Geological and isotopic geochemical constraints on the evolution of the Fuping Complex, North China Craton

Abstract

The Neoarchean to Paleoproterozoic Fuping Complex together with the adjacent Hengshan and Wutaishan complexes form the middle part of the Central Zone that separates the North China Craton into the Eastern and Western Archean continental blocks. The Fuping Complex comprises three major lithological assemblages: the ∼2.50 Ga Fuping trondhjemite-tonalite-granodiorite (TTG) gneisses, the Wanzi paragneisses, and the 2.08 and 2.02 Ga Nanying granitic gneisses. The TTG gneisses contain abundant enclaves of highly-metamorphosed supracrustal rocks, including ∼2.70 Ga mafic granulites and amphibolites with εNdt of +3.29 to +3.96 and TDM of 2.72-2.82 Ga, and are characterized by TDM of 2.76-3.04 Ga and a linear correlation between εNdt (-1.64 to +0.96) and 1/Nd, indicative of mixing of melts derived from the ∼2.70 Ga metabasic rocks and ∼3.0 Ga crustal materials. Mafic dikes along the Chengnanzhuang shear zone were most likely emplaced at ∼2.31 Ga and have εNdt of +2.24 to +4.78 and TDM of 2.34-2.59 Ga. The Nanying granitic gneisses with εNdt of -4.04 to -5.24 were most likely related to partial melting of the ∼2.70 Ga supracrustal rocks and/or the ∼2.50 Ga TTG gneisses. These geological relationships and isotopic data suggest that the Fuping Complex probably formed from the following five major tectonomagmatic events: (1) mafic magmatism and early crustal growth at ∼2.7 Ga, with the possible existence of older (∼3.0 Ga) crust(s); (2) collision-related crustal thickening, underplating of basaltic magma, high-grade metamorphism, crustal anatexis and TTG magmatism at ∼2.5 Ga; (3) extensional deformation and emplacement of the mafic dikes and the Nanying granitic plutons along the Chengnanzhuang shear zone (∼2.5 to ∼2.0 Ga); (4) S-type granitic magmatism and associated amphibolite-facies metamorphism (∼2.0 to ∼1.80 Ga); and (5) emplacement of granitic pegmatite dikes at ∼1.80 Ga. © 2002 Elsevier Science B.V. All rights reserved.