steeply plunging axes. Initial flexural flow folding f ollowed by limb stretching and shearing of the major structure is invo ked to explain apparently contradictory symmetries and shear senses. T his folding event, and the associated strain distribution, controlled the emplacement of a syntectonic pegmatite dike swarm. Dikes occur pre ferentially within the high strain domain, and are either boudinaged o r folded depending on their orientation. A late system of narrow ducti le shear zones overprint all earlier structures.