Provenance analysis of Permian sandstones in the central and southern Da Xing'an Mountains, China: Constraints on the evolution of the eastern segment of the Central Asian Orogenic Belt

Modal, chemical and U-Pb zircon data from Permian sandstones in the central and southern Da Xing'an Mountains (eastern Inner Mongolia, China) constrain, for the first time, plate collision processes between the northern margin of the North China craton and the composite Erguna-Xing'an-Songliao block. The study area is located between the Ondor Sum-Xar Moron and Hegenshan suture zones of the eastern segment of the Central Asian Orogenic Belt. Modal and geochemical analyses of Permian sandstones suggest derivation from dissected continental arc and recycled orogenic sources. LA-ICP-MS U-Pb detrital zircon data from sandstones indicate Early Permian to earliest Triassic maximum depositional ages (278 ± 4 Ma to 249 ± 3 Ma). These data also show two uniform age groups of 270-280 Ma and 310-320 Ma, and we interpret their source to be mainly the Sonidzuoqi-Xilinhot-southern Xi Ujimqin magmatic arc in the north (the southern margin of the Xing'an-Erguna block). The sample from the Upper Permian to lowermost Triassic Linxi Formation in the Linxi area also contains zircons with age groups of ~ 1800 Ma and ~ 2500 Ma, consistent with derivation from the northern margin of the North China craton, which lies to the south. Therefore, the collision between the North China craton and the Xing'an-Erguna block began during the deposition of the Linxi Formation, and the final closure of the intervening oceanic basin occurred during ca. Late Permian-earliest Triassic times, forming the Ondor Sum-Xar Moron suture zone.

► Two Upper Paleozoic magmatic arcs in southeast margin of CAOB are identified. ► Several Paleozoic steps in the closure of the Paleo-Asian ocean are recognized. ► Age groups of ~ 1800 and ~ 2500 Ma indicate an origin from the North China Craton. ► The final formation of the CAOB occurred in Late Permian to earliest Triassic.