Located at the northernmost corner of the Deerbugan metallogenic belt and in the northeastern part of the Mongolian-Hinggan amalgamated massif, the newly found Chalukou ore deposit is the largest molybdenum polymetallic deposit ever discovered in China. It contains 1.34 Mt of Mo (metal), 0.37 Mt of Pb-Zn and 4 200 t of Ag. As a part of the evaluation project of the molybdenum deposit, mineral exploration around Chalukou is still underway. Combined with field geological observations and petrological evidence, the authors hold that the ore-forming materials might have been derived from a mixed source of depleted mantle-and crustal-derived magma or fluids. The Re-Os isochron age of the molybdenite separates at Chalukou indicates that late Jurassic intraplate granitoid magmatism and relevant molybdenum polymetallic mineralization in the northernmost part of the Great Hinggan Mountains were active after the latest Paleozoic collision between the Siberian plate and the Mongolian-Hinggan amalgamated massif.