PAN Cheng-yu1, WU Yu1*, LIU Chang1, WANG Feng-gang1, TIAN Jian-ji1, XU Wei2, HAN Wen-wen2, XIAO Chang-hao3, ZHANG Wen-gao3
(1. Beijing Research Institute of Uranium Geology, CNNC Key Laboratory of Uranium Resources Exploration and Evaluation Techniques, Beijing 100029, China;
2. No.280 Institute of Nuclear Industry, Guanghan 618300, China; 3. Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China)
Abstract: The Dajishan uranium polymetallic deposit, which is located in the Southwestern Guizhou, China, has been regarded as a carbonaceous-siliceous-pelitic rock-type uranium deposit. However, the mineralization characteristics and genesis of this uranium polymetallic deposit are poorly studied. In the present paper, α track etching, microscope identification, laser Raman spectroscopy, scanning electron microscope, and electron probe microanalysis are used to carry out detailed studies of the ore fabrics, mineral compositions, and occurrence of uranium of the Dajishan uranium polymetallic deposit. The results show that uranium polymetallic ores, with brecciated, disseminated, and veinlet structures, contain a large amount of pyrite, marcasite, molybdenite, and organic matter, and a small amount of galena and sphalerite. Uranium occurred as invisible uranium and microscopic pitchblende, which is mostly in form of disseminated tiny particles within the metallic sulfide grains, or in form of irregular clumping and flocculent patches along the edges or gaps of different mineral grains, with minor pitchblende occurred as irregular veinlets or stockwork veins filling in cracks of carbonate fragments of breccias. With the combination of general geological characteristics that uranium orebodies strictly hosted in faults and interstratified fracture zones, the strong hydrothermal alteration of host rocks, and relatively low U contents of wall rocks, it is believed that the Dajishan uranium polymetallic deposit should be assigned to the low-temperature hydrothermal uranium deposit.
Keywords: Ore characteristics; occurrence of uranium; genesis of deposit; the Dajishan uranium polymetallic deposit; Xingyi, Guizhou
ACTA MINERALOGICA SINICA Vol. 41, No.1, 2021, page 23-32