Abstract:

Fold thrust zones in northern edge of Western Kunlun and in southern edge of Southern Tianshan,with different structural features,are developed in southern and northern Kashi depression,respectively.The fold thrust zone in southern edge of Southern Tianshan is characterized by its S-N zonation and E-W segmentation;deformation in the eastern segment is generally stronger than that in the western segment,and it is also affected by the Talas Ferghana fracture.The fold-thrust zone in northern edge of Western Kunlun is relatively heavily influenced by the Pamir Arc.The ophiolitic melange in the orogenic zone have been involved in the thrust zone where many formations are inverted.Besides,a large Wupoer-Piaoertuokuoyi piggyback basin is developed.Difference between the pre-Mesozoic in the two fold thrust zones is significant,while it decreases progressively upward,indicating that Kashi depression has evolved into a unique sedimentary unit since Mesozoic.The unconformities do not strictly correspond to each other in the two fold thrust zones.The number of unconformities in the fold thrust zone in northern edge of Western Kunlun is larger,and the horizon is lower than that in the southern edge of Southern Tianshan,revealing that the development of the former is a little bit earlier and the thrusting is stronger than that of the latter.

Key words: Tarim basin, Kashi depression, fold thrust zone, structural feature