The Jinchang quartz diorite pluton is located in the south part of western Qinling Orogen, western China.  Mafic microgranular enclaves （MMEs） are widespread in the pluton,  and are mostly rounded or irregular elongated in morphology.  They commonly have sharp to transitional contact to the host intrusion.  Common presence of needle-like apatite in MMEs, which, however, occurs as short crystals in the host rocks, suggests mixing of mafic and felsic magmas in the formation of the Jinchang quartz diorite.  Petrographic evidence and U-Pb ages demonstrate that the Jinchang quartz diorite was emplaced in a post-collisional extensional environment, which could have facilitated partial melting of enriched lithospheric mantle and lower crust, and subsequently mixing of mafic and felsic magmas to form the quartz diorite.