## 4 Results
### Major and Trace Elements  
Experimental analysis of major and trace elements indicates that the Qiongzhusi shale in well Z201 shows increased concentrations of Al and Ba compared to other elements in the region (Table 3). The Al content ranges from 2% to 8%, with an average of 6.77%; Ba content varies between 1190 and 1730 ppm, averaging 1472.26 ppm; V content ranges from 54 to 1795 ppm, averaging 486.90 ppm; Ni content is comparatively low, ranging from 12 to 142 ppm, with an average of 73.7 ppm. Compared to the post-Archean average shale (PAAS), the Qiongzhusi shale exhibits significant enrichment in V, while Ni, Cr, Zr, Sr, and Co show depletion. The remaining elements show comparable concentrations to those in the PAAS.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & & & & & & & & \multicolumn{2}{c}{**Mineral Content/\%**} \\ \cline{5-8}
**Sample** & **Depth/m** & **Interval** & & & & & & **Clay Mineral** \\
**Number** & & & & & & & & **Moaliolite, Illite, Mixed Layer** & **Pyrite** \\ \hline Z1 & 4451.74 & Q\({}_{2}\) & 36 & 19 & 4 & 7 & 31 & 3 \\ Z2 & 4455.09 & Q\({}_{2}\) & 36 & 19 & 4 & 7 & 31 & 3 \\ Z3 & 4463.15 & Q\({}_{2}\) & 38 & 17 & 6 & 4 & 32 & 6 \\ Z4 & 4466.28 & Q\({}_{2}\) & 39 & 13 & 5 & 5 & 34 & 4 \\ Z5 & 4469.09 & Q\({}_{2}\) & 34 & 12 & 9 & 8 & 32 & 4 \\ Z6 & 4471.31 & Q\({}_{2}\) & 35 & 14 & 5 & 4 & 37 & 5 \\ Z7 & 4480.52 & Q\({}_{2}\) & 38 & 15 & 6 & 6 & 31 & 4 \\ Z8 & 4483.91 & Q\({}_{2}\) & 40 & 13 & 7 & 6 & 30 & 5 \\ Z9 & 4485.82 & Q\({}_{2}\) & 38 & 13 & 8 & 5 & 33 & 5 \\ Z10 & 4486.04 & Q\({}_{2}\) & 36 & 15 & 8 & 5 & 3 & 4 \\ \hline Z11 & 4502.42 & Q\({}_{1}\)\({}^{2}\) & 38 & 18 & 8 & 4 & 29 & 4 \\ Z12 & 4505.37 & Q\({}_{2}\)\({}^{2}\) & 43 & 33 & 3 & 2 & 17 & 3 \\ Z13 & 4548.07 & Q\({}_{1}\)\({}^{2}\) & 41 & 35 & 2 & 2 & 18 & 3 \\ Z14 & 4552.08 & Q\({}_{1}\)\({}^{2}\) & 41 & 31 & 2 & 2 & 18 & 6 \\ Z15 & 4554.15 & Q\({}_{2}\)\({}^{2}\) & 44 & 28 & 2 & 3 & 21 & 3 \\ Z16 & 4555.98 & Q\({}_{1}\)\({}^{2}\) & 38 & 34 & 4 & 3 & 19 & 3 \\ Z17 & 4558.1 & Q\({}_{1}\)\({}^{2}\) & 39 & 32 & 1 & 3 & 2 & 3 \\ Z18 & 4560.21 & Q\({}_{2}\)\({}^{2}\) & 41 & 33 & 1. & 2 & 18 & 4 \\ Z19 & 4572.46 & Q\({}_{1}\)\({}^{2}\) & 41 & 37 & 2 & 2 & 16 & 3 \\ Z20 & 4592.57 & Q\({}_{1}\)\({}^{2}\) & 42 & 36 & 2 & 2 & 17 & 2 \\ Z21 & 4612.22 & Q\({}_{1}\)\({}^{2}\) & 43 & 30 & 2 & 2 & 18 & 5 \\ \hline Z22 & 4749.16 & Q\({}_{1}\)\({}^{1}\) & 40 & 37 & 3 & 2 & 16 & 3 \\ Z23 & 4751.47 & Q\({}_{1}\)\({}^{1}\) & 45 & 34 & 3 & 3 & 10 & 5 \\ Z24 & 4757.96 & Q\({}_{1}\)\({}^{1}\) & 25 & 19 & 13 & 28 & 11 & 3 \\ Z25 & 4758.91 & Q\({}_{1}\)\({}^{1}\) & 40 & 40 & 4 & 3 & 10 & 4 \\ Z26 & 4761.15 & Q\({}_{1}\)\({}^{4}\) & 40 & 37 & 5 & 4 & 11 & 4 \\ Z27 & 4767.74 & Q\({}_{1}\)\({}^{1}\) & 48 & 31 & 2 & 6 & 9 & 4 \\ Z28 & 4769.68 & Q\({}_{1}\)\({}^{1}\) & 49 & 11 & 2 & 14 & 10 & 4 \\ Z29 & 4771.83 & Q\({}_{1}\)\({}^{1}\) & 68 & 17 & 2 & 1 & 9 & 3 \\ Z30 & 4773.93 & Q\({}_{1}\)\({}^{1}\) & 80 & 5 & 4 & 1 & 9 & 2 \\ Z31 & 4777.87 & Q\({}_{1}\)\({}^{1}\) & 77 & 10 & 7 & 0 & 5 & 1 \\ \hline \hline \end{tabular} Caption: Q\({}_{2}\): Qiong 2 member, Q\({}_{1}\)\({}^{2}\): Qiong 1-2 submember, Q\({}_{1}\)\({}^{1}\): Qiong 1-1 submember.  
\end{table}
Table 2: Mineral composition content of Qiongzhusi formation shale in the southern Sichuan Basin.