Garnet-bearing granulite facies rock xenoliths from late Mesozoic volcaniclastic breccia, Xinyang, Henan Province

This paper presents the primary results of petrologic, mineralogical and pe trochemical studies of garnet-bearing granulite facies rock xenoliths from Xinyang, Henan Province. These xenoliths, which are found in a pipe of late Mesozoic volcaniclastic breccia, are of high density (3.13-3.30 g/cm(3)) a nd high seismic velocity (Vp = 7.04-7.31 km/s), being products of underplat ing of basaltic magmas and had experienced granulite facies metamorphism. T he underplating and metamorphism took place before the eruption of the host rock. Petrographical studies and equilibrium T-P calculations show that th ese xenoliths were captured at a 49 km depth and experienced at least a 16 km uplift before they were captured. The dynamics of the uplift could be re lated to the continent-continent collision between the North China plate an d the Yangtze plate during the Triassic.