The Kunyushan Complex emplaced between the SuLu Ultrahigh-Pressure-Metmorphic belt and the Jiaodong terran, eastern Shandong province, mainly consists of the Duogushan, Washan, Wuzhuashan, Laoshifen and Liulinzhuang granitoids. Here, we mainly discuss the geochemistry and petrogenesis of the Duogushan and Washan sodium-rich granites which belong to the calc-alkaline and high-potassium calc-alkaline series respectively. They have SiO2 = 69 similar to 71%, high aluminium ( Al2O3 > 15%, SiO2 = 70%) and alkaline contents including Na2O = 3.54 similar to 4.88%, K2O = 2.11 similar to 4.44% K2O + Na2O = 5.65 similar to 9.02% and Na2O/K2O = 0.9 similar to 1.9 consistent with Na-rich granite, LILE ( e.g. Ba > 1440mug/g, Sr > 650mug/g) and LREE enrichment but HFSE depletion ( e. g. Nb, Ta, P and Ti) in the primitive mantle normalized spidergram, and steep REE patterns ( La-n/Yb-n > 12, Y < 18mug/g and Yb < 2mug/g, no or weak anomalies of Eu). These geochemical features are similar to Archaean TTG, Adakite, Na-rich granite of Cordillera Blankca Batholith and as well as many other Mesozoic granites in eastern China. the typical calc-alkalic differentiation trend of arc volcanic suites is different from the trondhjemitic trend of the TTG and Adakite, but closely simlar to Na-rich granites from the Cordillera Blanca Batholith of Peru. The reported Sr-Nd isotopic components (Sr-87/Sr-86 i = 0.7097 similar to 0.7098, and epsilon(NJ) ( t) = - 19.6 similar to -20.0) and inherited magmatic zircons with ages of 700 similar to 800Ma from the Kunyushan sodium-rich granites, rule out genesis related to newly basaltic lower crust and mass from the Jiaodong block which has reported U-Pb concordant ages of 2600 similar to 2900Ma. There is no coeval basic or intermediate magma known from the Jiaodong erea, implys that these granites are unlikely to be derived by fractionation of mantle-derived magma or magmatic modification via magma mixing, fractionation and/ or AFC process reported for the genesis of other sodium-rich granites occurring in eastern China. Partial melts of young subducted ocean crust can also be excluded because no ocean crust occurs in the Su-Lu UHP metamorphic belt during the Mesozoic. Hence, the sodium-rich granites are most likely to be generated by dehydrational partial melting of thick mafic lower crust of the South China block as a result of basaltic underplating which is perhaps triggered by lithosphere thinning beneath North China Craton. The geochemistry of the Kunyushan sodium-rich granites with low Y, Yb contents and high Sr/Y, ( La/Yb)(n) ratios indicate that garnet and amphibole, but not feldspar, are dominant residues which would drop into lithosphere due to their relatively high density. Furthermore, the sodium-rich granites formation suggests that thickened lower mafic crust in response to continental collision, was still present between 160Ma and 140Ma, and as well as various petrogenesis of the sodium-rich granites in eastern China.
