Geochronology, geochemistry, and Hf Isotope of the granites from the Mo deposits in Fengning region, China: implications for tectonic evolution and mineralization of the North China Craton

The Dacaoping and Sadaigoumen Mo deposits were recently discovered along the northern margin of the North China Craton. In this paper, we present new zircon U–Pb ages, Hf isotope data, and whole-rock major and trace element data for the monzogranite and granodiorite in the Dacaoping Mo deposit and the monzogranite in the Sabagaogoumen Mo deposit, and we use these data to constrain the metallogenic epoch and the tectonic background in the area. Combined with previous data, we suggest four phases of mineralization in the Dacaoping and Sabagaogoumen Mo deposits; these phases are 248 Ma, 236 Ma, 147 Ma, and 140 Ma. The Early Triassic monzogranite and Early Cretaceous granodiorite in the Dacaoping Mo deposit and the Middle Triassic monzogranite in the Sabagaogoumen Mo deposit are I-type granite with similar geochemical characteristics. The Triassic granites formed in a collisional–post-collisional setting between the North China plate and the Siberian plate, and the Cretaceous granodiorite formed from the rapid thinning of the lithosphere. Their source rock should mainly originate from the partial melting of ancient crustal material. Compared with other Mo deposits in the region, we can further divide these Mo deposits into three phases, namely (1) Triassic (ca. 248–223 Ma), (2) Early–Middle Jurassic (ca. 187–165 Ma), and (3) Late Jurassic–Early Cretaceous (ca. 155–130 Ma), which are consistent with the times of magmatic activity. These activities occurred during the collision and post-collision between the North China plate and the Siberian plate after the Paleo-Asian Ocean’s closure, intracontinental orogeny, and rapid thinning of the lithosphere, respectively.