Evolution Process Of River Terraces In Lv-liang Mountain And Its Influence On Landslide Development

In the Lvliang mountain,the Yellow River and the terraces are well developed,which make it become a suitable area for studying the chronological sequence of river terraces.At the same time,the geological structure of the area is complex,the terrain differs greatly,and the landslides occur frequently.It is a high-risk area of geological hazards,which provides convenient research conditions for exploring the evolution process of river terrace sand the development law of landslides.In this paper,based on the project of “Urban Geological Disaster Investigation in the Lvliang Mountain” of Xi'an Geological Survey Center,we systematically investigate the typical river terraces and overlying loess deposits and the distribution of landslides in the research area.By using the methods of Quaternary chronology and photoluminescence dating,we obtaine the distribution laws and chronological sequence of terraces,and then we explore the influence of river distance and river density on landslides development by using the information measurement method,and analyze the relationship between river terrace development and the active period of neotectonics movement.The main results and conclusions are as follows:(1)Due to the intermittent uplift of the earth's crust,multi-level terraces are formed in the water system of Lvliang Mountain.Through the systematic survey and mapping of the main rivers in the research area,it's found that both the Xinshui River and the Duanchun River Basin have T1?T6 terraces,the Qingshui River Basin has T1?T6 terraces too,and the E River has T1?T2 terraces.(2)The formation age of the T1?T6 terraces of the Xinshui River is calibrated,and the valley cutting rate is calculated.The results showed that the valley cutting rate is the highest in the early T5 period,and the tectonic movement is also the strongest.Subsequently,the cutting rate decreases in T4 period,and then rises in T3 period.Finally,it's tended to be stable in T2?T1 period.(3)Through the analysis of the position phase diagram of terraces,it's found that the terrace of Xinshui river Basin is sensitive to the Quaternary tectonic uplift,and the terrace uplift amplitude of T6 ? T1 is obtained.(4)Take Xinshui River as an example to reconstruct the pattern of ancient water system and obtain the distribution of terraces.(5)By analyzing the distribution characteristics of landslides in the watershed of the study area,it's found that the distribution of landslide has a good correlation with the river density and the river distance.The higher the river density is,the better the development of landslides will be,and within a certain range,the closer the landslide is to the river,the more developed it is.