基于河流地貌指数的澜沧江断裂南段构造活动性研究OA北大核心CSTPCD

The southern section of the Lancang River fault zone in the Southwest Sanjiang area(from Xiaowan to Jinghong)develops along the Lancang River valley and is considered an important window for studying the tectonic evolution of the Southwest Sanjiang area and even the deformation mechanism of the southeastern margin of the Qinghai⁃Tibetan Plateau.Currently,there is still a lack of systematic research on the spatial distribution patterns of the tectonic activity characteristics of the Lancang River fault zone.Geomorphic indices are sensitive to the tectonic activity of faults and can intuitively reflect the characteristics and distribution patterns of tectonic activity.Therefore,based on the digital elevation model(DEM)with a resolution of 30 meters,this study extracted 210 secondary basins on the western side(right bank)of the southern segment of the Lancang River basin and obtained the area⁃altitude integral(HI),basin asymmetry factor(AF),basin shape index(BS),valley floor width⁃height ratio(VF),normalized stream power index(SLK),mountain front sinuosity(Smf)value,and normalized channel steepness index(Ksn)of each secondary basin.Based on this,the relative strength of tectonic activity(Iat)was comprehensively obtained from various geomorphic indices.The analysis revealed that non⁃tectonic factors(such as precipitation and lithology)in the study area do not have a significant impact on the various geomorphic indices of the southern segment of the Lancang River fault.Tectonic activity is the main influencing factor dominating the changes in various geomorphic indices,showing that the activity of the southern segment of the Lancang River fault zone is stronger near the fault and at the intersection of faults.The tectonic activity of the southern segment of the Lancang River fault zone shows obvious segmented characteristics,with high and low activity levels interspersed.The northern part of the fault from Xiaowan to Manwan shows stronger activity,while the activity in the central and southern parts from Manwan to Nazhao,Nazhao to Qianliu,Nuozhadu to Mengwang,and Jinghong is moderate.This reflects that the tectonic activity at different positions of the same fault zone on the southeastern margin of the Qinghai⁃Tibet Plateau also varies,not showing a simple linear change pattern,but possibly influenced by the comprehensive effects of different scales and natures of surrounding tectonic activities.The neotectonic movements on the southeastern margin of the Qinghai⁃Tibet Plateau exhibit diversity and complexity.