China Water Resources Beifang Investigation Design and Research Co., Ltd., Tianjin 300222, China

Jianzang granodiorite in western Qinling is located at Luoda Town of Gannan Tibetan Autonomous Prefecture in Gansu Province. The whole rock geochemical characteristics show that the contents of SiO₂ are 65.36%~68.72%, Al₂O₃ are 15.42%~16.80%, MgO are 0.66%~1.62%, Na₂O are 3.10%~4.29% and K₂O are 2.45%~4.04%. The total alkali content of the rock is Na₂O+K₂O=2.96%~8.23%. The granodiorite is rich in potassium and aluminum contents, belongs to the high-potassium-calcium-alkaline series. The chondrite-normalized REE patterns are characterized by high LREEs and low HREEs without Eu anomalies.Jianzang granodiorite has the characteristic of adakite which is characterized by high Sr and low Y, and (La/Yb)_N=33.85~101.03. The magma originates were derived from the partial melting of delaminated lower crust and were contaminated by the mantle peridotite during the ascent. The granodiorite are post-orogenic granitoids which were formed in a transitional tectonic setting from syn-(compressional setting) to post-collision (extensional setting).