Early Cretaceous lawsonite eclogites and related high-pressure rocks occur as tectonic inclusions within serpentinite mélange south of the Motagua fault zone, Guatemala. Petrologic and microtextural analyses of mafic high-pressure rocks reveal three metamorphic stages linked to several deformational textures. The prograde stage represents an incipient eclogitization and is preserved in prograde garnet, along with an older S 1 –S 2 foliation. The prograde assemblage is garnet ( X Mg = ∼0.22) + omphacite (∼52 mol% jadeite) or jadeite (∼83 mol % jadeite) + lawsonite + chlorite + rutile + quartz ± phengite (3.6 Si p.f.u.); some rocks also have ilmenite and rare ferro-glaucophane. Lawsonite in garnet of some lawsonite eclogites contains rare pumpellyite inclusions. The presence of synmetamorphic brittle deformation, inclusions of pumpellyite, Fe 2+ -Mg distribution coefficients between omphacite inclusions and adjacent garnet with Ln( K D ) = 2.7–4.5, and garnet-clinopyroxene-phengite thermobarometry suggest that eclogitization initiated at temperature ( T ) = ∼300 °C and pressure ( P ) > 1.1 GPa, and continued to T = ∼480 °C and P = ∼2.6 GPa. In contrast, the retrograde eclogite-facies assemblage is characterized by reversely zoned garnet rims and omphacite ± glaucophane + lawsonite + rutile + quartz ± phengite (3.5 Si p.f.u.) along the S 3 foliation. Garnet-phengite-clinopyroxene thermobarometry yields P = ∼1.8 GPa and T = ∼400 °C. The youngest, blueschist-facies assemblage (glauco-phane + lawsonite + chlorite + titanite + quartz ± phengite) locally replaces earlier mineral assemblages along S 4 crenulations. The inferred prograde P - T trajectory lies near a geotherm of ∼5 °C km −1 , comparable to the calculated thermal and petrologic structure of the NE Japan subduction zone. These petrologic characteristics indicate: (1) the basalt-eclogite transformation may occur at T = ∼300 °C in cold subduction zones, (2) glaucophane-bearing prograde assemblages are rare during incipient eclogitization in cold subduction zones, and (3) the chlorite-consuming reactions that form Fe-Mg-Mn garnet are more effective than the lawsonite-consuming reaction that forms a grossular component. At depths of ∼100 km in cold subduction zones, dehydration embrittlement may be caused by such chlorite-consuming reactions.