Evolution of Paleozoic West Junggar Basin, NW China: Seismic data, detrital zircon evidence from Earth's oldest alkali lake deposit

The Permian Fengcheng Formation of the Western Junggar region in the Southwestern Central AsianOrogenic Belt (CAOB) represents one of Earth's oldest alkali lake deposits. Here, we present a comprehen-sive study of the stratigraphy, petrography, two-dimensional seismic data, U-Pb geochronology, and Hfisotope analysis of detrital zircons of this deposit. The results, in conjunction with published data, reflectthe tectonic evolution of southwestern CAOB. The ages of detrital zircons indicate that the FengchengFormation deposition is inferred to have concluded the early Permian Kungurian. The Hf isotopes of detri-tal zircons indicate that the detritus for the Fengcheng Formation was derived from upper crustal mag-matic sources. The West Junggar Basin preserves the records of three Paleozoic tectonic stages. The firststage occurred in the Early Paleozoic and involved intraoceanic subduction and arc-continent collision.The second stage involved the Carboniferous closure of the Junggar Ocean following successive fillingof oceanic basins. The final stage occurred in the Early Permian and was related to intracontinental riftingand tectonic inversion. The results of comparing the comprehensive data of U-Pb ages and Hf isotopes of2537 zircons from West Junggar, Tianshan and Altay show that the orogenic belts to the south of theCAOB experienced similar plate kinematics and vertical crustal growth in the Paleozoic. (c) 2024 China University of Geosciences (Beijing) and Peking University. Published by Elsevier B.V. onbehalf of China University of Geosciences (Beijing). This is an open access article under the CC BY-NC-NDlicense (http://creativecommons.org/licenses/by-nc-nd/4.0/).