Sedimentary environment evolution of the paleochannel in the middle reaches of Hutuo River since 150, 000 years and its response of climate change

Palaeochannel records the evolution information of regional drainage system structure and sedimentary environment in geological history, which is of great theoretical significance to the restoration of palaeoenvironment and the evolution law of drainage system. Based on a Quaternary borehole (L2) in the paleochannel of the alluvial and diluvial fan of Hutuo River, detailed lithological characteristics, grain size parameters and optical ages, the development periods and sedimentary environment evolution of the paleochannel in the middle of Hutuo River since 150, 000 years and its response of climate change was discussed. The results show that the sedimentary environment evolution of the study area is mainly composed of three paleochannel development periods and two river stabilization periods since 150, 000 years. It has a good correspondence with the deep-sea oxygen isotope stage and the climate change indicated. The three periods of paleochannel development correspond to the second, fourth and sixth stages of the deep-sea oxygen isotopes, and the cold climate respectively. Two river stabilization periods corresponds to the third and fifth stages of the deep-sea oxygen isotopes, and the warm climate respectively. The third paleochannel (about 151~118 ka) was formed by the combination of tectonic uplift caused by the republican movement 150 thousand years ago and the cold-dry climate during the penultimate glaciation. The second palaeochannel (about 76~36 ka) is the result of intermittent regional tectonic uplift and climate change. And the first palaeochannel (about 26~5 ka) was the result of climate change during the last glacial maximum.