The Archean crust-mantle interaction in the Jiaoliao microblock, North China Craton: Constraints on the Neoarchean subduction regime

Abstract

Whether plate subduction or mantle plume activity dominated the formation of the Archean crust is hotly debated. Neoarchean crust-mantle interaction and crustal evolution are instructive for researching continental crustal growth and reworking, and cratonic evolution processes. The Jiaoliao microblock contains abundant Archean rocks and is the largest and oldest microblock in the eastern part of the North China Craton. We present new data of the petrology, geochemistry, and geochronology of amphibolite enclaves in Neoarchean granitoids and amphibolite lenticles in Neoarchean supracrustal rocks from the western Jiaoliao microblock in eastern Hebei. Bulk rock composition indicates low to moderate SiO2 (45.2–56.6 wt%) and high MgO (Mg# = 0.44–0.75) contents, depletion in high field strength elements (Nb, Ta, Zr, Hf) and enrichment in light rare earth elements (Rb, Ba). The protoliths were calc-alkaline gabbros and gabbroic diorites with LA-ICP-MS zircon U-Pb ages of 2554–2482 Ma, positive zircon εHf(t) values of +1.64 to +5.45, and TDM1 model ages peaking at ca. 2.7 Ga. They were derived from partial melting of lithospheric mantles that were subsequently enriched by different degrees of slab-derived fluids and sedimentary melts. Subsequent amphibolite-facies metamorphism affected these intrusive rocks, suggested by mineral assemblages of magnesio-hornblende, plagioclase (An = 1–30), magnesian biotite with minor edenite, and phlogopite. We conduct a comparative analysis of the four main crystalline basements in eastern Hebei, northern Liaoning, eastern Shandong, and western Shandong within and around the Jiaoliao microblock. The main body of the Jiaoliao microblock is suggested to be located in eastern Hebei - northern Liaoning - eastern Shandong and the formation of the microblock from the Mesoarchean to early Paleoproterozoic can be divided into three stages, including the crustal growth and reworking at 3.17–2.85 Ga, the mantle plume activity restricted in Shandong at 2.77–2.60 Ga, and the subduction and accretion at 2.78–2.45 Ga. The late Neoarchean arc-related magmatism in northern Liaoning, eastern Hebei, eastern Shandong, and western Shandong indicates the subduction of oceanic crust beneath the western margin of the Jiaoliao microblock, which is like the modern plate tectonics regime.