Cenozoic evolution of the Pamir and Tien Shan mountains reflected in syntectonic deposits of the Tajik Basin

Abstract The NE Tajik Basin in Central Asia, compressed between the ranges of the Tien Shan in the north and the Pamir in the south, is a key region for understanding the evolution of these mountain systems. Erosion and deposition history of the NE Tajik Basin and the adjoining orogens since the late Oligocene is reflected in the sedimentary record. The sedimentary rocks of the NE Tajik Basin are composed of thick units of proximal braided river deposits. They reflect large fluvial plains extending from the margins of the Northern Pamir and the Southern Tien Shan mountains, but are not related to the established lithostratigraphic scheme. Almost all Oligocene–Pliocene synorogenic deposits of the NE Tajik Basin were derived from the northern Pamir ranges, except upper Miocene–Recent proximal deposits close to the active margin of the Tien Shan. Initial uplift in some areas of the SW Tien Shan since the Oligocene was followed by a phase of low-energy sedimentation and a predominance of the southern source area. Since the middle Miocene, erosion of the ranges has occurred with the proximal sedimentation of coarse fluvial deposits along the northern margin of the Tajik Basin.

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