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[[File:West Tian Shan mountains.jpg|thumb|West Tian Shan mountains]]
[[File:West Tian Shan mountains.jpg|thumb|West Tian Shan mountains]]
The [[Tian Shan]] is a 2500&nbsp;km long, up to 7400&nbsp;m high, range extending through western [[China]], [[Kazakhstan]], and [[Kyrgyzstan]].<ref name="Jolivet">{{cite journal| author =Jolivet et. al.| title =Mesozoic and Cenozoic Tectonic History of the Central Chinese Tian Shan: Reactivated Tectonic Structures and Active Deformation | journal =Tectonics| Volume = 29 | date =2010 | pages =1-30}}</ref> The central part of the Chinese Tian Shan comprises several [[intermontane]] basins separated by up to 4500-5000&nbsp;m high ranges.<ref name="Jolivet"/> The Tian Shan contains two late [[Paleozoic]] sutures.<ref name="Allen">{{cite journal| author =Allen et. al.| title =Paleozoic accretion and Redeformation of the Chinese Tien Shan Range, Central Asia | journal =Geology| Volume = 18 | date = February 1990 | pages =128-131}}</ref> The older, southern [[suture (geology)|suture]] marks the collision of a [[passive margin]] at the north of the [[Tarim Basin|Tarim]] block and an active [[continental margin]]; subduction under the latter was to the north.<ref name="Allen"/> The younger, northern suture separates a northern [[Carboniferous]] [[island arc]] from an active [[continental margin]] developed over a south-dipping [[subduction zone]].<ref name="Allen"/> The intracontinental weakness of Asia's interior has caused [[deformation (science)|deformation]] in the Tian Shan Range after the collision of [[India]] into [[Asia]].<ref name="Molnar1975">{{cite journal| author =Molnar and Tapponnier| title =Cenozoic Tectonics of Asia: Effects of a Continental Collision | journal =Science | Volume = 189 | date =8 August 1975 | pages =419-426}}</ref> The predominant mode of deformation in the area is [[thrust faulting]].<ref name="Molnar1975"/> The Chinese Tian Shan displays lateral variations in magnitudes of deformation, estimates range from 2.12 to 21&nbsp;km of [[crustal shortening]].<ref name="Burchfiel">{{cite journal| author =Burchfiel et. al.| title =Crustal Shortening on the Margins of the Tien Shan, Xinjiang, China | journal =International Geology Review| Volume = 41 | date =1999 | pages =665-700}}</ref>
The [[Tian Shan]] is a 2500&nbsp;km long, up to 7400&nbsp;m high, range extending through western [[China]], [[Kazakhstan]], and [[Kyrgyzstan]].<ref name="Jolivet"/> The central part of the Chinese Tian Shan comprises several [[intermontane]] basins separated by up to 4500-5000&nbsp;m high ranges.<ref name="Jolivet"/> The Tian Shan contains two late [[Paleozoic]] sutures.<ref name="Allen"/> The older, southern [[suture (geology)|suture]] marks the collision of a [[passive margin]] at the north of the [[Tarim Basin|Tarim]] block and an active [[continental margin]]; subduction under the latter was to the north.<ref name="Allen"/> The younger, northern suture separates a northern [[Carboniferous]] [[island arc]] from an active [[continental margin]] developed over a south-dipping [[subduction zone]].<ref name="Allen"/> The intracontinental weakness of Asia's interior has caused [[deformation (science)|deformation]] in the Tian Shan Range after the collision of [[India]] into [[Asia]].<ref name="Molnar1975"/> The predominant mode of deformation in the area is [[thrust faulting]].<ref name="Molnar1975"/> The Chinese Tian Shan displays lateral variations in magnitudes of deformation, estimates range from 2.12 to 21&nbsp;km of [[crustal shortening]].<ref name="Burchfiel"/>


==Regional background==
=Regional background=
A late [[Paleozoic]] continent-continent collision along Tarim's northern margin created an [[orogenic belt]] along the southern part of the [[Tian Shan]].<ref name="Allen1993">{{cite journal| author =Allen et. al.| title =Paleozoic Collision Tectonics and Magmatism of the Chinese Tien Shan | journal =Tectonophysics| Volume = 220 | date =1993 | pages =89-115}}</ref> The main [[vergence]] of this collision was toward the south; the northern edge of the [[Tarim Block]] was a north facing [[passive continental margin]] prior to collision. The collision exhumed and [[eroded]] [[Devonian]] [[sediments]] in the northwestern part of the [[Tarim Basin]]; [[fold (geology)|fold]]s are gentle, [[long-wavelength]] structures. During the [[Carboniferous]] and Early [[Permian]], [[clastics]] and [[carbonates]] were deposited [[unconformity|unconformably]] over gently tilted Devonian rocks. <ref name="Carroll">{{cite journal| author =Carroll et. al.| title =Late Paleozoic Tectonic Amalgamation of Northwestern China: Sedimentary Record of the Northern Tarim, Northwestern Turpan, and Southern Junggar Basins. | journal =Geol. Soc. Am. Bull.| Volume = 107 | date =1995 | pages =571-594}}</ref> Several fragments and [[island arcs]] collided with Asia's southern margin in the [[Mesozoic]], creating deformation and [[Tectonic uplift|uplift]] in the [[Tian Shan]] and [[Kunlun Shan]] to the north and south of the Tarin Basin and generating pulses of uplift and nonmarine deposition in it. Mesozoic deformation was minor or absent in most of the basin interior.<ref name"Allen1994">{{cite journal| author =Allen et. al.| title =Cenozoic Tectonics in the Urumqi-Korla Region of the Chinese Tien Shan | journal =Geol. Rundsch.| Volume = 83 | date =1994 | pages =406-416}}</ref> The collision of [[India]] with [[Asia]] is the latest in this series of events. <ref name="Hendrix">{{cite journal| author =Hendrix et. al.| title =Sedimentary Record and Climatic Implications of Recurrent Deformation in the Tian Shan | journal =Geol. Soc. Am. Bull.| Volume = 104 | date =1992 | pages =53-79}}</ref> [[Crustal shortening]] is the predominant style of [[Cenozoic]] deformation in the Tian Shan,<ref name="Yin">{{cite journal| author =Yin et. al.| title =Late Cenozoic Tectonic Evolution of the Southern Chinese Tian Shan | journal =Tectonics| Volume = 17 | date =February 1998 | pages =1-27}}</ref> which propagated outward and rose progressively as a wedge-shaped block.<ref name="Yang">{{cite journal| author =Yang et. al.| title =Deformation Patternand Fault Rate in the Tianshan Mountains Inferred from GPS Observations | journal =Science in China| Volume = 51 | date =August 2008 | pages =1064-1080}}</ref>. There are also [[dextral]] NW-SE trending [[strike slip faults]], which either merge with or crosscut east-west trending [[thrust systems]]. The [[Talas-Fergana Fault]] is the longest of these structures.<ref name=Allen1999">{{cite journal| author =Allen et. al.| title =Late Cenozoic tectonics of the Kepingtage Thrust Zone | journal =Tectonics| Volume = 18 | date =August 1999 | pages =639-654}}</ref>
A late [[Paleozoic]] continent-continent collision along Tarim's northern margin created an [[orogenic belt]] along the southern part of the [[Tian Shan]].<ref name="Allen1993"/> The main [[vergence]] of this collision was toward the south; the northern edge of the [[Tarim Block]] was a north facing [[passive continental margin]] prior to collision. The collision exhumed and [[eroded]] [[Devonian]] [[sediments]] in the northwestern part of the [[Tarim Basin]]; [[fold (geology)|fold]]s are gentle, [[long-wavelength]] structures. During the [[Carboniferous]] and Early [[Permian]], [[clastics]] and [[carbonates]] were deposited [[unconformity|unconformably]] over gently tilted Devonian rocks. <ref name="Carroll"/> Several fragments and [[island arcs]] collided with Asia's southern margin in the [[Mesozoic]], creating deformation and [[Tectonic uplift|uplift]] in the [[Tian Shan]] and [[Kunlun Shan]] to the north and south of the Tarin Basin and generating pulses of uplift and nonmarine deposition in it. Mesozoic deformation was minor or absent in most of the basin interior.<ref name="Allen1994"/> The collision of [[India]] with [[Asia]] is the latest in this series of events. <ref name="Hendrix"/> [[Crustal shortening]] is the predominant style of [[Cenozoic]] deformation in the Tian Shan,<ref name="Yin"/> which propagated outward and rose progressively as a wedge-shaped block.<ref name="Yang"/>. There are also [[dextral]] NW-SE trending [[strike slip faults]], which either merge with or crosscut east-west trending [[thrust systems]]. The [[Talas-Fergana Fault]] is the longest of these structures.<ref name="Allen1999"/>


==GPS velocity field==
=GPS velocity field=
Most of the convergence between the Tarim Basin and the [[Kazakh Platform]] is absorbed within the Tian Shan, localized zones of shortening at rates of ~2mm/yr to as many as 6mm/yr lie within the Tian Shan.<ref name="Zubovich">{{cite journal| author =Zubovich et. al.| title =GPS Velocity Field for the Tien Shan and Surrounding Regions | journal =Tectonics| Volume = 29 | date =2010 | pages =1-23}}</ref> The [[GPS]] [[velocity field]] reveals that the total amount of convergence in the Tian Shan is not uniformly distributed across the range, with 80-90% of the North-South shortening absorbed along the southern and northern edges, and relatively little deformation accommodated within the interior.<ref name="Yang"/> Slip rates on NW-SE trending strike-slip faults range from 1-4&nbsp;mm/yr.<ref name="Yang"/> Slip rates on WE-SN trending gently-dipping [[detachment fault]] vary from 10-13&nbsp;mm/yr for the southwest Tian Shan to 2-5&nbsp;mm/y for eastern Tian Shan.<ref name="Yang"/> The [[elastic strain]] confined in the upper crustal layer above the [[detachment]] ultimately releases through infrequent great [[earthquakes]] in the Tian Shan, resulting in considerable folding and faulting at their margins.<ref name="Yang"/> A recent GPS velocity field study estimates the Tarim Basin is thrust beneath the Tian Shan at ~4-7&nbsp;mm/yr.<ref name="Zubovich"/> GPS data places a bound of ~4mm/yr on the rate of crustal shortening across the [[Chatkal]] and neighboring ranges on the northwest margin of the [[Ferghana Valley]], and they limit the present day slip rate on the right lateral Talas Ferghana Fault to less than ~2&nbsp;mm/yr.<ref name="Zubovich"/> GPS data supports geologic evidence that indicates the northern margin of the Pamir overthrusts the [[Alay Valley]] and requires a rate of at least 10-15&nbsp;mm/yr.<ref name="Zubovich"/>
Most of the convergence between the Tarim Basin and the [[Kazakh Platform]] is absorbed within the Tian Shan, localized zones of shortening at rates of ~2mm/yr to as many as 6mm/yr lie within the Tian Shan.<ref name="Zubovich"/> The [[GPS]] [[velocity field]] reveals that the total amount of convergence in the Tian Shan is not uniformly distributed across the range, with 80-90% of the North-South shortening absorbed along the southern and northern edges, and relatively little deformation accommodated within the interior.<ref name="Yang"/> Slip rates on NW-SE trending strike-slip faults range from 1-4&nbsp;mm/yr.<ref name="Yang"/> Slip rates on WE-SN trending gently-dipping [[detachment fault]] vary from 10-13&nbsp;mm/yr for the southwest Tian Shan to 2-5&nbsp;mm/y for eastern Tian Shan.<ref name="Yang"/> The [[elastic strain]] confined in the upper crustal layer above the [[detachment]] ultimately releases through infrequent great [[earthquakes]] in the Tian Shan, resulting in considerable folding and faulting at their margins.<ref name="Yang"/> A recent GPS velocity field study estimates the Tarim Basin is thrust beneath the Tian Shan at ~4-7&nbsp;mm/yr.<ref name="Zubovich"/> GPS data places a bound of ~4mm/yr on the rate of crustal shortening across the [[Chatkal]] and neighboring ranges on the northwest margin of the [[Ferghana Valley]], and they limit the present day slip rate on the right lateral Talas Ferghana Fault to less than ~2&nbsp;mm/yr.<ref name="Zubovich"/> GPS data supports geologic evidence that indicates the northern margin of the Pamir overthrusts the [[Alay Valley]] and requires a rate of at least 10-15&nbsp;mm/yr.<ref name="Zubovich"/>


==Tectonic Subdivisions==
=Tectonic Subdivisions=
[[File:TianShan Tectonic Map.jpg|thumb|right|General Tectonic Map of the Tian Shan modified from Jolivet 2010. The Kazakh Platform is to the northwest (not seen in this image).]]
[[File:TianShan Tectonic Map.jpg|thumb|right|General Tectonic Map of the Tian Shan modified from Jolivet 2010. The Kazakh Platform is to the northwest (not seen in this image).]]
===Kuqa Foreland===
==Kuqa Foreland==
The [[Kuqa Basin]] is bounded by the [[Tarim Basin]] to the south and the Tian Shan [[orogenic belt]] to the north. The Kuqa depression was probably part of the north Tarim continental margin at the [[Paleozoic]] time.<ref name="Jia">{{cite journal| author =Jia et al., 1998 D. Jia, H.-F. Lu, D.-S. Cai, S.-M. Wu, Y.-S. Shi and C.-M. Chen.| title =Structural features of northern Tarim Basin: implications for regional tectonics and petroleum traps. | journal =AAPG Bulletin.| Volume = 81 | date =1998 | pages =147–159}}</ref> The paleo-Tian Shan ocean, experienced multi-stage open-close cycles during the Paleozoic, closed at the end of Early Permian and formed the paleo-Tian Shan collisional orogenic belt.<ref name="Jia"/> The formation and evolution of the [[Kuqa foreland]] fold belt is related to the multi-phase reactivated and uplifted Tian Shan orogenic belt during the [[Mesozoic]]-[[Cenozoic]].<ref name="Jia"/> Under the [[Compression (geology)|compressive]] [[tectonic loading]] and [[gravitational loading]], the Kuqa depression became an intra-continental [[foreland basin]]. The [[cross-section]] of the basin is asymmetric and its depositional center lies close to the Tian Shan orogenic belt, the sediment thickness thinned towards the Tarim [[craton]].<ref name="Jia"/>
The [[Kuqa Basin]] is bounded by the [[Tarim Basin]] to the south and the Tian Shan [[orogenic belt]] to the north. The Kuqa depression was probably part of the north Tarim continental margin at the [[Paleozoic]] time. The paleo-Tian Shan ocean, experienced multi-stage open-close cycles during the Paleozoic, closed at the end of Early Permian and formed the paleo-Tian Shan collisional orogenic belt. The formation and evolution of the [[Kuqa foreland]] fold belt is related to the multi-phase reactivated and uplifted Tian Shan orogenic belt during the [[Mesozoic]]-[[Cenozoic]]. Under the [[Compression (geology)|compressive]] [[tectonic loading]] and [[gravitational loading]], the Kuqa depression became an intra-continental [[foreland basin]]. The [[cross-section]] of the basin is asymmetric and its depositional center lies close to the Tian Shan orogenic belt, the sediment thickness thinned towards the Tarim [[craton]].<ref name="Jia"/>


===Borohoro Range===
==Borohoro Range==
To the north, the [[Borohoro Range]] seperates the [[Yili Basin]] from the North Tian Shan [[piedmont]] in the [[Junggar Basin]]. The basement of the Borohoro Range is mainly composed of a [[Devonian]] to Carboniferous [[magmatic arc]] intruded by Devonian [[granitoids]].<ref name="Zhou">{{cite journal| author =Zhou, D., S. A. Graham, E. Z. Chang, B. Wang, and B. Hacker.| title =Paleozoic tectonic amalgamation of the Chinese Tian Shan: Evidence from a transect along the Dushanzi‐Kuqa Highway, in Paleozoic and Mesozoic Tectonic Evolution of Central and Eastern Asia: From Continental Assembly to Intracontinental Deformation | journal =Geological Society of America.| Volume = 194| date =2001 | pages =71–99}}</ref> On the southern and northern sides of the range, the basement is capped by Permian sediments, mainly carbonates.<ref name="Jolivet"/> The Borohoro Range is itself separated in two compartments by the small, elongated [[Hexilagen basin]] in which Early [[Jurassic]] [[coal]] series are exposed.<ref name="Jolivet"/>
To the north, the [[Borohoro Range]] seperates the [[Yili Basin]] from the North Tian Shan [[piedmont]] in the [[Junggar Basin]]. The basement of the Borohoro Range is mainly composed of a [[Devonian]] to Carboniferous [[magmatic arc]] intruded by Devonian [[granitoids]].<ref name="Zhou"/> On the southern and northern sides of the range, the basement is capped by Permian sediments, mainly carbonates.<ref name="Jolivet"/> The Borohoro Range is itself separated in two compartments by the small, elongated [[Hexilagen basin]] in which Early [[Jurassic]] [[coal]] series are exposed.<ref name="Jolivet"/>


===Yili Basin===
==Yili Basin==
The [[Yili basin]] lies souths of the Borohoro Range and is bordered by sutures and [[fault zone]]s in the western Chinese Tian Shan belt.<ref name="Wang">{{cite journal| author =Bo Wang, Michel Faure, Liangshu Shu, Dominique Cluzel, Jacques Charvet, Koen De Jong and Yan Chen.| title = Paleozoic tectonic evolution of the Yili Block, western Chinese Tianshan | journal = Bulletin de la Societe Geologique de France.| Volume = 179 | issue =5 | date = September 2008 | pages =483-490}}</ref> Like the rest of the Tian Shan belt, the Yili block underwent a polyphase evolution including [[subduction]] of [[oceanic crust]] and collision with [[micro-continents]] and [[volcanic arc]]s.<ref name="Wang"/> The southern boundary of the Yili basin is formed of [[Proterozoic]] basement and Early Paleozoic platform sediments, tectonically overlain by oceanic high-pressure [[metamorphic]] rocks and [[ophiolites]].<ref name="Wang"/> It has been involved in a south-dipping subduction associated with the closure of the paleo-Tian Shan Ocean and the subsequent [[collision]] with a [[micro-continent]] correlated with Central Tian Shan.<ref name="Wang"/> This tectonic event resulted in top-to-the-north [[ductile]] thrusting observed in oceanic high pressure metamorphic rocks and Proterozoic basement as well.<ref name="Wang"/> During the Late Paleozoic, the northern boundary of the Yili basin was an active continental margin related to the southward subduction of the North Tianshan oceanic basin, this boundary is represented by Late [[Carboniferous]] [[turbidite]] and ophiolitic melange.<ref name="Wang"/> The southern and northern boundaries have been both reworked by Permian strike-slip faults.<ref name="Wang"/>
The [[Yili basin]] lies souths of the Borohoro Range and is bordered by sutures and [[fault zone]]s in the western Chinese Tian Shan belt. Like the rest of the Tian Shan belt, the Yili block underwent a polyphase evolution including [[subduction]] of [[oceanic crust]] and collision with [[micro-continents]] and [[volcanic arc]]s. The southern boundary of the Yili basin is formed of [[Proterozoic]] basement and Early Paleozoic platform sediments, tectonically overlain by oceanic high-pressure [[metamorphic]] rocks and [[ophiolites]]. It has been involved in a south-dipping subduction associated with the closure of the paleo-Tian Shan Ocean and the subsequent [[collision]] with a [[micro-continent]] correlated with Central Tian Shan. This tectonic event resulted in top-to-the-north [[ductile]] thrusting observed in oceanic high pressure metamorphic rocks and Proterozoic basement as well. During the Late Paleozoic, the northern boundary of the Yili basin was an active continental margin related to the southward subduction of the North Tianshan oceanic basin, this boundary is represented by Late [[Carboniferous]] [[turbidite]] and ophiolitic melange. The southern and northern boundaries have been both reworked by Permian strike-slip faults.<ref name="Wang"/>


===Issyk-Kul and Fargana Basins===
==Issyk-Kul and Fargana Basins==
The general [[strike and dip|strike]] of the Tian Shan ranges is East-Northeast, but there are significant deviations, especially near the major [[Talas-Fergana fault]].<ref name="Cobbold">{{cite journal| author =P.R. Cobbold, E. Sadybakasov, J.C. Thomas.| title =Cenozoic Transpression and Basin Development, Kyrghyz Tienshan Central Asia | journal =Geodynamic Evolution of Sedimentary Basins, International Symposium.| Country= Moscow | date =2004 | pages =181-202}}</ref> A striking feature of western Tian Shan is the large number of [[intermontane]] [[basin]]s containing Cenozoic rocks, prominent basins include the [[Fergana Basin]] in the southwest, the [[Issyk-Kul Basin]] in the east and [[Naryn Basin]] in the south.<ref name="Cobbold"/> On the edges of the Tian Shan, there are foreland basins with Cenozoic sediments several km thick. The Talas-Fergana fault is an active [[strike slip fault]] in which [[Quaternary]] offset is about 10&nbsp;km and the total offset since the Paleozoic is about 200km.<ref name="Cobbold"/> In the Issyk-Kul and Fergana basins, [[Jurassic]] [[sandstones]] and coal bearing [[shale]]s of continental origin unconformably overlie Carboniferous (and older) rocks.<ref name="Cobbold"/> In Issyk-Kul, the stratigraphic sequence is only a few hundred meters thick and consists mainly of [[quartzite sandstones]].<ref name="Cobbold"/> In Fergana, it is less than 1km thick. Metamorphosed ophiolites mark the suture of the Paleozoic [[Turkestan Ocean]].<ref name="Cobbold"/> This suture runs along the southern edge of the Naryn basin and is offset right laterally by the Talas-Fergana fault.<ref name="Cobbold"/> It then runs along the southern edge of the Fergana basin, before veering northwards toward the [[Aral Sea]] and the [[Urals]].<ref name="Cobbold"/>
The general [[strike and dip|strike]] of the Tian Shan ranges is East-Northeast, but there are significant deviations, especially near the major [[Talas-Fergana fault]]. A striking feature of western Tian Shan is the large number of [[intermontane]] [[basin]]s containing Cenozoic rocks, prominent basins include the [[Fergana Basin]] in the southwest, the [[Issyk-Kul Basin]] in the east and [[Naryn Basin]] in the south. On the edges of the Tian Shan, there are foreland basins with Cenozoic sediments several km thick. The Talas-Fergana fault is an active [[strike slip fault]] in which [[Quaternary]] offset is about 10&nbsp;km and the total offset since the Paleozoic is about 200km. In the Issyk-Kul and Fergana basins, [[Jurassic]] [[sandstones]] and coal bearing [[shale]]s of continental origin unconformably overlie Carboniferous (and older) rocks. In Issyk-Kul, the stratigraphic sequence is only a few hundred meters thick and consists mainly of [[quartzite sandstones]]. In Fergana, it is less than 1km thick. Metamorphosed ophiolites mark the suture of the Paleozoic [[Turkestan Ocean]]. This suture runs along the southern edge of the Naryn basin and is offset right laterally by the Talas-Fergana fault. It then runs along the southern edge of the Fergana basin, before veering northwards toward the [[Aral Sea]] and the [[Urals]].<ref name="Cobbold"/>


==References==
=References=
{{Reflist |refs=<ref name="Allen">{{cite journal |last=Windley |first=B.F. |first2=M. B. |last2=Allen |first3=C. |last3=Zhang |first4=Z-Y |last4=Zhao |first5=G-R |last5=Wang |display-authors=1 |date=February 1990 |title=Paleozoic accretion and Cenozoic Redeformation of the Chinese Tien Shan Range, Central Asia |journal=Geology |volume=18 |issue=2 |pages=128–131 |doi=10.1130/0091-7613(1990)​018<0128:PAACRO>​2.3.CO;2}}</ref>
{{Reflist}}

<ref name="Allen1993">{{cite journal |last=Allen |first=M.B. |first2= B.F.2 Windley |first3=Chi |last3=Zhang |display-authors=1 |date=1993 |title=Paleozoic Collision Tectonics and Magmatism of the Chinese Tien Shan |journal=Tectonophysics |volume=220 |issue=1-4 |pages=89-115 |doi=10.1016/0040-1951(93)90225-9 }}</ref>

<ref name="Allen1994">{{cite journal |last=Allen |first=M.B. |first2= B.F.2 Windley |first3=Chi |last3=Zhang |display-authors=1 |date=1994 |title=Cenozoic Tectonics in the Urumqi-Korla Region of the Chinese Tien Shan |journal=Geologische Rundschau |volume=83 |issue=2 |pages=406-416 |doi=10.1007/BF00210554}}</ref>

<ref name="Allen1999">{{cite journal|last=Allen |first=M.B. |first2=Stephen J. |last2=Vincent |first3=Paul J. |last3= Wheeler |display-authors=1 |date=August 1999 |title=Late Cenozoic tectonics of the Kepingtage thrust zone: Interactions of the Tien Shan and Tarim Basin, northwest China |journal=Tectonics |volume=18 |issue=4 |pages=639-654 |doi=10.1029/1999TC900019 }}</ref>

<ref name="Burchfiel">{{cite journal |last=Burchfield |first=B.C. |first2=E. T. |last2=Brown |first3=Deng |last3=Qidong |first4=Feng |last4=Xianyue |first5=Li |last5=Jun |first6=Peter |last6=Molnar |first7=Shi |last7=Jianbang |first8=Wu |last8=Zhangming |first9=You |last9=Huichuan |display-authors=1 |title=Crustal Shortening on the Margins of the Tien Shan, Xinjiang, China |date=1999 |journal=International Geology Review |volume=41 |isse=8 |pages=665-700 |doi=10.1080/00206819909465164}}</ref>

<ref name="Carroll">{{cite journal |last=Carroll |first=A.R. |first2=S. A. |last2=Graham |first3=M. S. |last3=Hendrix |first4=D. |last4=Ying |first5=D. |last5=Zhou |display-authors=1 |date=1995 |title=Late Paleozoic Tectonic Amalgamation of Northwestern China: Sedimentary Record of the Northern Tarim, Northwestern Turpan, and Southern Junggar Basins |journal=Geological Society of America Bulletin |volume=107 |issue=5 |pages=571-594 |doi=10.1130/​0016-7606(1995)​107<0571:LPTAON>​2.3.CO;2 }}</ref>

<ref name="Cobbold">{{cite conference |first=P.R. |last=Cobbold |first2=E. |last2=Sadybakasov |first3=J.C. |last3=Thomas. |display-authors=1 |date=2004 |title=Cenozoic Transpression and Basin Development, Kyrghyz Tienshan Central Asia |booktitle=Geodynamic Evolution of Sedimentary Basins, International Symposium|conference=(Moscow, May 18–23, 1992) |location=Paris|publisher=Technip |pages=181-202 |url=http://books.google.ca/books?id=jbuKCvyRCsgC&lpg=PP1&pg=PA183 |isbn=2710806924}}</ref>

<ref name="Hendrix">{{cite journal |last=Hendrix |first=Marc S. |first2=Stephan A. |last2=Graham |first3=Alan R. |last3=Carroll |first4=Edward R. |last4=Sobel |first5=Cleavy L. |last5=Mcknight |first6=Benjamin J. |last6=Schulein |first7=Zuoxun |last7=Wang |display-authors=1 |date=1992 |title=Sedimentary Record and Climatic Implications of Recurrent Deformation in the Tian Shan: Evidence from Mesozoic strata of the north Tarim, south Junggar, and Turpan basins, northwest China |journal=Geological Society of America Bulletin |volume=104 |issue=1 |pages=53-79 |doi=10.1130/​0016-7606(1992)​104<0053:SRACIO>​2.3.CO;2}}</ref>

<ref name="Jia">{{cite journal |first= Dong |last=Jia |first2=Huafu |last2=Lu |first3=Dongsheng |last3=Cai |first=4Shimin |last4=Wu |first5=Yangshen |last5=Shi |first6=Chuming |last6=Chen |display-authors=1 |date=1998 |title=Structural Features of Northern Tarim Basin: Implications for Regional Tectonics and Petroleum Traps |journal=AAPG Bulletin. |volume=81 |issue=1 |pages=147–159}}</ref>

<ref name="Jolivet">{{cite journal |last=Jolivet |first=M. |first2=S. |last2=Dominguez |first3=J. |last3=Charreau |first4=Y. |last4=Chen |first5=Yongan |last5=Li |first6=Qingchen |last6=Wang |display-authors=1 |date=2010 |title=Mesozoic and Cenozoic Tectonic History of the Central Chinese Tian Shan: Reactivated Tectonic Structures and Active Deformation |journal=Tectonics |volume=29 |pages=1-30 |doi=10.1029/2010TC002712}}</ref>

<ref name="Molnar1975">{{cite journal |last=Molnar |first=Peter |first2=Paul |last2=Tapponnier |display-authors=1 |date=8 August 1975 |title=Cenozoic Tectonics of Asia: Effects of a Continental Collision |journal=Science |issue=4201 |volume=189 |pages=419-426 |doi=10.1126/science.189.4201.419 |jstor=1740465}}</ref>

<ref name="Wang">{{cite journal |first=Bo |last=Wang |first2=Michel |last2=Faure |first3=Liangshu |last3=Shu |first4=Dominique |last4=Cluzel |first5=Jacques |last5=Charvet |first6=Koen |last6=De Jong |first7=Yan |last7=Chen |display-authors=1 |date=September 2008 |title=Paleozoic tectonic evolution of the Yili Block, western Chinese Tianshan |journal=Bulletin de la Société Géologique de France |volume=179 |issue=5 |pages=483-490 |doi=10.2113/​gssgfbull.179.5.483}}</ref>

<ref name="Yang">{{cite journal |last=Yang |first=Shao Min |first2=Jie Li and Qi Wang |display-authors=1 |date=August 2008 |title=Deformation Pattern and Fault Rate in the Tianshan Mountains Inferred from GPS Observations |journal=Science in China, Series D: Earth Sciences |volume=51 |issue=8 |pages=1064-1080 |doi=10.1007/s11430-008-0090-8}}</ref>

<ref name="Yin">{{cite journal |last=Yin |first=A. |first2=S. |last2=Nie |first3=P. |last3=Craig |first4=T. M. |last4=Harrison |first5=F. J. |last5=Ryerson |first6=Qian |last6=Xianglin |first7=Yang |last7=Geng |display-authors=1 |date=February 1998 |title=Late Cenozoic Tectonic Evolution of the Southern Chinese Tian Shan |journal=Tectonics |volume=17 |issue=1 |pages=1-27 |doi=10.1029/97TC03140}}</ref>

<ref name="Zhou">{{cite journal |last=Zhou |first=Da |first2=Stephan A. |last2=Graham |first3=Edmund Z. |last3=Chang |first4=Baoyu |last4=Wang |first5=Bradley |last5=Hacker |display-authors=1 |date=2001 |title=Paleozoic tectonic amalgamation of the Chinese Tian Shan: Evidence from a transect along the Dushanzi-Kuqa Highway |journal=GSA Memoirs |volume=194 |pages=71–99 |doi=10.1130/0-8137-1194-0.23}} (Published as ''Paleozoic and Mesozoic tectonic evolution of central Asia: from continental assembly to intracontinental deformation'', ISBN 0-8137-1194-0)</ref>

<ref name="Zubovich">{{cite journal|last=Zubovich |first=Alexander V. |coauthors= and al. |date=2010 |title=GPS Velocity Field for the Tien Shan and Surrounding Regions |journal=Tectonics |volume=29 |pages=1-23 |doi=10.1029/2010TC002772}}</ref>}}
[[category:Geology of Central Asia]]
[[category:Geology of Central Asia]]
[[Category:Tectonics]]
[[Category:Tectonics]]

Revision as of 22:46, 17 November 2011

West Tian Shan mountains

The Tian Shan is a 2500 km long, up to 7400 m high, range extending through western China, Kazakhstan, and Kyrgyzstan.[1] The central part of the Chinese Tian Shan comprises several intermontane basins separated by up to 4500-5000 m high ranges.[1] The Tian Shan contains two late Paleozoic sutures.[2] The older, southern suture marks the collision of a passive margin at the north of the Tarim block and an active continental margin; subduction under the latter was to the north.[2] The younger, northern suture separates a northern Carboniferous island arc from an active continental margin developed over a south-dipping subduction zone.[2] The intracontinental weakness of Asia's interior has caused deformation in the Tian Shan Range after the collision of India into Asia.[3] The predominant mode of deformation in the area is thrust faulting.[3] The Chinese Tian Shan displays lateral variations in magnitudes of deformation, estimates range from 2.12 to 21 km of crustal shortening.[4]

Regional background

A late Paleozoic continent-continent collision along Tarim's northern margin created an orogenic belt along the southern part of the Tian Shan.[5] The main vergence of this collision was toward the south; the northern edge of the Tarim Block was a north facing passive continental margin prior to collision. The collision exhumed and eroded Devonian sediments in the northwestern part of the Tarim Basin; folds are gentle, long-wavelength structures. During the Carboniferous and Early Permian, clastics and carbonates were deposited unconformably over gently tilted Devonian rocks. [6] Several fragments and island arcs collided with Asia's southern margin in the Mesozoic, creating deformation and uplift in the Tian Shan and Kunlun Shan to the north and south of the Tarin Basin and generating pulses of uplift and nonmarine deposition in it. Mesozoic deformation was minor or absent in most of the basin interior.[7] The collision of India with Asia is the latest in this series of events. [8] Crustal shortening is the predominant style of Cenozoic deformation in the Tian Shan,[9] which propagated outward and rose progressively as a wedge-shaped block.[10]. There are also dextral NW-SE trending strike slip faults, which either merge with or crosscut east-west trending thrust systems. The Talas-Fergana Fault is the longest of these structures.[11]

GPS velocity field

Most of the convergence between the Tarim Basin and the Kazakh Platform is absorbed within the Tian Shan, localized zones of shortening at rates of ~2mm/yr to as many as 6mm/yr lie within the Tian Shan.[12] The GPS velocity field reveals that the total amount of convergence in the Tian Shan is not uniformly distributed across the range, with 80-90% of the North-South shortening absorbed along the southern and northern edges, and relatively little deformation accommodated within the interior.[10] Slip rates on NW-SE trending strike-slip faults range from 1-4 mm/yr.[10] Slip rates on WE-SN trending gently-dipping detachment fault vary from 10-13 mm/yr for the southwest Tian Shan to 2-5 mm/y for eastern Tian Shan.[10] The elastic strain confined in the upper crustal layer above the detachment ultimately releases through infrequent great earthquakes in the Tian Shan, resulting in considerable folding and faulting at their margins.[10] A recent GPS velocity field study estimates the Tarim Basin is thrust beneath the Tian Shan at ~4-7 mm/yr.[12] GPS data places a bound of ~4mm/yr on the rate of crustal shortening across the Chatkal and neighboring ranges on the northwest margin of the Ferghana Valley, and they limit the present day slip rate on the right lateral Talas Ferghana Fault to less than ~2 mm/yr.[12] GPS data supports geologic evidence that indicates the northern margin of the Pamir overthrusts the Alay Valley and requires a rate of at least 10-15 mm/yr.[12]

Tectonic Subdivisions

General Tectonic Map of the Tian Shan modified from Jolivet 2010. The Kazakh Platform is to the northwest (not seen in this image).

Kuqa Foreland

The Kuqa Basin is bounded by the Tarim Basin to the south and the Tian Shan orogenic belt to the north. The Kuqa depression was probably part of the north Tarim continental margin at the Paleozoic time. The paleo-Tian Shan ocean, experienced multi-stage open-close cycles during the Paleozoic, closed at the end of Early Permian and formed the paleo-Tian Shan collisional orogenic belt. The formation and evolution of the Kuqa foreland fold belt is related to the multi-phase reactivated and uplifted Tian Shan orogenic belt during the Mesozoic-Cenozoic. Under the compressive tectonic loading and gravitational loading, the Kuqa depression became an intra-continental foreland basin. The cross-section of the basin is asymmetric and its depositional center lies close to the Tian Shan orogenic belt, the sediment thickness thinned towards the Tarim craton.[13]

Borohoro Range

To the north, the Borohoro Range seperates the Yili Basin from the North Tian Shan piedmont in the Junggar Basin. The basement of the Borohoro Range is mainly composed of a Devonian to Carboniferous magmatic arc intruded by Devonian granitoids.[14] On the southern and northern sides of the range, the basement is capped by Permian sediments, mainly carbonates.[1] The Borohoro Range is itself separated in two compartments by the small, elongated Hexilagen basin in which Early Jurassic coal series are exposed.[1]

Yili Basin

The Yili basin lies souths of the Borohoro Range and is bordered by sutures and fault zones in the western Chinese Tian Shan belt. Like the rest of the Tian Shan belt, the Yili block underwent a polyphase evolution including subduction of oceanic crust and collision with micro-continents and volcanic arcs. The southern boundary of the Yili basin is formed of Proterozoic basement and Early Paleozoic platform sediments, tectonically overlain by oceanic high-pressure metamorphic rocks and ophiolites. It has been involved in a south-dipping subduction associated with the closure of the paleo-Tian Shan Ocean and the subsequent collision with a micro-continent correlated with Central Tian Shan. This tectonic event resulted in top-to-the-north ductile thrusting observed in oceanic high pressure metamorphic rocks and Proterozoic basement as well. During the Late Paleozoic, the northern boundary of the Yili basin was an active continental margin related to the southward subduction of the North Tianshan oceanic basin, this boundary is represented by Late Carboniferous turbidite and ophiolitic melange. The southern and northern boundaries have been both reworked by Permian strike-slip faults.[15]

Issyk-Kul and Fargana Basins

The general strike of the Tian Shan ranges is East-Northeast, but there are significant deviations, especially near the major Talas-Fergana fault. A striking feature of western Tian Shan is the large number of intermontane basins containing Cenozoic rocks, prominent basins include the Fergana Basin in the southwest, the Issyk-Kul Basin in the east and Naryn Basin in the south. On the edges of the Tian Shan, there are foreland basins with Cenozoic sediments several km thick. The Talas-Fergana fault is an active strike slip fault in which Quaternary offset is about 10 km and the total offset since the Paleozoic is about 200km. In the Issyk-Kul and Fergana basins, Jurassic sandstones and coal bearing shales of continental origin unconformably overlie Carboniferous (and older) rocks. In Issyk-Kul, the stratigraphic sequence is only a few hundred meters thick and consists mainly of quartzite sandstones. In Fergana, it is less than 1km thick. Metamorphosed ophiolites mark the suture of the Paleozoic Turkestan Ocean. This suture runs along the southern edge of the Naryn basin and is offset right laterally by the Talas-Fergana fault. It then runs along the southern edge of the Fergana basin, before veering northwards toward the Aral Sea and the Urals.[16]

References

  1. ^ a b c d Jolivet, M.; et al. (2010). "Mesozoic and Cenozoic Tectonic History of the Central Chinese Tian Shan: Reactivated Tectonic Structures and Active Deformation". Tectonics. 29: 1–30. doi:10.1029/2010TC002712.
  2. ^ a b c Windley, B.F.; et al. (February 1990). "Paleozoic accretion and Cenozoic Redeformation of the Chinese Tien Shan Range, Central Asia". Geology. 18 (2): 128–131. doi:10.1130/0091-7613(1990)​018<0128:PAACRO>​2.3.CO;2. {{cite journal}}: zero width space character in |doi= at position 24 (help)
  3. ^ a b Molnar, Peter; et al. (8 August 1975). "Cenozoic Tectonics of Asia: Effects of a Continental Collision". Science. 189 (4201): 419–426. doi:10.1126/science.189.4201.419. JSTOR 1740465.
  4. ^ Burchfield, B.C.; et al. (1999). "Crustal Shortening on the Margins of the Tien Shan, Xinjiang, China". International Geology Review. 41: 665–700. doi:10.1080/00206819909465164. {{cite journal}}: Unknown parameter |isse= ignored (help)
  5. ^ Allen, M.B.; et al. (1993). "Paleozoic Collision Tectonics and Magmatism of the Chinese Tien Shan". Tectonophysics. 220 (1–4): 89–115. doi:10.1016/0040-1951(93)90225-9. {{cite journal}}: |first2= missing |last2= (help)CS1 maint: numeric names: authors list (link)
  6. ^ Carroll, A.R.; et al. (1995). "Late Paleozoic Tectonic Amalgamation of Northwestern China: Sedimentary Record of the Northern Tarim, Northwestern Turpan, and Southern Junggar Basins". Geological Society of America Bulletin. 107 (5): 571–594. doi:10.1130/​0016-7606(1995)​107<0571:LPTAON>​2.3.CO;2. {{cite journal}}: zero width space character in |doi= at position 9 (help)
  7. ^ Allen, M.B.; et al. (1994). "Cenozoic Tectonics in the Urumqi-Korla Region of the Chinese Tien Shan". Geologische Rundschau. 83 (2): 406–416. doi:10.1007/BF00210554. {{cite journal}}: |first2= missing |last2= (help)CS1 maint: numeric names: authors list (link)
  8. ^ Hendrix, Marc S.; et al. (1992). "Sedimentary Record and Climatic Implications of Recurrent Deformation in the Tian Shan: Evidence from Mesozoic strata of the north Tarim, south Junggar, and Turpan basins, northwest China". Geological Society of America Bulletin. 104 (1): 53–79. doi:10.1130/​0016-7606(1992)​104<0053:SRACIO>​2.3.CO;2. {{cite journal}}: zero width space character in |doi= at position 9 (help)
  9. ^ Yin, A.; et al. (February 1998). "Late Cenozoic Tectonic Evolution of the Southern Chinese Tian Shan". Tectonics. 17 (1): 1–27. doi:10.1029/97TC03140.
  10. ^ a b c d e Yang, Shao Min (August 2008). "Deformation Pattern and Fault Rate in the Tianshan Mountains Inferred from GPS Observations". Science in China, Series D: Earth Sciences. 51 (8): 1064–1080. doi:10.1007/s11430-008-0090-8. {{cite journal}}: |first2= missing |last2= (help); Invalid |display-authors=1 (help)
  11. ^ Allen, M.B.; et al. (August 1999). "Late Cenozoic tectonics of the Kepingtage thrust zone: Interactions of the Tien Shan and Tarim Basin, northwest China". Tectonics. 18 (4): 639–654. doi:10.1029/1999TC900019.
  12. ^ a b c d Zubovich, Alexander V. (2010). "GPS Velocity Field for the Tien Shan and Surrounding Regions". Tectonics. 29: 1–23. doi:10.1029/2010TC002772. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  13. ^ Jia, 4Shimin; et al. (1998). "Structural Features of Northern Tarim Basin: Implications for Regional Tectonics and Petroleum Traps". AAPG Bulletin. 81 (1): 147–159.{{cite journal}}: CS1 maint: numeric names: authors list (link)
  14. ^ Zhou, Da; et al. (2001). "Paleozoic tectonic amalgamation of the Chinese Tian Shan: Evidence from a transect along the Dushanzi-Kuqa Highway". GSA Memoirs. 194: 71–99. doi:10.1130/0-8137-1194-0.23. (Published as Paleozoic and Mesozoic tectonic evolution of central Asia: from continental assembly to intracontinental deformation, ISBN 0-8137-1194-0)
  15. ^ Wang, Bo; et al. (September 2008). "Paleozoic tectonic evolution of the Yili Block, western Chinese Tianshan". Bulletin de la Société Géologique de France. 179 (5): 483–490. doi:10.2113/​gssgfbull.179.5.483. {{cite journal}}: zero width space character in |doi= at position 9 (help)
  16. ^ Cobbold, P.R.; et al. (2004). "Cenozoic Transpression and Basin Development, Kyrghyz Tienshan Central Asia". Geodynamic Evolution of Sedimentary Basins, International Symposium. (Moscow, May 18–23, 1992). Paris: Technip. pp. 181–202. ISBN 2710806924. {{cite conference}}: Unknown parameter |booktitle= ignored (|book-title= suggested) (help)
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