The Altay Formation mainly consists of meta-clastic sediments, with minor meta-volcanic rocks, which widely distributed in the Chonghu’er, Kelan and Maizi Basins of South Altay, and can provide important constraints on the tectonic evolution of the Altay orogenic belt（AOB）. The current geochronological study for the detrital zircons of the Altay Formation shows that the ages of them are mainly concentrated in 417～383 Ma and 507～445 Ma, and only rarely are Proterozoic and Archean. Meanwhile, a few zircon ages range from 380～354 Ma, which are consistent with the ages of the Altay Formation tuff and rhyolite（376～354 Ma）. Comprehensive research suggests that the Altay Formation was formed during the Middle-Late Devonian（382～354 Ma）. The feldspar quartz sandstone of the Altay Formation is a near-source sediment with less sorted and poor rounded. The sources of the sandstone are mainly from the Devonian volcanic rocks, followed by the Late Cambrian-Early Ordovician volcanic rocks and Ordovician granites. The feldspar quartz sandstone samples have high La/Sc（3.9～6.3）, La/Y（1.0～1.6）, and low Sc/Cr（0.2～0.4）ratios, which are similar to clastic rocks deposited in continental arc settings. Combined with Th-Co-Zr/10, Th-Sc-Zr/10 and La-Th-Sc discriminate diagrams, it is believed that the Altay Formation was formed in a tectonic setting associated with the island arc（the back-arc basin）, which provides important evidence for studying the Devonian tectonic evolution of the AOB.
Li Yan Geng Xinxia Li Qiang Zhang Zhixin Wang Xu Yang Junjie. Constraining the deposition time and sedimentary environments of the Altay Formation in Altay, Xinjiang[J]. Chinese Journal of Geology, 2019, 54(1): 34-61.