SEDIMENTARY CHARACTERISTICS OF THE TILLITE IN YINTUN AND YONGNING FORMATIONS, NANHUA SYSTEM, IN LIAONING PROVINCE
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摘要: 通过对辽宁地区出露的新元古代殷屯组、永宁组调查研究取得了新认识，认为辽宁地区存在南华纪地层，以新元古代殷屯组、永宁组为代表，可划分出二次冰川活动（二个冰期和一次间冰期）的沉积，自下而上为殷屯冰期（第一次冰期）、八家子间冰期、河冰期（第二次冰期）.依据殷屯组和永宁组冰碛物组合特点及接触关系，并结合碎屑锆石U-Pb（LA-ICP-MS）同位素测年成果，推测辽宁南华系殷屯组、永宁组形成时代应小于1000 Ma，与南方南华纪形成的时间基本接近或略早（约850 Ma）.Abstract: 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).
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Key words:
- Nanhua System /
- Yintun Formation /
- Yongning Formation /
- tillite /
- glacial period /
- zircon LA-ICP-MS U-Pb age /
- Liaoning Province
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