Discovery of eclogite inclusions and its geological significance in early Jurassic intrusive complex in Xuzho-northern Anhui, eastern China

The early Jurassic intrusive complex is chiefly made of monzodioritic porphyry in northern Anhui and northern Jiangsu, which emplaced in 1191 Ma. The intrusive complexes contain a lot of eclogite inclusions which belong to eclogite and garnet-pyroxenite. The inclusions had undergone eclogite facies high-pressure metamorphism and amphibolite facies retrogressive metamorphism. The garnets in eclogite inclusions are mainly almandine varieties and clinopyroxenes are omphacite and augite. The mineral assemblage and P-T estimation results show that P-T conditions of eclogite facies metamorphism and amphibolite facies retrogressive metamorphism are over 1.2-1.5 GPa, 709-861degreesC and 0.7-1.03 GPa, 666-738degreesC, respectively. The discovery of the high-pressure xenoliths not only is of important significance to understand the composition and structure of deep crust in southern edge of North China Platform, but also can be of important influence on realizing the subduction-collision-exhumation evolutional process of the Dabie-Sulu ultrahigh-pressure (UHP) metamorphic belt.