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71.
���ʻ���̽��ƻ���չ���й������������������ƻ��о� 总被引:2,自引:1,他引:2
??????????????????????????????????????????????????? ????SGG-Doppler??VLBI???????????????????????????й???????????????????????????????SGG-Doppler-VLBI???????????????????????? 相似文献
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班公湖-怒江缝合带是国内外备受关注的特提斯构造域的重要组成部分,可为恢复和反演特提斯洋构造演化提供重要依据。对南羌塘地块南缘洞错地区晚白垩世花岗闪长斑岩进行了详细的岩石学、锆石U-Pb定年、全岩地球化学和Lu-Hf同位素研究。锆石U-Pb定年和Lu-Hf同位素研究结果显示,该花岗闪长斑岩形成时代为74.1±1.1 Ma,εHf(t)值为4.5~6.9。全岩地球化学特征显示,其为高钾钙碱性系列,富集轻稀土元素,轻重稀土元素分馏较强,具弱负Eu异常;富集Rb、Th、U、K和Pb,亏损Ba、Nb、Ta、La、Ce、P和Ti。该花岗闪长斑岩为加厚新生下地壳部分熔融的产物。在综合区域最新研究成果的基础上,认为该花岗闪长斑岩形成于后碰撞环境,为班公湖-怒江洋闭合后岩石圈拆沉的产物。 相似文献
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Qing Wang Yuanyuan Kong Wen Zhang Jianping Chen Peihua Xu Huizhong Li Yiguo Xue Xiaoqing Yuan Jiewei Zhan Yujie Zhu 《Arabian Journal of Geosciences》2016,9(18):718
A method was developed to analyze the susceptibilities of 541 regional basins affected by debris flows at the Wudongde Dam site in southwest China. Determining susceptibility requires information on source material quantity and occurrence frequency. However, the large number of debris flows can hinder the individual field investigation in a each small basin. Factors that may trigger debris flows can be identified using remotely sensed interpretation information. Susceptibility analysis can then be conducted based on these factors. In this study, SPOT5 satellite imagery, digital elevation models (DEM), a lithology distribution map, and rainfall monitoring data were used to identify 12 debris flow trigger factors: basin relief ratio, slope gradient in the initiation zone, drainage density, downslope curvature of the main channel, vegetation coverage, main channel aspect, topographic wetness index, Melton’s ruggedness number, lithology, annual rainfall, form factor, and cross-slope curvature of the transportation zone. Principal component analysis was used to obtain the eight principal components of these factors that contribute to susceptibility results. Then, a self-organizing map method was adopted to analyze the principal components, which resulted in a debris flow susceptibility classification. Field validation of 26 debris flow basins was used to evaluate the errors of the susceptibility classification, as well as assess the causes of such errors. The study found that principle component analysis and self-organizing map methodologies are good predictors of basin susceptibility to debris flows. 相似文献
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Two-dimensional landslide dynamic simulation based on a velocity-weakening friction law 总被引:3,自引:3,他引:0
Surprisingly, hypermobility (high velocity and long run-out) is a remarkable feature of large landslides and is still poorly understood. In this paper, a velocity-weakening friction law is incorporated into a depth-averaged landslide model for explaining the higher mobility mechanism of landslides. In order to improve the precision of the calculation, a coupled numerical method based on the finite volume method is proposed to solve the model equations. Finally, several numerical tests are performed to verify the stability of the algorithm and reliability of the model. The comparison between numerical results and experimental data indicates that the presented model can predict the movement of landslide accurately. Considering the effect of velocity-weakening friction law, the presented model can better reflect the hypermobility of landslide than the conventional Mohr–Coulomb friction model. This work shows that the application of a universal velocity-weakening friction law is effective in describing the hypermobility of landslide and predicting the extent of landslides. 相似文献