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Field investigations show that the surface wave magnitude (Ms) 8.1 Central Kunlun earthquake (Tibetan plateau) of 14 November 2001 produced a nearly 400-kilometer-long surface rupture zone, with as much as 16.3 meters of left-lateral strike-slip along the active Kunlun fault in northern Tibet. The rupture length and maximum displacement are the largest among the co-seismic surface rupture zones reported on so far. The strike-slip motion and the large rupture length generated by the earthquake indicate that the Kunlun fault partitions its deformation into an eastward extrusion of Tibet to accommodate the continuing penetration of the Indian plate into the Eurasian plate.

The Tianshan Range is one of the longest and highest mountain belts in Central Asia, stretching east-west for ~2500 km. Uplift of this late Paleozoic orogenic belt resulted from intracontinental deformation caused by the collision of the Indian and Eurasian plates during the Cenozoic era. To constrain the timing of Cenozoic tectonic deformation of the Tianshan Range, we analyzed the magnetostratigraphy of 3780-m-thick Neogene deposits from the Kuqa foreland basin of southern Tianshan. The geometry measurements and magnetic fabric data show that syntectonic growth strata began to accumulate at ~6.5 Ma ago, indicating that crustal shortening initiated in the latest Miocene. The increase in sedimentation rate and an abrupt change of the magnetic fabric parameters also occurred at 6.5 Ma, accompanied by onset of syntectonic growth strata. The latest Miocene crustal shortening is a signifi cant tectonic event in the foreland basin of the southern Tianshan Range in response to the India-Eurasia collision.

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Abstract. The topographic evolution of continents and especially the growth and dismembering of mountain ranges plays a major role in the tectonic evolution of orogenic systems, as well as in regional or global climate changes. A large number of studies have concentrated on the description, quantification and dating of relief building in active mountain ranges. However, deciphering the topographic evolution of a continental area submitted to recurrent tectonic deformation over several hundred millions of years remains a challenge. Here we present a synthesis of the tectonic, geochronological and sedimentological data available on the intracontinental Tian Shan Range to describe its general topographic evolution from Late Palaeozoic to Early Tertiary. We show that this evolution has occurred in two very distinct geodynamic settings, initiating during the Carboniferous in an ocean subduction -continent collision tectonic context before becoming, from Early Permian, purely intra-continental. We show that during most of the Mesozoic, the topography is mostly characterized by a progressive general decrease of the relief. Nonetheless localized, recurrent deformation induced the formation of small-scale reliefs during that period. These deformations were driven by far field effects of possibly several geodynamic processes in a way that still remains to be fully understood.

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