An analysis of the deformation characteristics of the Quele salt nappe in the western Kuqa foreland thrust belt

The western Kuqa foreland thrust belt hosts the best surface salt structures in China, and hence can be regarded as a natural laboratory for salt structure research. Previous researches have been mainly focused on the underground salt structures, such as the identification of the underground salt structures, the segmentation of the underground salt structures and the formation mechanism of the salt structures, while the researches on the surface salt structures in this region are relatively less. Based on previous researches, the authors used the methods of field mapping, seismic interpretation and remote sensing images interpretation to analyze the deformation characteristics of the Quele salt nappe in the western Kuqa foreland thrust belt. The development of the Quele salt nappe was controlled by the Quele thrust fault, and the salt rock of Kumugeliemu Group rose to the surface with the thrust fault. The Quele salt nappe is characterized by segmentation, and the deformation characteristics change from west to east. In the western and central part of the Quele salt nappe, the overburden of the salt is intact, and the salt rose to the surface only along the thrust frontier of the nappe. The salt structure pattern of the western and central part of the Quele salt nappe belongs to "open-toed advance salt sheet". Nevertheless, in the eastern part of the Quele salt nappe which is also called Charerhan Namakier, the overburden of the salt was eroded and the salt was driven to flow downward by gravity after the migration of the salt to the surface. The Charerhan Namakier belongs to "extrusive advance salt sheet". The topography of the Charerhan Namakier has been strongly affected by the surface runoff and rainfall, which has caused a lot of karst caves and salt hills to form at the surface of the Charerhan Namakier. Heavy rainfall could affect the advance way of the namakier, making the Namakier advance as "surging flow". The deformation characteristics of the competent interlayers can reflect the rheological strength of the salt. The deformation patterns of the competent layers inside the Charerhan Namakier are more complicated, indicating that the salt in the Charerhan Namakier has experienced stronger rheology, resulting from the lack of limit of the overburden and the full effect from the surface runoff and rainfall.