He-Ar isotopes were measured from fluid inclusions in six samples of the Dajiangping pyrite orebody III and orebody IV., The
He values range from 0.13 to 2.55Ra, and the
Ar values range from 348 to 443. These data indicate that mantle-derived fluids contributed to the ore-forming fluids. This study suggests that the hot fluids from the deep mantle intruded into the ore body along a thrust fault, and hydrothermed the orebody. This caused differentiation of the orebody resulting in the formation of the banded orebody III and the massive orebody IV. Pb isotopes from the ore and wall rocks were also measured in this study.
Pb values range from 18.075 to 18.292,
Pb values range from 16.654 to 15.737, and
Pb values range from 38.401 to 38.781. These ratios indicate that orebody III is very similar to the wall rock, whereas orebody IV has lower Pb/Pb ratios than wall rock. The data support the interpretation that mantle fluid intruded into the entrapping Pre-Sinian basement migmatite, causing lower Pb isotope ratios in orebody IV.