Abstract
Abstract Diverse Neoarchean granitoid assemblages, which generally include tonalitesâtrondhjemitesâgranodiorites (TTGs) and various K-rich granitoids, are prevalent in most basement terranes of the North China Craton. However, the Hengshan terrane is an exceptional case in the North China Craton; it is dominated by late Neoarchean sodic diorite-TTGs (DTTGs) and sanukitoids. These sanukitoids are the only high-K granitoids and show Mg-rich chemical features. The late Neoarchean DTTGs and sanukitoids were generated at ca. 2486â2537 Ma and show an intimate spatial association. The granitoid assemblages of the DTTGs and sanukitoids are characterized by high Mg# [100 Ă Mg/ (Mg + Fetotal)] values (43â65) and enriched in light rare earth elements, large ion lithophile elements, heterogeneous zircon LuâHf (ΔHf = â1.6 to +7.4), and whole-rock SmâNd (ΔNd = +0.9 to +4.2) isotopic components, which indicates that they may be derived from varying degrees of interactions between mantle peridotite and subduction-related materials. Combined with the relatively high apparent geothermal gradient (âŒ17 ± 2 °C/km) and the relatively low basal heat flow of continental crust (âŒ25 ± 5 mW mâ2), the crustmantle interaction process indicates that the occurrence of late Neoarchean high-Mg magmatism was closely related to warm oceanic slab subduction in the Hengshan terrane, and the featured lithological association of DTTGs and sanukitoids most likely developed in the active continental margin at the end of the Archean.
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