Cenozoic tectono-sedimentary evolution of the N margin of Tibet Plateau-New model based on seismic data from SW Tarim Basin

Abstract:

West Kunlun Mountains and SW part of the Tarim Basin located North from the Tibet Plateau collectively form the northernmost segment of the vast Cenozoic deformation zone and associated depositional areas formed in course of the India – Euroasia collision. Four seismic transects from the SW Tarim Basin (Yecheng - Hotan area) calibrated by deep wells were used in order to assess lateral variations of a structural style and syn-tectonic sedimentation in this part of the basin. Cenozoic sedimentary infill of the SW Tarim Basin consists of Paleogene evaporites of variable thickness (from 100 m up to 1 km), and up to 6 kilometers of Neogene-Quaternary terrestrial clastics.

The Western Kunlun Mountains and Tarim Basin are characterized by presence of two evaporitic detachments, and regional basement thrust that controlled its tectonic framework and structural evolution. A shallow thrust system was connected to Paleogene evaporites (Aertashi Formation) as a detachment. The deep thrust system beneath frontal Kunlun embraces Cambrian to Permian strata and merges into deeper detachment related to the middle Cambrian evaporites (Awatage Formation). A large-scale structural wedge consisting of slivers built of Cambrian to Permian rocks formed within the Western Kunlun Mountains from late Miocene to Quaternary. Its growth resulted in progressive uplift of the Kunlun Mountains front. Jade Anticline, large intra-basinal structure located in the central part of the SW Tarim Basin and interpreted previously as a regional wrenching zone was reinterpreted as a thin-skinned syn-depositional “fish tail” structure, detached in the Paleogene evaporites and formed in Quaternary above local basement elevation related to the deep basement thrust.

Two uplift stages have occurred in western Kunlun Mountains and Southwestern Tarim Basin since the Miocene. During late Miocene, wedging along the SW Tarim resulted in uplift of the N margin of Kunlun Mountain. From Pliocene to Quaternary zone of compressional deformations migrated towards the basin interior, Shallow detachment continued to be active in Pliocene and Quaternary, and this led to formation of intra-basinal Jade anticline. The Cenozoic tectono-sedimentary evolution of Western Kunlun Mountains and SW Tarim basin illustrates complex interaction between sedimentation and tectonic processes active at various depths, from relatively shallow subsurface to Precambrian basement.