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THE tillites in the Nantuo Formation of the Sinian System is considered contemporary with theVaranger ice age. The manganese deposits in the Nantuo Formation are most suitable to iso-topic dating and may record the precious information on paleo-ocean chemistry. However,there have heen different views and disputations about their origin and age for a long time. The Sinian System in the Yangtze region is divided into 3 formations from base to top:the Nantuo Formation, the Doushantuo Formation and the Dengying Formation. The Nantuo
THE tillites in the Nantuo Formation of the Sinian System is contemporary with theVaranger ice age. The manganese deposits in the Nantuo Formation are most suitable to iso-topic dating and may record the precious information on paleo-ocean chemistry. However, there have heen different views and disputations about their origin and age for a long time. The Sinian System in the Yangtze region is divided into 3 formations from base to top: the Nantuo Formation, the Doushantuo Formation and the Dengying Formation. The Nantuo