LA-ICP-MS zircon U-Pb ages and geological sig-nificance of granodiorite from Zongwulong tectonic belt in Delingha, Qinghai Province

Based on a study of zircon U-Pb dating and rock geochemical analysis of granodiorite from Zongwulong tectonic belt in Shidiquan area of Delingha, the authors revealed that the granodiorite has the characteristics of island arc or active continental margin granite. The original rock may be salic crust or the product of crustal melting formed in Early Neoproterozoic (870.0±4.5Ma). The granodiorite samples yielded ages of 870.0±4.5Ma and 443.3±2.3Ma respectively. The age of 870.0±4.5Ma represents provenance in-herited zircon age, which reflects the tectonic magmatic event during the Neoproterozoic, whereas the other age of 443.3±2.3Ma in-dicates the time of zircon crystallization of the granodiorite, which shows that the emplacement occurred in the Late Ordovician. Comprehensive analyses suggest that the granodiorite in the Zongwulong tectonic belt was related to plate convergent collisional orogeny of the Caledonian period on the northern margin of the Qaidam Basin, confirming that the formation of the rock in the Zongwulong tectonic belt did not wholly occurred in Hercynian-Indosinian period.