The Laowan deposit is a large gold deposit in the Qinling-Dabie orogenic belt where pyrite is the main Au-bearing mineral phase.We present results from the occurrences of gold,trace elements and sulfur isotopes of pyrite,and hydrogen and oxygen isotopes of quartz and calcite to elucidate the sources of ore-forming fluid;the genesis of pyrite and the ore-forming process.rnFrom field observations,five generations of pyrite are identified;one formed in a metamorphic-diagenetic epoch(PyⅠ),and the others during four mineralization stages:1)the coarse-grained pyrite-quartz stage(PyⅡ),2)the quartz and medium-to fine-grained pyrite stage(PyⅠ),3)the polymetallic sulfide stage(PyⅣ),and 4)the carbonate-quartz stage(PyⅤ).Gold mainly occurs in PyⅢ and PyⅣ.We find that Au,Ag,Pb,and Cu are incorporated into pyrite as micro-/nano-inclusions and that Co,Ni,As,and Se enter the pyrite lattice via isomorphous replacement.rnThe Co/Ni values and Se concentrations indicate that Pyl formed from metamorphic hydrothermal fluids and that pyrites(PyⅡ,PyⅢII,and PyⅣ)from the ore-forming stages typically reflect a hydrothermal genesis involving magmatic fluid.rnThe δ34S values of PyⅠ(1.45 ‰-2.09‰)are similar to that of plagioclase amphibole schist,indicating that S was primarily derived from wall rock,while those of PyⅡ,PyⅢ,and PyIV(3.10‰-5.55‰)suggest that S was derived from the Guishanyan Formation and the Laowan granite.The four mineralization stages show a systematic decrease in 8D(from-77.1‰ to-82.8‰,-84.7‰,and-102.7‰),while the δ18OH2O values showed a gradual decrease from 5.7 to 2.7‰,1.0‰,and-1.3‰.These data show that the ore-forming fluid was similar to a mixture of magmatic and meteoric waters.Thus,we conclude that the Laowan gold deposit is related to magmatic-hydrothermal fluid.