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

Abstract

A Middle Devonian suprasubduction zone ophiolite, the Careo´n 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.