Fig. 4

Cross-plot for the stable carbon and oxygen isotope results of Wudaoliang stromatolites. Data of the Miocene Wudaoliang drill core carbonates are quoted from Wu et al. (2009); data of the Miocene-Pliocene Dingqinghu and the Eocene-Oligocene Niubao lacustrine carbonates are from Rowley and Currie (2006); data of the Eocene Fenghuoshan lacustrine carbonates are from Cyr et al. (2005); and, the data on the recent travertine in central Tibetan Plateau are from Niu et al. (2013). The greyish arrow indicates a trend of increasing evaporation from the Eocene to the Miocene in the northern Tibetan Plateau