Zircon U-Pb age, Hf isotopic compositions of Dapuchaihe adakites in eastern Jilin Province and their significance

Based on geochemical evidence, the quartz diorites from Dapuchai, eastern Jilin Province, belong to typical adakites derived from partial melting of thickened lower crust. Zircon U-Pb dating by LA-ICPMS technique indicates that the studied plutons were emplaced during Late Jurassic with an age of 164. 9 +/- 0. 8Ma. Zircon Hf analyses conducted by LA-MC-ICPMS show that these adakites have variational epsilon(Hf)(165Ma) values from -5.02 to 5.43, and Hf model ages from 965Ma to 1622Ma, indicating that the primary magma of the adakites originated from mixing of two different magma, one from partial melting of pre-existing crustal source that was separated from a depleted mantle source during the Middle Proterozoic; While the other magma from asthenospheric mantle through underplating during 985 similar to 1304Ma, indicative of an important crustal growth beneath the studied area.