LA-ICPMS Zircon U-Pb Dating for Three Indosinian Granitic Plutons from Central Hunan and Western Guangdong Provinces and Its Petrogenetic Implications

The LA-ICPMS zircon U-Pb geochronology of three typically Indosinian granitic plutons yielded weighted mean 206Pb/238U ages of 214.1±5.9 Ma and 210.3±4.7 Ma for the biotite monzonitic granites from the Xiema and Xiangzikou plutons in Hunan Province,and 205.3±1.6 Ma for biotite granite from the Napeng pluton,western Guandong Province,respectively,showing a similar late Indosinian age of crystallization.In combination with other geochronological data from Indosinian granites within the South China Block(SCB),it is proposed that those late Indosinian granites with an age of ~210 Ma and the early Indosinian granites(230-245 Ma)have the similar petrogenesis in identical tectonic setting.The Indosinian granites within the SCB might be the products of anatexis of the thickening crust in a compressive regime.These data provide a further understanding for the temporal and spatial distribution of the Indosinian granites and the dynamic evolution of the SCB.