Isotopes and Geochronology of the Meixian-type Pb-Zn-(Ag)Deposits,Central Fujian Rift,South China:Implications for Geological Events

Central Fujian Rift is another new and important volcanogenic massive sulfide Pb‐Zn polymetallic metallogenetic belt. In order to find out the material genesis and mineralization period of Meixian‐type Pb‐Zn‐Ag deposits, S and Pb isotope analysis and isotope geochronology of ores and wall rocks for five major deposits are discussed. It is concluded that the composition of sulfur isotope from sulfide ore vary slightly in different deposits and the mean value is close to zero with the δ³⁴S ranging from ?3.5%‰ to +5.6%‰ averaging at +2.0‰, which indicates that the sulfur might originate from magma or possibly erupted directly from volcano or was leached from ore‐hosted volcanic rock. The lead from ores in most deposits displays radioactive genesis character (²⁰⁶Pb/²⁰⁴Pb>18.140, ²⁰⁷Pb/²⁰⁴Pb>15.584, ²⁰⁸Pb/²⁰⁴Pb>38.569) and lead isotope values of ores are higher than those of wall rocks, which indicates that the lead was likely leached from the ore‐hosted volcanic rocks. Based on isotope data, two significant Pb‐Zn metallogenesis are delineated, which are Mid‐ and Late‐Proterozoic sedimentary exhalative metallogenesis (The single zircon U‐Pb, Sm‐Nd isochronal and Ar‐Ar dating ages of ore‐hosted wall rocks are calculated to be among 933–1788 Ma.) and Yanshanian magmatic hydrothermal superimposed and alternated metallogenesis (intrusive SHRIMP zircon U‐Pb and Rb‐Sr isochronal ages between 127–154 Ma).