Late Cenozoic deformation of the northeastern Pamir and the west Kunlun Mountains: Insights from anisotropy of magnetic fabrics and sedimentary analysis

Abstract

Understanding the late Cenozoic temporal and spatial development of northeastern Pamir and the west Kunlun Mountains (WKMs) is critical for our knowledge of intracontinental orogeny in Central Asia. In this study, sedimentary analyses and anisotropy of magnetic fabrics (AMF) studies were conducted in four sections along the foreland of the northeastern Pamir and the WKMs. Combined with the results of previous researches, our AMF and sedimentological results reveal a shift in paleocurrent directions from variable azimuths in the Kelizuoyi Formation to northward-directed azimuths in the upper strata in the Kekeya, Keliyang and Keyikejia sections, suggesting a gradually northward migration of the WKMs and its foreland basin. Since the early Miocene, the prevailing drainage systems in the Aertashi and Paojianggou sections have been mainly controlled by the northeastern Pamir and the drainage systems in the Kekeya, Keliyang and Keyikejia sections were controlled by the uplift of the WKMs. The constant paleocurrent and regional strain directions in the Paojianggou section support a pre-existing arcuate Pamir since the early Miocene. Under these circumstances, the evolution of late Cenozoic sediment succession and the characteristics of the AMF in the Paojianggou section were mainly controlled by crustal thickening and exhumation of the Pamir.