A Permian intermediate-sulfidation epithermal Pb–Zn–Ag deposit in the northern margin of North China Craton

Abstract

Recent Pb–Zn–Ag exploration in the northern margin of North China Craton has made significant new discoveries. Here we report one Pb–Zn–Ag deposit in the Shaolanghe orefield with typical signatures of intermediate-sulfidation epithermal deposits. Zhangjiagou Pb–Zn–Ag mineralization occurs within the Early Permian quartz diorite and Late Permian andesite. Three mineralization stages were identified: white quartz–rhodochrosite–sulfide Pb–Zn–mineralization stage (I), smoky quartz–sulfide Pb–Zn–Ag–mineralization stage (II), and calcite–quartz non–mineralization stage (III). Four sphalerite samples yield the Rb–Sr age of 265.3 Ma, indicating that Pb–Zn–Ag mineralization was associated with the Late Permian andesite. The liquid-rich fluid inclusions of Stage I show low–medium temperatures of 190–270 °C and low salinities (1–3 wt%), and those of Stage III are slightly lower (190–250 °C, 0.5–2 wt%), suggesting a low-salinity, low-temperature H2O–NaCl fluid system for the Zhangjiagou deposit. The H–O–C isotopic signatures indicate a mixed fluid of magmatic water with meteoric water. S and Pb isotopes suggest magmatic source for Zhangjiagou Pb–Zn–Ag mineralization, most likely shallow hydrous intermediate magma. Collectively, these geological, geochronological, and geochemical features indicate that Zhangjiagou is an intermediate-sulfidation epithermal Pb–Zn–Ag deposit.