[en] Rb-Sr and Pb/Pb whole rock isochrons on the Qorqut Granite Complex yield ages of 2530 +- 30 Myr and 2580 +- 80 Myr respectively. A model relating initial Sr and Pb isotopic compositions of the Qorqut granites to the Sr and Pb isotopic compositions of the Amitsoq gneisses (ca. 3700 Myr) and Nuk gneisses (ca. 2900 Myr) at 2550 Myr ago, as well as Sr and Pb contents of the gneiss units, suggests that between 40 and 50% of the Qorqut granite magma was generated by partial melting of Amitsoq gneisses, and the remainder by partial melting of Nuk gneisses. (author)