Geochemistry, zircon U–Pb, and molybdenite Re–Os geochronology of the Mo deposit in Fengning region, Hebei Province, China

Abstract

The Dacaoping and Sadaigoumen Mo deposits were recently discovered along the northern margin of the North China Craton. The newly determined Re–Os isochronous age of molybdenite from the Dacaoping Mo deposit is ca. 147 Ma, and the Re–Os model age of molybdenite from the Sadaigoumen Mo deposit is ca. 248 Ma, which represents two of their respective mineralization stages. Combined with previous data, we suggest four phases of mineralization in the Dacaoping and Sabagaogoumen Mo deposits; these phases are 248, 236, 147, 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. The partial melting of the lower crust is the main reason for their formation, and small amounts of mantle‐derived components were added. Compared to other Mo deposits in the region, we can further divide these Mo deposits into three phases, namely, (a) Triassic (ca. 248–223 Ma), (b) Early–Middle Jurassic (ca. 187–165 Ma), and (c) 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.