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作为藏北宽频地震国际合作INDEPTH-IV项目后续工作的一部分,项目组于2010年9月—2011年8月期间在柴达木盆地东缘和祁连造山带中段,大致沿北东方向部署了25个宽频地震观测台。通过对记录的地震事件面波和台站间环境噪音互相关格林函数频散曲线的提取和面波层析成像的研究发现,研究区地壳和上地幔顶部的横波速度结构由柴达木盆地东缘向阿拉善地体西南缘发生了非常明显的横向变化。介于二者之间的祁连造山带存在明显的中下地壳低速异常。地壳厚度大致由柴达木盆地东缘的62km向北东至阿拉善地体西南缘迅速减薄至大约38km。
As part of the follow-up work of the INDEPTH-IV project on international cooperation in broadband seismic in northern Tibet, the project team deployed in the east of the Qaidam Basin and the middle section of the Qilian orogenic belt from September 2010 to August 2011, 25 broadband seismic observatories. Based on the correlation analysis of the dispersion curve of Green’s function and the cross-wave tomography, the cross-wave velocity structure of the top of the crust and the upper mantle in the study area is determined by the cross-correlation between the recorded seismic event surface wave and the station ambient noise. Alashan Southwest edge of the margin occurred a very significant lateral changes. The Qilian orogenic belt between the two shows obvious low-velocity anomalies in the middle and lower crust. The thickness of the crust is rapidly reduced to about 38km from 62km east to Qaidam basin to the southwest edge of Alxa terrane.