Zircon U-Pb dating and Lu-Hf isotope analysis of metamorphic intrusive rocks in the Jiapigou area of southern Jilin Province and their tectonic implications.

The Jiapigou metamorphic terrane is an important part of the Archean basement in the northeast of the North China Craton, whose tectonic evolution from Neoarchean to Paleoproterozoic remains controversy for a long time. Based on detailed field geological investigation, three representative metamorphic intrusive rocks involving charnockite, metagabbro and metabasic dyke in the Jiapigou area were studied on zircon REE, zircon U-Pb chronology and zircon Lu-Hf isotope geochemistry. The results suggest that the emplacement age of charnockite was determined as 2504 +/- 8Ma with metamorphic age of 2476 +/- 13 Ma. Its zircon (1) values are 1.72-5.1 with HI model ages of 2.822.66Ga, indicating that the rock derived from partial melting of juvenile crust. The emplacement age of meta-gabbro (amphibolite) was determined as 2529 +/- 14Ma with a metamorphic age of 2484 +/- 23 Ma. The meta- basic dyke (garnet amphibolite) has an emplacement age of 2195 +/- 15Ma and a metamorphic age of 1930 +/- 14Ma. The magmatic zircons from the meta-basic dyke show abnormally high (1) values (7-15) and significant depletion of heavy REE, indicating that the parent magma was originated from the garnet-bearing lithospheric mantle. Combining other geological information, it can be concluded that the tectonic thermal event during the Late Neoarchean (2.50-2.48Ga) in the southern Jilin region was dominated by large-scale mantle plume. The middle to late Paleoproterozoic (2.2-1.84Ga) tectonic thermal event was related to collisional orogeny occurred in the edge of the craton.