Zircon LA-ICP-MS U-Pb dating and Lu-Hf isotopic system of Dongjiangkou, Zhashui, and Liyuantang granitoid intrusions, South Qinling belt, central China

The Dongjiangkou, Zhashui, and Liyuantang granitoid intrusions occur near the Shang-Dan fault. Zircon U-Pb dating yielded the following crystallization ages: 246.8 +/- 2.5Ma for the Dongjiangkou granodiorite, 233.6 +/- 1.3Ma for the Zhashui granite, 956.1 +/- 4.5Ma for the Liyuantang quartz monzonite, and 203.6 +/- 2.2Ma for the Liyuantang granite. The accompanied zircon in situ Lu-Hf isotopic analysis gave two-stage Hf model ages (t(DM2)) of 1.4 similar to 1.6Ga, 1.0 similar to 1.3Ga, 1.0 similar to 1.3Ga, and 1.0 similar to 1.3Ga for these granitoids respectively. The closure of the Mian-Lue Ocean at about 250Ma was followed by the collision of the Yangtze Craton and North China Craton resulted in the formation of the Qirding orogenic belt, meanwhile, partial melting of crustal rocks took place during the subduction of the Yangtze plate and South Qinling massif and genrated the Early-Middle Triassic granitoids at 246.8 similar to 233.6Ma. Subsequently, at about 220Ma, the "Yangtze" slab was detached and induced upwelling of the asthenosphere. Widespread partial melting of the subducted continental crust and the upper lithosphere mantle produced adakitic and associated mafic inclusions in Late Triassic (199.0 similar to 224.8Ma).