Sulphur and metal sources of polymetallic vein-type, sedimentary exhalative-type and Mississippi Valley-type Zn–Pb deposits along the southeast margin of the Yangtze Block

Abstract

Three types of zinc-lead deposits, including polymetallic vein-type, sedimentary-exhalative (SEDEX), and Mississippi valley-type (MVT) Zn–Pb deposits, have been discovered along the southeast margin of the Yangtze Block. A systematically comparative study on the sulphur and metal sources for these deposits, is absent, which significantly limits the understanding of the metallogenic model and geological exploration. Thus, in order to reveal the S and Pb sources of Pb–Zn deposits, an investigation of trace elements of sphalerite and of S–Pb isotopic compositions of sulphides in these three types of Zn–Pb deposits was conducted in this study. We found that, in the vein-type, SEDEX, and MVT Zn–Pb deposits, (1) the sulphur was derived respectively from granitic magmatism related to the Guangxi Orogeny, early Cambrian stratified seawater and connate water; (2) the lead isotope variation indicates that the ore-forming metals were mainly derived from the granitic hydrothermal fluids for vein-type deposits, from basement rocks for SEDEX deposits, and mainly from early Cambrian sedimentary rocks for MVT mineralization. The Nanhua rifting lead to the syngenetic Zn-Pb mineralization, while the Guangxi Orogeny resulted in magmatic-hydrothermal vein mineralization at depth and in MVT mineralization at the shallow crustal levels.