## 3 Results
### Normalized REE Distribution Patterns  
The C1 chondrite-normalized pattern, which smooths the elements distribution curve and enables comparison with the standard sample, is often used to eliminate the jaggedness of the REE odd-even effect that occurs during weathering process [30; 31; 37; 38; 39; 40]. The C1 chondrite-normalized REE distribution patterns are shown in Figure 5. The curves of these two profiles exhibited the same models: both soil and bedrocks tilted to the right and relatively flat after Sm. This indicates that LREE are enriched in the profile, whereas HREE are relatively deficient. All REE distribution patterns showed relatively tendencies in bedrock, RSI, and surface soil. This trend reflected the inheritance of crusts materials from bedrock. Two profiles expressed the V-shaped troughs for Sm anomalies, indicating negative Sm anomalies in each layer of both SC and TG profile. Ce displayed a disordered appearance, generally, showing V-type negative anomalies and nearly positive anomalies at the RSI. All elements' C1 chondrite-normalized lines in profiles were higher than Vietnam bedrock chondrite-normalized lines (SC01 and TG01). Therefore, the tropical carbonate weathering crusts always have a high REE accumulative effect.  
In the bedrock-normalized REE distribution pattern (Figure 6), the weathering crust showed significant REE enrichment. The \(\Sigma\)REE was more than 10 times higher than in the bedrock. The curves showed the same tendency from RSI to topsoil. The SC showed a right-out characteristic, which means LREE enrichment and HREE loss. Ce presented a positive Ce anomaly valley in both SC and TG profiles. The REE in RSI showed extremely high and fluctuating changes.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c c} \hline \hline
**Elements** & **La** & **Ce** & **Pr** & **Nd** & **Sm** & **Eu** & **Gd** & **Tb** & **Dy** & **Ho** & **Er** & **Tm** & **Yb** & **Lu** & **EREE** & **References** \\ \hline Loess & 32.3 & 67.4 & 7.00 & 28.8 & 5.70 & 12.7 & 4.60 & 0.80 & 4.40 & 0.90 & 2.60 & 0.40 & 2.60 & 0.40 & 194 & [22] \\ QS & 41.0 & 83.0 & 9.70 & 32.0 & 6.40 & 1.20 & 5.60 & 1.00 & 5.40 & 1.60 & 3.80 & 0.60 & 3.60 & 0.70 & 196 & [34] \\ UCC & 30.0 & 60.0 & 8.20 & 28.0 & 6.00 & 1.20 & 5.40 & 0.90 & 3.00 & 1.20 & 2.80 & 0.50 & 3.00 & 0.50 & 184 & [35] \\ LE & 16.4 & 30.8 & 3.70 & 17.8 & 2.90 & 0.60 & 2.90 & 0.40 & 2.50 & 0.40 & 1.00 & 0.20 & 1.30 & 2.00 & 92.0 & [36] \\ DSC & 6.90 & 5.40 & 3.40 & 4.60 & 2.00 & 1.20 & 1.20 & 1.90 & 0.90 & 1.30 & 0.60 & 0.80 & 0.50 & 0.70 & 0.40 & 31.0 & [14,27,32] \\ LSC & 11.3 & 15.5 & 4.80 & 7.10 & 2.50 & 0.90 & 1.70 & 0.80 & 1.30 & 0.60 & 0.80 & 0.40 & 0.70 & 0.40 & 49.0 & [14,27,32] \\ PDC & 101 & 172 & 34.0 & 138 & 36.0 & 7.00 & 25.0 & 5.00 & 21.0 & 4.00 & 10.0 & 2.00 & 11.0 & 2.00 & 566 & [14,27,32] \\ PLC & 83.0 & 121.6 & 22.0 & 87.1 & 19.2 & 4.10 & 18.2 & 2.70 & 15.7 & 2.90 & 7.80 & 1.10 & 6.60 & 0.90 & 393 & [14,27,32] \\ DNV & 2.08 & 3.94 & 0.48 & 1.92 & 0.38 & 0.08 & 0.4 & 0.07 & 0.38 & 0.09 & 0.23 & 0.05 & 0.36 & 0.05 & 12.7 & this research \\ LNV & 81.1 & 7.74 & 1.25 & 4.58 & 0.8 & 0.15 & 0.66 & 0.11 & 0.68 & 0.12 & 0.31 & 0.05 & 0.34 & 0.07 & 29.2 & this research \\ PDV & 62.3 & 134 & 14.2 & 56.9 & 11.5 & 2.41 & 10.5 & 2.01 & 11.1 & 2.21 & 6.48 & 1.13 & 6.53 & 1.21 & 381 & this research \\ PLV & 70.3 & 102 & 15.9 & 62.1 & 12.7 & 2.58 & 12.3 & 2.37 & 12.8 & 2.55 & 7.14 & 1.21 & 6.37 & 1.11 & 386 & this research \\ \hline \multicolumn{11}{c}{* UCC, upper continental crust [35]; QS, quaternary sediments; LE, lithosphere on the Earth; DSC, dolomite in China; LSC, limestone in China; PLC, profile on limestone in Southern China; PDC, profile on dolomite in Southern China; DNV, dolomite in Northern Vietnam; LNV, limestone in Northern Vietnam; PDV, profile on dolomite in Northern Vietnam; PLV, profile on limestone in Northern Vietnam.} \\ \end{tabular}
\end{table}
Table 3: Comparison of REE concentration (ppm) in different rocks, sediments, and soils on the Earth*.