Analysis of Characterization of Quaternary Sedimentation and Evolution in the Lhasa La Basin,Tibet

The Lhasa Basin is an important component part of the Lhasa-Rhido Interarc Basin, in which the Quaternary System is relatively developed and has many types of genesis. It is important to analyze the composition of the Quaternary, sedimentary characteristics and depositional environment in the basin to study the evolution of the Tibetan Plateau. The Quaternary in the area is mainly composed of the upper Pleistocene-Holocene, the upper Pleistocene for the moraine deposition, Holocene is mainly alluvial, flood alluvial, flood, swamp accumulation and modern riverbed, river floodplain, river beach sedimentation and wind sand accumulation; sedimentary phase mainly alluvial phase, flood phase, wind and moraine phase of several major categories. Through the field measurement of geological profiles and combined with the analysis of the former borehole data, the Quaternary stratigraphy in the area is divided and compared, and their respective depositional sequences and the relative relationship between the old and the new have been initially established. In addition to the influence of regional tectonic movement, the sediments of different genesis in the basin are also very closely related to the Quaternary climate change process in the region, especially during the Late Quaternary period, no matter it is the river alluvial deposits or alpine moraines, the evolution is closely related to the regional climate fluctuation process.