LIU Jia-wei1, LI Sheng-rong1,2*, YUAN Mao-wen1, LI Shi-sheng1, ZHI Ze-ya1, WEN Zi-hao1
(1. School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China;
2. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing10083, China)
Abstract: Formation ages of the Huashan and Wenyu granitoid plutons are similar to those of gold deposits in the Xiaoqinling gold district. It is known that most gold deposits are clustered around the Wenyu pluton. To compare similarities and differences of magmatic properties of the Huashan and Wenyu two plutons will be helpful to judge their influences on the gold mineralization. In this paper, the oxygen fugacity of magma has been constrained using valence states of manganese ions in apatites and titanium contents in zircons of the two plutons. The calculation results show that magmatic oxygen fugacities of the Huashan pluton change from -9.3 and -5.1, while those of the Wenyu pluton range from -8.5 and -6.1. They are all plotted above the HM Buffer line in a field of high oxygen fugacity. It is believed that Au prefers to migrate in oxidized states of Au+ or Au3+ and precipitate in reduced state of native gold. Therefore, the magma of the Huashan and Wenyu granitic plutons had no chance to form a geochemical barrier to precipitate gold but is favorable to let gold migrate to favorable structural spaces in the periphery.
Keywords: Magmatic oxygen fugacity; granitic pluton; apatite; zircon; Xiaoqinling gold district
ACTA MINERALOGICA SINICA Vol. 39, No.5, 2019, page 494-506
