# Chemical Signatures of Ge in Magnetic of Wugang BIF, China
## 3 Results and Discussion
### Geochemical Properties of Ge in Magnetite in Various Ore Deposits
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline  & **Ge** & **Ti** & **V** & **Mg** & **Al** & **Cr** & **Mn** & **Co** & **Zn** & **Ga** & **Ni** \\ \hline Min & 3.3 & 40 & 2.5 & 17 & 78 & 0.4 & 244 & 0.4 & 6.8 & 0.5 & \(<\)0.01 \\ Max & 11 & 262 & 17 & 953 & 1764 & 405 & 4205 & 22 & 119 & 6.5 & 22 \\ Median & 4.7 & 54 & 3.9 & 135 & 341 & 4.5 & 622 & 1.2 & 43 & 0.8 & 4.0 \\ Standard deviation & 1.0 & 46 & 3.1 & 240 & 356 & 32 & 594 & 5.1 & 25 & 1.2 & 3.9 \\ \hline \end{tabular}
\end{table} 
Table 2: Trace element abundance of magnetite from Wugang BIF (n = 140, ppm). radius and the overall charge balance), oxygen fugacity, magma composition, and coexisting minerals [50]. [PERSON], [PERSON], [PERSON], [PERSON], and [PERSON] [50] investigated the relationship between the oxygen fugacity and concentration of Ge using quartz-ulvospinel-ilmenite-fayalite (QUILF) equilibrium modeling. They concluded that the Panzhihua and Baima intrusions crystallized under high oxygen and possessed a slightly higher concentration of Ge compared to other intrusions in the Emeishan large igneous province, indicating that Ge can easily enter the magnetite structure at higher oxygen fugacities. The magnetite in this study contained concentrations of 3.3-11.2 ppm of Ge (average 5.1 ppm), 40.1-261.5 ppm of Ti (average 80.6 ppm), 2.5-17.2 ppm of V (average 5.3 ppm), 17.0-952.5 ppm of Mg (average 211.7 ppm), and 77.7-1763.8 ppm of Al (average 404.5 ppm) (Table 2, Figure 3). Magnetites from the Wugang BIF have enriched concentrations of Ge with values higher than those of the bulk continental crust [51]. In the Ti + V and Al + Mn discrimination diagrams [12], the trace element compositions of magnetite plot slightly outside the BIF field owing to lower Ti + V and Al + Mn values, which reflect the complex genetic conditions of the Wugang BIF (Figure 4). The dissolution-reprecipitation processes (DRP) process can be deduced using the textural and compositional data of magnetite, which is evidence of the hydrothermal origin of magnetite. Magnetite affected by DRP has distinct textural features of secondary magnetite intergrown with relict primary magnetite, and this secondary magnetite exhibits a porosity-rich texture [52]. The magnetite in the Wugang BIF had low Al and Si contents with abundant porosity, and it can be assumed that geological events and subordinate variations in oxygen and sulfur fugacity in the fluid caused the DRP in magnetite in the Wugang BIF. The porous texture might be related to volume loss and lead to easy fluid infiltration owing to an increase in the effective permeability; therefore, magnetite dissolution occurs [52]. The narrow ranges of trace elements with respect to the composition of Ge in magnetite, as shown in Figure 3, are indicative of an original fluid source of the Wugang BIF. The partition coefficients of trace elements are primarily controlled by temperature [53], with increasing and decreasing trends in trace-element concentrations [14]. In addition, the concentration of Ge in water positively correlates with temperature [54]. However, there is still no clear evidence of a relationship between the Ge concentration in magnetite and the crystallization temperature [22]. The Ge in magnetite was positively correlated with Cr, Ni, Zn, Al, Ti, Mg, Ga, and V and slightly negatively correlated with Co (Figure 4). The chemical behavior of Ge was assumed to be similar to those of Cr, Ni, Zn, Al, Ti, Mg, Ga, and V. In addition, the positive correlations between these trace elements and Ge indicated the compatibility of Ge with magnetite [33]. In conclusion, the textural, compositional, and geochemical data for magnetite from the Wugang BIF confirm its hydrothermal origin and indicate the compositional signatures of the original hydrothermal fluids.