Fabric Development in a Middle Devonian Intraoceanic Subduction Regime: The Careón Ophiolite (Northwest Spain)

Abstract

A Middle Devonian suprasubduction zone ophiolite, the Careón Unit (northwest Spain), displays amphibolite‐facies ductile deformation fabrics related to the onset of the Rheic Ocean closure. Two different fabrics, an early high‐T foliation and a subsequent lower‐T foliation, each of which characterized by distinct deformation mechanisms, have been identified in two distinct crustal‐scale shear zones of the same ophiolitic thrust sheet. Combined quantitative texture analysis by electron backscattered diffraction and time‐of‐flight neutron diffraction, were carried out on the shear zones and correlated with micro‐ and macrostructural data. The results indicate that the regional lineation and shear zone kinematics (east‐west, top‐to‐the‐east) represent fabrics developed essentially during the intraoceanic subduction of the Rheic Ocean, and their orientation may be considered a reference vector for convergence models in this part of the Variscan belt.