【正】1 Introduction Laozhaiwan gold deposit,a part of"Golden Triangle"in Yunnan-Guizhou-Guangxi,was located in Jiumo village in Guangnan county,Yunnan province.The main ore-bearing stratum of the deposit was Posongchong Formation(D1 ps)of the lower Devonian.The structure was well-developed in this area,the ore bodies produced which mainly controlled by the faults.There was a diabasic dike in the northwest of this area,where the grade of the ore bodies was higher.2 S isotope geochemistry The composition ofδ34S in pyrites was 5.644‰~