Petrogenesis and Geological Significance of the Quartz Monzonites in the Jinling Area, Western Shandong Province

Jinling complex pluton is a key part of the Mesozoic magmatic belt in the eastern North China Craton. However, its petrogenesis is still being debated. The Jinling complex, mainly composed of biotite diorites, hornblende diorite, augite diorites, (quartz) monzonites, and quartz diorites, is outcropped in Huashan and Heitieshan. This paper studies the zircon geochronology, zircon Hf isotope, and Sr-Nd-Pb isotope of quartz monzonites. The samples have high contents of Cr, Ni, V, Al2O3, Ba, Sr, and are enriched in LREEs, LILEs (K, Ba, Sr), depleted in HREEs, and HFSEs (Nb, Ta, Ti). The samples with captured zircons of similar to 2.5 Ga yield a weighted mean age of similar to 127 Ma, and the zircons have negative values of epsilon(Hf)(t) from -3.2 to -9.4 while the ratios of Pb-208/Pb-204, Pb-207/Pb-204, Pb-206/Pb-204 37.75 similar to 38.15, 15.41 similar to 15.43, 17.59 similar to 17.98, respectively. The ratios of Th/U are from 3.77 to 3.82, while the values of mu and omega are 9.18 and from 35.72 to 36.15. Meanwhile, the ratios of Sr-87/Sr-86 are higher than the ones of the mantle. Geochemical and isotopic features indicate that the quartz monzonites derived from the subcontinental lithospheric mantle that probably assimilated ancient NCC upper crust materials (similar to 15-20%) during the magma ascent in a lithospheric extension setting.