GEOMORPHIC FEATURES OF THE SHULE RIVER DRAINAGE BASIN IN QILIANSHAN AND ITS INSIGHT INTO TECTONIC IMPLICATIONS |
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| Authors: | SU Qi YUAN Dao-yang XIE Hong SHAO Yan-xiu LIANG Ming-jian Lanzhou Institute of Seismology China Earthquake Administration Lanzhou China Lanzhou National Observatory of Geophysic |
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| Institution: | 1. Lanzhou Institute of Seismology, China Earthquake Administration, Lanzhou 730000, China;
2. Lanzhou National Observatory of Geophysics, Lanzhou 730000, China;
3. Earthquake Administration of Sichuan Province, Chengdu 610000, China |
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| Abstract: | Because of the strong uplift of the Qilian Shan since late Cenozoic,the drainage basins that are derived from the mountains have undergone strong tectonic deformation.So the typical geomorphology characteristics of these drainage basins may indicate the strong tectonic movement in the region.For example,the Shule River drainage basin,which originates from the western part of the Qilian Shan owns unique geomorphology characteristics which may indicate the neotectonic movement.
Stream networks of the Shule drainage basin extracted from the DEM data based on GIS spatial analysis technology are graded into five levels using Strahler classification method.Four sub-catchments,numbered 1,2,3 and 4 are chosen for detailed analysis.Furthermore,the four sub-catchments,the hypsometric integral curves,Hack profiles,SL index and average slope of the Shule drainage basin are determined by GIS tools.In addition,we analyzed the slope spectrum of the Shule drainage basin.
The average elevation of the Shule drainage basin is very high,however,the slope of the drainage basin is very low,the gentle slope occupies so large area proportion that the slope spectrum shows a unimodal pattern and a peak value is in low slope region (0°~5°),so tectonic movement has a strong influence on the drainage basin.Under the intensive impact of the tectonic movement of the active fault and regional uplift,the hypsometric integral curve is sigmoid,revealing that the Shule drainage basin is in the mature stage.The Hack profile is on a convex,the longitudinal profile is best fitted by linear fitting and the abnormal data of the SL index of the Shule River has a good fit with the section through which the active fault traverses,that means the tectonic movement of the active fault has strong influence on the river's SL index.It is worth noting that lithologic factors also have great impact on the river geomorphology in some sections.
According to the above analysis,we recognize that in the interior of active orogen,the evolution of river geomorphology usually is influenced by tectonic movement and reveals the regional neotectonics in turn. |
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| Keywords: | Shule River drainage basin hypsometric integral Hack profile SL index geomorphology |
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