Located　in　the　southwestern　Fujian　Province,　the　Tongkeng　ore　deposit　in　Liancheng　is　a　newly　discovered　molybdenum　deposit.　The　molybdenum　mineralization　occurs　within　the　contact　zone　between　the　granite　porphyry　stock　formed　in　the　first　stage　of　late　Yanshanian　magmatic　event　in　Tongkeng　area　and　late　Paleozoic　metamorphic　rocks.　Ore　bodies　are　charactered　by　vein,　veinlet　and　disseminated.　Re-Os　dating　of　six　molybdenite　samples　collected　from　the　major　ore　body　shows　that　the　isochron　age　is　(115.7±1.1)　Ma　and　the　model　ages　range　from　115.1　Ma　to　116.7　Ma,　with　an　average　value　of　(115.8±0.8)　Ma.　It　can　be　considered　that　both　the　granite-porphyry　and　associated　molybdenum　mineralization　were　formed　in　Early　Cretaceous,　and　that　both　were　derived　by　the　late　Yanshanian　tectonic-magmatic　event　in　the　southwestern　Fujian　depression.　Combined　with　isotopic　age　data　from　other　adjacent　molybdenum　deposits,　it　can　be　inferred　that　the　early　Yanshanian　large-scale　molybdenum　mineralization　in　the　southwestern　Fujian　depression　formed　during　the　transition　stage　from　the　Indosinian　sustained　platform　to　active　continental　margin,　and　accompanied　by　compressing　and　uplifting　in　early　Yanshanian　(about　160-145　Ma);　the　late　Yanshanian　tectonic　conversion　from　compressing　to　tension　(about　125-105　Ma)　resulted　in　the　magmatism　which　seemed　to　be　the　dominant　factor　for　the　late　Yanshanian　molybdenum　deposit.　©,　2015,　Jilin　University　Press.　All　right　reserved.