Abstract:

 High precision 230Thdating of the tufas deposited on different terraces of Mian River at Niangziguan shows that the ages of the oldest tufas on the terrace II are between ~406 ka and ~466 ka, which are much higher than those dated by the thermoluminescence method earlier, indicating that the tufas on the terrace II deposited during the Marine Isotope Stage (MIS) 12/11 of the middle Pleistocene but not in the late Pleistocene as suggested in early studiesIt was inferred that the tufas on the terrace III of Mian River deposited earlier, possibly during the MIS 14/13 of the middle PleistoceneThe 230Thdating of the top tufa on the terrace I shows that the tufa deposited 5 ka ago, i.e., before the middle HoloceneCombined dimensions of tufa deposits with their carbon and oxygen isotopic compositions (δ13C, δ18O), it shows that all the tufas on the terraces of Mian River were formed mainly under hot and humid climateHowever, from the time when the tufa on the terrace II was formed till now, the tendency of climate change was towards drier and colder, and the vegetation in Nangziguan spring watershed degraded gradually

Key words: tufa; 230Thdating; carbon and oxygen stable isotopes; climatic and environmental change; Marine Isotope Stage 11; Holocene; Niangziguan Spring Watershed