The genesis of the Jianzhupo Pb-Zn-Sb polymetallic deposit in northwestern Guangxi: Evidence from the characteristics of trace elements, rare earth elements, and hydrogen and oxygen isotopes of sphalerite

The Danchi metallogenic belt, located in the northeast of the Youjiang basin, is an important non-ferrous metal ore concentration area in southern China, and the Jianzhupo deposit, the largest and most representative large-scale Pb-Zn-Sb polymetallic deposit in the Wuxu ore field in the southern section of the deposit, consisting of vein Pb-Zn-Sb orebody and newly discovered stratified Sn polymetallic orebody. In this paper, through the analysis of trace elements, rare earth elements, and H-O isotopes of sphalerite, the differences in metallogenic characteristics of the two types of ore bodies are compared and studied, and the source of ore-forming fluids and the genesis of deposits are further discussed. The results show that sphalerite in different types of ore bodies in the Jianzhupo deposit is relatively enriched in Fe, Cu, Pb, Sn and Sb, and depleted in Ga, Ge, Co and Ni, which is similar to typical magmatic hydrothermal deposits. Meanwhile, the total amount of rare earth in the stratified ore body (ΣREE=12.80×10⁻⁶~44.31×10⁻⁶) is higher than that in the vein ore body (ΣREE=3.34×10⁻⁶), with obvious LREE and HREE fractionation and Eu depletion. The results of H-O isotope analysis of sphalerite show that δD=−81.8‰~−69.2‰, δ¹⁸O=2.1‰~5.2‰ (vein orebody); δD=−109.4‰~−75.2‰, δ¹⁸O=−4.0‰~4.0‰ (stratified orebody), indicating that the ore-forming fluids of the two types of ore bodies are mixed fluids with different proportions of magmatic hydrothermal and atmospheric precipitation. The above characteristics show that the Jianzhupo deposit belongs to magmatic hydrothermal Pb-Zn deposit, and the ore-forming materials (fluids) of vein ore bodies and stratified ore bodies are mainly derived from magmatic hydrothermal fluid.