The characteristics of ore-controlling fault and its relationship to uranium mineralization in Shangwei area, Southern Jiangxi Province

Shangwei area is in southernmost Longnan County, Jiangxi Province. The Yanshanian Shangwei granite complex pluton is strictly controlled by NE-trending Mashishan fault zone and Exing fault and occurs in the NE-trending oval form. It is a uraniumbearing granite body, where there exist known uranium deposit No. 291 and No. 292 uranium ore spot. Due to strong faulting, alterations and mineralizations are abundant in main fault belts. Geological survey reveals that the fracture tectonic system in Shangwei area is mainly formed by 6 NE-trending faults, 11 NNE-trending faults and some NW-NWW trending faults. The NE-and NNEtrending faults include silicified fault (QF₃, QF₄), quartz fault (QF₇~QF₉), silicified fractured fault (QF₁, QF₂, QF₅ and QF₆) and altered cataclastic fault (F₁, F₂, F₃ and F₇). The NW-trending fault is usually filled with intermediate basic veins (501~504). NNE-trending faults are intimately related to uranium mineralization, and are thus the main ore-bearing faults. Uranium orebody occurs within the NNE-trending faults and bears a close relation to silicified breccia and cataclastic altered rock. The attitude of NNE-trending fault controls the dip of the orebody, its property controls the mineralization types, the deformation behaviour controls the horizontal zoning characteristics of mineralization and alternation, and the fault and the veins obviously control the shape of rich uranium orebody.