Fluid evolution of the Qiman Tagh W-Sn ore belt, East Kunlun Orogen, NW China

•The Qiman Tagh W-Sn ore belt in East Kunlun, China was formed during 430–412 Ma.•W-Sn Mineralization presents as greisen, skarn and quartz vein related to granites.•Quartz and cassiterite have CO2-rich and aqueous FIs, wolframite only has aqueous.•Fluids originated from syncollisional grantite, evolved from CO2-rich to CO2-poor.•Fluid immiscibility, mixing and cooling facilitated deposition of ore metals.