High-pressure granulite from Jixian, Eastern Hebei, the North China Craton: implications for Neoarchean to early Paleoproterozoic collision tectonics

Abstract

AbstractPrecambrian high-pressure (HP) granulites provide important information for reconstructing ancient continental nuclei. Here we report granulites in Eastern Hebei, North China Craton (NCC). They experienced three metamorphic events related to Neoarchean–early Paleoproterozoic orogenesis. The garnet–clinopyroxene granulite defines the M1 event at P–T conditions of 11–13 kbar and 780–830°C, while the two-pyroxene granulite was produced during the M2 event at 7–9 kbar and 850–950°C. Both the garnet–clinopyroxene and two-pyroxene granulites experienced amphibolite retrogression during the M3 event at 5–7 kbar and 710–730°C. Geochemical compositions of these granulites exhibit affinity to island-arc andesites. Zircon U–Pb dating shows that their magmatic precursors were erupted at c. 2538 Ma, and have experienced two-stage growth of zircon rims at c. 2458 and c. 2285 Ma, respectively. The c. 2458 Ma age may represent orogenic events during the amalgamation of micro-continental blocks of the eastern NCC, and the c. 2285 Ma age may be interpreted as the effect of late Paleoproterozoic magmatism. We suggest that the Neoarchean andesitic protoliths of the granulites were metamorphosed at HP granulite-facies conditions during collision of micro-continental blocks, and then exhumed to shallow levels. These early Paleoproterozoic HP granulites recorded the amalgamation of micro-continental blocks to reach the cratonization of the eastern NCC.