ISOTOPIC COMPOSITION OF XIAZHANGZI GOLD DEPOSIT AND ITS GEOLOGICAL IMPLICATION

The oxygen and hudrogen isotopic compositions of inclusion water in Xiazhangzi gold deposit are respectively δD=-91.7‰——73.l/‰ and δ¹⁸O_H2o=5.6‰-6.23‰.The mineralizing fluids of the deposit come from magmatic and meteoric water With a narrow range of change, the S-isotopic compositions are nearly all minus and the average equilibrium temperature varies from 208℃ to 240℃; the average isotopic composition of total sulphur in the mineralizing fluids ranges from -19.70‰ to -20.64‰, indicating that atom group H₂S prevailed in the fluids and the sulphur derived from the crystal basement in this area. The Rb-Sr isotopic isochron value (105±7.2Ma) of quartz fluid inchusions implies a late Yanshanian mineralization. This deposit is of epi-mesothermal vein type related with magmatic hydrothermal solution.