REE Geochemical Features of Ore-hosted Volcanic Rocksin the Nibao Gold Deposit, Southwest Guizhou, China

Basaltic andesite, as the highest gold content ore-hosted rock in the Nibao gold deposit, has highest gold grade of 32.5×10^-6, and total rare earth elements (ΣREE) contents ranging from 176.78×10^-6 to 431.98×10^-6 with an average in 237.4×10^-6. Their LREE/HREE ratios are 5.36~10.19, forming a figure gentle-dipped on the right side, according with the REE partition model of the intermediate-basic magma rock. The samples of highest ΣREE content are situated at the top of volcanic cycle, containing the highest gold grade ore. Furthermore, there is a roughly positive correlation between the gold grade of orebody and the thickness of basaltic andesite. According to the regulation of assimilation and contamination of upwelling magma, the medium-basic volcanic rocks were developed from basic rocks as the temporal order, while gold and REE were enriched gradually, which represent the residual magma enrichment and metallogenesis features of volcanic cycle. Therefore, the Nibao gold deposit is related to the residual magma eruption of Emeishan basalt, which is the large scale gold deposit related to the volcanism in Yunnan-Guizhou-Guangxi gold metallogenic province.