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2015 GSA Annual Meeting in Baltimore, Maryland, USA (1-4 November 2015)

Paper No. 65-3
Presentation Time: 2:05 PM

THE XIANSHI URANIUM DEPOSIT, SOUTH CHINA: THE WORLD’S LARGEST SOURCE OF VORLANITE (CAU6+)O4


LUO, Jin-cheng1, FAYEK, Mostafa2, HU, Ruizhong3, BI, Xianwu3 and HAWTHORNE, Frank C.4, (1)Geological Sciences, University of Manitoba, Winnipeg, MB R3T2N2, Canada, (2)Geological Sciences, University of Manitoba, 240 Wallace Bldg, 125 Dysart Road, Winnipeg, MB R3T2N2, Canada, (3)Institute of Geochemistry, Chinese Academy of Sciences, 46 Guanshui Road, Guiyang, 550002, China, (4)Geological Sciences, University of Manitoba, 125 Dysart Road, 240 Wallace Bldg, Winnipeg, MB R3T 2N2, Canada, fayek@cc.umanitoba.ca

Vorlanite, ideally (CaU6+)O4 [Fm3(_)m, a = 5.393(3) Å, V = 156.87 Å3, Z = 2], is a rare uranium mineral that usually occurs in trace amounts in volcanic environments. Here we report the first deposit-scale occurrence of vorlanite from the Xianshi granite-hosted uranium deposit, South China.

The Xianshi uranium deposit, located in the southeastern part of the Guidong granite complex, is a major source of uranium in South China. The uranium mineralization from this deposit is spatially associated with the Cretaceous mantle-derived mafic dykes. Three distinct generations of uranium minerals (135 ± 4 Ma, 113 ± 2 Ma and 104 ± 2 Ma) have been identified based on petrography, field relations and geochronology, indicating that the Xianshi uranium deposit has experienced at least three hydrothermal events that are related to three episodes of mantle-derived mafic dykes.

Vorlanite from this deposit is dark gray to black, has distinct XRD and Raman spectra, and higher Si, Pb and Na and lower Ca contents compared to vorlanite from other localities (e.g. Russia, Israel, Mexico). These differences indicate that the uranium in vorlanite from the Xianshi deposit is more oxidized than uranium in previously described vorlanite. In addition, vorlanite from the Xianshi deposit is the dominant ore-mineral of uranium. Therefore, mining and milling of this ore body need to take into consideration the chemical composition and physical properties of this mineral.

Session No. 65

T134. Radiation Effects, Mineralogy, and Materials Science of Actinides II: In Honor of Rodney C. Ewing, 2015 Roebling Medalist
Sunday, 1 November 2015: 1:30 PM-5:30 PM
Room 317 (Baltimore Convention Center)
Geological Society of America Abstracts with Programs. Vol. 47, No. 7, p.202
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