High-Pressure (∼2000 MPa) Kyanite- and Glaucophane-bearing Pelitic Schist and Eclogite from Cordillera de la Costa Belt, Venezuela

Cretaceous melange of the Cordillera de la Costa belt, north–central Venezuela, there are knockers of eclogite, barroisite-bearing eclogite, and pelitic glaucophane schist. These occur in a metamorphic melange matrix that locally consists of marble, serpentinite, amphibolite, actinolite schist, feldspathic schist and gneiss, graphitic schist, chloritoid schist, and garnet-bearing mica schist. The protoliths for these various rock types exhibit a wide age range (Cambrian to Early Cretaceous?). Recently discovered knockers of pelitic glaucophane schist contain Mg-glaucophane + paragonite + kyanite + garnet + talc + graphite + rutile + quartz. The coexistence of kyanite and Mg-glaucophane suggests minimum P ∼2000 MPa at T > 600°C. Eclogite knockers from the same outcrop contain garnet and clinopyroxene which yield ∼500°C for cores, ∼700°C for rims, and P ≥ 1200 MPa. The assemblage garnet–biotite–phengite–albite within schists of the melange matrix of this locality indicates metamorphic conditions of T = 450–520°C at P = 1800 MPa. Because all lithologies in this outcrop record high-P conditions, this metamorphic melange formed before or during peak metamorphism in a mid-Cretaceous subduction zone.