An Investigation On Quaternary Geology And Geomorphology Of Qilian Mountains And Its Adjacent Areas

Qilian Mountains and adjacent areas are located in the northeastern margin of the Qinghai-Tibet Plateau,sensitive to the uplift and expansion of the Qinghai-Tibet Plateau.The sedimentary sequences,paleontology,palaeoclimate,river terraces and tectonic topography of the basin are well responded and recorded in the Qilian Mountains and the Quaternary geology and geomorphology.Over the years,different scholars have studied mountain and basin evolution and stratigraphic division from the perspective of independent basins in the region.Based on the study of regional Quaternary tectono-sedimentary evolution,this paper is based on the classification of Qilian and its adjacent Quaternary tectonic landforms,basin sedimentary sequences,paleontological and palaeoclimatic characteristics and sedimentary systems.Stratigraphy and geomorphology were divided.Based on the comparative study on the uplift and chronology of the river terrace in the area,this paper reveals the overall uplift characteristics of the Qilian Mountains recorded in the Quaternary period,the uplift and time difference of different regions,and the Qilian Mountains,L response mode.Based on the four representative profiles of the area,the Quaternary climate evolution model of different landforms in Qilian Mountains was established according to the indexes of sporopollen,grain size,magnetic susceptibility and heavy minerals.On this basis,the Qilian Mountains and adjacent areas of the first "Qilian Mountains and adjacent Quaternary geology and geomorphology map".The paper has obtained the following research results:1.According to the sedimentary characteristics of different regions and the principle of basin sedimentary sequence,geomorphic evolution,paleontology and climatic characteristics,the Quaternary strata in this area are divided into four parts:Guide,Lanzhou-Xining,Jiuquan-Zhangye,Republican,Chaibei,Subei-gate,Qinghai Lake area.2.According to the similar tectonic evolution background and tectonic geomorphic features,the same geomorphic unit has unique basin sedimentary filling characteristics and regional climatic characteristics and biota characteristics,divided into:eastern loess plateau geomorphic area;midwest mountain plateau landform Area;corridor Jiuquan-Zhangye-Wuwei basin area landform area;Qinghai-Tibet northern margin Qaidam-Gonghe geomorphic area and Guide-Xunhua basin area.3.Based on the comparative analysis of the age data of the Qilian Mountains and the Quaternary since the Quaternary,the tectonic activity period of Qilian Mountains and adjacent areas is analyzed at least 5 times.That is,the first tectonic activity of about 1.6Ma;the second tectonic activity of 1.2-0.6Ma,including the first tectonic activity of 1.2,0.8 and 0.6Ma;the third tectonic activity of 0.45-0.25Ma;0.2-0.08Ma Of the first four tectonic activities,including 0.15,0.1Ma a tectonic activity;0.08Ma since the fifth phase of tectonic activity.The Qilian Mountains and the adjacent areas have not found the river terrace above the age of 1.80Ma-2.6Ma,so that the Quaternary early tectonic activity can not be analyzed by river terrace record.The average uplift rate of the Qilian Mountains and its adjacent areas in the east and southeast areas is about 0.25mm/a since 1.80Ma,and the average elevation is about 450m,and the area has risen about 600m since 2.60Ma.The tectonic uplift reflected in the Qilian Mountains and the northeastern part of the adjacent area is stronger than that of the east and the southwest,and the Qilian Mountains and the western part of the adjacent area have been uplifted or over 600m since the Quaternary.4.The establishment of the eastern loess area,western mountain glacier area,northern Hexi corridor area and Linxia basin Quaternary climate evolution model.5.Through the field investigation and indoor data processing,the above conclusions compiled in the "Qilian Mountains and adjacent areas of Quaternary geology and geomorphology map" for the future development of Qilian Mountains and neighboring Quaternary research to help.