Abstract:

The study on the formation and evolution of geomorphology and the surface erosion of paleo-drainage of the Yuanmou paleolithic site and its surrounding region can well reveal the coupling relationship between tectonic uplift, climate, ecological environment and ancient human activities on the southeastern margin of the Tibetan Plateau. The geomorphologic formation and evolution and the surface erosion of its internal paleo-drainage around the Yuanmou paleolithic site, have profoundly influenced by the multiple tectonic uplifts and paleo-drainage reorganization on the southeastern Tibetan Plateau (SETP) since the Eocene. The ancient bedrock of the paleo-planation surface and the Cenozoic strata above the river terraces have formed a surface weathering crust under long-term physical and chemical processes, becoming an important ecological barrier for the distinctive regional ecological environment, Agricultural and livestock production, and ancient human activities. Based on magnetostratigraphic chronology, tectonic events, and lithofacies changes, our study systematically elucidated the development, formation, and breakup processes of the geomorphology from the paleo-planation surface, the paleo-drainage and the river terraces. The research results indicate that the Yuanmou paleolithic site and its surrounding region have undergone significant tectonic events and paleo-drainage reorganization events in different periods since the Cenozoic, such as during the late Oligocene to early Miocene, early Late-Miocene, early Pliocene, late Early-Pleistocene, middle Pleistocene, late Pleistocene and Holocene, and ultimately formed to its present configuration. In addition, the formation process of the Yuanmou Paleolithic Site is highly related to the formation of the third paleo-planation surface and the development of river terraces, reflecting the close association between ancient human activities and tectonic movements, paleo-drainage changes, and their controlled geomorphic evolution patterns. This work would provide significant geological evidence for exploring the impact mechanisms of geomorphic processes and ecological environment changes on the survival activities of Yuanmou Man and other ancient humans, and also offer essential proof for future archaeological work on ancient humans and Paleolithic artifacts in the Yuanmou Paleolithic Site and its surrounding region.

Key words: Tibetan Plateau, Yuanmou hominin site, planation surface, paleo-drainage, river terrace