Uplift events of the Qinghai–Tibetan Plateau and environmental evolution of the southwest monsoon since 2.7 Ma, recorded in a long lake sediment core from Heqing, China

The tectonic-sedimentary cycles and environmental evolution in the southwest monsoon area since 2.7 Ma were reconstructed, based on the analysis of lithology, grain size, carbonate content, loss-on-ignition (LOI) and pollen in a 737.72 m sediment core from Heqing Basin, China. The results indicated that the lake basin was formed in about 2.7 Ma. Continuous lacustrine sediment was preserved since 2.7 Ma. Three stages of tectonic-sedimentary cycle were revealed: 2.7–1.5 Ma, 1.5–0.9 Ma and 0.9–0 Ma. The environmental evolution in Heqing area was influenced by the uplift of the Qinghai–Tibetan Plateau, the resulting variation of southwest monsoon and the earth orbital-scale periodicity.