Ore Geology Reviews | 2019
Geochronology and geochemistry of the Dasuji Mo deposit in the northern margin of the North China Block: Implications for ore genesis and tectonic setting
Abstract
Abstract The Dasuji Mo deposit is located in the northern margin of the North China Block (NCB). In this paper, we present the whole-rock major and trace elements and the Sr–Nd isotopic data, zircon U–Pb and Hf isotopic data, and molybdenite Re–Os data for the units associated with the deposit. Laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) dating of zircons from the granite porphyry yielded an age of 220.3\u202f±\u202f0.7\u202fMa, which was interpreted to be the emplacement age of this intrusion. The molybdenite Re–Os dating yielded model ages of 219.9–217.4\u202fMa, an isochron age of 222.1\u202f±\u202f4.7\u202fMa, and a weighted mean model age of 218.9\u202f±\u202f1.6\u202fMa, representing the timing of the formation of the Mo mineralization. The Dasuji granite porphyry contains high-K calc-alkaline and peraluminous rocks and is characterized by relatively high LREEs and low HREEs; depleted Ba, Sr, P and Ti; and negative Eu anomalies and are of highly fractionated I-type granitoids. The whole-rock eNd(t) and zircon eHf(t) values for the granite porphyry range from −13.9 to −12.8 and −16.4 to −7.3, respectively, indicating that the magma was generated by the partial melting of ancient lower crust materials. The Dasuji Mo deposit may have formed in a post-collisional extensional setting.