minerals Article Geochronology and Geochemistry of Uraninite and Coffinite: Insights into Ore-Forming Process in the Pegmatite-Hosted Uraniferous Province, North Qinling, Central China Feng Yuan 1, Shao-Yong Jiang 1,*, Jiajun Liu 2,*, Shuai Zhang 2, Zhibin Xiao 3, Gang Liu 2 and Xiaojia Hu 4 1 State Key Laboratory of Geological Processes and Mineral Resources, Collaborative Innovation Centre for Exploration of Strategic Mineral Resources, School of Earth Resources, China University of Geosciences, Wuhan 430074, China;
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[email protected] (G.L.) 3 Tianjin Center, China Geological Survey, Tianjin 300170, China;
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[email protected] (J.L.); Tel.: +027-67883058 (S.-Y.J.) Received: 5 July 2019; Accepted: 2 September 2019; Published: 13 September 2019 Abstract: The biotite pegmatites in the Shangdan domain of the North Qinling orogenic belt contain economic concentrations of U, constituting a low-grade, large-tonnage pegmatite-hosted uraniferous province. Uraninite is predominant and ubiquitous ore mineral and coffinite is common alteration mineral after initial deposit formation. A comprehensive survey of the uraninite and coffinite assemblage of the Chenjiazhuang, Xiaohuacha, and Guangshigou biotite pegmatites in this uraniferous province reveal the primary magmatic U mineralization and its response during subsequent hydrothermal events. Integrating the ID-TIMS (Isotope Dilution Thermal Ionization Mass Spectrometry) 206Pb/238U ages and U-Th-Pb chemical ages for the uraninites with those reported from previous studies suggests that the timing of U mineralization in the uraniferous province was constrained at 407–415 Ma, confirming an Early Devonian magmatic ore-forming event.