Zhiyuan He

Bo Wang
email: bwang@nju.edu.cn

Xinghua Ni

Johan De Grave

Stéphane Scaillet

Yan Chen

Jiashuo Liu

Xin Zhu

Structural and kinematic evolution of strike-slip shear zones around and in the Central Tianshan: insights for eastward tectonic wedging in the southwest Central Asian Orogenic Belt

Keywords: Conceptualization, Field Investigation, Methodology, Writing -original draft Conceptualization, Field Investigation, Methodology, Writing - Late Paleozoic, Tianshan/Tien Shan, Intracontinental deformation, Transcurrent tectonics, Oblique convergence and accretion, Block rotation

  L'archive ouverte pluridisciplinaire

Introduction

Transcurrent tectonics generally refers to large strike-slip faulting system in which the displacement vector is parallel to the strike of fault due to plate motions on a sphere [START_REF] Freund | Kinematics of transform and transcurrent faults[END_REF][START_REF] Onstott | Proterozoic transcurrent tectonics: palaeomagnetic evidence from Venezuela and Africa[END_REF][START_REF] Beck | On the mechanism of tectonic transport in zones of oblique subduction[END_REF][START_REF] Sylvester | Strike-slip faults[END_REF].

Transcurrent tectonics usually forms at plate boundaries by oblique plate convergence [START_REF] Allen | Transcurrent faults in continental areas[END_REF][START_REF] Fossen | Strain modeling of transpressional and transtensional deformation[END_REF][START_REF] Dewey | Transpression and transtension[END_REF], and accretionary orogeny [START_REF] Mann | Global catalogue, classification and tectonic origin of active restraining-and releasing bends, on strike-slip fault systems[END_REF]. It can also develop as a transfer zone in a rift setting or a fold-and-thrust belt [START_REF] Wilson | A new class of faults and their bearing on continental drift[END_REF][START_REF] Moore | Tectonics of the Najd transcurrent fault system, Saudi Arabia[END_REF]. As one important manifestation, strike-slip shear zones stand for a deep version of intracontinental transcurrent tectonics characterized by plastic deformation and a tabular to sheet-like, planar or curviplanar domains [START_REF] Berthé | Orthogneiss, mylonite and non-coaxial deformation of granites: the example of the Shear zones and mylonites South Armorican Shear Zone[END_REF][START_REF] Ramsay | Shear zone geometry: a review[END_REF][START_REF] Fossen | Structural Geology[END_REF][START_REF] Davis | Structural geology of rocks and regions[END_REF]. Continental-scale strike-slip shear zones typically exhibit ductile deformation fabrics with steeply-dipping foliations [START_REF] Davis | Structural evolution of the Whipple and South Mountains shear zones, southwestern United States[END_REF][START_REF] Tapponnier | The Ailao Shan Red River metamorphic belttertiary left-lateral shear between Indochina and south China[END_REF][START_REF] Leloup | The Ailao Shan-Red River shear zone (Yunnan,China), tertiary transform boundary of Indochina[END_REF][START_REF] Cao | Deep crustal expressions of exhumed strike-slip fault systems: shear zone initiation on rheological boundaries[END_REF][START_REF] Zhang | Intra-continental transpression and gneiss doming in an obliquely convergent regime in SE Asia[END_REF]. As a prominent dynamic process occurring in continental crust, they delimit mechanical and rheological anomalies that tend to be reactivated or have distinct impact on structural evolution during subsequent phases of tectonism (e.g., [START_REF] Daly | Rift basin evolution in Africa: the influence of reactivated steep basement shear zones[END_REF][START_REF] Holdsworth | The recognition of reactivation during continental deformation[END_REF][START_REF] Metelkin | Late Mesozoic tectonics of Central Asia based on paleomagnetic evidence[END_REF][START_REF] Bercovici | Mechanisms for the generation of plate tectonics by two-phase grain-damage and pinning[END_REF]. Thus, understanding the structural patterns and kinematics of strike-slip shear zones as well as their J o u r n a l P r e -p r o o f tectonic mechanisms is an important issue in continental dynamics research.

The Tianshan (Tien Shan) Orogen lies in the southernmost part of the Central Asian Orogenic Belt (CAOB), or the Altaïds, which is the largest Phanerozoic orogenic system on the world formed by progressive amalgamation of various microcontinents, island arcs, seamounts, oceanic plateaus, and accretionary complexes [START_REF] Şengör | Evolution of the Altaid tectonic collage and Palaeozoic crustal growth in Eurasia[END_REF][START_REF] Jahn | Granitoids of the Central Asian Orogenic Belt and continental growth in the Phanerozoic[END_REF][START_REF] Xiao | Accretion leading to collision and the Permian Solonker suture, Inner Mongolia, China: termination of the central Asian orogenic belt[END_REF][START_REF] Windley | Tectonic models for accretion of the Central Asian Orogenic Belt[END_REF][START_REF] Wilhem | The Altaids of Central Asia: a tectonic and evolutionary innovative review[END_REF]. Following successive accretions to the northern margin of the Tarim Craton in late Paleozoic, the Tianshan Orogen and adjacent areas underwent large-scale transcurrent tectonics that greatly influenced the tectonic framework of the SW CAOB [START_REF] Allen | Junggar, Turfan and Alakol basins as Late Permian to Early Triassic extensional structures in a sinistral shear zone in the Altaid orogenic collage, Central-Asia[END_REF][START_REF] Şengör | Paleotectonics of Asia: fragments of a synthesis[END_REF][START_REF] Laurent-Charvet | Palaeozoic late collisional strike-slip deformations in Tianshan and Altay, eastern Xinjiang, NW China[END_REF][START_REF] Ludwig | ISOPLOT 3.00: a Geochronology Toolkit for Microsoft Excel[END_REF]Wang et al., 2007a[START_REF] Wang | Evolution of calc-alkaline to alkaline magmatism through Carboniferous convergence to Permian transcurrent tectonics, western Chinese Tianshan[END_REF]Wang et al., , 2014;;[START_REF] Li | Structural evolution of the Irtysh Shear Zone (northwestern China) and implications for the amalgamation of arc systems in the Central Asian Orogenic Belt[END_REF][START_REF] Li | Tectonic evolution of the Chinese Tianshan Orogen J o u r n a l P r e -p r o o f from subduction to arc-continent collision: Insight from polyphase deformation along the Gangou section[END_REF]. Therefore, recognizing the styles of transcurrent deformation is crucial for deciphering the orogenic history and tectonic transition from convergent to intracontinental evolution of this giant belt.

One of the most remarkable features of the Tianshan Orogen is the occurrence of two large-scale ductile shear zones that are parallel to major ophiolitic sutures (i.e. the North Tianshan Fault-Main Tianshan Shear Zone and Nalati-Baluntai Fault, respectively) (Figs. 1 and2). Numerous studies have suggested that these two shear zones resulted from Permian regional transpressional and/or transtensional tectonics, with evidence of both general dextral strike-slip shearing and folding induced by lateral displacements [START_REF] Yin | A Phanerozoic palinspastic reconstruction of China and its neighboring regions[END_REF][START_REF] Shu | A large-scale Palaeozoic dextral ductile strike-slip zone: the Aqqikkudug-Weiya zone along the northern margin of the Central Tianshan belt, Xinjiang, NW China[END_REF][START_REF] Laurent-Charvet | Palaeozoic late collisional strike-slip deformations in Tianshan and Altay, eastern Xinjiang, NW China[END_REF][START_REF] Ludwig | ISOPLOT 3.00: a Geochronology Toolkit for Microsoft Excel[END_REF]Y. Wang et al., 2008;[START_REF] Wang | Evolution of calc-alkaline to alkaline magmatism through Carboniferous convergence to Permian transcurrent tectonics, western Chinese Tianshan[END_REF]Wang et al., , 2014;;de Jong et al., 2009; J o u r n a l P r e -p r o o f [START_REF] Pirajno | Intracontinental strike-slip faults, associated magmatism, mineral systems and mantle dynamics: examples from NW China and Altay-Sayan (Siberia)[END_REF][START_REF] Tang | Deformational characteristics of ductile shear zones in northern and southern margins of eastern central Tianshan[END_REF][START_REF] Branquet | Synkinematic mafic/ultramafic sheeted intrusions: emplacement mechanism and strain restoration of the Permian Huangshan Ni-Cu ore belt (Eastern Tianshan, NW China)[END_REF][START_REF] Cai | Age and tectonic evolution of ductile shear zones in the eastern Tianshan-Beishan orogenic belt[END_REF]. However, other authors proposed that pure shear strain related to N-S coaxial compressional tectonics was responsible for the formation of the Jueluotage shear zone (middle segment of the Main Tianshan Shear Zone) and the Baluntai Fault, based on symmetrical structures observed [START_REF] Xu | Characteristics and dynamic origin of the large-scale Jiaoluotage ductile compressional zone in the eastern Tianshan Mountains, China[END_REF][START_REF] Yang | Vertical and horizontal strain partitioning of the Central Tianshan (NW China): evidence from structures and 40 Ar/ 39 Ar geochronology[END_REF]. Thus, there is no consensus on the mechanism and geodynamic setting of their deformation so far. In addition to these large shear zones along boundaries between major continental units, several subordinate strike-slip faults were also reported within some continental blocks, in which mylonitic rocks are widespread (e.g., Xingdi Fault, [START_REF] Cai | Age and tectonic evolution of ductile shear zones in the eastern Tianshan-Beishan orogenic belt[END_REF]Hulashan Fault, Lin et al., 2013; Wulasitai shear zone, [START_REF] Yang | Ductile shearing zones occurring along the northern and southern boundaries of the central Tianshan block[END_REF]He et al., 2018a). However, structural data are scarce from these high-strain shear zones. Meanwhile, it is also poorly understood how they were formed and responded to the complex accretionary and collisional orogenesis, and what their structural relationship is with large transcurrent tectonics marking the boundaries of tectonic units. Further investigation is therefore needed to obtain more information on the activity of these shear zones.

In this study, we investigated two contiguous strike-slip shear zones, namely, the Xiaergou and Wulasitai shear zones, which hitherto have been poorly studied. The former is a connecting part between the North Tianshan Fault and the Main Tianshan Shear Zone along the northern boundary of the Yili -Central Tianshan blocks, and the latter is a subordinate shear zone inside the Central Tianshan (Fig. 2; [START_REF] Yang | Ductile shearing zones occurring along the northern and southern boundaries of the central Tianshan block[END_REF]He et al., 2018a). The detailed structural, kinematic and geochronological data allow J o u r n a l P r e -p r o o f us to explore the possible formation mechanism of these strike-slip shear zones developed at different scales and opposite kinematic features under an overall consistent deformation regime. This study also places further constraints on the post-orogenic intracontinental evolution of the Tianshan Orogen, and provides new insights into the eastward wedging of tectonic units between the Tarim and Siberian blocks.

Regional Geology

Tectonic units in the Chinese Tianshan

The Tianshan Orogen stretches east-west for about 2500 km from eastern Xinjiang in NW China to central Uzbekistan (Fig. 1). This orogenic belt was built by multi-stage subduction of the Paleo-Asian oceanic plate and the subsequent welding between the Kazakhstan-Yili block and Tarim Craton during the Paleozoic (e.g., [START_REF] Allen | Paleozoic collisional tectonics and J o u r n a l P r e -p r o o f magmatism of the Chinese Tien Shan, Central Asia[END_REF][START_REF] Gao | Paleozoic tectonic evolution of the Tianshan Orogen, northern China[END_REF][START_REF] Gao | Tectonic evolution of the South Tianshan orogen and adjacent regions, NW China: geochemical and age constraints of granitoid J o u r n a l P r e -p r o o f rocks[END_REF][START_REF] Charvet | Palaeozoic structural and geodynamic evolution of eastern Tianshan (NW China): welding of the Tarim and Junggar plates[END_REF][START_REF] Charvet | Palaeozoic tectonic evolution of the Tianshan belt, NW China[END_REF]Wang et al., 2008[START_REF] Wang | Paleozoic tectonics of the southern Chinese Tianshan: Insights from structural, chronological and geochemical studies of the Heiyingshan ophiolitic mélange (NW China)[END_REF]Wang et al., , 2018;;[START_REF] Xiao | Paleozoic multiple accretionary and collisional tectonics of the Chinese Tianshan orogenic collage[END_REF], and was reactivated during the Meso-Cenozoic as a far-field response of Qiangtang-Lhasa and India-Asia collisions (e.g., [START_REF] Molnar | Cenozoic tectonics of Asia: effects of a continental collision[END_REF][START_REF] Avouac | Active thrusting and folding along the northern Tien Shan, and Late Cenozoic rotation of the Tarim relative to the Junggar and Kazakhstan[END_REF][START_REF] De Grave | Distant effects of India-Eurasia convergence and Mesozoic intracontinental deformation in Central Asia: constraints from apatite fission-track thermochronology[END_REF][START_REF] Glorie | Exhuming the Meso-Cenozoic Kyrgyz Tianshan and Siberian Altai-Sayan: a review based on low-temperature thermochronology[END_REF]. The Chinese segment of the Tianshan Orogen is sandwiched between the Junggar and Tarim basins (Fig. 1B). According to the differences in basement nature and tectonic settings, the Chinese Tianshan is traditionally subdivided into four tectonic units separated by regional crustal-scale faults, namely, the North Tianshan,

J o u r n a l P r e -p r o o f

Yili Block, Central Tianshan and South Tianshan from north to south (Fig. 2; [START_REF] Xiao | Tectonic Evolution of the Northern Xinjiang and its adjacent regions[END_REF][START_REF] Xiao | Paleozoic accretionary and collisional tectonics of the Eastern Tianshan (China): implications for the continental growth of central Asia[END_REF][START_REF] Gao | Paleozoic tectonic evolution of the Tianshan Orogen, northern China[END_REF][START_REF] Charvet | Palaeozoic structural and geodynamic evolution of eastern Tianshan (NW China): welding of the Tarim and Junggar plates[END_REF].

The North Tianshan is an accretionary complex formed by the subduction and accretion of the Junggar -North Tianshan oceanic plate. It is composed of late Paleozoic sedimentary-volcanic sequences and magmatic intrusions, which occur in the Kazakhstan-Yili blocks to the west and around the Turpan-Hami (Tu-Ha) basin in the east. (e.g., [START_REF] Wang | Late Paleozoic tectonic evolution of the northern West Tianshan, NW China[END_REF][START_REF] Han | Age, geochemistry, and tectonic implications of a late Paleozoic stitching pluton in the North Tian Shan suture zone, western China[END_REF][START_REF] Zhang | Tectonic evolution from subduction to arc-continent collision of the Junggar ocean: constraints from U-Pb dating and Hf isotopes of detrital zircons from the North Tianshan belt, NW China[END_REF][START_REF] Wali | Carboniferous-Early Permian magmatic evolution of the Bogda Range (Xinjiang, NW China): implications for the Late Paleozoic accretionary tectonics of the SW Central Asian Orogenic Belt[END_REF]. The Yili Block represents the eastern part of the Kazakhstan microcontinent, and is a wedge-shaped area between the North and Central Tianshan blocks (Figs. 1B and 2), it consists of Meso-to Neoproterozoic basements, Paleozoic sedimentary covers and magmatic arc rocks that were generated mostly by the southward subduction of the Junggar oceanic plate (e.g., [START_REF] Gao | Paleozoic tectonic evolution of the Tianshan Orogen, northern China[END_REF][START_REF] Gao | Tectonic evolution of the South Tianshan orogen and adjacent regions, NW China: geochemical and age constraints of granitoid J o u r n a l P r e -p r o o f rocks[END_REF][START_REF] Hu | Crustal evolution and Phanerozoic crustal growth in northern Xinjiang: Nd isotopic evidence. Part I. Isotopic characterization of basement rocks[END_REF][START_REF] Charvet | Palaeozoic structural and geodynamic evolution of eastern Tianshan (NW China): welding of the Tarim and Junggar plates[END_REF][START_REF] Charvet | Palaeozoic tectonic evolution of the Tianshan belt, NW China[END_REF]Wang et al., 2007bWang et al., , 2014a;;[START_REF] Liu | Detrital zircon ages of Proterozoic meta-sedimentary rocks and Paleozoic sedimentary cover of northern Yili Block: implications for the tectonics of microcontinents in the Central Asian Orogenic Belt[END_REF][START_REF] Cao | Late Paleozoic arc magmatism in the southern Yili Block (NW China): insights to the geodynamic evolution of the Balkhash-Yili continental margin, Central Asian Orogenic Belt[END_REF]Zhu et al., 2019a). Bordered by the Main Tianshan Shear Zone to the north and the Baluntai Fault to the south, the Central Tianshan refers to a ribbon-like domain extending from the Nalati Range in the west to Xingxingxia areas in the east (Fig. 2), it consists of Precambrian metamorphic basement (e.g., [START_REF] Hu | Crustal evolution and Phanerozoic crustal growth in northern Xinjiang: Nd isotopic evidence. Part I. Isotopic characterization of basement rocks[END_REF][START_REF] He | Zircon U-Pb and Hf isotopic studies of the Xingxingxia Complex from Eastern Tianshan (NW China): significance to the reconstruction and tectonics of the southern Central Asian Orogenic Belt[END_REF][START_REF] He | Mesoproterozoic continental arc magmatism and crustal growth in the eastern Central Tianshan Arc Terrane of the southern Central Asian Orogenic Belt: geochronological and geochemical evidence[END_REF]He et al., , 2018b;;[START_REF] Gao | Record of assembly and breakup of Rodinia in the Southwestern Altaids: evidence from Neoproterozoic magmatism in the Chinese Western Tianshan Orogen[END_REF][START_REF] J O U R N A L P R E -P R O O F Wang | The Central Tianshan Block: A microcontinent with a Neoarchean-Paleoproterozoic basement in the southwestern Central Asian Orogenic Belt[END_REF], early Paleozoic magmatic arc sequences, late Paleozoic sedimentary strata and Paleozoic intrusions (e.g., [START_REF] Shi | SHRIMP zircon U-Pb dating of the Gangou granitoids, Central Tianshan Mountains, Northwest China and tectonic significances[END_REF][START_REF] Dong | Syn-and post-collisional granitoids in the Central Tianshan orogen: geochemistry, geochronology and implications for tectonic evolution[END_REF][START_REF] Lei | Zircon U-Pb chronology and Hf isotope of the Xingxingxia granodiorite from the Central Tianshan zone (NW China): implications for the tectonic evolution of the southern Altaids[END_REF][START_REF] Ma | The Paleozoic evolution of Central Tianshan: geochemical and geochronological evidence[END_REF][START_REF] Zhong | Structural overprints of early Paleozoic arc-related intrusive rocks in the Chinese Central Tianshan: Implications for Paleozoic accretionary tectonics in SW Central Asian Orogenic Belts[END_REF]. The South Tianshan is confined to the region between the Nalati -Baluntai faults and the northern Tarim margin. This unit contains an early Paleozoic J o u r n a l P r e -p r o o f continental arc and late Paleozoic sedimentary cover, which were formed during the successive closure of the South Tianshan Ocean and several back-arc basins (e.g., [START_REF] Gao | Paleozoic tectonic evolution of the Tianshan Orogen, northern China[END_REF][START_REF] Gao | Tectonic evolution of the South Tianshan orogen and adjacent regions, NW China: geochemical and age constraints of granitoid J o u r n a l P r e -p r o o f rocks[END_REF][START_REF] Wang | Structural and geochronological study of high-pressure metamorphic rocks in the Kekesu section (northwestern China): implications for the late Paleozoic tectonics of the Southern Tianshan[END_REF][START_REF] Wang | Paleozoic tectonics of the southern Chinese Tianshan: Insights from structural, chronological and geochemical studies of the Heiyingshan ophiolitic mélange (NW China)[END_REF]Wang et al., , 2018;;[START_REF] Jiang | Paleozoic ophiolitic mélanges from the South Tianshan Orogen, NW China: geological, geochemical and geochronological implications for the geodynamic setting[END_REF][START_REF] Alexeiev | Tectono-stratigraphic framework and Palaeozoic evolution of the Chinese South Tianshan[END_REF][START_REF] Han | Late Paleozoic subduction and collision processes during the amalgamation of the Central Asian Orogenic Belt along the South Tianshan suture zone[END_REF]Zhong et al., 2017[START_REF] Zhong | Deformed continental arc sequences in the South Tianshan: New constraints on the Early Paleozoic accretionary tectonics of the Central Asian Orogenic[END_REF].

Large-scale shear zones in the Chinese Tianshan

The main tectonic units described above contact with each other by large-scale shear zones that extends roughly east-west and are sub-parallel to the ophiolitic mélange zones developed along the Bayingou -Mishigou -Gangou and Atbashi -Kekesu -Wuwamen areas (Figs. 1 and 2; Wang et al., 2008;[START_REF] Charvet | Palaeozoic tectonic evolution of the Tianshan belt, NW China[END_REF].

The Main Tianshan Shear Zone (MTSZ) [START_REF] Shu | A large-scale Palaeozoic dextral ductile strike-slip zone: the Aqqikkudug-Weiya zone along the northern margin of the Central Tianshan belt, Xinjiang, NW China[END_REF][START_REF] Laurent-Charvet | Palaeozoic late collisional strike-slip deformations in Tianshan and Altay, eastern Xinjiang, NW China[END_REF]Liu et al., 2020) is the tectonic boundary between the North Tianshan and Central Tianshan and it stretches for over 700 km from Xiaergou-Gangou eastward to Weiya (Fig. 1B) [START_REF] Xigmr | Xi'an Institute of Geology and Mineral Resources)[END_REF]. Along this shear zone, Precambrian schists and gneisses, Paleozoic granitoids and volcanics, as well as ophiolitic rocks were mylonitzed and they generally exhibit sub-vertical mylonitic foliations with sub-horizontal stretching lineation [START_REF] Shu | A large-scale Palaeozoic dextral ductile strike-slip zone: the Aqqikkudug-Weiya zone along the northern margin of the Central Tianshan belt, Xinjiang, NW China[END_REF](Shu et al., , 2002;;[START_REF] Laurent-Charvet | Palaeozoic late collisional strike-slip deformations in Tianshan and Altay, eastern Xinjiang, NW China[END_REF][START_REF] Ludwig | ISOPLOT 3.00: a Geochronology Toolkit for Microsoft Excel[END_REF][START_REF] Li | Tectonic evolution of the Chinese Tianshan Orogen J o u r n a l P r e -p r o o f from subduction to arc-continent collision: Insight from polyphase deformation along the Gangou section[END_REF]. Consistent asymmetric fabrics indicate a right-lateral strike-slip movement, with thrusting and/or normal faulting components,probably formed in transpressional and/or transtensional settings [START_REF] J O U R N A L P R E -P R O O F Laurent-Charvet | Late Paleozoic strike-slip shear zones in eastern central Asia (NW China): new structural and geochronological data[END_REF]Wang et al., 2008;[START_REF] Yang | Late Early Permian (266 Ma) N-S compressional deformation of the Turfan basin, NW China: the cause of the change in basin pattern[END_REF][START_REF] Li | Tectonic evolution of the Chinese Tianshan Orogen J o u r n a l P r e -p r o o f from subduction to arc-continent collision: Insight from polyphase deformation along the Gangou section[END_REF]Liu et al., 2020). The North J o u r n a l P r e -p r o o f Tianshan Fault (NTF) is essentially the westward continuation of the MTSZ and it runs into Kazakhstan, separating the Yili block to the south from the Chinese North Tianshan to the north (Fig. 2). Kinematic features along the NTF also indicate a dextral ductile shearing [START_REF] Zhou | Paleozoic tectonic amalgamation of the Chinese Tian Shan: Evidence from a transect along the Dushanzi-Kuqa Highway[END_REF][START_REF] Wang | Late Paleozoic tectonic evolution of the northern West Tianshan, NW China[END_REF][START_REF] Wang | Evolution of calc-alkaline to alkaline magmatism through Carboniferous convergence to Permian transcurrent tectonics, western Chinese Tianshan[END_REF]de Jong et al., 2009;[START_REF] Yang | Late Early Permian (266 Ma) N-S compressional deformation of the Turfan basin, NW China: the cause of the change in basin pattern[END_REF][START_REF] Zhu | Zircon U-Pb and muscovite 40 Ar/ 39 Ar geochronology of the gold-bearing Tianger mylonitized granite, Xinjiang, northwest China: implications for radiometric dating of mylonitized magmatic rocks[END_REF]Liu et al., 2020).

The Nalati Fault (NF) occurs along the Haerke-Nalati ranges in the South Tianshan (Fig. 1B), and is a large ductile shear zone ~5-15 km wide (e.g., [START_REF] Wang | Structural and geochronological study of high-pressure metamorphic rocks in the Kekesu section (northwestern China): implications for the late Paleozoic tectonics of the Southern Tianshan[END_REF][START_REF] Charvet | Palaeozoic tectonic evolution of the Tianshan belt, NW China[END_REF][START_REF] Han | Late Carboniferous collision between the Tarim and Kazakhstan-Yili terranes in the Western segment of the South Tianshan Orogen, Central Asia, and implication for the Northern Xinjiang, western China[END_REF]. It continues eastwards to merge with the NTF near the Bingdaban area (Figs. 1B and2). This ductile shear zone was active mainly in the Permian and reworked the Carboniferous suture zone (Akeyazi-Kekesu ophiolite mélanges and high-pressure metamorphic belt) (Fig. 1B) formed by the subduction of the South Tianshan oceanic plate (e.g., [START_REF] Gao | Paleozoic tectonic evolution of the Tianshan Orogen, northern China[END_REF][START_REF] Gao | Tectonic evolution of the South Tianshan orogen and adjacent regions, NW China: geochemical and age constraints of granitoid J o u r n a l P r e -p r o o f rocks[END_REF]Lin et al., 2009;[START_REF] Qian | Early Paleozoic tectonic evolution of the Chinese South Tianshan Orogen: constraints from SHRIMP zircon U-Pb geochronology and geochemistry of basaltic and dioritic rocks from Xiate, NW China[END_REF][START_REF] Wang | Evolution of calc-alkaline to alkaline magmatism through Carboniferous convergence to Permian transcurrent tectonics, western Chinese Tianshan[END_REF][START_REF] Wang | Structural and geochronological study of high-pressure metamorphic rocks in the Kekesu section (northwestern China): implications for the late Paleozoic tectonics of the Southern Tianshan[END_REF][START_REF] Long | Geochemical and geochronological studies of granitoid rocks from the Western Tianshan Orogen: implications for continental growth in the southwestern Central Asian Orogenic Belt[END_REF][START_REF] Xu | Geochemistry and geochronology of Paleozoic intrusions in the Nalati (Narati) area in western Tianshan, Xinjiang, China: Implications for Paleozoic tectonic evolution[END_REF]Zhong et al., 2017[START_REF] Zhong | Deformed continental arc sequences in the South Tianshan: New constraints on the Early Paleozoic accretionary tectonics of the Central Asian Orogenic[END_REF]. Diverse mylonites, foliated meta-sedimentary rocks and gneissic granitoids are well exposed in this shear zone, and structural studies from the Kekesu high-pressure metamorphic belt and north of Bayinbulak (Fig. 1B) indicate dextral kinematics (XBGMR, 1993;[START_REF] Li | Tectonic analysis of Laerdun Daban of West Tianshan Mountains, China[END_REF]Wang et al., 2007c[START_REF] Wang | Structural and geochronological study of high-pressure metamorphic rocks in the Kekesu section (northwestern China): implications for the late Paleozoic tectonics of the Southern Tianshan[END_REF]Lin et al., 2009;[START_REF] Zhong | Deformed continental arc sequences in the South Tianshan: New constraints on the Early Paleozoic accretionary tectonics of the Central Asian Orogenic[END_REF].

The Baluntai Fault (BF) stands for the boundary between the Central Tianshan to the northeast and the South Tianshan to the southwest [START_REF] Alexeiev | Tectono-stratigraphic framework and Palaeozoic evolution of the Chinese South Tianshan[END_REF]Wang et al., 2018;[START_REF] Zhong | Deformed continental arc sequences in the South Tianshan: New constraints on the Early Paleozoic accretionary tectonics of the Central Asian Orogenic[END_REF]. It extends from the north of Bayinbulak, nearly parallel to the NTF -MTSZ, to the Sangshuyuanzi area to the east (Figs. 1B and2) (XIGMR, J o u r n a l P r e -p r o o f 2007). Foliated schists and gneisses, mylonitic rocks and ductilely deformed granitoids are widely distributed along the BF, which also partially reworked the Wuwamen -Guluogou ophiolite mélanges (Fig. 2) (XBGMR, 1993[START_REF] Yang | Ductile shearing zones occurring along the northern and southern boundaries of the central Tianshan block[END_REF][START_REF] Deng | Timing of the formation of the Sangshuyuanzi ductile shear zone in the central segment of the South Tianshan and its tectonic significance[END_REF]M. Wang et al., 2014;Wang et al., 2018). Localized coaxial pure strain was described in the south of Baluntai regions and was considered as the result of N-S compression [START_REF] Yang | Vertical and horizontal strain partitioning of the Central Tianshan (NW China): evidence from structures and 40 Ar/ 39 Ar geochronology[END_REF]; however, most structural investigations from the Sangshuyuanzi, Baluntai areas and their eastward continuation demonstrated dextral strike-slip shearing [START_REF] J O U R N A L P R E -P R O O F Laurent-Charvet | Late Paleozoic strike-slip shear zones in eastern central Asia (NW China): new structural and geochronological data[END_REF]Y. Wang et al., 2008;[START_REF] Wang | Evolution of calc-alkaline to alkaline magmatism through Carboniferous convergence to Permian transcurrent tectonics, western Chinese Tianshan[END_REF][START_REF] Xu | J o u r n a l P r e -p r o o f Paleo-Asian and Tethyan tectonic systems with docking the Tarim block[END_REF][START_REF] Cai | Age and tectonic evolution of ductile shear zones in the eastern Tianshan-Beishan orogenic belt[END_REF][START_REF] Zhong | Structural overprints of early Paleozoic arc-related intrusive rocks in the Chinese Central Tianshan: Implications for Paleozoic accretionary tectonics in SW Central Asian Orogenic Belts[END_REF][START_REF] Li | Tectonic evolution of the Chinese Tianshan Orogen J o u r n a l P r e -p r o o f from subduction to arc-continent collision: Insight from polyphase deformation along the Gangou section[END_REF].

Overall geometry, structures and kinematics of the Xiaergou and

Wulasitai shear zones

Our structural investigations were conducted along several sections crossing the Xiaergou and Wulasitai shear zones around and within the Central Tianshan (Figs.

2-10). In the following sections, we present the main lithological units in the two shear zones and their structural and kinematic features.

Xiaergou Shear Zone

As the eastern part of the NTF, the Xiaergou Shear Zone (XSZ) is a ~NW-SE trending mylonitic belt with a width of ~3-5 km, and was locally reworked or J o u r n a l P r e -p r o o f truncated by brittle reverse and/or left-lateral strike-slip faults (Figs. 2 and3). Due to difficult physical conditions our field observations were limited to a 5-km-long section mainly along its strike near the Xiaergou village (Figs. 3B and4).

Lithological units

Silurian to Devonian marine sequences were affected by the ductile deformation along the XSZ. Silurian meta-sediments belong to the middle Ahebulake Group and consist of marbles, greywackes, schists, phyllites and calcareous sandstones with interlayered tuff. Devonian sequences are represented by the middle Tiangeer Group that is dominated by basaltic tuffs, tuffaceous sandstones and marbles (XBGMR, 1993). Both groups are in contact with each other along a steep N-dipping reverse fault (Figs. 3 and4).

Early Paleozoic granodiorites and late Paleozoic granites are well exposed within and across the shear zone (Figs. 3B and4). The late Paleozoic granites were dated at ~370-337 Ma (zircon U-Pb ages) and were interpreted to be related to the subduction of the North Tianshan oceanic plate and the collision between the Central and North Tianshan (including Tu-Ha basin) during the early Carboniferous [START_REF] Ma | The Paleozoic evolution of Central Tianshan: geochemical and geochronological evidence[END_REF][START_REF] Yin | Geochronology, petrogenesis, and tectonic significance of the latest Devonian-early Carboniferous I-type granites in the Central Tianshan, NW China[END_REF]. In addition, numerous undeformed granitic and diabase dykes of unknown ages intruded into Silurian-Devonian meta-sedimentary and volcanic rocks as well as the Paleozoic plutons (Figs. 3 and4). The mylonitic foliations and stretching lineation are usually defined by elongated quartz and feldspar ribbons and mica aggregates (Figs. 5 and6). In the Silurian-Devonian metasedimentary rocks, the S1 is predominantly dipping to the ~N-NNE with variable dip angles ranging from 42° to 76°, and is parallel to the locally preserved S0 bedding planes (Fig. 4A-B). The K-feldspar porphyroclasts are elongated and oriented parallel to the shearing foliations. In addition, mylonitic felsic dykes intruding the marbles and schists also exhibit steep foliations and sub-horizontal mineral stretching lineation, which are defined by a preferred orientation of elongated feldspar and quartz grains (Figs. 4C and5D). Leuco-granitic dykes and their host granitic pluton both display ~NE-SW-striking mylonitic foliations with ~ENE/WSW plunging lineation (Figs. 4A-B and5A), which are oblique to the general strike of the shear zone, probably due to localized rotation related to the NE-striking brittle reverse fault (Fig. 4A).

Disjunctive cleavage in granodiorites shows a general strike of 160°, sub-parallel to the shear zone; and shear bands suggest a dextral sense of shearing (Fig. 5E). In J o u r n a l P r e -p r o o f highly deformed marbles, sheath folds and A-type folds were well preserved, whose hinges are parallel to the stretching lineation; on the X-Z plane (perpendicular to foliation and parallel to lineation), the asymmetric fold shapes present a dextral shearing (Fig. 5F). S-C fabrics can be recognized in marbles as well, the S-foliation is represented by elongated calcite veins, and a dextral sense of movement is also indicated (Fig. 5G). It is worth noting that sinistral shearing was also occasionally preserved, as revealed by asymmetric quartz lens in a small-scale greenschist outcrop (Fig. 5H). Under microscope, mylonitic granitoids and tuffaceous sandstones contain plenty of kinematic indicators, such as S-C fabrics, feldspar bookshelf texture, sigmoid asymmetric feldspar porphyroclasts and mica pressure shadows showing a principal dextral sense of shearing (Fig. 6A-D), sinistral kinematics was only locally developed and is associated with dextral kinematics (Fig. 6E-F).

Wulasitai Shear Zone

The Wulasitai shear zone (WSZ) is a remarkable subordinate high-strain deformation zone occurring within the Central Tianshan, it extends NW-SE, nearly parallel to the NTF and BF, for more than 40 km with variable widths of ~1-5 km (Figs. 2 and7). This high-strain mylonitic belt merged westwards into the NF, and it is covered eastwards by strongly weathered granites, vegetation and glacier (Fig. 2), it is possible that the WSZ connects the MTSZ in the Yuergou area [START_REF] Xigmr | Xi'an Institute of Geology and Mineral Resources)[END_REF].

J o u r n a l P r e -p r o o f

Lithological units

A variety of rocks are well exposed along the WSZ and were significantly deformed by ductile shearing, they mainly include Proterozoic paragneiss, early Paleozoic sedimentary rocks and granodiorites, and late Paleozoic granites (Fig. 7B; XBGMR, 1993).

Proterozoic paragneiss occur north of the Wulasitai village (Fig. 7B) and were previously assigned to the Paleoproterozoic Xingxingxia Group (XBGMR, 1993;[START_REF] Xigmr | Xi'an Institute of Geology and Mineral Resources)[END_REF]. However, recent zircon U-Pb dating indicated that some of these meta-sedimentary rocks were likely deposited in the early Devonian to late Carboniferous [START_REF] Shu | The formation and evolution of ancient blocks in Xinjiang[END_REF]Wang et al., 2018). Early Paleozoic meta-sedimentary rocks dominantly comprise paragneiss, marbles, greenschists, deformed quartz sandstones and greywackes, they were considered as Silurian in age, but some of them were recently constrained as Devonian (He et al., 2018a).

Paleozoic plutonic rocks along the WSZ include early Paleozoic granodiorites and late Paleozoic granites intruding the "Proterozoic" and "Silurian" meta-sedimentary rocks (Fig. 7B). Migmatites are frequently associated with the granodiorites and can also be observed in the meta-sandstones. Some late Paleozoic granites exposed along the WSZ were dated at ~354-332 Ma (He et al., 2018a).

These ductilely deformed and metamorphosed sedimentary rocks are unconformably covered by undeformed and gently tilted Jurassic sandstones (Fig. 7B).

J o u r n a l P r e -p r o o f

Structures and kinematics

Along the WSZ, ~E-W or ~NW-SE-striking, diversely S/SW-or N/NE-dipping mylonitic foliations (S1) and associated mineral stretching lineation (L1) are well developed in most lithological units (Figs. 8 and9A-E). The dip angles of foliations vary from 30° to 80°, and the plunging angles of lineation are 3°-40° (Fig. 8). In general, the steeper foliations bearing shallower lineation occur along the straight segment, and gentle foliations with nearly down-dip lineation are mostly observed at the turning segment of the WSZ (Figs. 7 and8). Silurian meta-greywackes underwent intensive ductile deformation displaying steep mylonitic foliations and gentle stretching lineation (Fig. 9A). Some paragneiss and phyllites show gently south-dipping foliations and sub-horizontal stretching lineation defined by elongated ribbons of felsic melts, and coeval sub-S-N crenulation cleavages (L1') represented by hinges of microfolds full of mica and sericite (Fig. 9B-C). In migmatites, foliation-parallel leucocratic veins reflect a low-degree partial melting, elongated K-feldspar and quartz ribbons in the leucosome indicate a syn-kinematic transport of melts (Fig. 9B). The granitic rocks were also ductilely deformed showing mylonitic foliations and ~E-W-trending stretching lineation characterized by elongated feldspar and quartz ribbons and oriented micas (Fig. 9D-E).

Overall bending geometry suggests that localized transpressional deformation affected the WSZ. For example, along a ~NE-SW profile across the bending segment J o u r n a l P r e -p r o o f of the WSZ, folded and duplicated quartz veins occur in mylonitic granites with the axial planes parallel to the S1 foliation, asymmetric folds and shear bands indicate a top-to-the-southwest shearing (Fig. 9F). Moreover, strike-slip motions along the WSZ were well recorded by a series of apparent kinematic indicators. At the field scale, asymmetric intrafolial microfolds in the meta-rhyolites (Fig. 9G), shear bands in the meta-sandstones (Fig. 9H), and fractured and offset felsic veins in the mylonitic granites (Fig. 9I) suggest a sinistral shearing along the strike of the shear zone. In addition, microscopic textures such as the sigmoid biotite mica fishes (Fig. 10A), shear bands and pressure shadows composed of mica around K-feldspar porphyroclasts (Fig. 10B-C), S-C fabrics and σ-type feldspar porphyroclasts (Fig. 10D-E) consistently demonstrate a sinistral sense of shear. However, dextral motion is also indicated by sigmoid quartz and feldspar porphyroclasts (Fig. 10F) that are occasionally visible in few samples showing predominantly sinistral shearing. et al., 2001;Stipp et al., 2002aStipp et al., , 2002b;;[START_REF] Passchier | Microtectonics[END_REF][START_REF] Law | Deformation thermometry based on quartz c-axis fabrics and recrystallization microstructures: a review[END_REF]. Here we estimated deformation temperatures of these two shear zones according to the criteria for quartz dynamic recrystallization proposed by Stipp et al. (2002a). The studied samples were collected from the axial parts of the shear zones (Figs. 4 and8) so that they may reflect the peak conditions of ductile shearing. In order to avoid possible large uncertainty brought by the sampling effect, at least two samples were taken from each sampling site for thin section observation. Detailed microstructural descriptions and temperature estimations are given in supplementary Table S1.

Temperature conditions of the ductile deformation

Our observations suggest that the sub-grain rotation is the dominant mechanism of quartz dynamic recrystallization in both the XSZ and WSZ (Fig. 11; Table S1). In a number of samples, numerous new small grains produced by both bulging and sub-grain rotation mechanisms occur around the original quartz grains, revealing a typical core-mantle structure (Fig. 11A, B andD), and the elongated quartz ribbons parallel to main foliations reflect intensive dislocation creep deformation (Fig. 11C, E andF). Grain boundary migration recrystallization appears more frequently in the XSZ (Fig. 11C), indicating a higher temperature condition compared to the WSZ.

Generally, deformation temperatures in the XSZ are estimated as ~460-510 °C, slightly higher than the temperature conditions of the WSZ (~450-485 °C) (Fig. 12; Table S1). In addition, feldspar only displays bulging recrystallization and no clear evidence for sub-grain rotation was identified in both shear zones, suggesting a maximum temperature threshold of ~550-600 °C for ductile shearing. It is noted that the estimated temperatures here only refer to the pervasive dextral shearing of the J o u r n a l P r e -p r o o f before, their corresponding deformation temperatures are thus difficult to be determined without efficient indicators.

Geochronology

In order to constrain the timing of ductile deformation, new isotopic data were obtained by zircon LA-ICP-MS U-Pb and biotite 40 Ar/ 39 Ar dating. Sample locations are marked on Figs. 4 and 8, analytical procedures are described in Appendix, and analytical data are provided in supplementary Tables S2 andS3.

Zircon U-Pb ages for pre-and syn-kinematic granitic dykes in the Xiaergou

Shear Zone

Pre-and syn-kinematic plutons develop along the XSZ. The syn-kinematic ones were emplaced during the ductile shearing, some occur as migmatitic veins due to in situ partial melting of the host rocks and some injected from deep-seated magma via foliations or faults (Hutton, 1988;[START_REF] Pitcher | The Nature and Origin of Granite[END_REF][START_REF] Pirajno | Intracontinental strike-slip faults, associated magmatism, mineral systems and mantle dynamics: examples from NW China and Altay-Sayan (Siberia)[END_REF]Wang et al., 2014b).

One distinct character of syn-kinematic dykes is that their distributions are only limited within the shear zone. This situation differs from that of the pre-kinematic dykes, which are distributed not only within but also outside the shear zone and they J o u r n a l P r e -p r o o f usually crosscut the shear zone or lithological boundaries [START_REF] Searle | Role of the Red River shear zone, Yunnan and Vietnam, in the continental extrusion of SE Asia[END_REF]Rolland et al., 2009;[START_REF] Cao | Oligo-Miocene shearing along the Ailao Shan-Red River shear zone: constraints from structural analysis and zircon U-Pb geochronology of magmatic rocks in the Diancang Shan massif, SE Tibet, China[END_REF][START_REF] J O U R N A L P R E -P R O O F Hu | Structural evolution of the eastern segment of the Irtysh Shear Zone: implications for the collision between the East Junggar Terrane and the Chinese Altai Orogen (northwestern China)[END_REF]. From the XSZ, one sample of pre-kinematic granite dyke and another of syn-kinematic dyke intruding the Silurian marbles and late Paleozoic granites (~370-337 Ma; [START_REF] Ma | The Paleozoic evolution of Central Tianshan: geochemical and geochronological evidence[END_REF][START_REF] Yin | Geochronology, petrogenesis, and tectonic significance of the latest Devonian-early Carboniferous I-type granites in the Central Tianshan, NW China[END_REF] (Fig. 4), were dated using the zircon LA-ICP-MS U-Pb method.

Sample 44-B was taken from a granitic dyke of ~1m wide (Fig. 13A), which displays sharp contact with the host rocks. Both the dyke and its host rocks show similar deformation fabrics, i.e., steeply N-dipping mylonitic foliations and shallowly plunging lineation, indicating a strike-slip shearing, and a pre-kinematic emplacement of the granite dyke. The sample mainly contains K-feldspar and quartz with minor biotite and muscovite (Fig. 13B). The zircon grains from this sample are commonly euhedral and 100-150 μm in length, their CL (Cathodoluminescence) images generally show well-developed concentric oscillatory zoning (Fig. 13C). A total of fifteen analyses were carried out on twelve zircons, showing Th/U ratios of 0.4-0.8 (Table S2), indicating a magmatic origin according to the descriptions of [START_REF] Corfu | Atlas of zircon textures[END_REF]. Therein, 12 out of 15 analyses yielded a concordant age of 311.9 ± 2.4 Ma (MSWD = 0.21; Fig. 13D), including two analyses on the modified rims (Nos. 1 and 14; Fig. 13C), while the unmodified parts of these two zircons yielded older 206 Pb/ 238 U ages of ~342 Ma and ~331 Ma (Fig. 13D), comparable to the ages of the host granites, from which these two zircons were likely derived. One additional zircon yielded much older age of ~431 Ma, and it is probably inherited. Sample 49-C was collected from another granitic dyke intruding the Silurian J o u r n a l P r e -p r o o f marbles and tuffaceous sandstones (Fig. 4). The dyke is ~1-1.5 m wide and shows boudinage structure and well-developed mylonitic foliations and stretching lineation (Fig. 13E), consistent with those of the host rocks. Generally parallel contact between the dyke and its host rocks to the main mylonitic foliations, and high-strain superplastic creep of quartz (Fig. 13F), i.e., high-temperature syn-magmatic deformation, indicate a syn-kinematic emplacement of the dyke. The sample is fine-grained and consists of feldspar, quartz and fine-grained muscovite (Fig. 13F).

Subhedral zircon crystals from this sample have length/width ratios of 2.5:1-1:1 with variable long axes of 50-200 μm (Fig. 13G). Sixteen zircons were dated, concordant and consistent results were obtained from nine zircons with typical oscillatory zoning, indicative of an igneous origin together with their relatively high Th/U ratios (0.14-1.25) (Fig. 13G; Table S2); these nine analyses yielded a weighted mean 206 Pb/ 238 U age of 294.6 ± 3.7 Ma (MSWD = 1.6; Fig. 13H), which is interpreted to represent the crystallization age of this syn-kinematic dyke. Five zircon grains yielded older ages ranging from ~332 Ma to ~1476 Ma, indicating derivation from older crustal rocks. Two additional analyses show high degrees of discordance (>10%) (Nos.

12 and 15; Table S2) of which the meaning is still unclear.

Biotite 40 Ar/ 39 Ar ages for meta-sedimentary rocks in the Wulasitai Shear Zone

Biotite 40 Ar/ 39 Ar dating was performed on two samples from meta-sedimentary rocks of the Silurian Ahebulake Group in the WSZ, both samples were collected from J o u r n a l P r e -p r o o f the axial part of the shear zone (Fig. 8B) and were subjected to intensive ductile shearing. Sample 01-B is a paragneiss and mainly composed of quartz, feldspar and biotite (Fig. 14A). Preferred orientation of biotite assemblages and quartz ribbons define foliations and lineation, and quartz shows undulose extinction and sub-grain rotation dynamic recrystallization (Fig. 14A). Sample 02-B is a meta-sandstone mainly containing quartz, plagioclase, K-feldspar and biotite (Fig. 14B). Despite sporadic distribution, elongation of fine-grained biotites assigned along the main foliations and lineation and filled in between the granular quartz and feldspar grains, which also show undulose extinction, bulging dynamic recrystallization, and sometimes grain boundary migration recrystallization or even probable superplastic creep as indicated by equidimensional quartz grains with relatively straight grain boundaries (Fig. 14B). Overall oblique orientation and sigmoidal shape of biotite aggregates indicate a sinistral sense of shearing (Fig. 14A-B).

The 40 Ar/ 39 Ar dating results of biotites from the meta-sedimentary rocks are plotted in Fig. 14C-F, all ages are laser step-heating ages, and errors are quoted at the 1σ level. The age spectrum of biotite sample 01-B of a paragneiss are somewhat scattered, without a clear trend through the degassing steps. Apart from the initial steps, the other analyses yielded apparent ages ranging from 295 to 306 Ma (Table S3), a Total-Gas Age (TGA) of 300.3 ± 2.5 Ma and a weighted mean age (WMA) of 300.5 ± 1.6 (MSWD = 3.7; 98% of 39 Ar K released) are calculated (Fig. 14C). For the biotite sample 02-B from a meta-sandstone, most analyses yielded generally consistent apparent ages (298-310 Ma) except one step that shows a much younger J o u r n a l P r e -p r o o f apparent age probably due to extremely low 39 Ar released (Table S3). The TGA and WMA of this sample are calculated at 303.0 ± 2.5 Ma and 303.4 ± 1.3 Ma (MSWD = 1.7; ~100% of 39 Ar K ), respectively (Fig. 14D).

Discussion

Kinematic significance of the Xiaergou and Wulasitai shear zones

According to the general geometry of the Xiaergou shear zone (XSZ), this structure forms the connecting segment between the North Tianshan Fault (NTF) and Main Tianshan Shear Zone (MTSZ) (Figs. 1 and2). Based on our structural observations and kinematic analysis of prevalent macro-and micro-kinematic characteristics, the XSZ is dominated by a simple dextral shearing. This is in agreement with previous investigations along both the NTF and MTSZ [START_REF] Shu | A large-scale Palaeozoic dextral ductile strike-slip zone: the Aqqikkudug-Weiya zone along the northern margin of the Central Tianshan belt, Xinjiang, NW China[END_REF][START_REF] Laurent-Charvet | Palaeozoic late collisional strike-slip deformations in Tianshan and Altay, eastern Xinjiang, NW China[END_REF][START_REF] Ludwig | ISOPLOT 3.00: a Geochronology Toolkit for Microsoft Excel[END_REF][START_REF] Wang | Late Paleozoic tectonic evolution of the northern West Tianshan, NW China[END_REF][START_REF] Wang | Evolution of calc-alkaline to alkaline magmatism through Carboniferous convergence to Permian transcurrent tectonics, western Chinese Tianshan[END_REF]de Jong et al., 2009;[START_REF] Li | Tectonic evolution of the Chinese Tianshan Orogen J o u r n a l P r e -p r o o f from subduction to arc-continent collision: Insight from polyphase deformation along the Gangou section[END_REF]. At the same time, sinistral shearing is only locally recognized along the XSZ. In the field, it only occurs in the greenschist from one observation site (Fig. 5H); in a few thin sections (samples 45-A and 52-B; Table S1), it was locally preserved along with the dominant dextral kinematics (Fig. 6E-F).

The Wulasitai shear zone (WSZ) was previously reported by [START_REF] Yang | Ductile shearing zones occurring along the northern and southern boundaries of the central Tianshan block[END_REF] near the Wulasitai village, and He et al. (2018a) traced this shear zone far westward and proposed that it can separate the Central Tianshan into northern and southern parts (Fig. 2). Based on our field and microscopic investigations, the WSZ J o u r n a l P r e -p r o o f geometrically is a bending strike-slip shear zone and is kinematically dominated by sinistral shearing (Figs. 7B and8), meanwhile, very limited dextral shearing can be distinguished in thin section (sample 06-B; Table S1) to be associated with the dominant sinistral kinematics (Fig. 10). In addition, at the bends and stepovers of the WSZ, a component of top-to-the-southwest shearing is also associated with the general sinistral shearing (Fig. 9F), and most likely resulted from strain partitioning due to transpression at the stepovers along the bending WSZ (Fig. 7), as commonly recognized in most bending strike-slip shear zones (e.g., [START_REF] Cunningham | Tectonics of strike-slip restraining and releasing bends[END_REF].

Therefore, both the XSZ and WSZ are characterized by a co-existence of opposite kinematic features. Four possibilities might potentially explain co-occurrence of these opposite kinematics within an identical shear zone: (1) strain localization along shear zone, (2) strain partitioning between conjugate structures, (3) low differential stress or coaxial shortening perpendicular to the shear zone, or (4) multi-stage simple shear events with rotated shortening directions. Localized NE-SW, NNW-SSE and N-S sinistral shearing was previously documented along the dextral MTSZ, and was interpreted as a subordinate left-lateral shear zone conjugated with the major WNW-ESE right-lateral shearing resulted from NNW-SSE bulk shortening [START_REF] Laurent-Charvet | Palaeozoic late collisional strike-slip deformations in Tianshan and Altay, eastern Xinjiang, NW China[END_REF][START_REF] Ludwig | ISOPLOT 3.00: a Geochronology Toolkit for Microsoft Excel[END_REF]. In addition, sinistral ductile shearing was also reported along the Baluntai Fault (or Southern Central Tianshan Fault) and considered as the result of clockwise rotation of Tarim with respect to Central Tianshan [START_REF] Deng | Timing of the formation of the Sangshuyuanzi ductile shear zone in the central segment of the South Tianshan and its tectonic significance[END_REF] or resulting from Devonian oblique convergence [START_REF] Li | Tectonic evolution of the Chinese Tianshan Orogen J o u r n a l P r e -p r o o f from subduction to arc-continent collision: Insight from polyphase deformation along the Gangou section[END_REF]. Some J o u r n a l P r e -p r o o f authors also proposed that the ductile shearing along the Central and North Tianshan formed under coaxial pure shear related to the NE-SW contraction induced by convergence between the Tarim and Central Tianshan blocks (e.g., [START_REF] Xu | Characteristics and dynamic origin of the large-scale Jiaoluotage ductile compressional zone in the eastern Tianshan Mountains, China[END_REF][START_REF] Yang | Vertical and horizontal strain partitioning of the Central Tianshan (NW China): evidence from structures and 40 Ar/ 39 Ar geochronology[END_REF].

In the cases of the XSZ and WSZ, strain partitioning mostly occurred along the bending segment of the WSZ as the top-to-the-SW shearing and changes of shear directions can be observed there (Figs. 7,9 and 10F). Shear directions also dramatically change in the XSZ but only in the overlapping segments between the overall NW-SE-striking ductile shear zone and the NE-SW-trending brittle strike-slip reverse faults (Fig. 4A). The latter cut across lithological boundaries and the mylonitic foliations of the shear zone, without any associated ductile deformation. They are not conjugate (subordinate) shear zones coeval to the NW-SE main shear zone, but rather posterior brittle faults. Local rotation related to these brittle reverse faults could be partially responsible for the changes of shear directions along the XSZ shear zone.

Even though, strain partitioning and strain localization are unlikely the reasons for the opposite kinematics in the XSZ and WSZ because kinematic senses remain consistent when the shear directions (foliations) change.

In addition, the general sub-E-W stretching lineation and consistently low plunging (Figs. 4 and8) in both the XSZ and WSZ indicate simple shear instead of pure shear or dominant coaxial contraction. Slight variations in lineation plunging directions and angles are the effects of bending of the shear zone and localized strain partitioning for the case of the WSZ, and the influence of localized fabrics rotation J o u r n a l P r e -p r o o f related to later reworking by reverse faults for the XSZ. Moreover, development of sheath folds and A-type folds in the XSZ (Fig. 5) and syn-kinematic granites in the WSZ (Fig. 9) also indicate quite high strain rate in both shear zones, and the possibility of low differential stress can be ruled out.

Considering that sinistral shearing is very locally preserved in the overwhelming dextral kinematics of the XSZ, and that locally recognized dextral shearing is observed only in a sample with predominant sinistral motions from the WSZ, it is most likely that these opposite kinematics in both shear zones formed in different stages of ductile deformation. In a multi-stage deformation belt like the Tianshan Orogen, the most pervasive structures should be the result of the most intensive and younger deformation events, and the fabrics formed in earlier deformation stage(s) could be rarely preserved due to later strong overprinting and replacement. Thus, it is reasonable to suggest that the occasionally observed sinistral kinematics in the XSZ and dextral kinematics in the WSZ might represent locally preserved fabrics of earlier deformation events. However, how and when these possible earlier structures were formed is still not clear, and localized development of coeval but opposite kinematics could not be completely excluded, thus, further investigations are needed in future.

Timing of strike-slip ductile shearing around and in the Central Tianshan

Along the MTSZ, the northern boundary of the Central Tianshan, mica 40 Ar/ 39 Ar ages of 290-242 Ma were obtained from the Gangou, Mishigou and Hongyuntan areas J o u r n a l P r e -p r o o f (Shu et al., 2002;[START_REF] J O U R N A L P R E -P R O O F Laurent-Charvet | Late Paleozoic strike-slip shear zones in eastern central Asia (NW China): new structural and geochronological data[END_REF][START_REF] Cai | Age and tectonic evolution of ductile shear zones in the eastern Tianshan-Beishan orogenic belt[END_REF], together with a muscovite 40 Ar/ 39 Ar plateau age of 309.7 ± 2.2 Ma for a mylonite from Mishigou [START_REF] Xu | J o u r n a l P r e -p r o o f Paleo-Asian and Tethyan tectonic systems with docking the Tarim block[END_REF], it is suggested the dextral shearing along the MTSZ occurred during the late Carboniferous to Early Triassic. Along the NTF, the westward continuation of the MTSZ, the age of dextral ductile shearing was constrained between ~270 and ~245 Ma by mica 40 Ar/ 39 Ar dating on mylonitic slates and foliated granites in the Du-Ku and Bingdaban areas [START_REF] J O U R N A L P R E -P R O O F Laurent-Charvet | Late Paleozoic strike-slip shear zones in eastern central Asia (NW China): new structural and geochronological data[END_REF]de Jong et al., 2009;[START_REF] Yang | Late Early Permian (266 Ma) N-S compressional deformation of the Turfan basin, NW China: the cause of the change in basin pattern[END_REF].

In this study, pre-and syn-kinematic granitic dykes in the XSZ yielded zircon U-Pb ages of 311.9 ± 2.4 Ma (Fig. 13D) and 294.6 ± 3.7 Ma (Fig. 13H), approximately overlapping the oldest mica 40 Ar/ 39 Ar ages from the MTSZ and NTF.

Taking into account that (1) igneous origins of the dated concordant zircons and both pre-and syn-kinematic features of the granite dykes, and (2) the estimated deformation temperatures (450-550 °C) are lower than crystallization temperature of igneous zircons and closure temperature of zircon U-Pb system (>700 °C; [START_REF] Cherniak | a l P r e -p r o o f Zircon[END_REF], but higher than the closure temperatures of biotite and muscovite argon system (365 ± 35 to 425 ± 70 °C; [START_REF] Harrison | Diffusion of 40 Ar in biotite: temperature, pressure and compositional effects[END_REF][START_REF] J O U R N A L P R E -P R O O F Harrison | Diffusion of 40 Ar in muscovite[END_REF][START_REF] Mcdougall | Geochronology and thermochronology by the 40 Ar/ 39 Ar method[END_REF][START_REF] Scibiorski | Rapid cooling and exhumation in the western part of the Mesoproterozoic Albany-Fraser Orogen, Western Australia[END_REF], we consider the new zircon U-Pb ages (312-295 Ma) of the pre-and syn-kinematic granite dykes as the maximum age, i.e. the initiation timing of the ductile dextral shearing along the XSZ, and previously published mica 40 Ar/ 39 Ar ages (290-242 Ma) for the MTSZ and NTF as the cooling ages of the ductile dextral shearing. It is worth noting that dextral shearing all along J o u r n a l P r e -p r o o f the NTF-XSZ-MTSZ could have been active diachronously along different segments.

The timing of earlier sinistral deformation along the XSZ cannot at this point be reliably constrained with the available data.

The WSZ represents a localized high strain belt inside the Central Tianshan (Fig. 2). Within the WSZ, our new biotite 40 Ar/ 39 Ar ages of 301-304 Ma were obtained from meta-sedimentary rocks showing sinistral kinematic fabrics (Fig. 10A-C). As the estimated deformation temperatures (>450 °C) of the WSZ are higher than the closure temperature of biotite argon system (335 ± 50 °C), we therefore regard the newly acquired 40 Ar/ 39 Ar ages as the cooling ages of the sinistral ductile deformation along the WSZ. Moreover, metamorphic zircons from a mylonitic greywacke of the Silurian Ahebulake Group within the WSZ yielded a mean age of ~312 Ma (He et al., 2018a). Thus, we infer that the sinistral shear of the WSZ likely took place during 312-301 Ma. As to the dextral deformation, its timing and regional context are however difficult to be constrained.

Along the Baluntai Fault (BF), southern boundary of the Central Tianshan, granitic mylonites from the Baluntai, Kumishi and eastward vicinities were dated at 311-248 Ma by 40 Ar/ 39 Ar dating on mica, feldspar and hornblende [START_REF] Yin | A Phanerozoic palinspastic reconstruction of China and its neighboring regions[END_REF][START_REF] J O U R N A L P R E -P R O O F Laurent-Charvet | Late Paleozoic strike-slip shear zones in eastern central Asia (NW China): new structural and geochronological data[END_REF][START_REF] Yang | Vertical and horizontal strain partitioning of the Central Tianshan (NW China): evidence from structures and 40 Ar/ 39 Ar geochronology[END_REF]Y. Wang et al., 2008;[START_REF] Xu | J o u r n a l P r e -p r o o f Paleo-Asian and Tethyan tectonic systems with docking the Tarim block[END_REF][START_REF] Cai | Age and tectonic evolution of ductile shear zones in the eastern Tianshan-Beishan orogenic belt[END_REF][START_REF] Li | Tectonic evolution of the Chinese Tianshan Orogen J o u r n a l P r e -p r o o f from subduction to arc-continent collision: Insight from polyphase deformation along the Gangou section[END_REF]. In the northern Kumishi area, a mylonitic gneissic granite was dated at 304 ± 2 Ma [START_REF] Li | Tectonic evolution of the Chinese Tianshan Orogen J o u r n a l P r e -p r o o f from subduction to arc-continent collision: Insight from polyphase deformation along the Gangou section[END_REF], and a syn-kinematic potassic granite showing high-temperature superplastic creep deformation features yielded zircon U-Pb age of 252 ± 4 Ma [START_REF] Wang | Evolution of calc-alkaline to alkaline magmatism through Carboniferous convergence to Permian transcurrent tectonics, western Chinese Tianshan[END_REF]. Dextral shear criteria are ubiquitous in J o u r n a l P r e -p r o o f the mylonitic rocks along the Baluntai-Wuwamen-Kumishi section [START_REF] Yin | A Phanerozoic palinspastic reconstruction of China and its neighboring regions[END_REF][START_REF] J O U R N A L P R E -P R O O F Laurent-Charvet | Late Paleozoic strike-slip shear zones in eastern central Asia (NW China): new structural and geochronological data[END_REF][START_REF] Wang | Evolution of calc-alkaline to alkaline magmatism through Carboniferous convergence to Permian transcurrent tectonics, western Chinese Tianshan[END_REF]Wang et al., , 2018;;[START_REF] Tang | Deformational characteristics of ductile shear zones in northern and southern margins of eastern central Tianshan[END_REF]Xu et al., 2011;[START_REF] Cai | Age and tectonic evolution of ductile shear zones in the eastern Tianshan-Beishan orogenic belt[END_REF]M. Wang et al., 2014;[START_REF] Zhong | Structural overprints of early Paleozoic arc-related intrusive rocks in the Chinese Central Tianshan: Implications for Paleozoic accretionary tectonics in SW Central Asian Orogenic Belts[END_REF][START_REF] Li | Tectonic evolution of the Chinese Tianshan Orogen J o u r n a l P r e -p r o o f from subduction to arc-continent collision: Insight from polyphase deformation along the Gangou section[END_REF].

Thus, the dextral ductile shearing along the BF occurred during the latest Carboniferous to the end of Permian, and are hence comparable to the age span of the dextral shearing along the MTSZ-NTF. In addition, within and outside of the BF and in the MTSZ, sinistral shearing and N-S contractional deformation were previously suggested to occur at ~399-393 Ma and ~358-356 Ma, respectively (Allen et al., 1993;[START_REF] Deng | Timing of the formation of the Sangshuyuanzi ductile shear zone in the central segment of the South Tianshan and its tectonic significance[END_REF][START_REF] Yang | Vertical and horizontal strain partitioning of the Central Tianshan (NW China): evidence from structures and 40 Ar/ 39 Ar geochronology[END_REF][START_REF] Li | Tectonic evolution of the Chinese Tianshan Orogen J o u r n a l P r e -p r o o f from subduction to arc-continent collision: Insight from polyphase deformation along the Gangou section[END_REF], prior to the dextral ductile shearing. Thus, the locally preserved sinistral kinematics recognized in the XSZ could be probably related also to this Devonian to early Carboniferous stage.

Farther westwards, the Nalati Fault (NF) also underwent dextral ductile deformation, which was dated by (1) mica 40 Ar/ 39 Ar plateau ages of ~285-252 Ma in mylonites [START_REF] Zhou | Paleozoic tectonic amalgamation of the Chinese Tian Shan: Evidence from a transect along the Dushanzi-Kuqa Highway[END_REF]Wang et al., 2007c;de Jong et al., 2009), (2) 277 ± 3 Ma zircon U-Pb age for a syn-kinematic intrusion in the Kekesu area [START_REF] Wang | Evolution of calc-alkaline to alkaline magmatism through Carboniferous convergence to Permian transcurrent tectonics, western Chinese Tianshan[END_REF], and (3) ~307 Ma to ~255 Ma metamorphic zircon U-Pb ages for strongly foliated early Paleozoic sandstones in the southern Nalati Range [START_REF] Zhong | Deformed continental arc sequences in the South Tianshan: New constraints on the Early Paleozoic accretionary tectonics of the Central Asian Orogenic[END_REF].

Therefore, the dextral ductile shearing along the NF took place from the late Carboniferous to end Permian, synchronous with the BF.

Implications for late Paleozoic eastward tectonic wedging in SW CAOB

J o u r n a l P r e -p r o o f

Strike-slip faults developed in the entire CAOB and played an important role in building this large accretionary and collisional orogenic system (e.g., Sengӧr et al., 1993;[START_REF] Allen | Paleozoic collisional tectonics and J o u r n a l P r e -p r o o f magmatism of the Chinese Tien Shan, Central Asia[END_REF][START_REF] Allen | Junggar, Turfan and Alakol basins as Late Permian to Early Triassic extensional structures in a sinistral shear zone in the Altaid orogenic collage, Central-Asia[END_REF][START_REF] Choulet | Late Paleozoic paleogeographic reconstruction of Western Central Asia based upon paleomagnetic data and its geodynamic implications[END_REF][START_REF] Li | Late Paleozoic closure of the Ob-Zaisan Ocean along the Irtysh shear zone (NW China): Implications for arc amalgamation and oroclinal bending in the Central Asian orogenic belt[END_REF][START_REF] Li | Geometry, kinematics and tectonic models of the Kazakhstan Orocline, Central Asian Orogenic Belt[END_REF]. There are different hypotheses concerning the formation mechanism and tectonic significance of these orogen-scale strike-slip shear zones. Many strike-slip faults subparallel to the orogens were considered to have formed during oblique subduction, duplicating and juxtaposing different fragments of the same arc, and shifting the magmatic front and overall geometry of orogens to form the oroclinal architecture of the Kazakhstan, SW CAOB [START_REF] Şengör | Evolution of the Altaid tectonic collage and Palaeozoic crustal growth in Eurasia[END_REF]Şengör andNatal'in, 1996, 2014). Alternatively, a growing number of recent studies showed that the magmatic arcs in the SW CAOB were formed by multi-stage subduction of various oceanic basins within the Paleo-Asian Ocean domain (e.g., [START_REF] Windley | Tectonic models for accretion of the Central Asian Orogenic Belt[END_REF][START_REF] Xiao | Accretion leading to collision and the Permian Solonker suture, Inner Mongolia, China: termination of the central Asian orogenic belt[END_REF][START_REF] Xiao | Paleozoic accretionary and collisional tectonics of the Eastern Tianshan (China): implications for the continental growth of central Asia[END_REF][START_REF] Wilhem | The Altaids of Central Asia: a tectonic and evolutionary innovative review[END_REF], and that the orogen-parallel strike-slip faults more likely resulted from intra-continental tectonism after the Carboniferous oblique collision between the Siberian and Tarim cratons [START_REF] Allen | Paleozoic collisional tectonics and J o u r n a l P r e -p r o o f magmatism of the Chinese Tien Shan, Central Asia[END_REF][START_REF] Allen | Junggar, Turfan and Alakol basins as Late Permian to Early Triassic extensional structures in a sinistral shear zone in the Altaid orogenic collage, Central-Asia[END_REF][START_REF] Yin | A Phanerozoic palinspastic reconstruction of China and its neighboring regions[END_REF][START_REF] Shu | A large-scale Palaeozoic dextral ductile strike-slip zone: the Aqqikkudug-Weiya zone along the northern margin of the Central Tianshan belt, Xinjiang, NW China[END_REF][START_REF] Buslov | Late Paleozoic-Early J o u r n a l P r e -p r o o f Mesozoic geodynamics of Central Asia[END_REF][START_REF] Wang | Evolution of calc-alkaline to alkaline magmatism through Carboniferous convergence to Permian transcurrent tectonics, western Chinese Tianshan[END_REF][START_REF] Pirajno | Intracontinental strike-slip faults, associated magmatism, mineral systems and mantle dynamics: examples from NW China and Altay-Sayan (Siberia)[END_REF].

In this context, Laurent- Charvet et al. (2002[START_REF] J O U R N A L P R E -P R O O F Laurent-Charvet | Late Paleozoic strike-slip shear zones in eastern central Asia (NW China): new structural and geochronological data[END_REF] and [START_REF] Cai | Age and tectonic evolution of ductile shear zones in the eastern Tianshan-Beishan orogenic belt[END_REF] emphasized the anticlockwise rotation of the Junggar block during the early Permian, which resulted in dextral shearing along the NTF -MTSZ and sinistral transpression of the Irtysh Shear Zone (ISZ) (e.g., [START_REF] Glorie | Tectonic history of the Irtysh shear zone (NE Kazakhstan): new constraints from zircon U/Pb dating, apatite fission track dating and palaeostress analysis[END_REF]. [START_REF] Li | Structural evolution of the Irtysh Shear Zone (northwestern China) and implications for the amalgamation of arc systems in the Central Asian Orogenic Belt[END_REF] suggested that such coeval dextral and sinistral shearing was controlled by the lateral migration of various units within the CAOB. Y. Wang et al. (2008) proposed that series of J o u r n a l P r e -p r o o f dextral strike-slip shearing were results of post-orogenic eastward extrusion of the CAOB between the Siberian and Tarim Cratons. Similar eastward extrusion tectonics was also documented by paleomagnetic studies (e.g., Wang et al., 2007a;[START_REF] Choulet | Late Paleozoic paleogeographic reconstruction of Western Central Asia based upon paleomagnetic data and its geodynamic implications[END_REF][START_REF] He | Crustal evolution of the Central Tianshan Block: Insights from zircon U-Pb isotopic and structural data from meta-sedimentary and meta-igneous rocks along the Wulasitai -Wulanmoren shear zone[END_REF]Zhu et al., , 2019b) ) suggesting that relative motions among the Kazakhstan-Yili, Junggar, Tu-Ha, Tarim and Siberia blocks during the late Carboniferous to Permian were characterized by significant anticlockwise rotations and accommodated by lateral displacement along major strike-slip faults (Wang et al., 2007a). The coeval horizontal displacements up to hundreds of kilometers along the large-scale shear zones (sinistral Irtysh and dextral NF-BF) favor an eastward tectonic wedging of Junggar-Yili-Central Tianshan in between the Siberia and Tarim blocks (Wang et al., 2007a).

Reliable geological and paleomagnetic data indicate that the Tianshan Orogen was formed by consumption of the Junggar-North Tianshan Ocean at ~310 Ma (e.g., [START_REF] Han | Age, geochemistry, and tectonic implications of a late Paleozoic stitching pluton in the North Tian Shan suture zone, western China[END_REF] and by welding of the Kazakhstan-Yili terrane with Tarim at ~320-310 Ma owing to the closure of the South Tianshan Ocean (e.g., [START_REF] Charvet | Palaeozoic tectonic evolution of the Tianshan belt, NW China[END_REF][START_REF] Wang | Final assembly of the Southwestern Central Asian Orogenic Belt as constrained by the evolution of the South Tianshan Orogen: links with Gondwana and Pangea[END_REF] and associated back-arc oceanic basins [START_REF] Wang | Paleozoic tectonics of the southern Chinese Tianshan: Insights from structural, chronological and geochemical studies of the Heiyingshan ophiolitic mélange (NW China)[END_REF](Wang et al., , 2018)). As mentioned above, although sinistral strike-slip kinematics recognized along the BF and MTSZ possibly resulted from the Devonian to early Carboniferous oblique subduction [START_REF] Li | Tectonic evolution of the Chinese Tianshan Orogen J o u r n a l P r e -p r o o f from subduction to arc-continent collision: Insight from polyphase deformation along the Gangou section[END_REF] Combined with previous structural and paleomagnetic studies, our new results further confirm that the previously welded Yili -Central Tianshan -Junggar blocks simultaneously moved eastwards and wedged in between the Siberian and Tarim cratons (Fig. 15A). This eastward wedging was accommodated by synchronous dextral strike-slip shearing along the NF and BF, and then by the sinistral strike-slip shearing along the ISZ since ~284 Ma [START_REF] Li | Structural evolution of the Irtysh Shear Zone (northwestern China) and implications for the amalgamation of arc systems in the Central Asian Orogenic Belt[END_REF]. The dextral ductile strike-slip shearing along the NTF -MTSZ could be the result of differential eastward displacement rates of Junggar relative to the Yili -Central Tianshan blocks. Similarly, the sinistral WSZ probably resulted from relatively lower displacement velocity of the northern part of the Central Tianshan (north of the WSZ) with respect to its southern part (south of the WSZ), likely due to the backstop effect of the Tu-Ha terrane (Fig. 15B). Meanwhile, it is noteworthy that the movement along the ISZ during earliest Permian was not well constrained due to lack of reliable geochronological data (e.g., [START_REF] J O U R N A L P R E -P R O O F Hu | Structural evolution of the eastern segment of the Irtysh Shear Zone: implications for the collision between the East Junggar Terrane and the Chinese Altai Orogen (northwestern China)[END_REF]. This interpretation could be tested with further kinematic and paleomagnetic studies to quantitatively assess the relative movement (rotation) rates between different tectonic units. Finally, the eastward tectonic wedging of the Kazakhstan-Yili, Central Tianshan and Junggar blocks was most likely triggered by the sub-E-W convergent orogenesis of the late Paleozoic Uralides related to the J o u r n a l P r e -p r o o f collision between the Baltica and Siberia blocks (e.g., [START_REF] Biske | Paleozoic Tian-Shan as a transitional region between the Rheic and Urals-Turkestan oceans[END_REF][START_REF] Ivanov | Tectonics of the Urals and adjacent part of the West-Siberian platform basement: Main features of geology and development[END_REF]. (2) The Wulasitai shear zone is generally a WNW-ESE-trending high-strain belt developing in the interior of the Central Tianshan. Geometric, structural and kinematic analyses suggest predominantly sinistral strike-slip shearing associated with top-to-the-SW thrusting at the NW-SE bending segment of the shear zone, and dextral kinematics is locally preserved. Biotite 40 Ar/ 39 Ar and metamorphic zircon U-Pb ages of meta-sedimentary rocks constrain the timing of the sinistral motion at ~312-301 Ma.

Conclusions

(3) New structural and geochronological data from the Xiaergou and Wulasitai shear zones together with the regional geological and paleomagnetic data suggest that the latest Carboniferous to Permian ductile strike-slip shear zones in the Tianshan Orogen, SW CAOB, formed in a post-orogenic intra-continental setting, and likely J o u r n a l P r e -p r o o f Nanjing Hongchuang Analytical Institute.

Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) U-Pb dating of zircon was conducted at the State Key Laboratory for Mineral Deposits Research, Nanjing University, using an Agilent 7500s ICP-MS connected to a New Wave 213nm laser ablation system with an in-house sample cell. Zircon standard GEMOC GJ-1 ( 207 Pb/ 206 Pb age of 608.5 ± 1.5 Ma; [START_REF] Jackson | The application of laser ablation-inductively coupled plasma-mass spectrometry to in-situ U-Pb zircon geochronology[END_REF] was measured to correct fractionation, and the accuracy was monitored using zircon standard Mud Tank with an intercept age of 732 ± 5 Ma [START_REF] Black | The age of the Mud Tank carbonatite, Strangways Range, Northern Territory. Bureau of Mineral Resources[END_REF].

Samples were analyzed in runs of 15 analyses including 5 analyses on standard zircons and 10 analyses on samples of unknow ages. All analyses were carried out using a beam with a 32 μm diameter and a repetition rate of 5 Hz.

U-Th-Pb isotopic ratios and ages were calculated from the raw signal data using the software package GLITTER. Correction for common Pb was performed via the EXCEL program ComPbCorr#3_15G (Anderson, 2002). U-Pb Concordia diagrams and probability density curves of ages were conducted using ISOPLOT 3.0 [START_REF] Ludwig | ISOPLOT 3.00: a Geochronology Toolkit for Microsoft Excel[END_REF]. Uncertainties are quoted at 1σ for individual analyses and at 2σ for mean ages.

A.2. Biotite 40 Ar/ 39 Ar dating

Single grains of biotite were carefully handpicked under a binocular microscope Ages and isotopes ratios are plotted and tabulated at ± 1σ and were calculated according to [START_REF] Scaillet | Numerical error analysis in 40 Ar/ 39 Ar dating[END_REF]. Weighted mean ages (WMA) are calculated by inverse-variance weighting of the steps pooled in the weighted mean. Total-Gas ages (TGA) are calculated by summing all fractions released and by quadratically propagating the attached errors. Pooled age errors include procedural errors, and decay constants and isotope abundance errors. QQ, Qaidam-Qinling (modified after [START_REF] Şengör | Evolution of the Altaid tectonic collage and Palaeozoic crustal growth in Eurasia[END_REF][START_REF] Jahn | Granitoids of the Central Asian Orogenic Belt and continental growth in the Phanerozoic[END_REF]. (B)

Figure and Table captions:

J o u r n a l P r e -p r o o f

Geological map of the SW CAOB, including major tectonic units and boundaries (after [START_REF] Windley | Tectonic models for accretion of the Central Asian Orogenic Belt[END_REF][START_REF] Choulet | Late Paleozoic paleogeographic reconstruction of Western Central Asia based upon paleomagnetic data and its geodynamic implications[END_REF]Wang et al., 2012;[START_REF] Cao | Late Paleozoic arc magmatism in the southern Yili Block (NW China): insights to the geodynamic evolution of the Balkhash-Yili continental margin, Central Asian Orogenic Belt[END_REF].

Abbreviations correspond to: IKMT, Ishim-Kyrgyzstan Middle Tianshan; SKNT, Stepnyak-Kyrgyz North Tianshan; ACNT, Aktau-Chinese North Tianshan; NB, North Balkhash; BY, Balkhash-Yili; CY, Chu-Yili; BA, Baidaulet-Akbastau; BC, Boshchekul-Chingiz; JB, Junggar-Balkhash; ZTS, Zharma-Tarbagatay-Saur; KM, Karamay; WJ, West Junggar; CNT, Chinese North Tianshan; CCT, Chinese Central Tianshan; BGD, Bogda; Bay, Bayinbulak; Gul, Guluogou; Kul, Kulehu; Wuw, Wuwamen. Numbers denote major faults: 1 = North Tianshan Fault (NTF), 2 = Main Tianshan Shear Zone (MTSZ), 3 = Nalati Fault (NF), 4 = Baluntai Fault (BF).

  J o u r n a l P r e -p r o o f Except for the undeformed granitic and diabase dykes intruding the XSZ, all other lithological units mentioned above underwent intensive ductile shearing, showing well-defined ~E-W or ~ENE-WSW-striking steep (40° to 78°) mylonitic foliations (S1) associated with pervasive stretching lineation (L1) gently plunging (<40°) to E/NE or W/SW (Figs. 4A-B and 5A-D). Both the strikes of S1 foliations and the plunges of L1 lineation are sub-parallel to the overall strike of the shear zone.

  Quartz is one of the most sensitive minerals during plastic deformation. In a shear zone, quartz can be deformed via different mechanisms under various temperature conditions. Previous studies established relationships between deformation mechanisms and physical conditions based on naturally and experimentally deformed rocks, e.g., types of quartz dynamic recrystallization and corresponding temperatures, are widely applied in studies of shear zones (e.g., HirthJ o u r n a l P r e -p r o o f

  , the more explicit and pervasive ductile strike-slip shearing around and within the Central Tianshan initiated almost simultaneously at 312-310 Ma, and lasted until the end of Permian, except along the WSZ. Despite uncertainties on the timing and genesis of the locally preserved (and possible earlier) J o u r n a l P r e -p r o o f dextral kinematics in the WSZ, we suggest that the latest Carboniferous to Permian (312-242 Ma) dextral strike-slip shearing along the MTSZ and BF, and the latest Carboniferous (312-301 Ma) sinistral strike-slip shearing along the WSZ occurred in post-orogenic intra-continental setting.

( 1 )

 1 The Xiaergou shear zone along the northern boundary of the Central Tianshan is the connecting segment between the North Tianshan Fault and Main Tianshan Shear Zone. Large-scale and sample-scale structural and kinematic analyses indicate principally ductile dextral strike-slip shearing with locally preserved sinistral kinematics. The timing of dextral ductile shearing is dated at ~312-295 Ma by U-Pb dating of zircons from pre-and syn-kinematic granitic dykes.

  J o u r n a l P r e -p r o o f from 0.3-2.0 mm size fractions of crushed rock samples 01-B and 02-B. The biotite grains were then cleaned in distilled water and acetone before being weighed into Al foil envelopes for irradiation.After neutron irradiation for 10 h in the CLICIT Cd-lined slot of the Corvallis Nuclear Reactor (Oregon State University, United States) along with the Fish Canyon Tuff sanidine standard (FCT 28.126 ± 0.019 Ma at 2σ)[START_REF] Phillips | Astronomical calibration of 40 Ar/ 39 Ar reference minerals using high-precision, multi-collector (ARGUSVI) mass spectrometry[END_REF],40 Ar/ 39 Ar analyses were performed using a high-resolution Helix SFT mass spectrometer outfitted to a home-built CO 2 -laser based extraction system featuring ultra-low argon blanks. Detailed operating conditions can be found in[START_REF] Corti | Aborted propagation of the Ethiopian rift caused by linkage with the Kenyan rift[END_REF].

Fig. 1 .

 1 Fig. 1. (A) Simplified tectonic divisions of East Asia showing the location of the

Fig. 2 .

 2 Fig. 2. Topographic and simplified geological map of the Central Tianshan and

Fig. 3 .

 3 Fig. 3. (A) Google Earth © Satellite image of the Xiaergou shear zone (XSZ). (B)

  J o u r n a l P r e -p r o o f

Fig. 4 .

 4 Fig. 4. (A) Structural map of the studied domain of the Xiaergou shear zone (XSZ)

Fig. 5 .

 5 Fig. 5. Field photographs of representative structures in the Xiaergou shear zone. (A)

Fig. 6 .

 6 Fig. 6. Photomicrographs showing kinematic features of representative mylonites

Fig. 7 .

 7 Fig. 7. (A) Google Earth © Satellite image of the Wulasitai shear zone (WSZ). (B)

Fig. 8 .

 8 Fig. 8. (A-C) Structural maps of the studied domains (see Fig. 7 for locations) along

Fig. 9 .

 9 Fig. 9. Field photographs of representative structures in the Wulasitai shear zone. (A)

Fig. 10 .

 10 Fig. 10. Photomicrographs of representative kinematic features of mylonites from the

Fig. 11 .

 11 Fig. 11. Microstructural characteristics of dynamically recrystallized quartz grains in

Fig. 12 .

 12 Fig. 12. Plots of estimated temperatures v.s. latitudes of sampling sites for the

Acknowledgements

We appreciate Mr. B. Wu (NJU) for his kind help in zircon LA-ICP-MS dating.

We thank two anonymous reviewers for detailed and constructive comments and Editor-in-Chief Prof. C. Passchier for his editorial handling. This study was co-sponsored by the National Natural Science Foundation of China (42011530146, 41772225, 41390445, 41222019), the Fundamental Research Funds for the Central Universities, the Open Fund of State Key Laboratory for Mineral Deposits Research (ZZKT-201603), the Fund for Scientific Research -Flanders (FWO, Bilateral Project VS06520N), LABEX VOLTAIRE (ANR-10-LABX-100-01), Région Centre ARGON, and EQUIPEX PLANEX (ANR-11-EQPX-0036).

Appendix: Analytical methods

A.1. Zircon U-Pb dating

Zircon grains from the samples 44-B and 49-C were concentrated via heavy liquids and magnetic separation techniques, and then hand-picked under a binocular microscope. Selected colorless zircons were mounted in epoxy resins and polished to approximately half-section thickness to expose the grains' center. In order to examine J o u r n a l P r e -p r o o f migration.

J o u r n a l P r e -p r o o f

Supplementary Table S1. Textural descriptions of quartz dynamic recrystallization and temperature estimations for the mylonitic rocks from the Xiaergou and Wulasitai shear zones. S2. LA-ICP-MS zircon U-Pb analytical data for the syn-kinematic granitic rocks in the Xiaergou shear zone. S3. Laser total fusion 40 Ar/ 39 Ar analytical data of single biotite grains from the meta-sedimentary rocks in the Wulasitai shear zone. J o u r n a l P r e -p r o o f

Supplementary Table

Supplementary Table

Declaration of competing interest

The authors declare that they are not aware of any competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

J o u r n a l P r e -p r o o f