Cenozoic tectonic and geodynamic evolution of the Kyrgyz Tien Shan Mountains: A review of geological, thermochronological and geophysical data

International audienceThe Ili-Balkhash Basin in southeastern Kazakhstan is located at the junction of the actively deforming mountain ranges of western Junggar and the Tien Shan, and is therefore part of the southwestern Central Asian Orogenic Belt. The basement of the Ili-Balkhash area consists of an assemblage of mainly Precambrian microcontinental fragments, magmatic arcs and accretionary complexes. Eight magmatic basement samples (granitoids and tuffs) from the Ili-Balkhash area were dated with zircon U-Pb LA-ICP-MS and yield Carboniferous to late Permian (~ 350-260 Ma) crystallization ages. These ages are interpreted as reflecting the transition from subduction to (post-) collisional magmatism, related to the closure of the Junggar-Balkhash Ocean during the Carboniferous – early Permian and hence, to the final late Paleozoic accretion history of the ancestral Central Asian Orogenic Belt. Apatite fission track (AFT) dating of 14 basement samples (gneiss, granitoids and volcanic tuffs) mainly provides Cretaceous cooling ages. Thermal history modeling based on the AFT data reveals that several intracontinental tectonic reactivation episodes affected the studied basement during the late Mesozoic and Cenozoic. Late Mesozoic reactivation and associated basement exhumation is interpreted as distant effects of the Cimmerian collisions at the southern Eurasian margin and possibly of the Mongol-Okhotsk Orogeny in SE Siberia during the Jurassic – Cretaceous. Following tectonic stability during the Palaeogene, inherited basement structures were reactivated during the Neogene (constrained by Miocene AFT ages of ~ 17–10 Ma). This late Cenozoic reactivation is interpreted as the far-field response of the India-Eurasia collision and reflects the onset of modern mountain building and denudation in southeast Kazakhstan, which seems to be at least partially controlled by the inherited basement architecture

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“…Thomas et al, 1999), magnetostratigraphy and structural geology (e.g. Abdrakhmatov et al, 1996;Buslov et al, 2007;Campbell et al, 2013).…”

Section: Latest Paleozoic To Cenozoic Intracontinental Evolutionmentioning

confidence: 99%

Late-Paleozoic emplacement and Meso-Cenozoic reactivation of the southern Kazakhstan granitoid basement

et al. 2015

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“…For example, the Issyk-Kul micro-continent had been a homogenous structure during a long time period, and the deformation reached its central part as late as Quaternary. At present, the strongest www.intechopen.com Seismic Hazard in Tien Shan: Basement Structure Control Over the Deformation Induced by Indo-Eurasia Collision 215 deformation processes are recorded along the micro-continent margins forming a system of thrusts and promoting the further subsidence of the Issyk-Kul lake bottom and formation of a pull-apart structure [Buslov et al, 2003[Buslov et al, , 2007. Anticlockwise rotation of the Tien Shan block continued and dextral strike-slip displacement along the Talass-Fergana fault zone occurred at rates of about 10-15 mm/yr.…”

Section: Discussionmentioning

confidence: 99%

“…These margins are defined by a system of overriding thrusts that promote the further subsidence of the Issyk-Kul basin bottom and the formation of a pull-apart structure ( fig. 5, 6) within the central Issyk-Kul basin [Buslov et al, 2003[Buslov et al, , 2007. The structural pattern of the pre-Mesozoic Tien Shan basement clearly influences the Mesozoic and Cenozoic reactivation of the Tien Shan orogen.…”

Section: Problem Solutionmentioning

confidence: 98%

“…2-4). These two processes are responsible for the formation of different structural-geodynamic Tien Shan provinces and are separated by the Talass-Fergana fault zone [Khudoley, 1993;Bakirov et al, 1996;Trapeznikov et al, 1997;Zubovich et al, 2001;Abad et al, 2003;Buslov et al, 2003Buslov et al, , 2007. These tectonic processes responsible for the complicated modern structure of the Tien Shan are still active.…”

Section: Problem Solutionmentioning

confidence: 99%

“…The basement of the Tian Shan consists of the Issyk-Kul (or Central Tien Shan or Ili) and Aktyuz-Boordin microcontinents. They are composed of Paleoproterozoic strongly metamorphosed rocks, covered by Neoproterozoic and Paleozoic volcanogenic-sedimentary and sedimentary rocks [Buslov et al, 2003;Mao et al, 2004;Konopelko et al, 2007;Solomovich, 2007;Wang et al, 2007a; www.intechopen.com Two distinct deformation pulses have been recognized in the Cenozoic evolution of Central Asia for the period of 35-0 Ma based on new and published GPS, magneto-telluric, seismic, thermochronologic, structural and paleogeographic data on the regions of Altai, Transbaikalia, Tien Shan, Pamir, Himalaya and Tibet [Dobretsov et al, 1996;Buslov et al, 1999Buslov et al, , 2003Buslov et al, , 2007Buslov, 2004;Abdrakhmatov et al, 1996Abdrakhmatov et al, , 2001Aitchison et al, 2007;De Grave & Van den haute, 2002;Molnar & Tapponnier, 1975;De Grave et al, 2004Sobel et al, 2006;Tapponnier & Molnar, 1979]. The first deformation pulse started relatively soon after the collision of India.…”

Section: Introductionmentioning

confidence: 99%

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Seismic Hazard in Tien Shan: Basement Structure Control Over the Deformation Induced by Indo-Eurasia Collision

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Rock‐glacier dams in High Asia

Blöthe

Rosenwinkel

Hoeser

et al. 2018

Earth Surf Processes Landf

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Rock glaciers in semiarid mountains contain large amounts of ice and might be important water stores aside from glaciers, lakes, and rivers. Yet whether and how rock glaciers interact with river channels in mountain valleys remains largely unresolved. We examine the potential for rock glaciers to block or disrupt river channels, using a new inventory of more than 2000 intact rock glaciers that we mapped from remotely sensed imagery in the Karakoram (KR), Tien Shan (TS), and Altai (ALT) mountains. We find that between 5% and 14% of the rock glaciers partly buried, blocked, diverted or constricted at least 95 km of mountain rivers in the entire study area. We use a Bayesian robust logistic regression with multiple topographic and climatic inputs to discern those rock glaciers disrupting mountain rivers from those with no obvious impacts. We identify elevation and potential incoming solar radiation (PISR), together with the size of feeder basins, as dominant predictors, so that lower‐lying and larger rock glaciers from larger basins are more likely to disrupt river channels. Given that elevation and PISR are key inputs for modelling the regional distribution of mountain permafrost from the positions of rock‐glacier toes, we infer that river‐blocking rock glaciers may be diagnostic of non‐equilibrated permafrost. Principal component analysis adds temperature evenness and wet‐season precipitation to the controls that characterise rock glaciers impacting on rivers. Depending on the choice of predictors, the accuracy of our classification is moderate to good with median posterior area‐under‐the‐curve values of 0.71–0.89. Clarifying whether rapidly advancing rock glaciers can physically impound rivers, or fortify existing dams instead, deserves future field investigation. We suspect that rock‐glacier dams are conspicuous features that have a polygenetic history and encourage more research on the geomorphic coupling between permafrost lobes, river channels, and the sediment cascades of semiarid mountain belts. © 2018 John Wiley & Sons, Ltd.

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Cenozoic tectonic and geodynamic evolution of the Kyrgyz Tien Shan Mountains: A review of geological, thermochronological and geophysical data

Cited by 95 publications

References 22 publications

Late-Paleozoic emplacement and Meso-Cenozoic reactivation of the southern Kazakhstan granitoid basement

Late-Paleozoic emplacement and Meso-Cenozoic reactivation of the southern Kazakhstan granitoid basement

Seismic Hazard in Tien Shan: Basement Structure Control Over the Deformation Induced by Indo-Eurasia Collision

Rock‐glacier dams in High Asia

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