The magmatic origin of propylitic alteration of the Zhengguang epithermal Au-Zn deposit, Heilongjiang, China: evidence from mineral compositions and H–O-Sr isotopes

The origin of propylitic fluids in intermediate sulfidation mineralization has not been investigated in detail. Here, we present an extensive petrographic, geochemical, and isotopic (O-H-Sr) study of propylitic epidote, chlorite, and calcite from the Zhengguang intermediate sulfidation epithermal Au-Zn deposit, NE China. Propylitic minerals can be divided into three main types based on their different textural occurrences, namely interstitial cement of clasts of hydrothermal breccia, replacement of primary plagioclase or hornblende, and vein infill of cracks, with late, minor calcite as amygdules in vesicles of andesite representing a fourth textural occurrence. The H-O isotope compositions and mass balance calculations suggest that most propylitic epidote records a dominant (> 50