Fozi　Mountain　National　Geopark　is　located　in　Zhenghe　County　in　the　northern　region　of　Fujian　Province,　where　the　volcanic　rocks　of　the　Zhaixia　Formation　of　the　Shimaoshan　Group　are　exposed.　Zircon　U-Pb　dating　and　geochemical　analysis　were　carried　out　to　constrain　its　age　and　tectonic　environment.　The　results　show　that　three　zircon　U-Pb　dating　samples　have　attained　ages　of　99.2　±　1.0　Ma,　99.6　±　0.8　Ma,　and　99.7　±　2.0　Ma.　Volcanic　rocks　in　the　core　scenic　area　of　Fozi　Mountain　were　formed　during　the　Late　Cretaceous　period.　Elemental　analysis　showed　that　these　volcanic　rocks　were　dominated　by　the　shoshonite　series.　They　include　gray　dacite　porphyry,　grayish-white　breccia　tuff,　volcanic　agglomerate,　and　gray　tuffaceous　sandstone.　These　rocks　were　characterized　by　high　silicon,　high　alkali　content,　and　rich　potassium　levels.　Lu-Hf　isotope　analysis　of　zircons　revealed　that　their　εHf(t)　values　varied　from　−8.7　to　−6.8.　The　corresponding　TDM2　values　were　primarily　distributed　in　the　range　of　1.71　Ga　to　1.59　Ga.　These　findings　indicated　that　the　magma　primarily　originated　from　the　partial　melting　of　the　Mesoproterozoic　crystalline　basement,　accompanied　by　a　small　number　of　mantle-derived　materials.　Tectonic　environment　analysis　indicated　that　these　rocks　were　formed　in　the　post-orogenic　intraplate　extensional　environment,　which　was　associated　with　the　back-arc　extension　or　lithospheric　thinning　caused　by　the　subduction　of　the　paleo-Pacific　plate　beneath　the　Eurasian　plate.　The　formation　of　these　volcanic　rocks　was　attributed　to　post-orogenic　magmatism.　©　2024　by　the　authors.