1503_651674.pdf — page 18

Chen et al.: Metallogenic setting and material source of Caihong copper-lead-zinc polymetallic deposit 
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APPLIED ECOLOGY AND ENVIRONMENTAL RESEARCH 15(3): 651-674. 
http://www.aloki.hu ● ISSN 1589 1623 (Print) ● ISSN 1785 0037 (Online) 
DOI: http://dx.doi.org/10.15666/aeer/1503_651674 
 2017, ALÖKI Kft., Budapest, Hungary 
hydrothermal solution. Obviously, single seawater source is difficult to have above 
characteristics, and it is believed that meteoric water could not participate in 
mineralization directly in the condition that mineralized field was buried deeply under 
the seawater, and kept away from terrestrial sources (Ohmoto, 1996). Therefore, it was 
thought that the mixture of magmatic water and corresponding period seawater was the 
fluid source mechanism in early stage. Accordingly, veined quartz sample points fell on 
the bottom left of primary magmatic water, which indicated that magmatic water should 
be one of the main fluid sources, While smaller δDSMOW value shows that fluid may 
include late atmospheric precipitation (Xiang et al., 2012).Veined mineralization in the 
late stage was formed into hydrothermal solution activity after magma period. 
Atmospheric precipitation cycled in the building with ore, and mixed with rising magma 
hydrothermal solution, which were the possible fluid source mechanism. 
 
Ore rare earth element evidence 
Because the difference of REE3+ ion radius and Fe2+, Cu2+, Zn2+ radius is large. 
Replacing cations in sphalerite or pyrite mineral lattice is difficult (1991). REE in the 
sulfide mainly exists in the fluid inclusion or lattice imperfection of minerals, thus REE 
composition characteristics of sulfide can directly reflect REE composition 
characteristics in the ore-forming fluid (Huston et al., 1995; Haas et al., 1995). Figure 
11b shows that ∑REE of veined sulfide is relative high, and has negative Eu anomaly, 
while ∑REE of lamellar sulfide is small, and the majority samples of lamellar sulfide 
have positive Eu anomaly (excepting for galena samples). Research shows that two 
causes may be attributed to the Eu anomaly generated by Ore. On one hand, rich Eu is 
inherited from ore-forming fluid when the ore is precipitated; on the other hand, Eu2+ is 
carried out by the subsequent effect of fluid after the ore is formed, because Eu 2+ with 
larger ion radius and smaller charge number are more easy to be carried out by the fluid 
compared with the other trivalent REE ion (Ding et al., 2003). Therefore, the positive 
Eu anomaly in the lamellar ore is not resulted from the effect of later geological 
processes. Research shows that the significant Eu positive anomaly and the relative 
enrichment of LREE are an important symbol for the composition of rare earth element 
in the submarine hydrothermal fluid (Bhatia, 1991; Haas et al., 1995; Klinkhammer and 
Edmond, 1994). From the observation and research of the modern submarine 
hydrothermal systems conducted by Mills and Elderfiel (1995), it is shown that sulfide 
generated in hydrothermal solution are similar with composition of hydrothermal fluid. 
The characteristics of REE of lamellar sulfide ore in mining area are similar with those 
in the submarine hydrothermal fluid, but with lower Eu positive value (1.25-2.50). So, 
we believe that the ore forming fluid of early satge of Caihong deposite include 
submarine hydrothermal fluid, while magmatic fluid component is mixed, because 
magmatic fluid will cause δEu value decreased in ore forming fluid (Ding et al., 2003). 
Furthermore, the galena sample in the lamellar sulfide has negative Eu anomaly. 
Generally, as the temperature decreases and oxygen fugacity changes, the weak Eu 
positive anomaly, no abnormalities or Eu negative anomaly may appear in the mineral 
when Eu2+ and Eu3+ accounts for a considerable proportion in the solution (Song, 2011). 
The weak negative Eu anomaly in the galena may indicated that it is formed in the late 
period of volcanic eruption, which conforms to fact that the generation of galena in 
polished sections of ores is posterior to other sulfide. 
On the other hand, the LREE in late veined ore sulfide is relatively rich, and has the 
moderate Eu negative anomaly. The characteristics of REE are similar with Zhong bao