The Jinman Cu polymetallic deposit is located within Middle Jurassic sandstone and slate units in the Lanping Basin of southwestern China. The Cu mineralization occurs mainly as sulfide-bearing quartz-carbonate veins in faults and fractures, controlled by a Cenozoic thrust-nappe system. A detailed study of fluid inclusions from the Jinman deposit distinguishes three types of fluid inclusions in syn-ore quartz and post-ore calcite: aqueous water (type A), CO2-H2O (type B), and CO2-dominated (type C) fluid inclusions.

The homogenization temperatures of CO2-H2O inclusions vary from 208 degrees C to 329 degrees C, with corresponding salinities from 0.6 to 4.6 wt.% NaCl equivalent. The homogenization temperatures of the aqueous fluid inclusions mainly range from 164 degrees C to 249 degrees C, with salinities from 7.2 to 20.2 wt.% NaCl equivalent. These characteristics of fluid inclusions are significantly different from those of basinal mineralization systems, but similar to those of orogenic or magmatic mineralization systems. The H and O isotope compositions suggest that the oreforming fluid is predominantly derived from magmatic water, with the participation of basinal brine. The delta S-34 values are widely variable between -9.7 parts per thousand and 9.7 parts per thousand, with a mode distribution around zero, which may be interpreted by the variation in physico-chemical conditions or by compositional variation of the sources. The mixing of a deeply sourced CO2-rich fluid with basinal brine was the key mechanism responsible for the mineralization of the Jinman deposit.