Using the teleseismic waveform data recorded by 12 permanent digital seismic stations from Xinjiang seismograph network and 10 campaign broadband digital seismic stations from Tienshan dynamics II term project located in the northeastern Pamir region in Xinjiang, we investigate the crustal thickness, Poisson's ratio and the depth of inter-crustal discontinuity beneath each station by grid search and stacking method of receiver function. The result shows five characteristics in the crustal structure. (1) Strong lateral crustal thickness variations exists in this area. The crust is thicker in the western and the southern parts of the Pamir region, but thinner in the eastern and the northern parts. The crustal thickness gradually deepens from 45 km to 55 km from the Tarim basin to the south Tienshan, and gradually deepens from 45 km in the Tarim basin to 69 km in the West Kunlun Mountain. (2) Along the profile of the Tienshan dynamics II project, the depth of inter-crustal discontinuity about is 13~16 km beneath the northern Tarim basin, and deepens to about 20 km to the north into the south Tienshan Orogen, but the inter-crustal discontinuity in further north under the south Tienshan mountains is weak. The depth changes of inter-crustal discontinuity may indicate that the Tarim basin basement subducts northward, and the front of the subduction slab may reach to the south Tienshan Mountain piedmont; (3) The crustal Poisson's ratio in the studied region changes significantly (about from 0.20 to 0.31), which suggests that the crust composition is complex. (4) There are no obvious relationship between the crust thickness and Poisson's ratio in this study area. But the Tienshan dynamics II project profile results show that the anti-correlation pattern exists between the crust thickness and Poisson's ratio from the north rim of the Tarim basin to the southwest Tienshan, suggesting that the Tienshan crustal thickening mainly due to the upper crust superimposed, and the upper crust main composition are felsic rocks. (5) The crustal thickness of this study area is relatively weak correlated to the elevation height (the correlation coefficients is 0.66). But the crustal thickness under 10 stations in the Tienshan dynamics II project are well correlated to the elevation height (correlation coefficient is 0.85), which may imply that the crust in a relatively well isostatic status along the profile.
- Crustal thickness
- Depth of inter-crustal discontinuity
- Northeastern Pamir region
- Poisson's ratio
- Receiver function