Eclogite inclusions from subducted metaigneous continental crust (Malpica‐Tui Allochthonous Complex, NW Spain): Petrofabric, geochronology, and calculated seismic properties

This study describes the strain geometry, crystal‐plastic deformational features, isotopic age of metamorphism, and calculated seismic properties of two medium‐temperature eclogite types from the Malpica‐Tui Allochthonous Complex of Variscan NW Iberia. The eclogite types are eclogites with coronitic garnets and eclogites with a planolinear fabric. Both of them were buried, deformed and recrystallized under maximum pressure and temperature of 2.6 GPa and 610–640°C, and subsequently exhumed in a late Devonian subduction channel. The metamorphic peak of the subduction‐exhumation cycle occurred ~375 Ma ago. Omphacite petrofabric ties eclogites with coronitic garnet to noncoaxial constrictional strain and eclogites with planolinear fabrics to noncoaxial flattening strain and stretching along the lineation. We also used omphacite crystallographic preferred orientations to calculate and constrain the seismic properties of the eclogites. The slight variations in petrophysical properties observed are interpreted to result from variations in the strain regime recorded by pristine eclogites, or from variations in the modal proportions of the constituent high‐pressure minerals. We foresee that eclogite in subduction metamorphic complexes might be either seismically undetectable or detected as planar features with high impedance contrasts relative to their host rocks. Key Points Petrofabric and radiometric age of Variscan medium‐T eclogites from NW Iberia deformed and recrystallized under 2.6 GPa and 610–640°C Identification of intracrystalline slip systems and deformation mechanisms of the HP mineral assemblage by means of EBSD determined LPOs Late Devonian deep subduction at ca. 375 Ma and subsequent subduction channel resetting still under relatively high ‐P