PETROLOGY AND HIGH-PRESSURE MINERAL ASSEMBLAGE OF MAFIC-ULTRAMAFIC ROCKS OF ULTRAHIGH-PRESSURE METAMORPHIC ZONE IN THE DABIE MOUNTAINS

The relation between eclogite and mafic-ultramafic rocks of Maowu Bixi ling and Nanshanling in Dabie Mountains represents three different kin ds of occurrence relations. Their protoliths are bedded cumulate forme d by crystallization differentiation of basic magma, which experienced ultrahigh-pressure metamorphism under the mantle condition at the dep th of more than 120-150 km during the collision-subduction between the Yangtze Plate and North China Plate. Ti-clinohumite+Ti-chondrodite+ma gnesite+Al-poor pyroxene is the typical high-pressure mineral assembla ge of mafic-ultramafic rocks which reveals the participation of H2O, C O2 and other volatiles-containing fluid in the ultrahigh-pressure meta morphism.