Geological Characteristics and Mineralization Mechanism of the No.207 Uranium Deposit in Longshoushan,Gansu Province

The No.207 uranium deposit is located in the west of Longshoushan metallogenic belt, which is characterized by complex geological structure and intensive magma activity. The major outcrops are lower Proterozoic metamorphic rocks (named Longshoushan Group) and Zhongtiaoian granite. Regional structure trends from northwest to southeast. Uranium mineralization in this ore deposit is mainly controlled by granite body and fracture structures. Uranium mineralization is characterized by obvious multiple stages. Uranium mineralization age is 1750Ma, indicating small time difference between the ore and the rock. The ore deposit possesses the common characteristics of the granite type uranium deposits. Based on regional geological setting and metallogenic characteristics of No.207 uranium deposit, this study analyzed the sources of ore-forming materials and fluids, and channels for transport of ore materials, established metallogenic model for the No.207 uranium deposit. It is concluded that the uranium metallogenesis of the ore deposit took place in a specific temporal-spatial domain controlled by the regional geological setting. Regional uranium-rich strata provided substances for metallogenesis and ore fluids derived from magmatic water, magma and postmagmatic hydrothermal fluids were carriers of uranium transport. The uranium metallogenic model emphasizes that the formation process of alaskite was a process of ore substance concentration.