Abstract:

Danghenanshan area lies in South Qilian Mountains which is a great metallogenic belt. In this area, the granitoids are composed of Zhazigou pluton,Jijiaogou pluton and Jiagongtai pluton and all related to mineralization of gold and copper. Zhazigou pluton is mainly constituted by granodiorite and intrudes Sinian Period volcanic rocks. Jijiaogou pluton is mainly constituted by quartz monzodiorite, Jiagongtai pluton is mainly constituted by plagiogranite,and they both intrude Ordovician Period clastic rocks. The Rb-Sr isochron ages of the three plutons are (510.85±14)Ma, (395.06±51)Ma and (355±91)Ma respectively, the former formed during early-middle  Cambrian Period,the latter two formed during Silurian Period and Devonian Period.This three plutons all-correspond to calc-alkaline series.In this series, Zhazigou pluton belongs to middle-potassium granodiorite series, Jiagongtai pluton belongs to high-potassium monzonite ones,and Jiagongtai pluton belongs to low-potassium trondhjemite ones.The granitoid characteristics of lithofacies, petrochemistry, trace elements and REE geochemistry indicate that this three plutons are all I-type granitoids, formed in active continental margin,and are the results of tectonic movement and and magmatism of middle-south Qilian Mountains during Caledonian.

Key words: Danghenanshan area, granitoids, lithofacies, isotope, geochemistry, tectonic setting, South Qilian Mountains