## 6 Conclusions  
To determine at which extent the geochemistry of Turkestan and Zarafshon ranges is reflected by the adjacent sedimentary material, 116 sediments, and an equal number of soil samples were collected along the Tadjik sector of Zarafshon river and its main tributaries Arthuch, Djidjikrul, Iskadardarya, Mogiyon, Sarvoda, Shing, and Yagnob. All elemental analysis were performed by Instrumental Neutron Activation Analysis given its ability to analyze row material, without any previous treatment such as acid dissolution. This permitted determination of mass fractions of 38 major and trace elements with a sensitivity of 1 mg/kg, in both sediments and soils samples. As for each collecting point, the distance between sediments and soils sampling was no greater than 10 m, it was possible to investigate the interrelationship between sediments and soils geochemistry. All data were compared and analyzed in correlation with similar data for the Upper Continental Crust (UCC) and North American Shale Composite (NASC). As a general conclusion, the distribution of mass fractions of all studied elements, except As, Sb and Hg showed a remarkable similarity in sediments and soils. In the case of the Presumed Contaminating Elements As, Sb and Hg, their mass fractions in few mines' adis located around Djidjikrut or Kanchoch tributaries exceeded two to three order of magnitude their  
Figure 7: The La vs. Th bi-plot (**a**) proving that both Zarafshon sediments and soils are significantly closer to UCC [17] and NASC [18] than to MORB [51, 52] as well as the eight REE average values of Zarafshon sediments and soils normalized to chondrite [53] together with the corresponding UCC data (**b**) [16]. \begin{table}
\begin{tabular}{c c c c c} \hline  & **La/Sm** & **Gd/Yb** & **Eu*** & **Th/U** \\ \hline Sediment & 4.91 \(\pm\) 1.8 & 1.92 \(\pm\) 1.3 & 0.69 \(\pm\) 0.27 & 3.23 \(\pm\) 1 \\ Soils & 5.81 \(\pm\) 2.4 & 1.49 \(\pm\) 1.1 & 0.8 \(\pm\) 0.32 & 3.03 \(\pm\) 0.9 \\ UCC & 6.6 & 1.9 & 0.72 & 2.96 \\ NASC & 5.56 & — & — & 2.53 \\ \hline \end{tabular}
\end{table} 
Table 3: The La/Sm, Gg/Yb, Eu* as well as the Th/U values for sediments and soils. For comparison, the same ratios corresponding to UCC [17] and NASC [18] are reproduced too. natural values. At the same time, mass fractions of both major and trace elements presented an increase variability characterized by coefficients of variation between 15 and 200% which could be attributed to the diversity of geological formation covering the Zarafshon catchment basin. A detailed analysis of the major element oxides pointed towards a felsic origin of the collected material, with a small contribution of mafic one, as the alkali-silica discriminating diagrams SiO\({}_{2}\)-Al\({}_{2}\)O\({}_{3}\)-Na\({}_{2}\)O + K\({}_{2}\)O + CaO suggested. At the same time, the K\({}_{2}\)O-Al\({}_{2}\)O\({}_{3}\)-CaO + Na\({}_{2}\)O ternary diagram pointed towards a certain degree of weathering processes. Only in some places we have noticed an increased amount of magnesium and calcium oxides, most probable related to local deposits of limestone and dolomite. Relevant information was obtained by analyzing the distribution of low mobility and incompatible Sc, Zr, La, Ce, Nd, Sm, Eu, Gd, Tm, Yb as well as Th and U. Accordingly, Sc presented an average mass fraction of 10 to 11 mg/kg, characteristic of a felsic origin, a hypothesis suggested also by the reciprocal distribution of mass fractions of Sc, Co, La, Hf, or Th, in sediments as well as in soils. The la/Th vs. Hf and Th/Sc vs. Zr/Sc bi-plots suggest the absence of a significant sorting and recycling process of sedimentary material. The REE distribution was shown to be almost identical for sediments and soils and closer to UCC and NASC. The same pattern was noticed in the case of negative Eu anomaly, which was shown to be closer to UCC and NASC.