Origin of late Neoarchean granitoid diversity in the Western Shandong province, North China Craton

摘要

Diverse late Neoarchean granitoids are widely exposed in the Western Shandong province (WSP). According to geological relationships, lithological features, magmatic zircon U-Pb-Lu-Hf isotopes and whole-rock chemical characteristics, eight main lithological assemblages are identified, and their petrogenesis is determined. (1) The similar to 2.54 Ga and similar to 2.51 Ga potassic granites show the highest SiO2 contents (67.06-75.84 wt%) and were sourced from partial melting of metamorphic greywackes. (2) The similar to 2.53 Ga quartz syenites exhibit the highest alkali contents (10.32-11.23 wt%) and were sourced from mantle-derived basaltic rocks and recycled sediments. (3) The similar to 2.53-2.52 Ga quartz diorites (less-differentiated sanukitoids) formed from partial melting of metasomatized mantle. (4) The similar to 2.53 Ga hornblendites have crystallization ages and Lu-Hf isotopes similar to those of the quartz diorites, implying that they are cogenetic cumulates from the quartz dioritic magmas. (5) The similar to 2.56-2.52 Ga tonalite-trondhjemite-granodiorite (TTG) gneisses were formed by melting of thickened crust. (6) The similar to 2.53 Ga high-Mg granodiorites (differentiated sanukitoids) were formed by mixing of crust-mantle melts. (7) The similar to 2.51-2.49 Ga gabbros originated from partial melting of fluid-metasomatized mantle. (8) The similar to 2.54-2.53 Ga high-Mg andesites (boninites) originated from partial melting of refractory mantle that experienced the extraction of basaltic magma at earlier stage and was then enriched in LILEs and LREEs by slab-derived melts.