An eclogite forms a 40-m-long tectonic lens enveloped in serpentinite within a metabasite-phyllite-marble unit of Permian-Triassic age in northwest Turkey. The eclogite consists mainly of garnet, omphacite, glaucophane, and epidote. It is associated with other lenses of serpentinite and metagabbro. Single-grain laser probe 40Ar/39Ar dating of phengites from the eclogite gives ages of 203 to 208 Ma, corresponding to the Triassic-Jurassic boundary. Regional geologic considerations also suggest a latest Triassic to earliest Jurassic metamorphic age for the eclogite and the enclosing metabasite-marble-phyllite unit. The eclogite, along with serpentinite and gabbro lenses, were probably emplaced as diapirs into the metabasite-phyllite-marble unit during Late Triassic subduction. The eclogite provides evidence for the often elusive Triassic subduction history of the Paleo-Tethys in the eastern Mediterranean area.