A total of 17 pieces of Ge isotope test data were obtained in the Xiaoqinling and Xiongershan areas (author of this article, 1997; Wang Yitian, 2002). The samples include three types of gold deposits and six types of gold deposits in the area. Mineral deposits (Table 5-10, 5-11), Wang Yitian’s samples were collected from the middle and deep tunnels of Xiaoqinling (quartz vein type gold mine), while the samples in this article were mainly collected from the surface or shallow tunnels of the gold mine in the Xiongershan area. middle.
Table 5-10 Analysis results of rare gas isotopes of gold deposits in the Xiongershan area (wB)
According to Wang Yitian’s research (Table 5-11), the quartz vein type gold deposits in Xiaoqinling The R/Ra range ranges from (0.29 to 1.8) Ra, which is 1 to 2 orders of magnitude higher than the crustal Ge isotope ratio, indicating that there is mantle Ge in the ore-forming fluid, but it is relatively lower than the mantle Ge value, indicating mineralization. Ge from crustal sources is ubiquitous in fluids, so the Ge isotopes in the ore-forming fluids of Xiaoqinling quartz vein-type gold deposits are a mixture of mantle and crust sources. On the Ge isotope composition map (Figure 5-15), the data points all fall in the transition zone between the mantle zone and the crust zone, close to the mantle zone, but all the data are clearly divided into two zones, among which samples 1, 5, and 6 , 7 are close to the mantle area, while samples 2, 3, and 4 are relatively deviated and closer to the crustal area. Samples 1, 5, 6, and 7 were collected from the second mineralization stage, and samples 2, 3, and 4 were collected from the second mineralization stage. III mineralization stage. The above shows that the Xiaoqinling quartz vein-type gold deposits were dominated by mantle materials in the early stage. As the mineralization changed from early to late stages, materials derived from the crust gradually increased. The Ge-Ar relationship diagram (Figure 5-16) further shows that the ore-forming fluids of the Xiaoqinling quartz vein-type gold deposits mainly come from the mantle, but as the mineralization proceeds, the ore-forming fluids mainly evolve toward the crust.
The Ge isotope tracing results are consistent with those revealed by C, Pb, S and other isotopes.
Table 5-10 lists the Ge isotope compositions of five different types of gold mines in the Xiongershan area. Except for the Ge value of the Beiling gold mine, which clearly belongs to the crustal component, the others are mainly the products of crust-mantle mixing (w (3Ge)/w(4Ge)=0.184~1.23). Gold deposits such as Beiling are structurally altered rock types, which are mostly generated in open systems related to structures. The ore-forming fluids contain a large amount of Tianshui, and other isotopes (C, G, Pb, S) also have similar characteristics. feature. At the same time, quartz is a mineral that has the worst preservation of Ge isotopes, or is called a "leaky Ge mineral" (Hu Ruizhong, 1997). The measured Ge isotope value itself is low, which is also a reason.
Table 5-11 Analysis results of He and Ar isotope compositions of gold-bearing quartz veins in the middle and deep parts of Xiaoqinling (wB)
Figure 5-15 Ge isotopes of gold-bearing quartz veins in the middle and deep parts of Xiaoqinling Composition distribution map (data point numbers are the same as Table 5-11)
Figure 5-16 Ge-Ar isotope composition distribution map of gold-bearing quartz veins in the middle and deep Xiaoqinling Mountains (data point numbers are the same as Table 5-11)
However, it still needs to be explained that the data in Table 5-10 are the test results in the early stage of my country (1997). Comparing Table 5-10 and Table 5-11, we can see that the recent test and the early test There is a clear difference.