## 4 Results
### Ferruginous Sandstone Uranium Minerals  
The EPMA result of the ferruginous sandstone shows that there are two main existing forms of uranium in the study area (Figure 8, Table 4): (1) Part of the uranium minerals are found in the residual heavy mineral. The accessory minerals are primarily zircon, touramaline, monazite, and barite. (2) The uranium minerals that occur in fissures of quartz, gypsum, and other debris particles displayed star shapes and banded bands. Small amounts of uranium minerals appear to be adsorbed dispersedly by ferruginous cementation, organic matter, pyrite and argillaceous cementation. It was found that the uranium exists in the form of pitchblende, and some REE was found using SEM in the ferruginous sandstone in the study area.  
Figure 8: Existence form of uranium minerals in the Wajid Sandstone. (**a,b**) Zircon minerals contain a small amount of uranium; (**c**) Uranium and thorium are wrapped in zircon; (**d**) Uranium is adsorbed by pyrite on the surface of quartz; (**e,f**) Uranium occur in fissures of gypsum and quartz. Qtz—quartz; Zrm—zircon; U-uranium; Th—thorium; Hem—hematite; Py—pyrite; Gp—gypsum.  
(2) U-Pb dating  
The U-Pb dating data of the ferruginous sandstone indicated that the primary metallogenic age of the uranium is 22.58 \(\pm\) 0.47 Ma (Figure 9, Table 5). This demonstrated that most of the uranium in the ferruginous sandstone was reformed during a later stage because the age of the mineralization was significantly younger than the age of the host rocks. The uranium mineralization primarily formed in the sedimentary and diagenetic stage and it was concentrated in the later stage. The uranium mineralization age of the later stage occurred during the Neogene.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multicolumn{10}{c}{**Test Results (wt\%)**} \\ \cline{2-13}  & **Test Point** & \(\mathbf{Y_{2}O_{3}}\) & \(\mathbf{SiO_{2}}\) & **FeO** & \(\mathbf{UO_{2}}\) & \(\mathbf{MgO}\) & \(\mathbf{Na_{2}O}\) & \(\mathbf{TiO_{2}}\) & \(\mathbf{Na_{2}O_{5}}\) & \(\mathbf{Al_{2}O_{3}}\) & **MnO** & **PbO** \\ \hline \multirow{2}{*}{**UA5.1/SM01**} & **1** & 1.15 & 12.57 & 0.18 & 22.83 & / & / & / & 51.96 & / & / & 0.13 & 0.15 \\ \cline{2-13}  & **2** & / & 29.66 & 0.19 & 10.81 & / & / & / & 7.67 & 0.07 & / & 0.06 & 1.16 \\ \hline \multirow{2}{*}{**UA5.1/SM 10**} & **1** & 1.03 & 25.01 & 0.28 & 5.77 & 0.04 & 0.49 & / & 30.67 & / & 0.69 & / & 0.86 \\ \hline \multirow{2}{*}{**UA5.1/SM 11**} & **1** & 0.19 & 1.38 & 1.83 & 87.86 & / & 1.04 & 0.61 & / & / & / & 1.33 & 0.28 \\ \cline{2-13}  & **2** & / & 13.41 & 1.91 & 60.58 & 0.14 & 0.08 & 0.16 & / & 0.16 & 0.04 & / & / \\ \cline{2-13}  & **3** & / & 30.08 & 2.14 & 48.46 & 0.07 & 0.14 & / & / & / & 0.01 & 0.24 & / \\ \cline{2-13}  & **4** & / & 1.20 & 1.19 & 91.18 & / & 0.19 & / & / & / & 0.07 & 1.02 & 0.14 \\ \cline{2-13}  & **5** & 0.30 & 3.72 & 2.42 & 82.09 & 0.06 & 1.19 & 0.16 & / & 0.29 & 0.03 & 0.58 & 0.28 \\ \hline \multirow{2}{*}{**Sample**} & \multicolumn{10}{c}{**Test Results (wt\%)**} \\ \cline{2-13}  & **Test point** & \(\mathbf{V_{2}O_{3}}\) & \(\mathbf{K_{2}O}\) & \(\mathbf{Nd_{2}O_{3}}\) & \(\mathbf{ CaO}\) & \(\mathbf{Ce_{2}O_{3}}\) & \(\mathbf{SO_{3}}\) & \(\mathbf{La_{2}O_{3}}\) & \(\mathbf{ZrO_{2}}\) & \(\mathbf{Pr_{2}O_{3}}\) & \(\mathbf{Pr_{2}O_{5}}\) & \(\mathbf{Sn_{2}}\) & **Total** \\ \hline \multirow{2}{*}{**UA5.1/SM01**} & **1** & 0.08 & 0.30 & / & 0.18 & / & / & / & 0.23 & / & 1.88 & / & 91.64 \\ \cline{2-13}  & **2** & / & / & / & / & 0.30 & 0.04 & 0.25 & 44.26 & 0.13 & 1.61 & / & 96.21 \\ \hline \multirow{2}{*}{**UA5.1/SM 10**} & **1** & 0.11 & 0.19 & / & 0.09 & / & / & / & 27.21 & 0.08 & 0.91 & / & 93.43 \\ \cline{2-13}  & **1** & / & 0.26 & / & 1.38 & 0.35 & 0.12 & / & 0.74 & / & 1.43 & / & 98.80 \\ \cline{2-13}  & **2** & / & 1.50 & 0.26