MAIN PROGRESS IN THE STUDY OF ARCHEAN-PALEOPROTEROZOIC ROCK ASSEMBLAGES OF THE WESTERN LIAONING PROVINCE

The Western Liaoning Province (WLP), one of the major Archean-Paleoproterozoic terranes in China, is located at the northeastern margin of the Eastern Block of the North China Craton (NCC). The region is composed dominantly of early Precambrian ancient rocks as one of the important terranes for studying the Neoarchean-Paleoproterozoic evolution of the NCC. The Archean rock assemblages include a large number of plutonic TTG gneisses and granitoid gneisses and a small amount of supracrustal rocks and the supracrustal rocks are frequently preserved as enclaves or tectonic blocks within the plutonic gneisses. The Paleoproterozoic (2.5-1.6 Ga) rocks belong to two major lithological units, namely the rift-related supracrustal rocks of the Changcheng Group and the alkaline plutonic complex. Geochemical and zircon U-Pb -Hf isotope data reveals the Neoarchean-Paleoproterozoic geologic succession of the WLP, and the major Archean magmatic and metamorphic event at~2.55-2.50Ga was recorded,which resulted from a subduction-related environment. The zircon U-Pb ages between~2.50-1.85 Ga were absent, but a late magmatic episode at~1.72-1.70 Ga was recorded in the WLP. The geochemical features of these~1.72-1.70 Ga magmatic rocks suggest that they are probably emplaced within a post-collisional setting that postdated the final amalgamation of the NCC.