Genesis of the Longtougou gold deposit, South Qinling Orogen, China: Constraints from ore geology, trace element, and S–Pb–H–O isotopes

•Three generations of pyrite are distinguished.•Ore-forming materials are derived from the underlying Paleozoic sedimentary rocks and magma.•Fluid mixing and change in redox state may be the mechanism for Au precipitation.•Au mineralization formed in the transition between compression and extension of intracontinental orogeny.