Stretching Lineations in High-Pressure Belts: the Fingerprint of Subduction and Subsequent Events Malpica-Tui Complex, NW Iberia)

The evolution of tectonic flow during the whole deformative history has been studied in an exposed continental subduction system of the Variscan belt. Macro- and microstructural data are used to establish the kinematics and flow geometry in the Malpica-Tui Complex of Northwest Iberia, Spain. Structural analysis reveals reorientation of the successive lineations by the following deformation event and, specially, by the last of them, late Variscan strike-slip tectonics. The original trend of lineations has been inferred by analyzing the deflection patterns in the lineation map. The data expose the role of thrust and nappe tectonics and non-coaxial deformation in the hinterland of a collisional belt showing a dominant orogen-parallel lineation pattern. The results shed light on the tectonic processes developed underneath the Rheic suture, thus contributing to a better understanding of the continental subduction-exhumation system developed at the outermost margin of northern Gondwana during the late Paleozoic. Following oblique subduction, contractional structures exhumed and emplaced the subduction system onto the adjacent mainland following vectors normal to the orogenic trend. Subsequently, extensional structures dismembered the tectonic pile, moving the pieces obliquely with respect to the collisional belt. Orogen-parallel strike-slip shear zones affected this part of the orogen later on, producing large reorientation of the preexisting tectonic fabrics towards their shear planes. The influence of late strike-slip tectonics on previous structural record is likely underestimated in comparable sectors of the Variscan belt, and might have blurred a former history of tangential tectonics, particularly in those domains close to the suture zones.