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山脉侵蚀速率的大小和时空分布信息是研究山脉构造—气候相互作用和地貌演化的关键切入点,其大小是受气候还是构造控制争论已久。宇宙成因核素10Be方法为从千年至万年尺度上定量研究流域平均侵蚀速率提供了一种先进和快捷的技术手段,为揭示侵蚀速率与现代气候和构造地貌因子的关系并进行相关分析提供了基础。利用该方法对北祁连山近现代侵蚀速率进行了研究。所采集的9个流域现代河沙样品,结合前人数据进行共同分析,结果显示该区侵蚀速率的变化范围为18.7~833 mm/ka,北祁连山中段的侵蚀速率约为323 mm/ka,该区侵蚀速率与降雨量没有明显的对应关系,但与流域平均坡度呈现很好的非线性关系,揭示坡度是该区侵蚀速率的最主要控制因素。通过对比北祁连山地表平均侵蚀速率和该区域的断层垂直滑动速率发现整体上该区域地表侵蚀速率要低于祁连山北缘断层的垂直滑动速率,反映了北祁连山正处于地形抬升和生长的过程之中。
The size of the erosion rate and the spatial and temporal distribution information of the mountains are the key entry points for studying the tectonic-climate interaction and landscape evolution of the mountains, and its size has been debated for a long time by climate or tectonic control. The cosmophilic radionuclide 10Be method provides an advanced and rapid technique for quantitatively studying the average erosion rate in the basin from the thousandth to the multi-year scales. It provides the basis for revealing and correlating the erosion rate with the climate and tectonic factors basis. Using this method, the erosion rate of the North Qilian Mountains was studied. The collected samples from 9 river basins of modern river sand combined with the previous data show that the erosion rate in this area ranges from 18.7 to 833 mm / ka, and the erosion rate in the middle part of the northern Qilian Mountains is about 323 mm / ka There is no obvious corresponding relationship between erosion rate and rainfall, but it shows a good nonlinear relationship with the average gradient of the basin, revealing that the slope is the most important factor controlling the erosion rate. By comparing the average surface erosion rates in the North Qilian Mountains and the vertical slip rates of the faults in the area, it is found that the overall surface erosion rate is lower than the vertical slip rate of faults in the northern margin of the Qilian Mountains, reflecting that the North Qilian Mountains are in the process of terrain elevation and growth .