关键词: 柴达木盆地, 莫霍面反演, 控制点, 阿尔金断裂带

Abstract: To investigate the deep dynamic causal mechanism of shallow deformation in the Qaidam Basin, this study utilized Bouguer gravity anomaly data with the deep seismic profiles and natural seismic tomography data as control points to obtain the best datum plane, and invert the spatial distribution morphology of the Moho surface. The results show that the spatial variations of shallow tectonic deformation also manifest significant differences in the Moho depth between the eastern and western parts of the Qaidam Basin. In the western part of the basin, shallow tectonic deformation is stronger with extensive development of thrust and shortening structures. The Moho surface is relatively deep, approximately 55-61 km. In contrast, the eastern part of the basin exhibits weaker deformation overall, mainly concentrated at the basin margins with the Moho surface being relatively shallow, approximately 48-61 km. Additionally, there is a large steep zone between the East Kunlun Mountains and the eastern Qaidam Basin, where the Moho surface can abruptly change by about 15 km. These features indicate that under the tectonic background of the northeastward extension of the Tibetan Plateau, the crust in the western Qaidam Basin has undergone significant shortening and thickening, while the eastern part still retains characteristics similar to a stable craton basin, with minimal changes in crustal thickness. The deep-cut strike-slip faulting of the Altyn Tagh Fault zone, which induces crust-mantle mixing, is likely a decisive factor leading to the shortening and thickening of the western Qaidam Basin, thereby resulting in the spatial differences in the Moho surface between the eastern and western parts.

Key words: Qaidam Basin, inversion of Moho surface, control points, Altyn Tagh Fault