论文摘要
Here, the principal data used for this study of about 400 GPS stations around the Namcha Barwa syntaxis（88-104°E, 20-34°N） are from the Crustal Movement Observation Network of China（CMONOC）. Besides the CMONOC data set, we collected three additional velocity data sets from Jade et al.（2017）, Zheng et al.（2017）, Gupta et al.（2015）, Kreemer et al.（2014）, Liang et al.（2013）, Banerjee et al.（2008）, Gan et al.（2007）, etc. These collected data are used to demonstrate the detailed deformation characteristics among different individual tectonic units within the area of interest, and produce a crustal motion image of the collision zone. The collected data from the GPS networks in the concerned areas has been amalgamated into a common fixed reference frame by using the least-square collocation method, as suggested in Zhan et al.（2015）. In order to get a continuous strain rate map of the plateau, we use a "spline in tension" technique（Wessel and Bercovici, 1998） with the tension parameter t = 0.95 to interpolate the GPS velocities on 0.5°～ 0.5°（longitude and latitude） grids, and then calculate the strain rate tensor in every 0.6°～ 0.6° area with the nine interpolated velocities on the grids. The tension parameter t（0 ≤ t < 1） in the spline in tension algorithm represents the portion of the strain energy resulting from tension relative to total strain energy（Wessel and Bercovici, 1998）. Notice that the strain energy here refers to strain within the spline, not strain in the Earth. When t = 0, the algorithm corresponds to a minimum curvature biharmonic spline. As the tension parameter increases, the squared curvature integrated over the entire surface becomes larger, and, as t =1, the algorithm approaches a whole data based linear interpolation（Gan et al., 2007）. As shown in the fig. 1 a, it depicts two significant maxima of compression rates and one peak value of dilatation rate. The dilatational strain tiptop rate of 113.7 nanostrain/year found around 100.9°E, 28.1°N has been explained by existence of a series of nearly N-S striking normal faults which are located in the post-arc active extensional accretionary region of the IndiaEurasia continental collision. One of the two topmost compression rates located in the north of the Himalayan Main Frontal Thrust around 27.5°N, between 93.7°-94.3°E and reaches nearly 115 nanostrain/year; the other reaching 80～152 nanostrain/year is located in the northeast margin of the Namcha Barwa syntaxis between 28.0°–29.5° N and 95.0–97.0° E, in which area the Himalayan Main Boundary Thrust and the Himalayan Main Frontal Thrust meet the Lohit Thrust and the Mishmi Thrust. Moreover, we also recognize several compression poles and extension poles with respect to the surroundings within the area of interest, and all of these poles are well-indicated to distribute along the major active faults. Notice that the obtained shear strain rate field in Figure 1 b shows that serious shear deformation are closely related to the plate bou
论文目录
文章来源
类型: 国际会议
作者: WEI Shaogang,XU Xiwei,GAN Weijun,WU Yanqiang
来源: 第九届世界华人地质科学研讨会 2019-06-01
年度: 2019
分类: 基础科学
专业: 自然地理学和测绘学,地质学,地球物理学
单位: The Institute of Crustal Dynamics,China Earthquake AdministrationThe First Monitoring and Application Center,China Earthquake AdministrationThe Institute of Geology,China Earthquake Administration
分类号: P228.4;P315.2
DOI: 10.26914/c.cnkihy.2019.028410
页码: 233-234
总页数: 2
文件大小: 252k
下载量: 1