Petrogenesis of Paleoproterozoic Liangcheng garnet granitoids in the Khondalite Belt, North China Craton

a The voluminous garnet granitoids are distributed in the Liangcheng area of eastern Khondalite Belt, North China Craton. The Liangcheng garnet granitoids are parautochthonous granites that occur within granulite-facies metasediments, accompanied by Xuwujia gabbronorites. They are characterized by high modal proportion of garnet (5% similar to 15%, locally up to 25%) and the presence of orthopyroxene. The Liangcheng garnet granitoids were formed at high temperature (> 850 similar to 900 degrees C) and high pressure (8 similar to 10kbar), which is different from typical S -type granite. They are strongly peraluminous S -type granites (A/CNK = 1.1 similar to 1.6) with lower SiO2(55% similar to 75%) and higher MgO + FeOT (5% similar to 14%) contents than typical S -type granites. The addition of 20% similar to 40% restites (gametites) and gabbronorites to the anatectic melts could be responsible for the more mafic composition of the garnet granitoids. The Liangcheng garnet granitoids were formed at 1.93 similar to 1.92Ga, which are consistent with the emplacement of gabbronorites (1.93Ga) and the ultra -high temperature (UHT) metamorphism (1.92Ga) in the area, suggesting that garnet granitoids were produced by large-scale melting of metasedimentary rocks under UHT condition as a result of the mafic underplating. The voluminous high -temperature granitic magmas and UHT granulites reflect the UHT characteristic in the Jining-Liangcheng area.