乌拉山分水岭的稳定性研究——来自χ值的证据  

Drainage divide stability at Wulashan, northern margin of the Ordos block, China: Evidence from the analysis of χ value

作　　者：白鸾羲 谭锡斌[1,2] 周朝 BAI Luanxi;TAN Xibin;ZHOU Chao(Institute of Geology,China Earthquake Administration,Beijing 100029,China;State Key Laboratory of Earthquake Dynamics,Beijing 100029,China;Exploration and Development Research Institute,SINOPEC East China Branch Company,Nanjing 210000,Jiangsu,China Drainage divide stability at Wulashan,northern margin of the Ordos block,China)

机构地区：[1]中国地震局地质研究所,北京100029 [2]地震动力学国家重点实验室,北京100029 [3]中国石化华东油气分公司勘探开发研究院,江苏南京210000

出　　处：《地质力学学报》2022年第4期513-522,共10页Journal of Geomechanics

基　　金：中国地震局地质研究所自主科技发展项目(F-21-02)。

摘　　要：分水岭的稳定性蕴含着重要的构造和气候信息,但是对于分水岭稳定性的判别标志目前还存在争议,从而导致对某些地区分水岭的稳定性形成不一致的结论。位于鄂尔多斯北缘的乌拉山分水岭稳定性目前存在两种不同的认识:通过两侧流域形态(袭夺弯、裂点等)分析认为乌拉山分水岭正在向北迁移;通过Gilbert参数对比法认为其处于稳定状态。为了检验乌拉山分水岭的稳定性以及上述各种判定方法的可靠性,研究采用χ值对比法对乌拉山分水岭的稳定性进行了研究。χ值分析揭示:如果设置较低的基准线(海拔1300 m),则分水岭南侧顶部χ值小于北侧同一高程的χ值;如果设置较高的基准线(约1800 m),则分水岭两侧的χ值在同一高程基本保持一致。以较高的基准线获得的χ值由于更靠近分水岭而受到块体差异抬升的干扰较小,更能反映分水岭的瞬时稳定性。因此,文章支持乌拉山分水岭处于稳定状态这一认识;同时文章对判断分水岭稳定性不同方法的局限性进行了讨论。The stability of drainage divides carries important tectonic and climatic information.However,there is still no consensus on the criterion for measuring the stability of drainage divides,which may lead to different conclusions.There are two different views on the stability of the divide at the Wulashan horst,northern margin of the Ordos block:The drainage divide is moving northward,according to the comparison of drainage-basin morphology(such as elbows of capture,knick points);The drainage divide remains stable,according to the comparison of Gilbert metrics.In this study,we used theχ-plot method to check both the stability of the Wulashan drainage divide and the reliability of the above methods.The analysis shows that theχvalue at the top of the northern side is higher than that at the same elevation of the southern side if a lower baseline was set(1300 m a.s.l.);If a higher baseline(~1800 m a.s.l.)is set,theχvalues on both sides of the divide are the same at the same elevation.Because the tilting has relatively less influence,theχ-plot with a higher baseline is more representative of the drainage divide stability.In summary,the result supports the view that the drainage divide at the Wulashan horst is at a steady state.Moreover,we discussed the limitations of the methods in measuring the stability of drainage divides.

关 键 词：分水岭 乌拉山地垒 χ值 掀斜 

分 类 号：P931.2[天文地球—自然地理学]