Eastward termination of the Solonker–Xar Moron River Suture determined by detrital zircon U–Pb isotopic dating and Permian floristics

Abstract

The Permian Solonker–Xar Moron River Suture in South Mongolia and Inner Mongolia of China represents a major tectonic boundary in Asia. The position of its eastward continuation in northeastern China has been debated for many years. In order to resolve this debate, we measured detrital zircons of the Cisuralian (Early Permian) plant fossil-bearing Hesheng Formation in the Yanbian area, Jilin Province. The detrital zircons have ages of ca. 2541–2535Ma, 1897–1832Ma, 458–452Ma, and 390–280Ma. We therefore conclude that the depositional age of the Hesheng Formation is younger than ca. 280Ma; this is consistent with paleontologic data that indicates an Artinskian–Early Kungurian age. The presence of Neoarchean and Paleoproterozoic zircons suggests that the Hesheng Formation may have a North-China affinity; the absence of Neoproterozoic and Pan-African zircons preclude detrital sources from the Jiamusi–Mongolia Block during the Cisuralian. This, combined with the Permian floristic and stratigraphic data, provides a clue that the Solonker–Xar Moron River Suture likely extends to the Wangqing–Hunchun region, in eastern Jilin Province.