Abstract:Recently, many medium - and large-scale fluorite deposits were identified in Zhejiang Province. However, the research on metallogenic rock mass is still relatively weak. In this paper, we report new zircon U–Pb geochronologic and whole-rock major and trace element data, for the Xiaoxuwu and Wufangli granites of the Tongli area of Northwest Zhejiang. The zircon U–Pb dating yielded magmatic crystallization ages of 145-140 and 135 Ma for Xiaoxuwu monzogranites and Wufangli fine-grained monzogranites, respectively. These new age data indicate that the Tongli plutons emplacement in the early Early Cretaceous, coeval with the regional late Mesozoic magmatism. Geochemically, the samples can be divided into two groups of calc-alkaline I-type and highly fractionated I-type granites. Our research indicated that the Xiaoxuwu I-type granites were derived by partial melting of metaigneous lower-crustal source while the Wufangli highly fractionated I-type granites underwent extensive fractional crystallization in the shallow magma chamber. Combined with the oceanward migration of late Mesozoic magmatic activity, we believe the slab rollback during oceanic subduction of paleo-Pacific was a reasonable explanation for the magmatism in Tongli area.