SEDIMENTARY CHARACTERISTICS OF THE TILLITE IN YINTUN AND YONGNING FORMATIONS, NANHUA SYSTEM, IN LIAONING PROVINCE

The term of Nanhua System was officially issued in the China Stratigraphic Chart in Guide of China Stratigraphy and Manual (revised edition) published in 2001. The stratotype section of Nanhua system was established mainly in Guizhou, Hunan and Hubei in south China. Whether Nanhua strata exist in north China, is a controversial issue for many researchers with different division schemes. Through research on Neoproterozoic Yintun and Yongning formations outcropped in Liaoning region, the authors obtain the new idea that Nanhua strata do exist in Liaoning. Represented by Neoproterozoic Yintun Formation and Yongning Formation, the sedimentation of two glacial movements (including two glacial periods and one interglacial period) can be recognized. Based on the assemblage features and contact relation of the till in Yintun and Yongning formations, combined with the detrital zircon U-Pb(LA-ICP-Ms) isotopic age data, the forming ages of Yintun and Yongning formations of Nanhua System in Liaoning are supposed to be less than 1000 Ma, which is almost at the same time or slightly earlier than the Nanhua System in south China(~850 Ma).