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.

The topographical evolution of tectonic systems, as well as the sedimentation pattern and depositional environments in the associated basins, are controlled by both tectonics and climate. In the region of the Tien Shan (Central Asia), the Jurassic–Lower Cretaceous period was marked by complex, low-intensity tectonic deformation and major climate changes from humid to arid conditions (Jurassic) to semi-arid conditions (Cretaceous). Using the sediment record in the Junggar, Tarim and Fergana basins to describe the tectonic evolution of the Tien Shan area during the Mesozoic thus requires differentiation between the tectonic and climatic influences on sedimentation. The conglomerates of the Upper Jurassic–Lower Cretaceous Kalaza Formation were commonly associated with renewed tectonic activity resulting from the docking of the Lhasa block along the southern margin of Asia. From sedimentology and sequence stratigraphy analyses of several sections in the Junggar, Tarim and Fergana basins, we reassess the main factors controlling the deposition of this formation. We show that, while some tectonic activity persisted throughout the Jurassic–Cretaceous transition, the switch from the sandy deposits of the Upper Jurassic Qigu Formation to the coarse deposits of the Kalaza Formation is largely linked to the development of an arid climate

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et al.. Unbalanced sediment budgets in the catchment-alluvial fan system of the Kuitun River (northern Tian Shan, China): Implications for mass-balance estimates, denudation and sedimentation rates in orogenic systems. Geomorphology, Elsevier, 2014, 214, pp. AbstractMass balances are often used to calculate sediment fluxes in foreland basins and denudation rates in adjacent mountain ranges on intermediate to long timescales (from a few tens of thousand to million years). Here, we study the simple Quaternary catchment-alluvial fan system of the Kuitun River, in northern Tian Shan, to discuss some ideas about sediment storage, release, and bypass in relatively short (a 100 km long) sediment routing systems. This study shows that the Kuitun catchment and piedmont areas clearly present evidence of a significant and temporary storage of sediments during the Pleistocene. These sediments were then excavated and delivered farther into the foreland basin during the Holocene. The difference between the volumes of materials released from the catchment and piedmont areas (5.5  1.7 km 3 ) and the volume stored in a contemporaneous fan downstream (2.6  0.6 km 3 )indicates that the latter did not trap the whole sediment load transported by the river. The alluvial fan was bypassed by 27 to 78% of this load toward its distal alluvial plain. If this value is well estimated, it implies a major volumetric partitioning of the deposits between the fan and the alluvial plain, with a very high sedimentation rate in the fan (1.97  0.52 mm.y -1 ) A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPTand a much lower one downstream (0.11  0.11 mm.y -1 ). However, this volumetric partitioning might only occur during periods with a very specific hydrological regime such as the Holocene deglaciation. Eventually, the peculiar sediment storage and release pattern within the Kuitun catchment and piedmont areas during the Pleistocene and Holocene complicates the calculation of mean palaeodenudation rates using either sediment budgets or in situ produced cosmogenic nuclides.

The strongly intracontinental Tian Shan region, in Central Asia represents a key area to understand the long term evolution of continents in general and Asia in particular. If its Paleozoic and Cenozoic geodynamics are well understood, its Mesozoic evolution remains poorly constrained. In order to decipher the paleogeographic and large-scale tectonic evolution of the Tian Shan area during the Jurassic, we compiled, detailed field analyses of sedimentary rocks acquired within and around the Chinese Tian Shan region together with previously published data. We present three paleogeographical maps corresponding to the late Earlyearly Middle Jurassic, late Middleearly Late Jurassic and Late Jurassic-Early Cretaceous transition periods. We provide a large-scale picture of the Jurassic paleogeographic and climatic evolution of the Tian Shan region and discuss the geological

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In the Mesozoic-Cenozoic continental deposits of the Tian Shan area, two main levels containing 17 pedogenic carbonates have been identified on both the southern and northern foothills of the range: 18 one in the Upper Jurassic series and one in the Upper Cretaceous-Lower Palaeocene series. In order 19 to reconstruct the palaeo-environmental and palaeo-topographic characteristics of the Tian Shan 20 area during these two periods, we measured the oxygen and carbon isotope composition of these 21 pedogenic carbonates (calcrete and nodules). The stable isotope compositions are homogeneous: 22 most  18 O values are between 21 and 25‰ and most  13 C values are between-4 and-6‰. No 23 distinction can be made between the calcrete and nodule isotopic compositions. The constancy of 24 isotopic values across the Tian Shan is evidence of a development of these calcification features in 25 similar palaeo-environmental conditions. The main inference is that no significant relief existed in 26 that area at the Cretaceous-Palaeogene boundary, implying that most of the present relief 27 developed later, during the Cenozoic. In addition to the pedogenic carbonates, few beds of 28 limestones interstratified in the Jurassic series of the southern foothills display oxygen and carbon 29 Manuscript 2 isotope compositions typical of lacustrine carbonates, ruling out brackish water incursion at that 30 period in the region. 31 32 Keywords: pedogenic carbonates-stable isotopes-Mesozoic palaeo-environment-Tian Shan 33 34 1. Introduction 35 Calcification is a ubiquitous phenomenon that occurs in a large variety of geological settings 36 including limestone diagenesis and continental weathering. In continental environments, under semi-37 arid conditions, the interaction between meteoric waters or groundwaters and sedimentary rocks 38 commonly leads to pedogenic calcification (e.g. Wright and Tucker, 1991; Alonso-Zarza, 2003; 39 Hasiotis et al., 2007). The resulting calcareous features correspond to the so-called calcretes and 40 occur as isolated nodules or rather continuous levels of carbonates (Retallack, 1997; Wright, 2008). 41 The oxygen and carbon isotope composition of such neo-formed carbonates provides information on 42 the palaeo-environments within which they precipitated (e.g. Alonso-Zarza, 2003). Indeed, while the 43 oxygen isotope composition of these carbonates depends upon processes taking place in the soil-44 ground water system, such as evaporation, it is also function of the composition of the meteoric 45 water. The later depends on the palaeo-latitude and the palaeo-altitude of the area, as well as on the 46 distance to the ocean from which the atmospheric masses are derived. In a specific region, any 47

The Mesozoic–Cenozoic uplift history of South Tianshan has been reconstructed in many ways using thermochronological analyses for the rocks from the eastern Kuqa Depression. The main difference in the reconstructions concerns the existence and importance of Early Cretaceous and Paleogene tectonic activities, but the existence of a Cenozoic differential uplift in the Kuqa Depression remains enigmatic. Here, we present new apatite fission‐track ages obtained for 12 sandstone samples from the well‐exposed Early Triassic to Quaternary sequence of the Kapushaliang section in the western Kuqa Depression. The results reveal that there were four pulses of tectonic exhumation, which occurred during the Early Cretaceous (peak ages of 112 and 105 Ma), Late Cretaceous (peak age of 67 Ma), Paleocene–Eocene (peak ages at 60, 53, and 36 Ma), and early Oligocene to late Miocene (central ages spanning 30–11 Ma and peak ages of 23 and 14 Ma), respectively. A review of geochronological and geological evidence from both the western and eastern Kuqa Depression is shown as follows. (1) The major exhumation of South TiansShan during the Early Cretaceous was possibly associated with docking of the Lhasa block with the southern margin of the Eurasian plate. (2) The Late Cretaceous uplift of the range occurred diachronically due to the far‐field effects of the Kohistan‐Dras Arc and Lhasa block accretion. (3) The Paleogene uplift in South Tianshan initially corresponded to the far‐field effects of the India–Eurasia collision. (4) The rapid exhumation in late Cenozoic was driven by the continuous far‐field effects of the collision between India and Eurasia plates. The apatite fission‐track ages of 14–11 Ma suggest that late Cenozoic exhumation in the western Kuqa Depression prevailed during the middle to late Miocene, markedly later than the late Oligocene to early Miocene activity in the eastern segment. It can be hypothesized that a possible differential uplift in time occurred in the Kuqa Depression during the late Cenozoic.