The M1 blueschist to epidote amphibolite metamorphism that defines the named metamorphic zones of the Sambagawa belt of Japan and coeval ductile D1 deformation overprinted and replaced formerly more extensive eclogite-facies rocks and obscured the original subduction-accretion architecture. Based on new field, structural, and petrographic observations, integrated with published geochronologic, structural, and metamorphic petrologic data, we propose that the eclogites were emplaced both as intact slabs as well as blocks-in-mélange. Some of the latter may record earlier eclogite burial, exhumation to the surface, sedimentation, and resubduction to eclogite-facies conditions. Syneclogitic D0 fabrics include widely distributed granoblastic fabrics, as well...