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The zircon SHRIMP dating of the Zhangtiantang granite gave an age of 159±7 Ma.,which shows that the granite was produced at the early Late Jurassic.The Ar-Ar plateau ages of biotite and K-feldspar from the Zhangtiantang pluton are 153.2±1.1 Ma and 135.8±1.2 Ma,respectively.The Ar-Ar anti-isochrone ages of biotite and K-feldspar are 152.5±1.7Ma and 135.4±2.7Ma,respectively.The ages represent the isotopic closure ages of minerals in the pluton.The Zhangtiantang granites are regarded as peraluminous crust-derived type granites to possess the typical geochemical characteristics of calc-alkaline rocks on continental margin,with enriched Si,K,Al(average value of A/CNK as 1.18),HREE,Rb,U,and Th,heavily depleted V,Cr,Co,Ni,Ti,Nb-Ta,Zr,Sr,P,and Ba,strongly negative Eu and common corundum normative(average value of C as 1.84).The εNd(t) values of the Zhangtiantang granite are-5.84 to-7.79,and t2DM values are 1.69 to 1.83 Ga,which indicates partial melting of continental-crust metamorphic sedimentary rocks during the Middle Proterozoic.The cooling history of the Zhangtiantang granitic pluton indicates that the cooling velocity of pluton was faster(about 67℃ /Ma) from zircon(158 Ma) to biotite(152 Ma),and was slower(about12℃ /Ma) from biotite(152.5 Ma) to K-feldspar(135.8 Ma).It can be deduced that the temporal gap(about 10 Ma) between the granite formmation and W-Sn mineralization in South China may be related to ordinary magma-hydrothermal processes by the variational cooling curve of the pluton.The Zhangtiantang pluton was formed in a compressive setting,with differentiation evolution and mineralization occurring in a relative relaxation setting.
The zircon SHRIMP dating of the Zhangtiantang granite gave an age of 159 ± 7 Ma., Which shows that the granite was produced at the early Late Jurassic. The Ar-Ar plateau ages of biotite and K-feldspar from the Zhangtiantang pluton are 153.2 ± 1.1 Ma and 135.8 ± 1.2 Ma, respectively. The Ar-Ar anti-isochrone ages of biotite and K-feldspar are 152.5 ± 1.7 Ma and 135.4 ± 2.7 Ma respectively. The ages represent the isotopic closure ages of minerals in the pluton. The Zhangtiantang granites are considered as peraluminous crust-derived type granites to possess the typical geochemical characteristics of calc-alkaline rocks on continental margin, with enriched Si, K, Al (average value of A / CNK as 1.18), HREE, Rb, U , and Th, heavily depleted V, Cr, Co, Ni, Ti, Nb-Ta, Zr, Sr, P, and Ba, strongly negative Eu and common corundum normative (average value of C as 1.84) values of the Zhangtiantang granite are-5.84 to-7.79, and t2DM values are 1.69 to 1.83 Ga, which shows partial melting of continental-crust metamorphic s edimentary rocks during the Middle Proterozoic. cooling history of the Zhangtiantang granitic pluton that that the cooling velocity of pluton was faster (about 67 ° C / Ma) from zircon (158 Ma) to biotite (152 Ma), and was slower (about12 ° C / Ma) from biotite (152.5 Ma) to K-feldspar (135.8 Ma) .It can be deduced that the temporal gap (about 10 Ma) between the granite formmation and W-Sn mineralization in South China may be related to ordinary magma- hydrothermal processes by the variational cooling curve of the pluton.The Zhangtiantang pluton was formed in a compressive setting, with differentiation evolution and mineralization occurring in a relative relaxation setting.