The tectonic evolution of the East Kunlun Orogen, northern Tibetan Plateau: A critical review with an integrated geodynamic model

Journal Pre-proofs The tectonic evolution of the East Kunlun Orogen, northern Tibetan Plateau: a critical review with an integrated geodynamic model Miao Yu, J.M. Dick, Chengyou Feng, Bin Li, Hui Wang PII: DOI: Reference:

S1367-9120(19)30520-6 https://doi.org/10.1016/j.jseaes.2019.104168 JAES 104168

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Journal of Asian Earth Sciences

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25 March 2019 27 November 2019 28 November 2019

Please cite this article as: Yu, M., Dick, J.M., Feng, C., Li, B., Wang, H., The tectonic evolution of the East Kunlun Orogen, northern Tibetan Plateau: a critical review with an integrated geodynamic model, Journal of Asian Earth Sciences (2019), doi: https://doi.org/10.1016/j.jseaes.2019.104168

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The tectonic evolution of the East Kunlun Orogen, northern Tibetan Plateau: a critical review with an integrated geodynamic model Miao Yu a, J. M. Dick a, Chengyou Feng b, *, Bin Li a, *, Hui Wang c, a

Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment

Monitoring, Ministry of Education, School of Geosciences and Info-Physics, Central South University, Changsha 410083, China b

MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources,

CAGS, Beijing 100037 c

Mineralization and Dynamics Laboratory of Chang'an University, Xi'an 710054, China

Abstract The East Kunlun Orogen is an integral component of the northern Qinghai-Tibet plateau. Here we synthesize the geologic, geochemical, geochronological and stratigraphical dataset and propose an integrated geodynamic model to illustrate the tectonic evolution of this orogen. This review also provides important insights on the complex Phanerozoic plate tectonic processes. We envisage the protracted multi-stage accretion and collision of a collage of terranes during the subduction and closure of the South Kunlun and Anemaqen oceans, from the Neoproterozoic to Early Mesozoic. The East Kunlun orogen is tectonically divided into the North Kunlun Terrane (NKT), South Kunlun Terrane (SKT), Muz Tagh-Anemaqen Terrane (MAT) and Hoh Xil-Bayan Har Terrane (HBT) from the north to south, of which evolution can be divided into six stages from Late Neoproterozoic-Early

*

Corresponding author at:: [email protected] (C.Y. Feng); [email protected] (B. Li)

Mesozoic age (550 Ma – 200 Ma): I. ca. 540–481 Ma; II. ca. 481–424 Ma; III. ca. 424–370 Ma; IV. ca. 370–271 Ma (magmatic gap); V ca. 271–224 Ma; and VI. ca. 224–201 Ma. The NKT, as an active continental margin initiated at ca. 450 Ma as a consequence of backarc ocean lithosphere subduction in the late Ordovician-middle Silurian (Stage II). The closure of back arc basin led to an oblique collision between the NKT and SKT during the early-middle Silurian (Stage II), and to a post-collisional environment in the late Silurian-middle Devonian (Stage III). The SKT and MAT developed as a young island arc, both carrying large amounts of ocean island arc granitoids (OAG) and SSZ (supra-subduction zone) type ophiolites together with island arc tholeiite (IAT), as a consequence of bidirectional subduction of Proto-Tethys Ocean (Stage I). During the collision between SKT and NKT , the SKT transformed from a young island arc into a mature island arc With thickening crust, and the granitoids geochemically evolved from the OAG to CAG-WPG in the late Ordovician-middle Silurian (Stage II). The collision between SKT and MAT probably occurred after the middle Devonian (Stage III), as evidenced from the absence of the upper Devonian strata in the SKT. The SKT and MAT is interpreted as an exotic terrane that has been accreted onto the continental margin and contributed significantly to the continental growth in this orogenic belt. A magmatic quiescence occurred during ca. 370–270 Ma (Stage IV) associated with subduction polarity reversal. A new subduction zone initiated at the southern margin of the MAT after the middle Permian (Stage V), which subsequently resulted in extensively development of calc-alkaline granitoids in the NKT, SKT and MAT. The progressive chronology change of granitoids from NKT to further south maybe the joint results of flat subduction and slab rollback which make magmatism center retrograde migrate towards the trench. The final closure of the Anemaqen Ocean might have occurred in the Late Triassic (Stage VI) as indicated by the upper Triassic Babaoshan terrestrial

molasse formation and development of CAGs and WPGs in the HBT, which resulted in the accretion of the North Qiang Tang microcontinent. Keywords: East Kunlun; Tectono-magmatic evolution; arc-continent collision; continental growth 1. Introduction The Qinghai-Tibet plateau has been a frontier area in solid earth sciences for over three decades, with its complex records of sequential accretion and collision, from north to south, of several microcontinents, flysch complexes, and island arcs onto the southern margin of Eurasia throughout the Neoproterozoic, Paleozoic, and early Mesozoic (Allegre et al., 1984; Chang et al., 1986; Dewey et al., 1988; Mo et al., 2007; Owens and Zandt, 1997; Sengör, 1979; Turner et al., 1993; Wu et al., 2019; Xu et al., 2006; Yin and Harrison, 2000; Zuza and Yin, 2017). However, attention was mostly focused on the Indo-Asian continental collision during the Cenozoic in the southern part of the Tibetan plateau. Since the East Kunlun Range form an important component in the northern part of the plateau, the geological history and tectonic regimes in this region are essential to understand the crustal evolution of the Tibetan plateau. The East Kunlun orogen preserves the history of multiple ocean basins, terranes, and island arcs, together with multistage ophiolites, together with large volumes of calc-alkaline magmatic suites, and large-scale thrust, strikes-slip and normal fault systems, providing an important window to evaluate Phanerozoic plate tectonic processes. The geologic evolution of the East Kunlun orogen has been studied by many researchers since 1980s. Jiang et al. (1986) proposed a “four openings and four closings” model for the crustal evolution of the East Kunlun Range. Yin and Harrison (2000) proposed an active-passive-active margin transitional model, in which the southern Kunlun-Qaidam terrane rifted from the southern Kunlun-Qaidam block in the early Permian, and a reworked orogenic belt was superposed on the

older early Paleozoic arc in the latest Permian (Wu et al., 2016). Xu et al. (2012) suggested a large-scale orogenic collage model involving multiple ocean basins, terrains, and island arcs in the Paleo-Tethys setting. Dong et al. (2018) put forward a subduction-accretion model to interpret the spatio-temporal tectonic framework during the Paleozoic-Triassic interval. Dai et al. (2013) conducted systematic thermochronological investigations to understand the pre-Cenozoic tectonic-magmatic history of the East Kunlun Range. Recently, some scholars proposed a bidirectional subduction model of the Proto-Tethys crust in the early Paleozoic between the Qaidam massif and Wanbaogou island arc (Chen et al., 2016; Zhao et al., 2017). In addition, a double-subduction model was also established to describe the mechanism of collision between the southern margin of the East Kunlun Terrane and the northern margin of the Songpan-Ganzi Terrane in the Permian–Triassic (Kapp et al., 2000; Pullen et al., 2008; 2015). Although these models clarify some of the questions, many unresolved controversies remain. The subduction polarity and closure time of the Paleo-Tethys Ocean remain enigmatic. Why the late Devonian-early Permian magmatism ceased in the North and South Kunlun Terranes (Fig. 1c), and instead experienced widespread deposition of Middle-Upper Carboniferous shallow marine carbonate rocks remain unknown. The characteristic tectonic features of the Qingshuiquan ophiolites: MOR-type, SSZ type or Alpine type (back arc basin) are also ambiguous. The North Kunlun Terrane shows a significant absence of pre-Silurian-Cambrian granitoids, but the South Kunlun and Anemaqen Terranes both experienced continuous magmatism from Cambrian to the Ordovician, which is also unanswered. The depositional environment of the Baishahe and Kuhai Group sedimentary rocks, and whether they constitute the metamorphic basement of the South Kunlun Terrane are yet to be solved.

The objective of this work is to provide a coherent picture of the pre-Cenozoic geologic framework of the northern Tibetan plateau, based on a comprehensive overview of the major pre-Cenozoic tectonic structures, and the occurrence of associated metamorphic, magmatic, and sedimentary rock units. We aim to better interpret the spatial and temporal relationships of various terranes in the northern Tibetan plateau, and to analyze the paleogeographic evolution of Tethys on the basis of the ophiolites, flysch/molasse facies sedimentation, paleontological evidence and syn-collisional magmatism that delineate the location of the Paleo-Tethyan suture in the southern margin of the Asian continent. 2. Structure Geology 2.1. Faults The East Kunlun Orogen hosts one of the most prominent and seismically active strike faults in the interior of the Tibetan plateau (Fig. 1b) (Clark et al., 2010; Cowgill et al., 2003; 2008; Yin et al., 2007). It is generally subdivided by the North Kunlun Fault (NKLF), Middle Kunlun Fault (MKLF), South Kunlun Fault (SKLF), Muz Tagh-Anemaqen Fault (MAF) from the north to the south, into different tectono-magmatic belts (Jiang, 1992; Luo et al., 1999; Yang et al., 1986), and is bounded by the Altun Fault (ATF) to the west and Wenquan Fault (WQF) to the east (Fig. 1b). In addition, most of these faults underwent a Cenozoic reactivation of deformation, which is closely related to the initiation of collision between India and Eurasia, despite the fact that the plate boundary was located more than 3000km to the south. (Clark et al., 2010). There are numerous Cenozoic thrust faults and potential strike-slip faults that together accommodate kilometers of displacement (Wu et al., 2019). The NKLF as a blind fault, stretches along the northern flank of the East Kunlun Range in an almost NWW direction, from the Dulan country in the east to the city of Golmud at the center (Fig.

1b). It swings to the NW at the city of Golmud and stretches into the Qiman Tagh area (Fig. 1b). The fault shows characteristics of a sinistral strike-slip system, in with the strike slip movement in the early Miocene (Fu et al., 2015). The MKLF is traverses the central part of the Eastern Kunlun orogenic as a linear structure extending from the Qingshuiquan area in the east, through the Naij Tal area in the middle, to the Tula area in the west (Fig. 1b). It swings to the NE in the Tula area and stretches to the Ake Tagh area in the southwest. Intense structural deformation occurred along this fault, with a NWW-SEE ductile shear zone, and the sinistral thrusting was activated earlier than the dextral strike-slip shearing (Li et al., 2014). The peak timing of deformation is constrained as 427 Ma and the cooling stage at 408 Ma obtained from the syn-kinematic hornblende and muscovite (40Ar/39Ar dating) from the high-angle thrust deformation belt in the Qingshuiquan area, further constraining the closure time of the early Paleozoic Proto-Tethys basin (Chen et al., 2002). The SKLF, a major ductile sinistral shear zone along the southern margin of the East Kunlun Range, runs from the Maqen area in the east, through the Xidatan and Bukedaban areas, to the Heiding Mountain in the west (Fig. 1b). This shear zone was formed as a result of oblique subduction of the Hoh Xil-Bayan Har Terrane in the early Mesozoic (Feng et al., 2017). Although it stretches for more than 1200 km, there is no major variation in the deformation and thrust characteristics between the eastern and western parts (Hu and Chen, 2010). The middle segment is nearly E-W-trending, which is composed of a 2-km-wide mylonite zone and mainly displays obvious left-lateral characteristics (Feng et al., 2017). It is a lithospheric vertical strike-slip fault with a depth of up to 250 km (Xu et al., 2001). The eastern and western segments are NW-SE-trending, which is composed of a series of southwest-verging thrust faults that form a suture zone and these lithospheric

faults dip steeply northward to a depth of 200 km (Xu et al., 1999). The whole fault system experienced a multistage superposed structural evolution (Kou et al., 2015; Zha et al., 2012). The main deforming time of the ductile shear zone is of 234–237 Ma (sericite 40Ar/39Ar dating) (Hu and Chen, 2010). However, the mylonitized granite in Xidatan and undeformed granite in Xiaonanchuan were used to define the main occurences of ductile shear zone. Their dating ages are of 199.3 ± 2.2 Ma and 196.4 ± 1.3 Ma, respectively, which indicates that the sinistral shear zone should have formed between 199–196 Ma (Feng et al., 2017). In the last stage, Permian-Triassic strata were thrusted over the Paleocene-Eocene Fenghuoshan Fm. and Oligocene Yaxicuo Fm. rocks along the SKLF (Wu et al., 2009). The MAF, as the boundary between the Muz Tagh-Anemaqen (MAT) and Hoh Xil-Bayan Har Terranes (HBT), is discontinuous at the central part of the East Kunlun Orogen (Fig. 1a), which is mainly composed of Muz Tagh Fault (MTF) in the west and Anemaqen Fault (AMF) in the east. It crosses from the Muz Tagh Mountain in the west, through the Buke Daban Peak and Hohsai Lake in the middle, to the Changmahe in the east. It shows high angle thrusted and NNE-dipping characters, which compels the Permian Suwemenk Fm. and Maerzheng Fm. southward thrusted on the Lower Triassic Bayan Har Gp., respectively in the west and east (Fig. 2a). In addition, it develops abundant cleavage, selvage, fault breccia and tectonic lens in the fault belt, which indicates a sinistral strike-slip shearing movement later (Shao et al., 2017). The felsic mylonite developing augen structures, S-C fabrics and rotational fragments in the belt shows strong plastic shearing deformation. To the Cenozoic, it was reactivated with the intracontinental adjustment in the south flank of Buqen Mt. and Muz Tagh Mt., which finally controls the framework of the MAT (Shao et al., 2017). The NW-trending WQF is the boundary between the East Kunlun Orogen and the West Qinling

Orogen, and crosses Elashan Mountain and turns to Qilian Mountain in the north (Fig. 1b). The Elashan Mountain is located in the easternmost segment of the East Kunlun Orogen, and in its eastern part, the metamorphic basement and Pre-Mesozoic sedimentary rocks were uplifted due to the NE-dipping thrust fault systems and the Wenquan dextral strike-slip fault (Jiang et al., 2008). Previous studies suggested that the Kunlun and Qinling orogens were part of a unified orogen before the WQF system developed (Chen et al., 2015; Ren et al., 2016; Shao et al., 2017). 2.2. Fold belts The East Kunlun Range underwent Caledonian, Hercynian and Indosinian orogenic events, and the effects of strong thrust and deformation are widespread. Particularly in the Anemaqen and Bayan Har Terranes, the Indosinian tectonic deformation is very intense as a result of the subduction of the Anemaqen Ocean. In the Xueshuihe-Luotuogou area within the central part of the South Kunlun Terrane, four deformation systems were identified mostly in Permian-Triassic strata on the basis of a comparative study of the structural deformation within the regional tectonic evolution (Zha et al., 2012). These are: 1) thrust folds were formed by the long-term northward subduction of the Tethys oceanic lithosphere, 2) rootless folds associated with the sinistral strike-slipping fault, 3) broad-gentle folds, isopachous folds, and asymmetrical folds probably controlled by the dextral strike-slip, and overprinted on the early deformation, and 4) broad and gentle folds with hinges stretching in NE direction. The South Kunlun accretionary complex experienced reformation and superimposition of the tectonic foliation during the plateau uplift. In the Qingshuiquan area, two groups of oblique-overturned folds developed in the Triassic Hongshuichuan flysch formation overlapping which each other. One group showing NWW axial

trace, is almost paralleled the major structural lines of the orogen. The other group maintains a NE direction, and is approximately perpendicular to the first group (Hou et al., 1999). These two groups, approximately vertically superposed on each other by the two north-east and north-west compressive stresses, were generated by three deformation mechanisms including flattening, pure shearing, and pure- simple shearing, indicating that the collisional stress may have come from two directions in the NE and NW. To the southeast of the East Kunlun Range, within the eastern part of the Hol Xil-Bayan Har belt, the fold system can be divided into three tectonic deformation zones from the south to the north as follows (Peng, 2015): 1) A tight fold thrust zone, formed through the subduction compressed deformation in the middle-late Triassic, generating the main NWW-SEE fold-thrust framework in the Bayan Har Mountains. 2) A broad and gentle fold thrust zone, formed as a consequence of the rapid uplift of the Tibetan Plateau in the Paleocene-Eocene (ca. 65–35 Ma)(Wang et al., 2010). 3) An inclined plunging fold thrust zone, probably associated with the NE oblique subduction of the Yangtze Plate (Xu et al., 2001). These three deformation zones are considered to be products of the same subduction-and convergence system in the middle-late Triassic but resulted from different tectonic styles (Peng, 2015). 2.3. Tectonic Framework The complex tectono-magmatic events in the East Kunlun orogenic belt have led to diverse views on its subdivision. Jiang et al. (1986) outlined three geotectonic units in the Eastern Kunlun Mountains based on the two boundaries of the MKLF and SKLF as follows. 1) The Northern Zone, composed of an early Paleozoic fold belt dominated by Ordovician marine sediments and low-grade metamorphic rocks, unconformably covered by the Devonian marine sandstones and conglomerates.

2) The Middle Zone, composed of the middle-late Proterozoic metamorphic rocks and Paleozoic-Mesozoic granitoids, overlain by the Devonian continental sandstones, conglomerates and volcanic rocks, and Carboniferous marine limestones and clastic sedimentary rocks. 3) The Southern Zone, composed of a major geosynclinal fold belt, including Permian-Triassic successions. Gu (1994) divided the East Kunlun orogenic belt into three zones: the North Kunlun magmatic arc zone, the Central Kunlun double-sided subduction zone, and the South Kunlun mélange zone. Pan et al. (1996) and Li et al. (2016) suggested that the Kunlun Mountains are composed of the North and South Kunlun Terrane separated by the Middle Kunlun suture zone. In another classification, Pan et al. (2002; 2012) subdivided the Kunlun Mountains into the North Kunlun magmatic arc zone, including Ordovician

and

Permian-Triassic

arc

granitoids,

and

the

Kangxiwar–Muztagh–Buqin

Mountain-Anemaqen subduction-accretion-collision zone, including remnant oceanic arc blocks and Sea Mountains. Xu et al. (2001) divided the East Kunlun Orogen into different terranes marked by the alternation of high-velocity and low-velocity seismic features: the North Kunlun Terrane (NKT) with low-velocity materials; the South Kunlun Terrane (SKT) with high-velocity materials; the Bayan Har-Songpan-Garze Terrane with variation in the eastern and western part. Dong et al. (2018) divided the East Kunlun orogen belt and adjacent regions into four units based on three mélange zones: the North Qimantagh belt, the Central Kunlun belt, the South Kunlun belt and the Bayan Har Terrane, although not all boundaries are clearly defined. However, Yu et al. (2017) thought that the Qiman Tagh orogen had independent tectonic evolution distinguished with East Kunlun orogen, which can be divided into the North and South Qiman Tagh Terrane along the boundaries of Adatan fault in the east and Baiganhu fault in the west (Wang et al., 2014). Although Dong et al. (2018) proposed that the South Qiman Tagh Terrane should be incorporated into the NKT, and named as the

Central Kunlun belt as a whole, we found that the South Qiman Tagh Terrane does not host early Paleozoic granitoids, in contrast with the NKT, which carries large amounts of Ordovician-Silurian granitoids. The significant contrast indicates that the both terranes were not in a same tectonic environment during the early Paleozoic. Therefore, we suggest that the Qiman Tagh Terrane should be excluded from the evolution of East Kunlun Orogen, and adopt the classification into four terranes based on the stratigraphy and distinct magmatic records as follows (Fig. 1b): The NKT lies between the MKLF and NKLF (Chang et al., 1986), which is composed of a large Precambrian basement and late Ordovician-late Triassic magmatic rocks associated with the Caledonian and Indosinian tectonic regimes (Fig. 1a) (Xiong et al., 2014; Yang et al., 2014). Late Ordovician ophiolites and early Silurian high pressure metamorphic rocks were discovered in the Suhaitu, Dagele and Qingshuiquan areas along the MKLF, which further constrain the MKLF as a boundary between the NKT and SKT (Fig. 1a) (Du et al., 2017b). The SKT, stretching from the Wenquan area in the east, through Wanbaogou area in the middle, to the Chader Tagh in the west, is bounded by the MKLF and the SKLF. It also witnessed the Caledonian to Indosinian events, and includes the Wanbaogou island arc and the Qingshuiquan back arc basin activities (Fig. 1a). Although the Qingshuiquan ophiolites and the volcanic rocks of the Wanbaogou formation are the key indicators (Fig. 2a), their genetic settings have been disputed. The MAT is divided at the Kunlun Pass into the Muz Tagh subterrane in the west and Anemaqen subterrane in the east (Fig. 1a). These subterranes are bounded by the South Kunlun Fault in the north, and the Muz Tagh and Anemaqen Faults in the south, respectively. They both experienced multi-stage tectonic activities, including the Caledonian, Hercynian and Indosinian events. Thus, they host abundant early Paleozoic intrusions and ophiolites, and a few early Mesozoic granitoids

(Fig. 1a). In addition, the MAT is almost entirely covered by the post-Carboniferous strata (Fig. 2a). The HBT is a triangular field tectonically bounded by Muztag-South Kunlun Fault-Anemaqen in the north, Xijir Ulan-Yushu-Jinsha River fault zone in the south, and the Longmenshan nappe structure zone in the east (Fig. 1a). It connects with the Songpan-Ganze terrane in the east and occupies a large part of the central Tibetan plateau, with the western extension defining a long and narrow belt, truncated by the left-slip Altyn fault (Yin and Harrison, 2000). Most areas in the terrane are covered by thick Permian-Triassic strata, and is characterized by the absence of pre-Permian strata, which were continuously aggraded in an oceanic environment (Fig. 2A) (Chen et al., 2011; Dong, 2015). The HBT has long been regarded as a deep-water turbidite basin during the Early Triassic, although isolated Middle Permian paleo-seamounts are also developed as nip blocks in the basin along the Zanayi-Geqiongniwa faults which are composed of basalts, basaltic andesites, and carbonates (Fig. 2A) (Dong, 2015; Zhu et al., 2004). 3. Stratigraphy 3.1. The North Kunlun Terrane The NKT is different from the SKT with respect to the Precambrian basement, and the magmatic and sedimentary units (He et al., 2016; Liu et al., 2005). The Precambrian units in the NKT are dominated by the Jinshuikou Gp. and Binggou Gp. The Jinshuikou Gp. is predominantly composed of the Upper Schist Formation and Lower Gneisses Formation, encompassing amphibolite- to granulite-facies metamorphosed granites and minor limestones that formed in the Paleoproterozoic and Mesoproterozoic (Fig. 3), and is inferred to have been deposited in ca.1.8-2.2 Ga (He et al., 2016). The Binggou Gp. is composed of the lower Qiujidonggou Fm. and upper Langyashan Fm. (Fig. 3), which deposited in a stable neritic basin environment. Its formation was

constrained to be from 1.0 – 1.7 Ga, belonging to the Mesoproterozoic (He et al., 2016), and the Langyashan Fm. maybe deposited in the ca. 1300–850 Ma as Late Mesoproterozoic-Early Neoproterozoic stromatolite assemblages are discovered in the upper carbonates (Bian et al., 2005). The Upper Devonian Maoniushan Formation, located in the Shuinichang area in the NKT is composed of a lower clastic rock group and an upper volcanic rock group. The rocks formed in a post-orogenic volcano-sedimentary molasse basin, which corresponds to the closure time of the Proto-Tethyan ocean (Zhang et al., 2010). It was deposited during the Late Silurian-Early Devonian (ca. 400–423 Ma) based on zircon U-Pb ages on rhyolites from different levels (Lu et al., 2010). The Upper Triassic Elashan Formation are dispersed in the Elashan Mountain area, at the conjunction of the Qinling, Qilian and Kunlun orogenic belts (Kui et al., 2010; Li and Liu, 2014). The formation is composed of a sequence of continental eruptions including some intermediate-acidic calc-alkaline high-potassium terrestrial volcanic rocks (Li et al., 2011). 3.2. The South Kunlun Terrane The Precambrian rocks in the SKT are mainly composed of the Archean to early Paleoproterozoic Baishahe Gp., late Paleoproterozoic to early Mesoproterozoic Kuhai Gp., and late Mesoproterozoic Xiaomiao Fm. (Chen et al., 2011; Wang et al., 2004). The Baishahe Gp., which is located in the Kekesha-Gouli-Wenquan areas in the eastern parts of the SKT, is mainly composed of gneiss, granulite, amphibolite, marble, with interbedded quartz schist and quartzite. The protoliths were deposited in the Paleoproterozoic and underwent high amphibolite-granulite facies metamorphism in the Neoproterozoic (Long et al., 2006). However, it is argued whether their depositional environment was an active continental margin or initial intra-continental rift basin setting (Chen et al., 2014; Long et al., 2006; Wang et al., 2007). The Kuhai Gp., composed mainly of

paragneisses, amphibolites and schists, is mainly exposed in the Kuhai-Wenquan areas, east of the Kunlun Range (Fig. 2a) (He et al., 2016). It is only distributed to the south of the Baishahe Gp. and the north of the Wanbaogou Gp., and locally in thrust nappes (Fig. 2a). Its protoliths might be a sequence of flysch formations including clastic rocks, intermediate-basic volcanic rocks and carbonates (Fig. 3) (Wang et al., 2007), which are sourced from the Jinshuikou Gp based on similar age ranges (Liu et al., 2016). Some models suggest that these rocks were formed in the late Paleoproterozoic to early Mesoproterozoic (ca. 1.8–1.4 Ma), and experienced metamorphism in the middle Neoproterozoic (ca. 770 Ma) (Wang et al., 2007). The Xiaomiao Fm., which is exposed in the Hatugou, Kekeket and Kekesha areas, is mainly composed of felsic metamorphic rocks (Fig. 2a) (Wang et al., 2016). In terms of its depositional environment, there are two controversial points: an intra-continental rift environment vs. a relatively stable environment (Chen et al., 2014). Although the depositional environments of Precambrian rocks are arguable, our prefer interpretation is that it experienced a continuous evolution from a continental rift to a bathyal-abyssal flysch formation. This evolution may be associated with a late Neoarchean–early Neoproterozoic global continent-building and -breakup event, including the breakup of the Paleoproterozoic-Mesoproterozoic Columbia supercontinent, and the early Neoproterozoic accretion of the Qaidam block to the Rodinia supercontinent (Li et al., 2015). The Wanbaogou Gp. is exposed in the Xiaonanchuan, Wenquangou, Yeniugou areas, along the Central Kunlun fault in the SKT. It is divided into five formations (Pan et al., 1996): 1) a lower clastic rock formation; 2) a basaltic-andesitic rock formation; 3) a greenschist formation; 4) a carbonate formation; and 5) an upper clastic rock formation. The stratigraphic sequences of the Wanbaogou Gp. record a depositional environment of ocean island arcs, which is typical of a

basement with oceanic island volcanic rocks capped by a sequence of carbonates, and faunas of low biodiversity and high variation with other places (A et al., 2003; Cai and Wei, 2007). The Wanbaogou basalts were formed in the Neoproterozoic (e.g. 762 ± 2 Ma) (Xu et al., 2016). The upper clastic rocks were separated from the Wanbaogou Group as a new formation and named as Salawula Formation, because Early Cambrian small-shell fossils and a detrital zircon U-Pb dating age of 538 ± 10 Ma were got in the upper clastic rocks (A et al., 2003; Ji, 1997). The Lower Cambrian Salawula Formation is only exposed in confined areas in the SKT and shows a sub-flysch characteristic (Fig. 2a), and unconformably overlies the Precambrian strata (Wu et al., 2017). It was deposited in a neritic shelf environment during the initial opening of the ocean (A et al., 2003). The Naij Tal Gp., which is composed of a sequence of intermediate-felsic volcanic rocks, clastic rocks and interbedded carbonate rocks, is widely distributed in the SKT (Fig. 2a). The Ordovician strata exposed around the Naij Tal district were originally divided into four formations from the bottom to top (Fig. 3) (Pan et al., 1996): i) Halabayigou Formation (O1, mainly composed of sandy slates); ii) Shuinichang Formation (lower Upper Ordovician, composed of phyllite and greywacke interbedded with marble and limestone); iii) Shihuichang Formation (upper Ordovician, composed of marble and crystalline limestone); and iv) the slip collapse turbidite formation (O, consisting of sandy turbidite and slip collapse turbidite intercalated with limestone and shale). The Naij Tal Gp. was inferred to be formed in the early Ordovician-late Silurian, based on the ages of the different meta-volcanic rocks (e.g. 474 ± 7.9 Ma, 468 ± 9 Ma, 450 ± 4.3 Ma and 419 ± 5 Ma) (Chen et al., 2013; Feng et al., 2005; Zhang et al., 2010; Zhu et al., 2006). There is continuing controversy in terms of its petrogenetic environment: 1) forearc accretion wedge (Li et al., 2007); 2) an ophiolitic mélange sequence in an extensional mid-ocean ridge setting (Cai et al., 2010); 3) a passive

continental margin environment (Ni et al., 2010); 4) a back-arc basin environment (Chen et al., 2013); and 5) oceanic island arc (Shi et al., 2017). The lower Silurian Wenquangou Fm., which is exposed in the Heidingshan region north of the Muz Tagh Mountain (Fig. 2a), contains metamorphic rocks, sandstone and mudstone, implying an abyssal-bathyal flysch facies environment (Ma et al., 2010; Zhao et al., 2010). The middle–upper Silurian Dabangou Formation, located to the west of Aqike Lake, is composed a series of limestones interlayered with clastic rocks (Ma et al., 2010). These were dominantly deposited in an epeiric open platform facies environment (Ma et al., 2010; Zhao et al., 2010). The Lower-Middle Devonian Burakbush Fm. occurs sporadically in the Kawar Mountain-Borak Rakery Lake area, stretching to the west in the Yantoushan-Heidingshan area, west of the SKT (Fig. 2a) (Wang, 2011). It is composed of a sequence of paralic sediments, including a sequence of upper clastic rocks and carbonates, and lower radiolarian cherts and a few interbedded volcanic clastics, silt sandstones and slates. Abundant middle Devonian Tetracoralla fossils are hosted in the upper carbonate formations (Ye et al., 2004), and a zircon U-Pb age of 401 ± 6 Ma for the interlayered metamorphosed basalts is reported (Zhu et al., 2006). The depositional environments are markedly different from those of the lower Devonian Maoniushan molasse formation in the NKT, suggesting an island-arc sedimentary formation (Ye et al., 2004). The Lower Carboniferous Tokuz Daban Fm., which is distributed between the Muz Tagh and Jingyuhu Faults (Fig. 2a), can be divided into upper and lower parts. The lower part is composed of lithic sandstone, silty mudstone, mudstone and interlayered radiolarian chert, reflecting a deep-sea basin environment; the upper part is composed of lithic sandstones, pebbly sandstones, and interbedded silt mudstone, indicating a multi rhythmic-circle bathyal-abyssal continental slope

turbidite environment (Ma et al., 2004). The Upper Carboniferous Haoteluowa Fm., a typical calcium detritus turbidite and silicalite formation, is composed of continental and volcanic clastic rocks, greywackes, sandstones, finestone and siltstone (Fig. 3) (Yin and Pan, 2008). They were both deposited in an active tectonic setting and were part of flysch in a multi-island ocean, containing neritic shelf and shore facies (Li et al., 2000). In contrast, Wu et al. (2017) considered that the Haoteluowa Fm. was formed in a passive continental margin setting related to the rifting between the East Kunlun and Bayan Har terranes. The Lower-Middle Permian strata, widely distributed in the Kawar Mountains, the west of the SKT (Fig. 2a), which can be divided into different formations (Tian and Wang, 2001): the Lower Permian Aqikkol Fm.; the lower Middle Permian Chader Tagh Fm.; and upper Middle Permian Qingshishan Fm.. It is mainly composed of marbles, feldspathic sandstones, conglomerates, mudstones and bioclastic limestones (Fig. 3) (Sun and Zhang, 1985). The depositional setting evolved from a long-term stable platform-marginal to a flat-lagoon environment. In addition, large amounts of Early Permian tetracorals and Middle Permian fusulinida faunas were found (Tian and Wang, 2001). The upper Permian Gequ Fm., sporadically occurring in the southern slope of the Burhan Budai Mountains, in the east SKT (Fig. 2a), is composed of fan delta-epeiric carbonate platform facies rocks involving conglomerates, sandstones and calcareous mudstones (Huang et al., 2017). It is a typical littoral-epeiric facies molasse formation that was deposited on an active continental margin (Yang et al., 2016). The Triassic strata occur throughout the SKT (Fig. 2a), including (Fig. 3)(Cai et al., 2008; Li et al., 2012; Wu et al., 2017): 1) Lower Triassic Hongshuichuan Fm. is composed of upper sandstones, slates and interlayered volcanic rocks, and lower sandy conglomerates, 2) Middle-Lower Triassic

Naocangjiangou Fm. is dominated by carbonates and interbedded clastic rocks; 3) middle Triassic Xilikete Fm. is a typical turbidite fan formation including feldspathic greywackes, conglomerates, calcareous and muddy siltstones; and 4) Upper Triassic Babaoshan Fm. is characteristic of a typical thick molasse formation, consisting of lower sandy conglomerates and upper lithic sandstones(Li et al., 2012)(Li et al., 2012)(Li et al., 2012)(Li et al., 2012)(Li et al., 2012)(Li et al., 2012)(Li et al., 2012). The depositional setting shows continuing transition from a forearc basin to a foreland basin environment. The Babaoshan Fm. unconformably overlying the Naochangjian Fm. represents the main continental collision events in the middle-late Triassic (Wu et al., 2017). 3.3. The Muz Tagh-Anemaqen Terrane The MAT is dominated by the Permian Buqin Mountain Group strata, which include the middle Permian Maerzheng Formation and lower-middle Permian Suwemenk Formation (Fig. 2a). The Carboniferous and Triassic strata are locally exposed, which are generally similar to the synchronous strata in the SKT (Fig. 3). The middle Permian Maerzheng Formation occurs widely in the MAT (Fig. 2a), from the Camelback Mountain-Muztag Mountain area in the west, through Buke Daban in the middle, to the Buqinshan-Maqen mélange belt in the east (Hu et al., 2013; Pei et al., 2015). In addition, it also occurs as discrete blocks between the Zanayi-Geqiongniwa and Yueguzonglie faults in the Bayan Har turbidite basin, and is thrust on the pre-Triassic strata (Fig. 2a). The Maerzheng Fm. in the two areas are very similar, both composed of volcanic basement including basalts and basaltic andesites, some with pillow structures (Zhu et al., 2004), and overlapped pre-Carboniferous strata and evolved from deep-sea basin to continental shelf environments, and incorporated intermediate-acidic volcanic deposits as well as limestone and sandstone (Yin and Pan, 2008). However, the petrogenetic

environment of Maerzheng Fm. has been disputed: 1) an ocean island tectonic setting on the basis of OIB geochemical affinity of the basalts from basement (Fig. 4c) (Zhu et al., 2004); 2) a mixing of recycled orogenic belt and island arc materials implying a change of the depositional environment from passive to active continental margin (Hu et al., 2013; Pei et al., 2015); 3) continually precipitated from continental clastic to turbidite deposition in a passive continental marginal environment (Min et al., 2009); 4) the late Permian and early Triassic trace fossils in the thrust-slip sandstone slices, belonging to the abyssal-bathyal flysch “Nereites” ichnofacies, provided evidence for an active margin setting (Tian et al., 1999). The lower-middle Permian Suwemenk Formation unconformably overlies the Maerzheng Fm. as thrust nappes (Zhang et al., 2000). It is mainly composed of the lower part of bioclastic limestones and reef limestones and the upper part of limestones and dolomites, and locally clastic rocks and volcanic clastic rocks, were deposited in littoral-neritic shelf facies and carbonate platform facies environments. Large amounts of middle Permian cold- and warm-type fusulinida faunas are discovered in the Suwemenk reef limestone formation (Ma et al., 2004; Zhao et al., 2013). 3.4. The Hoh Xil-Bayan Har Terrane The Bayan Har Group, widely distributed from Hoh Xil in the west, through Qingshuihe in the middle, to Gander in the east (Fig. 2a), is separated into three formations: 1) Lower Triassic Changmahe Fm. is divided into the upper part of sandstones interbedded with slates and limestones, and the lower part of conglomerates and many exotic blocks; 2) Lower-Middle Triassic Gander Fm. conformably covering on the Changmahe Fm., is composed of sandstones interlayered with a few slates; and 3) upper Triassic Qingshuihe Fm. is classified into a lower part of slates interbedded with sandstones, and an upper part of clastic, feldspar-quartz and sandstones interbedded slates. The

Bayan Har Group strata from east to west, from bottom to top show an evolution from passive continental margin to active continental margin, and continental or oceanic island arc (Dong, 2015). 4. High-pressure metamorphism belts The newly discovered high-pressure metamorphic belt, occurring the in Lalingzaohuo, Langmuri and Wenquan areas along the two sides of the Middle East Kunlun Fault (Fig. 1a), is generally composed of eclogite, high-pressure granulite and garnet amphibolite (Chen et al., 2008; Guo et al., 2017; Li et al., 2006; Meng et al., 2013; Qi et al., 2016). The eclogite-facies P-T conditions are generally estimated as 1.5 to 2 Gpa (corresponding to about 50-70 km burial depth) and 600 to 700°C (Fig. 4). The granulite facies conditions are took place under temperature of 700–850°C and pressure of 0.8–12 kbar (Fig. 4). The retrograde garnet-amphibolite facies pressure and temperature were calculated to be 0.7–0.75 Gpa and 520–550°C (Fig. 4). All the conditions of peak and retrograde metamorphism are between the geothermal gradients of 10°C/Km and 20°C/Km (Fig. 4). The clockwise P-T-t paths from prograde to retrograde stage reflect a tectonic evolution from subduction to collision environment (Fig. 4). The peak metamorphic ages of the eclogite facies in the Suhaitu, Dagele, Langmuri and Wenquan areas range from early Silurian to early Devonian (e.g. 431. 9± 2.3, 428 ± 2 Ma, 411.1 ± 1.9Ma) (Meng et al., 2013; Qi et al., 2014; Qi et al., 2016). Li et al. (2006) reported a zircon SHRIMP U-Pb age of 507.7 ± 8.3 Ma for granulite facies in the Qingshuiquan area. However, Zhang et al. (2003) inferred that granulite-facies metamorphism occurred in the middle Ordovician (e.g. 460 ± 8 Ma). In this study, we got a zircon LA-ICP-MS U-Pb age of 419.5 ± 2.1 Ma (all dating of 437.2–402.2 Ma) (unpublished) for granulite facies in the Langmuri area. The eclogites in the western parts of East Kunlun formed later than those in the eastern part, and the pressure and temperature of formation are higher than the eastern parts, which

might be a result of oblique subduction and convergence. Moreover, these ages indicate that the earliest stages of collision might have occurred in the Middle Silurian (ca. 432 Ma) in the eastern parts, and sustained to the Early Devonian (ca. 411 Ma) in the western parts. These eclogites together with a series of granulites in the Central East Kunlun Fault zone represent an evolution from subduction to collision event during this time, and provide new constraints for the formation of Central Kunlun suture zone in Early Paleozoic (Meng et al., 2013; Qi et al., 2014). 5. Suture zones In the East Kunlun Orogen, the Muztagh-Anemaqen suture and Aqike-Qingshuiquan suture zone have been reasonably outlined through the development of the southern ophiolite mélange belt (Muztagh-Anemaqen belt) and the middle ophiolite mélange belt (Aqike-Qingshuiquan belt) (Fig. 1a) (Zhang et al., 2004). 5.1. Muz Tagh-Anemaqen suture zone The Muz Tagh-Anemaqen suture zone, extending from the Muztagh area in the west to the Anemaqen area in the east, is mainly distributed along the southern margin of the East Kunlun Range (Fig. 1a) (Robinson et al., 2009; Zhang et al., 2008). It is significantly outlined based on the abundant development of the Muz Tagh-Anemaqen ophiolite mélange belt which extends from the Muztagh, through Naij Tal, Buqinshan and Majixueshan, to the Maqen areas in the MAT (Fig. 1a). It is dominantly composed of meta-peridotite, mafic-ultramafic cumulates, sheeted dikes and basaltic lavas and radiolarian chert. In addition, the early Silurian and early Carboniferous-early Permian radiolarians were obtained from the mélange belts (Ma et al., 2004; Wang and Yang, 2004). Furthermore, the Muz Tagh-Anemaqen suture zone can be divided into two parts: the eastern Buqinshan-Anemaqen and western Muztagh ophiolite zones (Wu et al., 2005), which formed in the

early Cambrian-early Silurian and early Carboniferous-early Permian, respectively (Li et al., 2017; Liu et al., 2011). They might have resulted from two stages of opening of an ancient oceanic basin in the Buqinshan-Anemaqen orogenic belt, indicating the formation of the Proto- and Paleo-Tethys (Zhang et al., 2004). In this study, two kinds of ophiolites are geochemically and chronologically identified (Fig. 5 and Table 1): the early Paleozoic (ca. 430–535 Ma) ones show a time-progressive evolution from island arc tholeiite (IATs) to calc-alkaline basalt (CAB), and to shoshonite (SHO) affinities (Fig. 5b), which is more similar to the SSZ (supra-subduction zone) type ophiolites (Dilek and Furnes, 2014); the latter ones are dominated by the N-MORB and OIB affinities (Fig. 5c), which probably resembles the P(plume)-type (Dilek and Furnes, 2014). Moreover, the late Carboniferous-middle Permian paleo-seamounts composed of carbonate cap and basaltic basement widely distributed in the Bayan Har basin and the neighboring Anemaqen areas, and correlated with mantle plume (Li et al., 2007). 5.2. Aqike Lake-Qingshuiquan suture zone The Aqike Lake-Qingshuiquan suture zone (AQSZ), extending from the Aqike Lake in the west, through the Tumuleke and Wanbaogou area in the middle, to the Qingshuiquan area in the west, is distributed throughout the MKLF (Fig. 1a) (Lu et al., 2006). It is figured out based on the development of the Aqike-Qingshuiquan ophiolite mélange belt, which is principally exposed in Aqike Lake, Tumuleke, Wanbaogou, Acite and Qingshuiquan areas, with a discontinuous distribution in the SKT (Hu et al., 2004). It is mainly composed of cumulate gabbros, diabase dykes, massive and pillow basalts, carbonates and radiolarian cherts. In addition, the Ordovician acritarchs and Early Silurian radiolarians in Early Paleozoic flysch rock slices from the mélange belt (Luo et al., 2006; Zhang et al., 2004). In this study, we got a zircon LA-ICP-MS U-Pb ages of 430.0 ± 2.5 Ma and

428.2 ± 2.2 Ma for the olivine pyroxenite from the Halongxiuma area (unpublished). The ophiolite fragments preserved in the Qingshuiquan area experienced high temperature and medium to high pressure granulite facies metamorphism, and were tectonically uplifted and exhumed to the present position (Li et al., 2006). In this study, the chronology and geochemistry of the basalts, gabbros and diabase dikes before early Silurian in the mélange belt can be divided into two groups (Fig. 5 and Table 1): the first one from the Mesoproterozoic to early Cambrian (ca. 1348 Ma–526 Ma) shows a geochemical evolution trend from MORB, through OIB to SHO affinity (Fig. 5a) (Feng et al., 2010; Kong et al., 2017), overlapping area between within-plate basalt (WPB) and mid-ocean ridge basalt (MORB) areas, and suggesting an oceanic island arc environment associated with the subduction of Proto-Tethys before the Early Cambrian; the second one from the early Cambrian to early Silurian (ca. 535–428 Ma) (Liu et al., 2013; Ren et al., 2009; Sang et al., 2016), falls near the E-MORB and CAB fields above the MORB-OIB array (Fig. 5b), suggesting extensive contamination by crustal material in a subduction environment, similar to the Alpine ophiolites formed in marginal ocean basins above subduction zones (Dong et al., 2018; Piccardo, 2016). In addition, the εNd(t) values of the early ophiolites range from +4.0 to +8.4 (Li et al., 2017), which is similar to the values from the Mariana and Banda intra-oceanic island arc magmatic rocks falling within a small range of εNd (t) from about +6.5 to +10 (Fig. 9) (DePaolo, 1988). Therefore, the early ophiolites in the NKT are associated with an intra-oceanic subduction. However, the εNd(t) values of late ophiolites in Halongxiuma area are variable between -9.1 and 1.8 (unpublished) (Fig. 9), which obviously shows a significant correlation with a subduction of backarc oceanic lithosphere and a contamination of crustal material at continental margin.

6. Magmatism The various terranes in the East Kunlun orogen witnessed multiple tectono-magmatic history and were significantly altered and overprinted. Four distinct tectono-magmatic belts can be spatially and temporally identified from north to south, corresponding to the division of the different terranes. In this study, the Early Neoproterozoic granitoids occurring in the NKT are selected to compare the other granitoids that developed at the different times (Fig. 6a), because they are generally considered as reworking products of acient continental crustal materials with minor mantle contribution in a syn-collisional setting, and correlated to the amalgamation of the Rodinia supercontinent (He et al., 2018; Wang et al., 2016). 6.1. The North Kunlun Terrane Early Silurian-middle Devonian granitoids are widely distributed in the NKT, but pre-Silurian granitoids are weak in the north of East Kunlun Range (Fig. 7a) (Chen et al., 2012). They can be geochemically and chronologically divided into three groups (Fig. 6b and Table 1): the early Silurian (ca. 438–430 Ma) group mainly plots in the CAG and Syn-COLG field; the late Silurian-early Devonian (ca. 422–407 Ma) one plots in the CAG and OAG fields; the middle Devonian (ca. 396 – 391 Ma) granitoids mainly plot in the WPG and OAG fields. In terms of the tectonic setting of early Silurian granitoids, there is a controversy between continental margin arc setting and initial continental crust collision (Qi, 2015; Wang et al., 2016; Wu et al., 2012). The early-middle Silurian granitoids show an affinity of CAG. In respect of late Silurian-early Devonian granitoids, their geochemical compositions show marked similarity to those in the SKT (Fig. 6c). Most scholars considered that early Devonian peraluminous granitoids were produced by the partial melting of crust materials in a collision setting (Liu et al., 2012). Subsequently, abundant middle Devonian

high-potassic calc-alkali peraluminous monzogranite-granodiorite assemblages were considered to be formed in the post-collisional setting (Long et al., 2006; Zhang et al., 2016). In addition, many middle Devonian A-type syenogranites were discovered in the Xiariham, Dagangou and Binggou areas, which might have been formed under the post-orogenic extensional conditions (Chen et al., 2013; Tian et al., 2016; Wang et al., 2013). The late Permian to late Triassic (ca. 270–200 Ma) magmatism is widely expressed in the eastern and central parts of the East Kunlun Mountains (Chen et al., 2015; Ding et al., 2015; Huang et al., 2014; Li et al., 2015; Ma et al., 2015), but only a few exposures have been recorded in the western part (Fig. 1a). In the NKT, the magmatism can be geochemically and chronologically divided into two stages (Fig. 6d): Late Permian-Middle Triassic (ca. 261 – 231 Ma) and Late Triassic (ca. 227–209 Ma). Although their geochemical characteristics show some overprints in the OAG field, significant differences are occurred in the CAG and Syn-COLG field (Fig. 6d). These features indicates that the Late Permian-Triassic magmas probably originated from the partial melting of the same ancient lower crust as a result of the different processes between mantle underplating and the thickened crustal delamination. Zhang et al. (2012) suggested that the Late Permian-Middle Triassic calc-alkaline granitoids were derived from dehydration melting of the mafic lower crust during the northward subduction of the Anemaqen paleo-ocean, whereas the Late Triassic alkaline syenogranites were produced by a high degree melting of the crust in a syn-collisional setting. Ren et al. (2016) considered that the geotectonic characteristics of these rocks from late Permian-middle Triassic to Late Triassic show a change from a subduction-collisional setting to a post-collisional or within-plate setting. The difference in the abundance and size of the MMEs (mafic microgranular enclaves) between the late Permian-middle Triassic and late Triassic granitoids is thought to result

from a magma mingling and mixing process between different volumes of enriched lithospheric mantle materials and partial melting components of the lower crust (Luo et al., 2014; Xiong et al., 2012), which is considered as a result of the slab break-off from the northward subduction of Anemaqen ocean (Xia et al., 2014). Statistical analysis of the εHf(t) values of the two stage granitoids reveals varied sources from crust and mantle (Fig. 8). The late Permian-middle Triassic granitoids show a strong mixing tendency between ancient crust and depleted mantle (MORB) in a subduction-collision stage, and late Triassic granitoids show a weak mixing between young crust and enriched mantle from a post-collisional to a within-plate stage. 6.2. The South Kunlun Terrane The SKT hosts voluminous Paleozoic granitoids (Fig. 7b) (Kong et al., 2014; Li et al., 2013; Qi, 2015; Ren et al., 2012). These rocks can be geochemically and chronologically divided into three groups (Fig. 6b and Table 1): middle Cambrian-early Ordovician (ca. 512 – 474 Ma) one plots in the OAG field; middle Ordovician-middle Silurian (ca. 454–424 Ma) one plots in the CAG and WPG fields; late Silurian-early Devonian (ca. 421 – 403 Ma) one plots in the CAG and OAG fields. The middle Cambrian-early Ordovician granitoids are geochemically similar to the calc-alkaline granitoids in the MAT, which probably implies an inner-oceanic subduction setting of the Proto-Tethys Ocean (South Kunlun Ocean) (Chen et al., 2016; Zhao et al., 2017). Many studies were conducted on the Silurian granitoids, and the main disputed point is about whether the Proto Tethys Ocean is closed during early Silurian (Li et al., 2013; Shi and Liu, 2014; Wang et al., 2012), which is probably associated with the special location sandwiched by Proto Tethys (South Kunlun Ocean) and back-arc ocean. First, the late Ordovician-middle Silurian

granitoids are completely different with the middle Cambrian-early Ordovician granitoids, but much closed to the Silurian granitoids in the NKT (Fig. 6b and c), which probably indicates an environment transition from young oceanic island arc to a mature arc related to the northward subduction (Li et al., 2014). The northward movement of SKT leads to the closure of the back arc basin and the initial arc-continental collision, which is supported by the early Silurian rapakivi granites and middle Silurian peraluminous granites found in the SKT to have formed by the partial melting of thickened crust in collisional stage (Cai et al., 2016; Shi et al., 2016; Wang et al., 2016). Second, the early Devonian high-K calc-alkaline and subalkaline metaluminous I type granitoids are compositionally different from the middle Ordovician-middle Silurian ones in the SKT, but shows a progressive evolution from upper crust affinity to lower crust (Fig. 6c) (Wang, 2011). Therefore, early Devonian granitoids in the SKT are good evidence for the environment transition from a collision to a post-collision. The collision between NKT and SKT maybe initiated at early Silurian and had been sustaining to middle Silurian, which is probably associated with an oblique subduction of back arc basin. Multistage magmatic activities from the late Permian to early late Triassic (ca. 257–225 Ma) are recorded in the eastern parts of the SKT (Dong et al., 2016), with few exposures in the central and western parts (Fig. 1a) (Wei et al., 2016). The late Permian-late Triassic (ca. 257–225 Ma) magmatic rocks plots in the OAG fields, and shows an affinity of lower crust continuous evolution as a consequence of partial melting of garnet amphibolite facies rocks in the thickening lower crust, which are distinguished from the magmas contemporaneously intruded in the NKT and MAT (Fig. 6d). The magmatism is generally characterized by intermediate-felsic, metaluminous-weakly peraluminous I-type granodiorite-monzogranite-syenogranite assemblages (Chen et al., 2013), which

were considered to be formed in a volcanic arc or continental marginal arc setting associated with the intense southward subduction of the Paleo-Tethys lithosphere (Liu et al., 2012). These rocks contain a large number of dioritic microgranular enclaves that were nearly simultaneously formed with the host rocks, as a consequence of magma mixing and mingling during the underplating of the mafic magma into the lower crust (Wei et al., 2016). 6.3. The Muz Tagh-Anemaqen Terrane The MAT is characterized by large amounts of early Paleozoic granitoids, but with only few late Paleozoic granitoids (Fig. 7c) (Li et al., 2017; Zhao et al., 2017). These rocks are dominated by late Cambrian-early Silurian (ca. 496 – 436 Ma) age, and geochemically plot in the OAG field (Fig. 6b and Table 1) showing similarity to the middle Cambrian-early Ordovician (ca. 497 – 471 Ma) tonalite-trondhjemite-granodiorite (TTG) rocks in the SKT (Qi, 2015; Ren et al., 2012), with compositions similar to Archean TTG which probably indicates a oceanic island arc setting (Yu et al., 2017; and references therein). Therefore, we postulate that they both occurred in the MAT and SKT should be formed in a similar tectonic setting in relation to the Proto-Tethyan subduction setting. Small-scale late Triassic magmatic activities are sporadically distributed in the MKT, including high-K calc-alkaline intermediate and intermediate felsic diorite-granodiorite intrusive rock assemblages (Li et al., 2013; Liu et al., 2015). The late Triassic rocks geochemically plot in the CAG field, and show upper-crustal affinity (Fig. 6d and Table 1), which may be the products of partial melting of upper crust during the collision between the MAT and Bayan Har Terrane. 6.4. The Hoh Xil-Bayan Har Terrane In the HBT, only late Triassic granitoids occasionally occur in the eastern parts (Zhang et al., 2006), but few are reported in the western and central part (Roger et al., 2003). Previous studies

indicate that these granitoids are of different types including adakitic, A-type, I-type and strongly peraluminous S-type, and were derived from the thickened continental crust during the Triassic convergence between the Yangtze, North China and North Tibet continental blocks (Ma et al., 2017; Zhang et al., 2006). The intermediate-felsic granodiorite-monzogranite-syenogranite associations can be geochemically and chronologically divided into two groups (Fig. 6d): the first group of ca. 221-216 Ma plot in the OAG and CAG (and Syn-COLG) fields, which is characteristic of metaluminous calc-alkaline features; and the second one of ca. 211-203 Ma fall in the WPG field, which is of peraluminous alkaline features. Their formation was considered to be correlated to the transition from the syn-collisional compressive to post-collisional extensional tectonic setting in the late Triassic (Zhang et al., 2007). A delamination model was proposed to explain the association of the late Triassic A-type granites and adakitic granitoids (Cai, 2010). 7. The evolution of the East Kunlun Orogen The East Kunlun Orogen, as a significant component of the Central Asian Orogenic Belt (CAOB), is approximately parallel to the Tibetan Plateau (Yu et al., 2017). Although the subduction-accretion-collision processes are ascribed for the tectonic evolution of the Qingling, Qilian and West Kunlun Orogens in the CAOB (Dong and Santosh, 2016; Song et al., 2013a; Song et al., 2012; Xiao and Santosh, 2014), some temporal and spatial distinctions lead to specific features of the East Kunlun Orogen. The East Kunlun Orogen, preserves abundant geological information about multistage evolution including continental break-up and oceanic enlargement in the Proterozoic, the subduction and closure of Proto- and Paleo-Tethys in the Paleozoic-early Mesozoic, intracontinental extension in the Mesozoic and depressed deformation in the Cenozoic (Wu et al., 2019). Particularly, the East Kunlun Orogen has evolved through long-term and complex subduction-accretion-collision

tectonic processes along the NKT, SKT, MAT and HBT zones. Its current framework is mainly considered to be solidified during the Paleozoic to early Mesozoic, although the within-plate deformation is also very important for crustal growth. A collage of terranes were accreted to the south margin of the Qaidam block as exotic island arcs and oceanic plateaus until the early Mesozoic, which significantly contributed to the crustal growth of the East Kunlun Range (Dong et al., 2018). Individually, each terrane preserves multiple evolutionary periods of tectono-magmatic history, which are significant references for the other orogens in the CAOB. The NKT carries a Precambrian basement, intruded by multistage plutonic complexes including Neoproterozoic, late Ordovician-early Devonian and middle Permian-late Triassic stage (Fig. 1a). The SKT consists of Proterozoic, Paleozoic and Mesozoic sedimentary rocks that were deposited in an oceanic island arc setting but also in a backarc setting (A et al., 2003; Cai and Wei, 2007), and experienced pre-early Devonian and middle Permian-middle Triassic magmatic events (Fig. 2b). The MAT is mainly composed of Paleozoic granitoids and lacks Early Mesozoic magmatic rocks, together with Permian turbidite and reef limestones representing a passive continental margin, which transformed into an active continental margin during the Triassic (Hu et al., 2013; Pei et al., 2015). The HBT hosts only late Triassic granitoids and upper Permian-late Triassic sedimentary rocks that were deposited in a neritic-abyssal continental slope to a neritic continental-shelf environment (Chen et al., 2011; Dong, 2015). On the basis of different tectonic events and environments, as well as distinct magma sources, the evolution of the East Kunlun Orogen can be divided into six main age groups from Late Neoproterozoic-Early Mesozoic age (550 Ma – 200 Ma) (Fig. 8): ca. 540–481 Ma, ca. 481–424 Ma, ca. 424–370 Ma, ca. 370–271 Ma (magmatic gap), ca. 271–224 Ma and ca. 224–201 Ma. They are

well consistent with the evolution trend in the Sr/Y and La/Yb ratios with age (>55 wt % SiO2) (Fig. 10). Moreover, the six stages can be further divided into different sub-stages based on the peak values of the Sr/Y and La/Yb ratios at ca. 515 Ma, 445 Ma, 401 Ma, 239 Ma and 216 Ma. Therefore, we outline a conceptual model for the crustal evolution of the East Kunlun Orogen (Fig. 11): 1) the early Paleozoic bidirectional subduction model; 2) late Paleozoic subduction polarity transition model; 3) early Mesozoic flat-slab subduction model. 7.1. The subduction of Proto-Tethys One of the difficulties for reconstructing the history of the East Kunlun Orogen is that several subduction zones, some with opposing subduction polarity, acted simultaneously in the South Kunlun Ocean area. The Proto-Tethyan South Kunlun Ocean persisted throughout the early Paleozoic, and may have been divided into many interconnected oceans by some elongated inner-oceanic island arcs (Fig. 12). First, the South Kunlun Terrane, primarily developed as an ocean island arc, evolved from the primitive stage of the Wanbaogou Gp. basalts and andesites to a mature stage of the Naij Tal Gp. andesites, dacites and rhyolites as a consequence of northward subduction of Proto-Tethyan South Kunlun oceanic lithosphere (Fig. 11a). In addition, it was intruded by the middle Cambrian-early Ordovician TTG (tonalite-trondhjemite-granodiorite) granitoid assemblages with OAG affinity and late Ordovician-early Silurian CAGs and WPGs (Table 1). The Wanbaogou Gp. reflects a depositional environment of typical ocean island arcs consisting of a basement with oceanic island volcanic rocks capped by a sequence of carbonates (Cai and Wei, 2007), and the geochemical characteristics of the Wanbaogou Group basalts indicates an oceanic island arc environment (Table 1). To the south of the Wanbaogou Gp. is a tectonic mélange belt, including an abyssal-bathyal continental slope and a deep-sea trench (Naij Tal Gp.), and abyssal-bathyal flysch

formation (Wenquangou Fm.) and subsequently imbricated in an accretionary wedge (Fig. 11b) (Shi et al., 2017). The geochemical features of late Silurian-early Devonian basalts in the SKT reflects a subduction environment at a continental margin (Table 1). The MAT, also developed as an ocean island arc, hosts early Cambrian-middle Silurian (ca. 501–516 Ma) SSZ type ophiolites (Liu et al., 2011), which show a geochemical evolution from the IAT to the calc-alkaline (CAB) field (Fig. 5b). These rocks indicate an intra-oceanic subduction setting (Fig. 11a). In supporting a related fashion, the Early Silurian diabase dykes in the Anemaqen mélange belt have similar chemical composition with IAB (Island arc basalt), which were closely related to the southward subduction of Proto-Tethyan South Kunlun oceanic lithosphere (Fig. 11a) (Chen et al., 2013; Liu et al., 2013; Ren et al., 2009). In addition, TTG granitoids showing OAG affinity were extensively emplaced during the late Cambrian-early Ordovician and early Silurian two stages. The late Cambrian-early Ordovician granitoids are geochemically similar to those OAGs exposed in the SKT, but the early Silurian granitoids are completely different from those intruded in the SKT (Fig. 6b). The similarities indicate that they both probably formed in intra-oceanic arc setting, likely correlating with the bidirectional subduction of the Proto-Tethys (South Kunlun Ocean) slab between them (Fig. 12a), and the variations reflect a diverse plate tectonic setting for the SKT, which might have collided with the NKT as a consequence of crustal thickening (Fig. 12b). A modern bidirectional subduction case in an intra-oceanic island arc system, the triangular area between the Philippines, Java, and New Guinea, is a good reference for understanding the history of the East Kunlun tectonic evolution (Hall, 2002; Macpherson et al., 2003). Although the subduction polarity of Proto-Tethyan oceanic crust remains disputed on southward or northward (Dong et al., 2011; Li et al., 2018; Song et al., 2013b; Xiao et al., 2009; Xu et al., 2006;

Zhao et al., 2015). Some scholars suggested that the ocean in Kunlun, Qaidam, and Qilian was northward subduction in early Paleozoic (Song et al., 2013b; Xu et al., 2006). In contrast, others argued that the Proto-Tethys in Kunlun, Qilian, and Qinling orogens was main of southward subduction (Li et al., 2018; Xiao et al., 2009) and ultimately promoted accretion at the northern edge of Gondwana continent. Compared with the West Kunlun Orogen (WKO), their work supports a general tectonic model for the northern Tibetan plateau in which island arcs or composite terranes were accreted to the Tarim block along a southward-dipping subduction zone (Xiao et al., 2004). Gehrels et al. (2003) summarized a back-arc model but supported the general multiple accretionary framework for the WKO, in which southward subduction played a key role followed by arc accretion, subduction polarity flip (northward subduction), and formation of an Andean-type active margin. Zuza and Yin (2017) suggested that the bidirectional closure of the Paleo-Asian Ocean occurred in the early Paleozoic within the CAOB and continued to the late Paleozoic. In addition to the almost coeval development of subduction related basalts and TTGs in the SKT and MAT, the both terranes coevally carried middle Ordovician-middle Silurian (ca. 467 – 430 Ma) ultramafic-mafic rocks. Although these rocks show distinctive compositional characteristics, their similar geochemical evolution trends show subduction-related affinity (Table 1). The slab steepening and crust thickening could explain these subtle geochemical distinctions. The subduction angle of the South Kunlun Ocean slab was increased due to the strong downward force as a consequence of progressively shrinking Proto Tethys Ocean (Fig. 12b), or through northeastward moving of the Gondwana along splays of the Muz Tagh and Anemaqen Faults (Li et al., 2018). At this time, the Tarim-Qaidam-Alax-North China blocks may have docked together to be accreted to the Gondwana supercontinent (Fig. 12b) (Gehrels et al., 2003; Li et al., 2018). Although the closure time of the

Proto-Tethyan South Kunlun Ocean has been disputed all the time (Wang et al., 2016; Yan et al., 2016), the sedimentary environment evolved from deep sea of Wenquangou Fm. to platform of the Dabangou Fm. maybe also hint a closure of the oceanic basin. After the amalgamation of Gondwana, a new Paleo-Tethyan Anemaqen ocean basin was rifted in the south of MAT (Fig. 12c). The Qingshuiquan ophiolite is interpreted to be derived from ascending mantle flows above a subduction zone (Fig. 11b) (Li et al., 2017). Generally, the asthenosphere above the mantle wedge is variably contaminated by fluids derived from the subducted slab. Therefore, the Qingshuiquan basalts have, to some degree, characteristics of subduction related magmas, which are very similar to E-MORB (Fig. 5b). These melts ascended and penetrated the extending continental crust. Meanwhile, they were contaminated by continental crust materials deposited in the backarc basin and thus progressively show a calc-alkaline signature (Fig. 5b). During the evolution of the backarc basin, the subduction-related component of the volcanic rocks increased, thus leading to the generation of the calc-alkaline volcanics. This scenario is very similar to modern backarc basin settings, such as Japan constituting the arc and Japan Sea constituting the backarc basin (Frisch et al., 2010). 7.2. The collision between the North and South Kunlun Terrane The central tectonic mélange belt of the East Kunlun is an important suture zone between the NKT and SKT, which is composed of Early Paleozoic blocks, incorporating ocean-crust type mixed rocks, island-arc calc-alkaline igneous rocks and the Naij Tal Group. Significant differences in terms of geodynamic evolution between the SKT and NKT are identified in this study. At the subduction margins of the South Kunlun island arc, large-scale compression was transferred to the upper plate. Therefore, compressional fold and thrust belts are occurred in the backarc basin area (Fig. 11b). The spreading velocity of the backarc basins was lower than the velocity of the retro-arc. Consequently,

the oceanic island arcs were pushed backwards and collided with the continental crust. The backarc ocean disappeared during the thrusting and uplifting process of the backarc basin. In addition, the oceanic lithosphere of the backarc basin subducted beneath the NKT, and caused the late Ordovician-middle Silurian magmatism in the NKT, which accompanied the thickening process of the lower curst (Fig. 11b). This is why there is no development of granitoids before late Ordovician (Fig. 7a). Furthermore, the absence of middle Silurian-middle Devonian strata and the unconformity between the upper Silurian-Lower Devonian (ca. 423–399 Ma) Maoniushan molasse Fm. also indicate the region between the SKT and NKT entered into a syn-collisional stage from the early to late Silurian to middle Devonian as a consequence of closure of the backarc oceanic basin (Fig. 11c) (Bian et al., 2004; Li et al., 2018). Further supporting this interpretation, the early-middle Devonian (ca. 419–401) interlayered basalts of the Burakbush Fm. exclusively occurred in the SKT show an evolution trend from E-MORB to calc-alkaline (Fig. 5c), which indicates that they probably formed in a subduction tectonic setting (Ye et al., 2004). The subduction progressively promoted backward movement of the SKT, and finally led to the collision between SKT and NKT (Fig. 11c). In support of the early to middle Silurian timing of collision between NKT and SKT, the NKT developed abundant A-type and I-type granitoids associated with the late Silurian-Middle Devonian (ca. 425–395 Ma) post collisional events (Chen et al., 2013; Li et al., 2013; Nan et al., 2014; Wang et al., 2018), and the middle Devonian A-type granites might mark the culmination (Liu et al., 2013; Wang et al., 2013). In addition, some late Silurian S-type granites related to the collision were found in these areas (Lu et al., 2013; Zhang et al., 2014). The numerous intermediate-mafic dikes developed in the NKT suggest a transitional setting from collisional compression to post-collisional

extension (Xiong et al., 2014; Yang et al., 2014). This transition is consistent with the high-angle thrust deformation timing of the MKLF at ca. 427–408 Ma and further constrains the closure of the Proto-Tethys between the NKT and SKT to be earlier than middle-Silurian (Chen et al., 2002). Furthermore, SKT developed the early Silurian rapakivi granites and the middle Silurian peraluminous S-type granitoids to have formed by the partial melting of thickened crust in collisional stage (Cai et al., 2016; Shi, 2014; Wang et al., 2016), and the early Devonian high-K calc-alkaline and subalkaline metaluminous I type granitoids in the SKT are good evidence for the transition from a collision to a post-collision environment (Wang, 2011). Therefore, the collision between NKT and SKT maybe initiated at early Silurian and had been sustaining to late Silurian, which is probably associated with an oblique subduction of back arc basin. Following collision, the intense compression and deformation led to granulite-gneiss and eclogite metamorphism in the back arc basin. The high pressure metamorphism belt probably represent the collision between the SKT and the NKT. The granulite facies metamorphism took place under temperatures of 760 – 880°C and pressures of 0.08 – 1.2 GPa in Qingshuiquan area. It might correspond to “soft collision” between small terranes or micro-continents (Ren et al., 1996), where the back arc basin turbidites were thrust on the South Kunlun island arc (Fig. 11B). The formation of granulites at ca. 460 Ma suggests that the collision might have initiated in the middle Ordovician. The metamorphosed granitic and granodioritic gneisses were subsequently exhumed in the late Ordovician-early Devonian (ca. 450 – 400 Ma) (Chen et al., 2007). Based on available information on the Qingshuiquan ophiolites, the abyssal-like peridotites with the associated terrigenous sediments and continental crustal rocks are considered to have been incorporated in the accretionary complex, and reached HP/LT metamorphic conditions. However, the eclogite facies rocks were buried to a

depth of ca. 50–70 km, corresponding to a pressure of 1.5–2 GPa in Suhaitu area in the middle of East Kunlun Range, which is much higher than that of the Qingshuiquan metamorphic rocks in the east of East Kunlun Range. The metamorphic temperatures of 600–700 °C is obviously lower than those of the Qingshuiquan metamorphic rocks, which reflects a “hard collision” between an island arc and continental margin (Ren et al., 1996), corresponding to the NKT and SKT, respectively, and occurred possibly during the late Silurian-early Devonian (ca. 428–411 Ma), followed by exhumation in the early Devonian (ca. 401 Ma) reflected by mid-crustal cooling 40Ar/39Ar muscovite ages (Kylander-Clark et al., 2012). The exhumation lasted more than 25 Myr, and was probably contributed by strike-slip faults (Yang and Li, 2006), or a process of ‘oblique extrusion’ during transformation from ‘normal’ to ‘oblique’ intracontinental subduction (Xu et al., 2006). 7.3. The collision between the Muz Tagh-Anemaqen Terrane and South Kunlun Terrane As a result of the bidirectional subduction of the South Kunlun Ocean, the disappearance of the intervening oceanic realm could have been rapid (Fig. 11B). The paleontological similarities of the Middle-Late Ordovician floating acritarch faunas, discovered in the SKT and MAT, suggest a small size and connected pools in South Kunlun Ocean between the two terranes, and the ocean gradually began to shrink (Bian et al., 2005). However, this is absolutely different from the acritarch ecological assemblages discovered in the in South China block during Early- Mid Ordovician(Yan and Li, 2010), which indicate that the both SKT and MAT were far away from the South China block (Fig. 12a and b). Subsequently, the bilateral arcs collided and amalgamated, and thus contributed to the growth of continents (Fig. 11D). Collision generally induces a transformation from a juvenile oceanic arc to mature continental crust (Saito and Tani, 2017). Adding to this complexity is a third subduction zone

that would be generated after eventual collision of the two island arcs (Fig. 11E). During the collision between the MAT and SKT, the South Kunlun oceanic plate disappeared and subsided into mantle in the north of the MAT, and a new subduction zone was brewing in the south of the MAT, which explains why a gap of felsic magmatic activities is occurred from Middle Devonian to Early Permian (Fig. 11D) (Niu, 2003). Following arc accretion in the north of MAT, as the compositional buoyancy contrast between the floated MAT oceanic island arc and sink oceanic lithosphere, a new subduction zone was generated at the newly formed Muz Tagh-Anemaqen suture zone, accompanying a change of subduction polarities from south-dipping to north-dipping (Fig. 11E)(Niu et al., 2015). Almost at the same time, the trench is greatly diminished and jammed in depth, and consequently subduction and magmatic activities will cease (Yu et al., 2017; and references are therein). Supporting this model, the lower-middle Permian Maerzheng turbidite formation shows a sedimentary environment change from a passive to an active continental margin, which implies opening of the Paleo Tethys-Anemaqen Ocean (Fig. 12c) (Li et al., 2018; Pei et al., 2015). The Paleo-Tethys, as a relic of the Early Paleozoic Proto-Tethys Ocean, opened in the Middle Devonian following a period of Early Devonian rifting. The North China, South China, Tarim and Indochina continental blocks are interpreted to have separated at this time. The Qaidam Block was considered as a part of the Tarim terrane and reached its current relative position to the Tarim Block by strike slip displacement along the Altun Tagh fault (Metcalfe, 2013). These continental blocks all preserve Gondwanan faunas in the Early Paleozoic and were located on the NE margin of Gondwana. The MAT was accreted to the SKT and reached tropical latitudes before the late Carboniferous, as indicated by coral reefs of the Haoteluowa Fm.. Following this, the both terranes subsided and became the basement for deposition of the Carboniferous sedimentary rocks. The upper Permian

Gequ ocean facies molasse formation developed both in the SKT and MAT, which probably indicates a closure of the South Kunlun Ocean in the late Permian (Fig. 11d). 7.4. The final closure of Paleo Tethys Ocean Diverse models and viewpoints were proposed for the final closure of Paleo-Tethys Ocean (Anemaqen Ocean) (Li et al., 2016; Mo et al., 2007). One controversy is that if a continent-continent collision occurred in the East Kunlun Mountain or if the East Kunlun orogen was involved an integrated Hercynian-Indosinian orogenic cycle (Ren, 2004). Another dispute is that when the Paleo Tethys-Anemaqen Ocean was completely closed (Li et al., 2018). Following the accretion of the MAT onto the SKT in the late Permian, a new subduction zone was activated, accompanying a change of subduction polarity (Fig. 12d). Following this, a new volcanic arc was built on the continental margin. The continental crust was thickened by the long-lasting magmatic activities (Fig. 11e). Abundant late Permian-late Triassic granitoids are exposed in the NKT, SKT, MAT and HBT in the north of the suture zone. They progressively intruded from the north to the south (Fig. 7): ca. 272–209 Ma in the NKT; ca. 268–245 Ma in the SKT; ca. 224–227 Ma in the MAT; and ca. 219–203 Ma in the HBT, which implies that the locus of magmatism retrograde migrated from the arc to the further southern accretion prism. Moreover, their geochemical features and evolution trends are completely different (Fig. 6d), which indicates various tectonic setting related magmatism from subduction through collision to post-collision environment (Table 1). The continuously chronological evolution of granitoids maybe result from the joint effect of flat subduction and slab rollback (Fig. 11e). The advancing flat slab scrapes off continental mantle lithosphere to fill the asthenospheric wedge, which makes magmatism absent in regions overlying flat slab segments (Axen et al., 2018; Manea et al., 2017). Subsequently, the slab rollback make the

magmatism center retrograde migrate towards the trench (Manea and Gurnis, 2007). To support this flat subduction model, some Early Carboniferous-Middle Permian oceanic plateaus or intra-oceanic seamounts developed along the new trench and scrapped-off on the MAT (Yang et al., 2017) (Fig. 11e). The presence of buoyant oceanic plateaus and overthrusting significantly facilitates slab flattening (Manea et al., 2017; Martinod et al., 2005). In the HBT, the late Triassic (ca. 219 – 203 Ma) intrusions are almost coeval with the folding of the Triassic strata (Hu et al., 2005), which might be related the partial melting of thickened lower crust in a post collisional environment, as a consequence of slab break off and asthenosphere upwelling (Fig. 11f). To the south of the arc, a shallow marine basin developed. The Bayan Har Group flysches and turbidites were deposited in the forearc basin, which were mainly derived from the eroded materials of the MAT and SKT. They were thrusted on the North Qiangtang Terrane (NQT) and MAT after the collision between them at ca. 224–227 Ma (Fig. 11f). The Bayan Har Group rocks were formed almost synchronously with the Triassic strata in the SKT, suggesting that the East Kunlun Range and its surrounding regions experienced long-lasting subsidence and sustained ocean transgression. Despite this, the main provenance of the Hongshuichuan Fm. and the Naocangjiangou Fm. was the East Kunlun orogen. In the late Triassic, the Anemaqen Ocean was finally closed as indicated by the upper Triassic Babaoshan terrestrial molasse formation, which unconformably covered on the neritic continental shelf facies Naocangjiangou Fm. The closure caused the North Qiangtang Terrane to be accreted on the East Kunlun continental margin, and resulted in the eventual formation of the Supercontinent Pangea (Li et al., 2016). The thick and buoyant oceanic crust resisted subduction and sheared off from the subducted oceanic basement (Fig. 11f). The peeling fragments of intermediate oceanic plateaus and foreland basin system become overthrust, underthrust, and subsequently folded

and deformed, dispersed and metamorphosed in the accretionary prism (Fig. 11f). The occurrence of Middle Permian radiolarian chert and thick abyssal red ooze in the MAT implies that the Anemaqen ocean was of great extent (Wang and Yang, 2004), and was probably connected with the Songpan-Garze Sea in the east. The Songpan-Garze Sea was surrounded by Laurasia, the North China Block, the South China Block and the Qiangtang Terrane in the late Permian, which appears to be related to the rifting of the Qiangtang Terrane off the South China block (Fig. 12d) (Huang et al., 1992). From the Late Carboniferous to Middle Permian, the Qiangtang Terrane drifted northward from 21.9° S to 3.4° N. By the Late Triassic, there were about 10° interval in paleolatitude (ca. 1000km) between the Qiangtang Terrane and the East Kunlun block, which reflects the existence of the Paleo-Tethys Ocean in the Triassic, and it is very large. In addition, the low diversity of fossils in the reefs or carbonate buildups in the oceanic islands also indicates the large size of the Anemaqen ocean basin (Wang and Yang, 2004), because deep ocean basin or deep trench considered as an impassable barrier could prevent benthic organisms from migrating. Based on reflection seismology, variations of crustal thickness are detected from the Qaidam block to the Qiangtang terrane (Jiang et al., 2006). The crustal thickness varies from ca. 70 km beneath the East Kunlun Mountain and Bayan Har terrane to ca. 50 km beneath the Qaidam Basin (Jiang et al., 2006). In spite of this, a southward dipping, continuous Moho between them is traced, with no abrupt Moho steps (Karplus et al., 2011). Southward subduction might be a direct cause of the crustal thickness variations, whereas the subduction records were broken by later northward subduction (Karplus et al., 2011). Further evidence for a change in subduction direction is the finding of an ancient discontinuous oceanic crust reflection between the upper and lower crusts based on deep-reflection seismic data (Liu et al., 2016). This discontinuity might be associated with the

southward subduction of the Proto-Tethys in the early Paleozoic resulting in an amalgamation of two continents. Moreover, the new model of complex uplift in the East Kunlun orogen proposed through the INDEPTH IV's seismic profiles (Liu et al., 2016), includes the northward subduction of the Paleo-Tethyan in the early Mesozoic, and northward compression of the Qiangtang Block beneath the Bayan Har Terrane in the Cenozoic. 8. Conclusions This study synthesized the geology, geochemistry, geochronology and topography of the East Kunlun Orogen, and helped us understand crustal growth and tectonic evolution through the dataset of pre-, syn-, and post-collisional magmatism. It has much referential significance to the other orogens in the Central Asian Orogenic Belt as the following major conclusions: 1) The South Kunlun oceanic lithosphere experienced double-sided subduction resulting in the formation of the South Kunlun island arc chains in the north and Muz Tagh-Anemaqen arc chains in the south during early Paleozoic. This was accompanied by the formation of the Qingshuiquan backarc basin in the backward of the South Kunlun island arc. 2) In the late Ordovician, the backarc ocean crust subducted beneath the Qaidam block to form the North Kunlun continental margin arc. The closure of back arc basin and caused the initial collision between South Kunlun island arc and North Kunlun continental margin in the early Silurian. The collision had been sustaining to the middle Silurian as a consequence of oblique subduction, and transferred into a post-collisional stage in the late Silurian-middle Devonian. 3) Following the closure of the South Kunlun Ocean basin in the middle Devonian (ca. 390 Ma), the MAT collided with the SKT. After the accretion of the MAT, the new subduction zone shifted outboard to the adjacent Anemaqen oceanic realm. The subduction polarity reversal led to the

quiescent of intermediate-felsic magmatic activities in the late Devonian-early Permian. 4) The flat subduction and slab rollback maybe result in the retrograde migration of magmatism center towards the trench. The eventual closure of the Anemaqen Ocean probably occurred in the late Triassic, leading to the collision between the North Qiang Tang Terrane and MAT. The flysch formations deposited in the ocean were uplifted and deformed. This collision also caused the islands in the ocean basin to be decoupled and thrust onto the margin.

Acknowledgements We thank Prof. Li Sanzhong Meng Fancong, Wu Chen and anonymous reviewers for their constructive and helpful suggestions. This study was jointly financially supported by the Natural Science Foundation of China (Grant 41802080), the Program of High-level Geological Talents(201309) and Youth Geological Talents (201112) of the China Geological Survey, Geological Survey Program (Grant 1212011085528) from the China Geological Survey, and the Scientific Research Fund (Grant201411025) of the Non-Commercial Unit from Ministry of Land and Re-sources, China.

References: A, C.Y., Wang, Y.Z., Ren, J.Q., Bao, G.P., 2003. Disintegration of the Wanbaogou Group and discovery of Early Cambrian strata in the East Kunlun area. Chinese Geology 30(2), 199-206 (in Chinese with English abstract). Allegre, C.O., Courtillot, V., Tapponnier, P., Hirn, A., Mattauer, M., Coulon, C., Achache, J., Jaeger, J.J., Scharer, U., Marcoux, J., Burg, J.P., Giradeau, J., Armijo, R., Gariepy, C., Gopel, C., Li, T.D., Xiao, X.C., Chang, C.F., Li, G.Q., Lin, B.Y., Teng, J.W., Wang, N.W., Chen, G.M., Han, T.L., Wang, X.B., Deng, W.M., Sheng, H.B., Cao, Y.G., Zhou, J., Qiu, H.R., Bao, P.S., Wang, S.C., Wang, B.X., Zhou, Y.X., Rong, H.X., 1984. Structure and evolution of the Himalaya–Tibet orogenic belt. Nature 307(5946), 17-22. Axen, G.J., van Wijk, J.W., Currie, C.A., 2018. Basal continental mantle lithosphere displaced by flat-slab subduction. Nature Geoscience 11(12), 961. Bian, Q.T., Li, D.H., Pospelov, I., Yin, L.M., Li, H.S., Zhao, D.S., Chang, C.F., Luo, X.Q., Gao, S.L., Astrakhantsev, O., 2004. Age, geochemistry and tectonic setting of Buqingshan ophiolites, north Qinghai-Tibet Plateau, China. Journal of Asian Earth Sciences 23(4), 577-596. Bian, Q.T., Zhu, S.X., Pospelov, I.I., Semikhatov, M.A., Sun, S.F., Chen, D.Z., Na, C.G., 2005. Discovery of the Jiawengmen stromatolite assemblage in the southern belt of Eastern Kunlun, NW China and its significance. Acta Geologica Sinica (English Edition) 79(4), 471-480. Cai, H.J., Zhang, J.M., Zhang, Q.L., 2016. Age and geological implications of Shasongwula rapakivi granite in East Kunlun Mountains. Northwestern Geology (in Chinese with English abstract). Cai, H.M., 2010. Petrogenesis of Indosinian granitoids and volcanic rocks in Songpan-Garze fold

belt: constrains for deep geologic processes, China University of Geosciences, Wuhan, 1-55 (in Chinese with English abstract). Cai, X.F., Luo, Z.J., Liu, D.M., Yuan, Y.M., 2008. The Xilikete Formation: an important lithostratigraphic unit of the Triassic system in the Eastern Kunlun region. Journal of Stratigraphy 32(4), 374-380 (in Chinese with English abstract). Cai, X.F., Wei, Q.R., 2007. Stratigraphic sequence of oceanic islands and palinspastic reconstruction of the Wanbaogou Group in the eastern Kunlun orogenic belt. Journal of Stratigraphy 31(2), 117-126 (in Chinese with English abstract). Cai, X.F., Wei, Q.R., Wang, A., Wang, H.L., Luo, Z.J., 2010. Speciality and approach of continental paleo-oceanographic studies -take structure restoration of Nachitai tectonic melange in the East Kunlun as an example. Bulletin of Mineralogy Petrology & Geochemistry 29(1), 98-106 (in Chinese with English abstract). Chang, C.F., Chen, N.S., Coward, M.P., Deng, W.M., Dewey, J.F., Gansser, A., Harris, N.B., Jin, C.W., Kidd, W.S., Leeder, M.R., 1986. Preliminary conclusions of the Royal Society and Academia Sinica 1985 geotraverse of Tibet. Nature(323), 501-507. Chen, G.C., Pei, X.Z., Li, R.B., Li, Z.C., Pei, L., Liu, Z.Q., Chen, Y.J., Liu, C.J., Gao, J.M., Wei, F.H., 2013. Geochronology and genesis of the Helegang Xilikete granitic plutons from the southern margin of the eastern East Kunlun orogenic belt and their tectonic significance. Acta Geologica Sinica 87(10), 1525-1541 (in Chinese with English abstract). Chen, J., Xie, Z.Y., Li, B., Tan, S.X., Ren, H., Zhang, Q.M., Li, Y., 2013. Petrogenesis of Devonian intrusive rocks in Lalingzaohuo area, Eastern Kunlun, and its geological significance. Journal of Mineralogy & Petrology 33(2), 26-34 (in Chinese with English abstract).

Chen, J.J., Fu, L.B., Wei, J.H., 2016. Geochemical characteristics of Late Ordovician granodiorite in Gouli area, Eastern Kunlun orogenic belt, Qinghai province: implications on the evolution of Proto-Tethys ocean. Earth Science 41(11), 1863-1882 (in Chinese with English abstract). Chen, N.S., Sun, M., He, L., Zhang, K.X., Wang, G.C., 2002. Precise timing of the Early Paleozoic metamorphism and thrust deformation in the Eastern Kunlun Orogen. Chinese Science Bulletin 47(13), 1130-1133 (in Chinese with English abstract). Chen, N.S., Sun, M., Wang, Q.Y., Zhang, K.X., Wan, Y.S., Chen, H.H., 2008. U-Pb dating of zircon from the central zone of the East Kunlun Orogen and its implications for tectonic evolution. Science in China Series D: Earth Sciences 51(7), 929-938 (in Chinese with English abstract). Chen, N.S., Wang, Q.Y., Zhao, G.C., Chen, Q., Shu, G.M., 2007. EMP chemical ages of monazites from Central Zone of the eastern Kunlun Orogen: Records of multi-tectono metamorphic events. Chinese Science Bulletin (English Edition) 52(16), 2252-2263. Chen, S.J., Li, R.S., Ji, W.H., Zhao, Z.M., Li, G.D., Liu, R.L., Dai, Z.G., Zhu, Y.T., 2011. Lithostratigraphy character and tectonic evolvement of Permian-Triassic in the Bayankala tectonic belt. Earthscience 36(3), 393-408 (in Chinese with English abstract). Chen, X.H., Gehrels, G., Yin, A., Zhou, Q., Huang, P.H., 2015. Geochemical and Nd–Sr–Pb–O isotopic constrains on Permo–Triassic magmatism in eastern Qaidam Basin, northern Qinghai-Tibetan plateau: Implications for the evolution of the Paleo-Tethys. Journal of Asian Earth Sciences 114, 674-692. Chen, X.H., George, G., Yin, A., Li, L., Jiang, R.B., 2012. Paleozoic and Mesozoic basement magmatisms of eastern Qaidam basin, northern Qinghai-Tibet plateau: LA-ICP-MS zircon U-Pb geochronology and its geological significance. Acta Geologica Sinica (English Edition) 86(2),

350-369. Chen, Y.X., Liu, C.J., Pei, X.Z., Li, X.B., Li, R.B., Li, Z.C., Chen, G.C., Pei, L., Yang, J., 2013. Zircon U-Pb age, geochemical characteristics and tectonic significance of meta-volcanic rocks from Naij Tal Group, east section of East Kunlun. Earth Science Frontiers 20(6), 240-254 (in Chinese with English abstract). Chen, Y.X., Pei, X.Z., Li, R.B., Li, Z.C., Pei, L., Liu, Z.Q., Chen, G.C., Liu, C.J., Yang, J., 2014. Rock association, geochemical characteristics and tectonic setting of the Xiaomiao Formation, east region of East Kunlun orogenic belt. Acta Geologica Sinica 88(6), 1038-1054 (in Chinese with English abstract). Chen, Y.X., Pei, X.Z., Li, R.B., Liu, Z.Q., Li, Z.C., Zhang, X.F., Chen, G.C., Liu, Z.G., Ding, S.P., Guo, J.F., 2011. Zircon U-Pb age of Xiao Miao Formation of Proterozoic in the Eastern section of the East Kunlun orogenic belt. Geoscience 25(3), 510-521(in Chinese with English abstract). Cheng, X., Wu, H.N., Diao, Z.B., Wang, H.J., Ma, L., Zhang, X.D., Yang, G., Hong, J.J., Ji, W.H., Li, R.S., 2013. Paleomagnetic data from the Late Carboniferous-Late Permian rocks in eastern Tibet and their implications for tectonic evolution of the northern Qiangtang-Qamdo block. Science China Earth Sciences 56(7), 1209-1220 (in Chinese with English abstract). Clark, M.K., Farley, K.A., Zheng, D., Wang, Z., Duvall, A.R., 2010. Early Cenozoic faulting of the northern Tibetan Plateau margin from apatite (U–Th)/He ages. Earth and Planetary Science Letters 296(1-2), 78-88. Cowgill, E., Yin, A., Harrison, T.M., Xiao Feng, W., 2003. Reconstruction of the Altyn Tagh fault based on UϋPb geochronology: Role of back thrusts, mantle sutures, and heterogeneous crustal strength in forming the Tibetan Plateau. Journal of Geophysical Research: Solid Earth 108(B7).

Dai, J.G., Wang, C.S., Hourigan, J., Santosh, M., 2013. Multi-stage tectono-magmatic events of the Eastern Kunlun Range, northern Tibet: insights from U–Pb geochronology and (U–Th)/He thermochronology. Tectonophysics 599, 97-106. DePaolo, D.J., 1988. Neodymium isotope geochemistry: an introduction. Springer-Verlag, Berlin Heidelberg New York London Paris Tokyo, 1-183. Dewey, J.F., Shackleton, R.M., Chang, C.F., Sun, Y.Y., 1988. The tectonic evolution of the Tibetan Plateau. Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences 327(1594), 379-413. Dilek, Y., Furnes, H., 2014. Ophiolites and their origins. Elements 10(2), 93-100. Ding, Q.F., Liu, F., Yan, W., 2015. Zircon U–Pb geochronology and Hf isotopic constraints on the petrogenesis of Early Triassic granites in the Wulonggou area of the Eastern Kunlun Orogen, Northwest China. International Geology Review 57(13), 1735-1754. Dong, J., 2015. Petrological characteristic and provenance analysis of the Triassic Bayan Har Group in Gander, Qinghai Province, China University of Geosciences (Beijing), Beijing, 1-65 (in Chinese with English abstract). Dong, L.Q., Dong, G.C., Huang, H., Bai, Y., 2016. Geochemical and zircon U-Pb dating characteristics and significance of the Tuluyin granites in the east of East Kunlun orogenic belt. Geology in China 43(5), 1737-1749 (in Chinese with English abstract). Dong, Y.P., He, D.F., Sun, S.S., Liu, X.M., Zhou, X.H., Zhang, F.F., Yang, Z., Cheng, B., Zhao, G.C., Li, J.H., 2018. Subduction and accretionary tectonics of the East Kunlun orogen, western segment of the Central China Orogenic System. Earth-Science Reviews 186, 231-261. Dong, Y.P., Santosh, M., 2016. Tectonic architecture and multiple orogeny of the Qinling Orogenic

Belt, Central China. Gondwana Research 29(1), 1-40. Dong, Y.P., Sun, S.S., Liu, X.M., He, D.F., Zhou, X.H., Zhang, F.F., Yang, Z., Zhou, D.W., 2018. Geochronology and geochemistry of the Yazidaban ophiolitic mélange in Qimantagh: constraints on the Early Paleozoic back-arc basin of the East Kunlun Orogen, northern Tibetan Plateau. Journal of the Geological Society 176(2), 306-322. Dong, Y.P., Zhang, G., Neubauer, F., Liu, X.M., Genser, J., Hauzenberger, C., 2011. Tectonic evolution of the Qinling orogen, China: review and synthesis. Journal of Asian Earth Sciences 41(3), 213-237. Du, W., Jiang, C.Y., Tang, Z.L., Xia, M.Z., Xia, Z.D., Ling, J.L., Zhou, W., Wang, B.Y., 2017. Discovery of the Dagele eclogite in East Kunlun, Western China and its zircon SHRIMP UϋPb ages: New constrains on the Central Kunlun suture zone. Acata Geologica Sinica (English Edition) 91(3), 1153-1154. Feng, C.Y., Zhang, D.Q., Dang, X.Y., 2005. SHRIMP zircon U-Pb dating of quartz albitite from the Tuolugou cobalt (gold) deposit, Golmud, Qinghai, China: constraints on the age of the Naij Tal Group. Geological Bulletin of China 24(6), 501-505 (in Chinese with English abstract). Feng, J.Y., Pei, X.Z., Yu, S.L., Ding, S.P., Li, R.B., Sun, Y., Zhang, Y.F., Li, Z.C., Chen, Y.X., Zhang, X.F., 2010. The discovery of the mafic-ultramafic melange in Kekesha area of Dulan County, East Kunlun region, and its LA-ICP-MS zircon U-Pb age. Geology in China 1, 006 (in Chinese with English abstract). Feng, L.Q., Gu, X.X., Zhang, Y.M., He, G., Kang, J.Z., 2017. Age and structural deformation of ductile shear zones on the southern margin of the East Kunlun Mountains. Geological Bulletin of China 36(6), 987-1000 (in Chinese with English abstract).

Frisch, W., Meschede, M., Blakey, R.C., 2010. Plate tectonics: continental drift and mountain building. Springer Science & Business Media, Sturtz GmbH, Wurzburg, 1-207. Fu, S.T., Ma, D.D., Guo, Z.J., Feng, C., 2015. Strike-slip superimposed Qaidam Basin and its control on oil and gas accumulation, NW China. Petroleum Exploration & Development 42(6), 778-789 (in Chinese with English abstract). Gehrels, G.E., Yin, A., Wang, X., 2003. Detrital-zircon geochronology of the northeastern Tibetan plateau. Geological Society of America Bulletin 115(7), 881-896. Gehrels, G.E., Yin, A., Wang, X.F., 2003. Magmatic history of the northeastern Tibetan Plateau. Journal of Geophysical Research: Solid Earth (1978–2012) 108(B9). Gu, F.B., 1994. Geological characteristics of East Kunlun and tectonic evolution in late Paleozoic-Mesozoic era. Qinghai Geology 4(1), 4-14 (in Chinese with English abstract). Guo, X.Z., Jia, Q.Z., Qian, B., Mi, J.R., Li, J.C., Kong, H.L., Yao, X.G., 2017. Geochemical characteristics of eclogites and garnet-amphibolites in East Kunlun high pressure metamorphic belt and their geodynamic setting. Journal of Earth Sciences and Environment 39(6), 735-750 (in Chinese with English abstract). Hall, R., 2002. Cenozoic geological and plate tectonic evolution of SE Asia and the SW Pacific: computer-based reconstructions, model and animations. Journal of Asian Earth Sciences 20(4), 353-431. Haschke, M., Siebel, W., Günther, A., Scheuber, E., 2002. Repeated crustal thickening and recycling during the Andean orogeny in north Chile (21–26 S). Journal of Geophysical Research: Solid Earth 107(B1). He, D.F., Dong, Y.P., Liu, X.M., Yang, Z., Sun, S.S., Cheng, B., Li, W., 2016. Tectono-thermal

events in East Kunlun, Northern Tibetan Plateau: evidence from zircon U–Pb geochronology. Gondwana Research 30, 179-190. He, D.F., Dong, Y.P., Liu, X.M., Zhou, X.H., Zhang, F.F., Sun, S.S., 2018. Zircon U–Pb geochronology and Hf isotope of granitoids in East Kunlun: Implications for the Neoproterozoic magmatism of Qaidam Block, northern Tibetan Plateau. Precambrian Research 314, 377-393. Hofmann, A.W., 1988. Chemical differentiation of the Earth: the relationship between mantle, continental crust, and oceanic crust. Earth and Planetary Science Letters 90(3), 297-314. Hou, G.J., Bai, Y.S., Wang, G.C., Zhang, K.X., Chen, N.S., Zhu, Y.H., 1999. Superimposed folds and corresponding deformation mechanism in foreland basins in Eastern Kunlun orogenic zone. Earth Science-Journal of China University of Geosciences 24(2), 125-128 (in Chinese with English abstract). Hu, A.Q., Hao, J., Zhang, G.X., Zhang, H.B., 2004. Whole-rock and minerals Sm-Nd isochron age of early Neoproterozoic ophiolites and its geological significance in the eastern Kunlun area, Xinjiang, China. Acta Petrologica Sinica 20(3), 457-462 (in Chinese with English abstract). Hu, J.M., Meng, Q.R., Shi, Y.R., Qu, H.J., 2005. SHRIMP U-Pb dating of zircons from granitoid bodies in the Songpan-Ganzi terrane and its implications. Acta Petrologica Sinica 21(3), 867-880 (in Chinese with English abstract). Hu, N., Pei, X.Z., Li, R.I., Li, Z.C., Liu, Z.Q., Pei, L., Liu, C.J., Chen, Y.X., Chen, G.C., Yang, J., 2013. Provenance and Tectonic Setting Study of the Maerzheng Formation at the Delistan of Buqingshan Area in the Southern Margin of East Kunlun. Acta Geologica Sinica 87(11), 1731-1747 (in Chinese with English abstract). Hu, X.L., Chen, W., 2010. Pilot study of southern Kunlun fracture at Bukedaban area of the west

part of East Kunlun. Journal of Qinghai University 10(1), 101-108 (in Chinese with English abstract). Huang, H., Niu, Y., Nowell, G., Zhao, Z., Yu, X., Zhu, D.C., Mo, X., Ding, S., 2014. Geochemical constraints on the petrogenesis of granitoids in the East Kunlun Orogenic belt, northern Tibetan Plateau: Implications for continental crust growth through syn-collisional felsic magmatism. Chemical Geology 370(4), 1-18. Huang, K.N., Opdyke, N.D., Peng, X.J., Li, J.G., 1992. Paleomagnetic results from the Upper Permian of the eastern Qiangtang Terrane of Tibet and their tectonic implications. Earth and Planetary Science Letters 111(1), 1-10. Huang, X.H., Zhang, H.J., Wang, X.L., Wang, X., Wang, Z.Y., Qi, Y.J., 2017. LA-ICP-MS U-Pb dating of detrital zircons from the Upper Permian Gequ Formation on the southern margin of the East Kunlun Mountains and its tectonics implications. Geological Bulletin of China 36(2-3), 258-269 (in Chinese with English abstract). Ikeda, Y., Nagao, K., Ishii, T., Matsumoto, D., Stern, R.J., Kagami, H., Arima, M., Bloomer, S.H., 2016. Contributions of slab fluid and sediment melt components to magmatism in the Mariana Arc–Trough system: Evidence from geochemical compositions and Sr, Nd, and noble gas isotope systematics. Island Arc 25(4), 253-273. Jacobsen, S.B., Wasserburg, G.J., 1980. Sm-Nd isotopic evolution of chondrites. Earth and Planetary Science Letters 50(1), 139-155. Ji, Q., 1997. Discovery of an Early Cambrian small-shelly fauna in the central sector of the East Kunlun Mountains, Qinghai, and its geological significance. Regional Geology of China 4, 428-431 (in Chinese with English abstract).

Jiang, C.F., 1992. Opening-closing evolution of the Kunlun Mountains. Opening closing tectonics of Kunlun Shan. Geological Memoirs, Series 5, 205-217 (in Chinese with English abstract). Jiang, C.F., Feng, B., Yang, J.S., Zhu, Z., Zhao, M., Chai, Y., Shi, X., Hu, J., 1986. An outline of the geology and tectonics of the Kunlun Mts. area. Bull. Inst. Geol. Chin. Acad. Geol. Sci 2, 70-80 (in Chinese with English abstract). Jiang, M., Galvé, A., Hirn, A., De Voogd, B., Laigle, M., Su, H.P., Diaz, J., Lépine, J., Wang, Y.X., 2006. Crustal thickening and variations in architecture from the Qaidam basin to the Qang Tang (North–Central Tibetan Plateau) from wide-angle reflection seismology. Tectonophysics 412(3), 121-140. Jiang, R.B., Chen, X.H., Dang, Y.Q., Yin, A., Wang, L.Q., Jiang, W.M., Wan, J.L., Li, L., Wang, X.F., 2008. Apatite fission track evidence for two phases Mesozoic-Cenozoic thrust faulting in eastern Qaidam Basin. Chinese Journal of Geophysics 51(1), 116-124 (in Chinese with English abstract). Kapp, P., Yin, A., Manning, C.E., Murphy, M., Harrison, T.M., Spurlin, M., Lin, D., Xi-Guang, D., Cun-Ming, W., 2000. Blueschist-bearing metamorphic core complexes in the Qiangtang block reveal deep crustal structure of northern Tibet. Geology 28(1), 19-22. Karplus, M.S., Zhao, W., Klemperer, S.L., Wu, Z., Mechie, J., Shi, D., Brown, L.D., Chen, C., 2011. Injection of Tibetan crust beneath the south Qaidam Basin: Evidence from INDEPTH IV wide-angle seismic data. Journal of Geophysical Research: Solid Earth 116(B7). Kong, H.L., Li, J.C., Li, Y.Z., Jia, Q.Z., Guo, X.H., Wang, Y., 2017. Zircon LA-ICP-MS U-Pb dating and its geological significance of the Halongxiuma pyroxene peridotite in East Kunlun, Qinghai province. Geological Science and Technology Information 36(1), 41-47 (in Chinese with

English abstract). Kong, H.L., Li, J.C., Li, Y.Z., Jia, Q.Z., Yang, B.R., 2014. Geochemistry and zircon U-Pb geochronology of Annage diorite in the eastern section from East Kunlun in Qinghai province. Geological Science & Technology Information 33(6), 11-17 (in Chinese with English abstract). Kou, L.L., Zhang, S., Zhong, K.H., Tian, C.S., 2015. A study of the deformation characteristics of the ductile shear zone in the Wulonggou gold ore concentration area, East Kunlun, Qinghai. Geology in China 42(2), 495-503 (in Chinese with English abstract). Kui, M.J., Bai, H.X., Gu, F.B., Miao, G.W., 2010. Division of East Kunlun tectonic magmatic belt and the rock tectonic combination in the late Variscan-Yanshanian period. Journal of Qinghai University 28(5), 49-55 (in Chinese with English abstract). Kylander-Clark, A.R., Hacker, B.R., Mattinson, C.G., 2012. Size and exhumation rate of ultrahigh-pressure terranes linked to orogenic stage. Earth and Planetary Science Letters 321, 115-120. Li, D.P., Li, X.L., Zhou, X.K., Wang, X.L., Li, W., Gao, X.P., Du, S.X., Dai, X.Y., Liu, Y.Q., 2007. Discovery of a Permian paleo-seamount in the western segment of the Bayan Har Mountains and its significance. Geological Bulletin of China 26(8), 996-1002 (in Chinese with English abstract). Li, H.K., Lu, S.N., Xiang, Z.Q., Zhou, H.Y., Guo, H., Song, B., Zheng, J.K., Gu, Y., 2006. SHRIMP U-Pb zircon age of the granulite from the Qingshuiquan area, Central Eastern Kunlun Suture Zone. Earth Science Frontiers 13(6), 311 (in Chinese with English abstract). Li, R.B., Pei, X.Z., Li, Z.C., Pei, L., Chen, G.C., Chen, Y.X., Liu, C.J., 2017. Late Cambrian SSZϋ type Ophiolites in Acite Zone, East Kunlun Orogen of Northern Tibet Plateau: Insights from Zircon UϋPb Isotopes and Geochemistry of Oceanic Crust Rocks. Acta Geologica Sinica 91(S1), 66-67.

Li, R.B., Pei, X.Z., Li, Z.C., Pei, L., Chen, G.C., Wei, B., Chen, Y.X., Liu, C.J., Wang, M., 2017. Cambrian (–510 Ma) ophiolites of the East Kunlun orogen, China: A case study from the Acite ophiolitic tectonic mélange. International Geology Review, 1-21. Li, R.B., Pei, X.Z., Li, Z.C., Sun, Y., Pei, L., Chen, G.C., Chen, Y.X., Liu, C.J., Wei, F.H., 2013. Regional tectonic transformation in East Kunlun orogenic belt in Early Paleozoic: constraints from the geochronology and geochemistry of Helegangnaren alkali-feldspar granite. Acta Geologica Sinica (English Edition) 87(2), 333-345. Li, R.S., Ji, W.H., Zhao, Z.M., Chen, S.J., Meng, Y., Yu, P.S., Pan, X.P., 2007. Progress in the study of the Early Paleozoic Kunlun orogenic belt. Geological Bulletin of China 26(4), 373-382 (in Chinese with English abstract). Li, S.P., Li, Y.X., Pan, T., Bai, Z.H., Wang, J., Shu, S.L., Li, X.X., Zhang, Z.Q., Zhao, H.X., 2012. Geochemistry and tectonic setting of marine volcanic rocks of Elashan area in Qinghai. Northwestern Geology 45(1), 124-133 (in Chinese with English abstract). Li, S.Z., Yang, Z., Zhao, S.J., Li, X.Y., Suo, Y.H., Guo, L.L., Yu, S., Dai, L.M., Li, S.J., Mu, D.L., 2016. Global Early Paleozoic orogens (II): subduction-accretionary-type orogeny. Journal of Jilin University (Earth Science Edition) 46(4), 968-1014 (in Chinese with English abstract). Li, S.Z., Zhao, S.J., Liu, X., Cao, H.H., Yu, S., Li, X.Y., Somerville, I., Yu, S.Y., Suo, Y.H., 2018. Closure of the Proto-Tethys Ocean and Early Paleozoic amalgamation of microcontinental blocks in East Asia. Earth-Science Reviews 186, 37-75. Li, X.B., Pei, X.Z., Liu, C.J., Chen, Y.X., Li, R.B., Li, Z.C., Chen, G.C., Wei, G.F., 2014. Ductile shearing in the eastern segment of Central Kunlun tectonic belt and its geological significance. Geology in China 41(2), 419-436 (in Chinese with English abstract).

Li, Y., Li, S., Wang, S.L., Wang, L., Shang, J., Zhang, Z.Q., Zhao, H.X., 2011. Geochemical characteristics and tectonic environment of the continental facies volcanic rocks in Elashan area, Qinghai Province. Northwestern Geology 44(4), 23-32 (in Chinese with English abstract). Li, Y.D., Liu, X.Y., 2014. Geochemistry and tectonic setting of late Triassic volcanic rocks in Reshui area, Qinghai. Northwestern Geology 47(3), 14-25 (in Chinese with English abstract). Li, Y.J., Mai, G.R., Peng, G.X., Zheng, D.M., Luo, J.C., Huang, Z.B., 2000. Preliminary approach to the geotectonic setting of Carboniferous flysch deposits in East Kunlun Mountains. Xinjiang Petroleum Geology 21(1), 45-49 (in Chinese with English abstract). Li, Y.Z., Kong, H.L., Li, J.C., Jia, Q.Z., Wang, J.Y., Namhka, N., 2015. Geochemistry and Zircon U-Pb geochronology of the Yueliangwan plagiogranite in the Wulonggou gold deposit, Qinghai province. Bulletin of Mineralogy, Petrology and Geochemistry 34(2), 401-409. Li, Z., Qiu, N., Chang, J., Yang, X., 2015. Precambrian evolution of the Tarim Block and its tectonic affinity to other major continental blocks in China: new clues from U–Pb geochronology and Lu–Hf isotopes of detrital zircons. Precambrian Research 270, 1-21. Li, Z.C., Pei, X.Z., Li, R.B., Pei, L., Liu, C.J., Chen, Y.X., Liu, Z.Q., 2014. Geochronology, geochemistry and tectonic setting of the Bairiqiete granodiorite intrusion (rock mass) from the Buqingshan tectonic mélange belt in the southern margin of East Kunlun. Acta Geologica Sinica (English Edition) 88(2), 584-597. Li, Z.C., Pei, X.Z., Li, R.I., Pei, L., Liu, C.J., Chen, Y.X., Zhang, Y.M., Wang, M., Xu, T., 2017. Early Ordovician island-arc-type Manite granodiorite pluton from the Buqingshan Tectonic Mélange Belt in the southern margin of the East Kunlun Orogen: constraints on subduction of the ProtoTethyan Ocean. Geological Journal 52(3), 510-528.

Li, Z.C., Pei, X.Z., Liu, Z.Q., Li, R.B., Pei, L., Chen, G.H., Liu, C.J., Chen, Y.X., Gao, J.M., Wei, F.H., 2013. Geochronology and geochemistry of the Gerizhuotuo diorites from the Buqingshan tectonic mélange belt in the southern margin of East Kunlun and their geologic implications. Acta Geologica Sinica 87(8), 1089-1103 (in Chinese with English abstract). Liu, B., Ma, C.Q., Guo, P., Zhang, J.Y., Xiong, F.H., Huang, J., Jiang, H.A., 2013. Discovery of the middle Devonian A-type granite from the Eastern Kunlun orogen and its tectonic implications. Earth Science 38(5), 947-962 (in Chinese with English abstract). Liu, B., Ma, C.Q., Jiang, H.A., Guo, P., Zhang, J.Y., Xiong, F.H., 2013. Early Paleozoic tectonic transition from ocean subduction to collisional orogeny in the Eastern Kunlun region: evidence from Huxiaoqin mafic rocks. Acta Petrologica Sinica 29, 2093-2106 (in Chinese with English abstract). Liu, B., Ma, C.Q., Zhang, J.Y., Xiong, F.H., Huang, J., Jiang, H.A., 2012. Petrogenesis of Early Devonian intrusive rocks in the east part of Eastern Kunlun Orogen and implication for Early Palaeozoic orogenic processes. Acta Petrologica Sinica 28(6), 1785-1807 (in Chinese with English abstract). Liu, J., Sun, F.Y., Li, L., Zhao, F.F., Wang, Y.D., Wang, S., Zhang, Y.T., 2015. Geochronology, geochemistry and Hf isotopes of Gerizhuotuo complex intrusion in west of Anyemaqen suture zone. Earth Science-Journal of China University of Geosciences 40(6), 965-981 (in Chinese with English abstract). Liu, J.N., Feng, C.Y., Qi, F., Li, G.C., Ma, S.C., Xiao, Y., 2012. SIMS zircon U-Pb dating and fluid inclusion studies of Xiadeboli Cu-Mo ore district in Dulan County, Qinghai Province, China. Acta Petrologica Sinica 28(2), 679-690 (in Chinese with English abstract). Liu, Q., Meng, F.C., Li, S.R., Feng, H.B., Jia, L.H., Tian, G.K., 2016. Geochronology of zircon from

the paragneiss of Kuhai Group in southern East Kunlun terrane. Acta Petrologica et Mineralogica 35(3), 469-483 (in Chinese with English abstract). Liu, Y.J., Genser, J., Neubauer, F., Jin, W., Ge, X.H., Handler, R., Takasu, A., 2005. 40 Ar/39 Ar mineral ages from basement rocks in the Eastern Kunlun Mountains, NW China, and their tectonic implications. Tectonophysics 398(3), 199-224. Liu, Z.Q., Pei, X.Z., Li, R.B., Li, Z.C., Zhang, X.F., Liu, Z.G., Chen, G.C., Chen, Y.X., Ding, S.P., Guo, J.F., 2011. LA-ICP-MS zircon U-Pb Geochronology of the two suites of ophiolites at the Buqingshan area of the A'nyemaqen orogenic belt in the southern margin of East Kunlun and its tectonic implication. Acta Geologica Sinica 85(2), 185-194 (in Chinese with English abstract). Liu, Z.W., Zhao, W.J., Wu, Z.H., Shi, D.N., 2016. Ancient oceanic crustal subduction of the East Kunlun orogenic belt: evidence from deep-reflection seismic data. Acta Geologica Sinica 90(8), 1692-1702 (in Chinese with English abstract). Liu, Z.W., Zhao, W.J., Wu, Z.H., Shi, D.N., Yang, S., Deng, S.G., 2016. East Kunlun Orogeny′s uplift uncovered by deep reflection seismic data in INDEPTH Č. Chinese Journal of Geophysics 59(9), 3211-3222 (in Chinese with English abstract). Long, X.P., Jin, W., Ge, W.C., Yu, N., 2006. Zircon U-Pb geochronology and geological implications of the granitoids in Jinshuikou, East Kunlun, NW China. Geochimica 35(4), 333-345 (in Chinese with English abstract). Lu, L., Wu, Z.H., Hu, D.G., Barosh, P.J., Hao, S., Zhou, C.J., 2010. Zircon U-Pb age for rhyolite of the Maoniushan Formation and its tectonic significance in the East Kunlun Mountains. Acta Petrologica Sinica 26(4), 1150-1158 (in Chinese with English abstract). Lu, L., Zhang, Y.L., Wu, Z.H., Hu, D.G., 2013. Zircon U–Pb dating of Early Paleozoic granites from

the East Kunlun Mountains and its geological significance. Acta Geoscientica Sinica 34(4), 447-454 (in Chinese with English abstract). Lu, S.N., Yu, H.F., Li, H.K., Chen, Z.H., Wang, H.C., Zhang, C.L., Xiang, Z.Q., 2006. Early Paleozoic suture zones and tectonic divisions in the “Central China Orogen”. Geological Bulletin of China 25(12), 1368-1380 (in Chinese with English abstract). Luo, M.F., Mo, X.X., Yu, X.H., Li, X.W., Huang, X.F., Yu, J.C., 2014. Zircon LA-ICP-MS U-Pb age dating, petrogenesis and tectonic implications of the late Triassic granites from the Xiangride area, East Kunlun. Acta Petrologica Sinica 30(11), 3229-3241 (in Chinese with English abstract). Luo, M.S., Zhang, K.X., Yin, H.F., Wang, G.C., Wang, Y.B., Chen, N.S., Hou, G.J., 2006. Petro-geochemistry characteristics of Longshigenggongma mélanges of Eastern Kunlun orogenic belt and paleoenvironment reconstruction. Geological Science and Technology Information 25(2), 19-24 (in Chinese with English abstract). Luo, Z.H., Deng, J.F., Cao, Y.Q., Guo, Z.F., Mo, X.X., 1999. On late Paleozoic-early Mesozoic volcanism and regional tectonic evolution of Eastern Kunlun, Qinghai Province. Geoscience 13(1), 51-56 (in Chinese with English abstract). Ma, C.Q., Xiong, F.H., Yin, S., Wang, L.X., Gao, K., 2015. Intensity and cyclicity of orogenic magmatism: An example from a Paleo-Tethyan granitoid batholith, Eastern Kunlun, northern Qinghai-Tibetan Plateau. Acta Petrologica Sinica 31(12), 3555-3568 (in Chinese with English abstract). Ma, H.D., Yang, Z.J., Wei, X.C., Li, X.Y., 2004. New results and major progress in regional geological survey of the Muztag and Jingyu Lake sheets. Geological Bulletin of China 23(5-6), 570-578 (in Chinese with English abstract).

Ma, H.D., Yang, Z.J., Wei, X.C., Tang, Z., Li, W.D., Li, X.Y., Li, S.L., Li, Y.A., Tu, Q.J., Kang, Z.W., 2010. Regional geological survey report of the People's Republic of China: Jingyuhu sheet. Geology Publishing House, Beijing, 1-197 (in Chinese with English abstract). Ma, Y.J., Xie, X.L., Yu, X.L., Yang, Y.Q., Li, J., Ma, W., 2017. U-Pb dating geological of zircon mineral, geochemical characteristics and significance of late Triassic intrusive rocks in Zharijia area, Qinghai. Mineral Exploration 8(2), 196-206 (in Chinese with English abstract). Macpherson, C.G., Forrde, E.J., Hall, R., Thirlwall, M.F., 2003. Geochemical evolution of magmatism in an arc-arc collision: The Halmahera and Sangihe arcs, eastern Indonesia. The Geological Society of London, Special Publications 219(1), 207-220. Manea, V., Gurnis, M., 2007. Subduction zone evolution and low viscosity wedges and channels. Earth and Planetary Science Letters 264(1-2), 22-45. Manea, V.C., Manea, M., Ferrari, L., Orozco-Esquivel, T., Valenzuela, R.W., Husker, A., Kostoglodov, V., 2017. A review of the geodynamic evolution of flat slab subduction in Mexico, Peru, and Chile. Tectonophysics 695, 27-52. Martinod, J., Funiciello, F., Faccenna, C., Labanieh, S., Regard, V., 2005. Dynamical effects of subducting ridges: insights from 3-D laboratory models. Geophysical Journal International 163(3), 1137-1150. Meng, F.C., Cui, M.H., Wu, X.K., Wu, J.F., Wang, J.H., 2013. Magmatic and metamorphic events recorded in granitic gneisses from the Qimantag, East Kunlun Mountains, Northwest China. Acta Petrologica Sinica 29(6), 2107-2122 (in Chinese with English abstract). Meng, F.C., Zhang, J.X., Cui, M.H., 2013. Discovery of Early Paleozoic eclogite from the East Kunlun, Western China and its tectonic significance. Gondwana Research 23(2), 825-836.

Metcalfe, I., 2013. Gondwana dispersion and Asian accretion: tectonic and palaeogeographic evolution of eastern Tethys. Journal of Asian Earth Sciences 66, 1-33. Min, W., Liu, A., Dai, C., Yong, H., Chen, H., Beijing, Guiyang, 2009. Late Paleozoic Strata and Tectonic Facies in the Northern Margin of the Eastern Kunlun Orogen and their Tectonic Implications. Acta Geologica Sinica 83(11), 1601-1611. Mo, X.X., Hou, Z.Q., Niu, Y.L., Dong, G.C., Qu, X.M., Zhao, Z.D., Yang, Z.M., 2007. Mantle contributions to crustal thickening during continental collision: evidence from Cenozoic igneous rocks in southern Tibet. Lithos 96(1), 225-242. Mo, X.X., Luo, Z.H., Deng, J., Yu, X., Liu, C., Yuan, W.M., Bi, X., 2007. Granitoids and crustal growth in the East Kunlun orogenic belt. Geological Journal of China Universities 13(3), 403-414 (in Chinese with English abstract). Nan, K.N., Jia, Q.Z., Li, W.Y., Ling, T., Kong, H.L., Li, J.C., Li, Y.Z., 2014. A comparative study on isotopic geochronology and tectonic-magmatic hydrothermal events of igneous rock in Qinghai province. Northwestern Geology 47(2), 51-61 (in Chinese with English abstract). Ni, J.Y., Hu, D.G., Zhou, C.J., 2010. Tectonic enviroment of Naij Tal Group in the East Kunlun orogenic belt. Journal of Geomechanics 16(1), 11-20 (in Chinese with English abstract). Niu, Y.L., 2003. Initiation of subduction zones as a consequence of lateral compositional buoyancy contrast within the lithosphere: a petrological perspective. Journal of Petrology 44(5), 851-866. Niu, Y.L., Liu, Y., Xue, Q.Q., Shao, F.L., Chen, S., Duan, M., Guo, P.Y., Gong, H.M., Hu, Y., Hu, Z.X., 2015. Exotic origin of the Chinese continental shelf: new insights into the tectonic evolution of the western Pacific and eastern China since the Mesozoic. Science Bulletin 60(18), 1598-1616. Owens, T.J., Zandt, G., 1997. Implications of crustal property variations for models of Tibetan

plateau evolution. Nature 387(6628), 37-43. Pan, G.T., Li, X.Z., Wang, L.Q., Ding, J., Chen, Z.L., 2002. Preliminary division of tectonic units of the Qinghai-Tibet Plateau and its adjacent regions. Geological Bulletin of China 21(11), 701-707 (in Chinese with English abstract). Pan, G.T., Wang, L.Q., Li, R.S., Yuan, S.H., Ji, W.H., Yin, F.G., Zhang, W.P., Wang, B.D., 2012. Tectonic evolution of the Qinghai-Tibet plateau. Journal of Asian Earth Sciences 53, 3-14. Pan, Y.S., Zhou, W.M., Xu, R.H., Wang, D.A., Zhang, Y.Q., Xie, Y.W., Chen, T.E., Luo, H., 1996. Geological characteristics and evolution of the Kunlun Mountains region during the early Paleozoic. Science in China (series D) 4(39), 337-347. Pearce, J.A., 1982. Trace element characteristics of lavas from destructive plate boundaries. Andesites, 528-548. Pearce, J.A., Harris, N.B., Tindle, A.G., 1984. Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. Journal of Petrology 25(4), 956-983. Pei, X.Z., Hu, N., Liu, C.J., Li, R.B., Li, Z.C., Chen, Y.X., Pei, L., Liu, Z.Q., Chen, G.C., Yang, J., 2015. Detrital composition, geochemical characteristics and provenance analysis for the Maerzheng Formation sandstone in Gerizhuotuo area, southern margin of East Kunlun region. Geological Review 61(2), 307-323 (in Chinese with English abstract). Peng, Y., 2015. The tectonic deformation characteristics and provenance analysis of Bayan Har mountains, China University of Geosciences (Beijing), Beijing, 1-69 (in Chinese with English abstract). Piccardo, G.B., 2016. Evolution of the lithospheric mantle during passive rifting: Inferences from the Alpine–Apennine orogenic peridotites. Gondwana Research 39, 230-249.

Pullen, A., Kapp, P., Gehrels, G.E., Vervoort, J.D., Ding, L., 2008. Triassic continental subduction in central Tibet and Mediterranean-style closure of the Paleo-Tethys Ocean. Geology 36(5), 351-354. Qi, S.S., 2015. Petrotectonic assemblages and tectonic evolution of the East Kunlun orogenic belt in Qinghai Province, China University of Geosciences, Beijing (in Chinese with English abstract). Qi, S.S., Song, S.G., Shi, L.C., Cai, H.J., Hu, J.C., 2014. Discovery and its geological significance of Early Paleozoic eclogite in Xiarihamu-Suhaitu area, western part of the East Kunlun. Acta Petrologica Sinica 30(11), 3345-3356 (in Chinese with English abstract). Qi, X.P., Fan, X.G., Yang, J., Cui, J.T., Wang, B.Y., Fan, Y.Z., Yang, G.X., Li, Z., Chao, W.D., 2016. The discovery of Early Paleozoic eclogite in the upper reaches of Langmuri in eastern East Kunlun Mountains and its significance. Geological Bulletin of China 35(11), 1771-1783 (in Chinese with English abstract). Ren, E.F., Zhang, G.L., Qiu, W., Li, H.X., Sun, Z.H., 2012. Characteristics of geochemistry and tectonic significance of Caledonian granite in the Maerzheng region in the south area of East Kunlun. Geoscience 26(1), 36-44 (in Chinese with English abstract). Ren, H.D., Wang, T., Zhang, L., Wang, X.X., Huang, H., Feng, C.Y., Claudia, T., Song, P., 2016. Ages, sources and tectonic settings of the Triassic igneous rocks in the easternmost segment of the East Kunlun orogen, central China. Acta Geologica Sinica (English Edition) 90(2), 641-668. Ren, J.H., Liu, Y.Q., Feng, Q., Han, W.Z., Gao, H., Zhou, D.W., 2009. LA-ICP-MS U-Pb zircon dating and geochemical characteristics of diabase-dykes from the Qingshuiquan area, eastern Kunlun orogenic belt. Acta Petrologica Sinica 25(5), 1135-1145 (in Chinese with English abstract). Ren, J.S., 2004. Some problems on the Kunlun-Qinling orogenic system. Northwestern Geology. Ren, J.S., Niu, B.G., Liu, Z.A., 1996. Microcontinents, soft collision and polycyclic suturing.

Continental Dynamics 1(1), 1-9 (in Chinese with English abstract). Robinson, P.T., Yang, J.S., Shi, R.D., Wu, C.L., Wang, X.B., 2009. Dur'ngoi ophiolite in East Kunlun, Northeast Tibetan plateau: evidence for paleo-Tethyan suture in Northwest China. Journal of Earth Science 20(2), 303-331. Roger, F., Arnaud, N., Gilder, S., Tapponnier, P., Jolivet, M., Brunel, M., Malavieille, J., Xu, Z., Yang, J., 2003. Geochronological and geochemical constraints on Mesozoic suturing in east central Tibet. Tectonics 22(4), 1037. Rudnick, R.L., Fountain, D.M., 1995. Nature and composition of the continental crust: a lower crustal perspective. Reviews of Geophysics 33(3), 267-309. Saito, S., Tani, K., 2017. Transformation of juvenile Izu–Bonin–Mariana oceanic arc into mature continental crust: An example from the Neogene Izu collision zone granitoid plutons, Central Japan. Lithos 277, 228-240. Sang, J.Z., Pei, X.Z., Li, R.B., Liu, C.J., Chen, Y.X., Li, Z.C., Chen, G.C., Yang, S., Wang, X.B., Chen, G., Deng, W.B., 2016. LA-ICP-MS zircon U-Pb dating and geochemical characteristics of gabbro in Qingshuiquan, east section of East Kunlun, and its tectonic significance. Geological Bulletin of China 35(5), 700-710 (in Chinese with English abstract). Sengör, A.M., 1979. Mid-Mesozoic closure of Permo-Triassic Tethys and its implications. Nature 279, 590-593. Shao, D., Ji, W., Li, R., Chen, S., Li, M., Shao, D., Ji, W., Li, R., Chen, S., Li, M., 2017. Structural analysis and deformation phases of the Buqingshan tectonic melange belt in the southern margin of east Kunlun. Northwestern Geology 50(1), 4-12 (in Chinese with English abstract). Shao, F.L., Niu, Y.L., Liu, Y., Chen, S., Kong, J.J., Duan, M., 2017. Petrogenesis of Triassic

granitoids in the East Kunlun Orogenic Belt, northern Tibetan Plateau and their tectonic implications. Lithos 282, 33-44. Shi, B., 2014. The genesis of the Caledonian peraluminous granites in Heihai region, the Eastern Kunlun, China University of Geosciences, Wuhan, 1-89 (in Chinese with English abstract). Shi, B., Liu, L., 2014. Petrological and geochemical characteristics of Early Silurian granites in Zaohuogou of eastern Kunlun and their geological significance. Global Geology 33(4), 758-767 (in Chinese with English abstract). Shi, B., Zhu, Y.H., Zhong, Z.Q., Jian, K.K., 2016. Petrological, geochemical characteristics and geological significance of the Caledonian peraluminous granites in Heihai region, Eastern Kunlun. Earth Science 41(1), 35-54 (in Chinese with English abstract). Shi, L.C., Cai, H.J., Xu, H.Q., Xu, B., Wei, Y.N., Zhao, M.F., 2017. Material composition characteristics of Naijtal Group in subduction accretion complex on the southern slope of East Kunlun Mountains. Geological Bulletin of China 36(2-3), 251-257 (in Chinese with English abstract). Song, S.G., Niu, Y.L., Su, L., Xia, X.H., 2013a. Tectonics of the North Qilian orogen, NW China. Gondwana Research 23(4), 1378-1401. Song, S.G., Niu, Y.L., Su, L., Xia, X.H., 2013b. Tectonics of the north Qilian orogen, NW China. Gondwana Research 23(4), 1378-1401. Song, S.G., Su, L., Li, X.H., Niu, Y.L., Zhang, L.F., 2012. Grenville-age orogenesis in the Qaidam-Qilian block: The link between South China and Tarim. Precambrian Research 220, 9-22. Stampfli, G.M., Hochard, C., Vérard, C., Wilhem, C., 2013. The formation of Pangea. Tectonophysics 593, 1-19.

Sun, Q.L., Zhang, L.X., 1985. Early Permian fusulinids from Alge Mountain of Xinjiang. Acta Palaeontologica Sinica 24(5), 503-510 (in Chinese with English abstract). Sun, S.S., McDonough, W.F., 1989. Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. Geological Society, London, Special Publications 42(1), 313-345. Tang, L.J., Jin, Z.J., Zhang, M.L., Liu, C.Y., Wu, H.N., You, F.B., Zhang, B.S., 2000. An analysis on tectono-paleogeography of the Qaidam Basin, NW China. Earth Science Frontiers 7(4), 420-429 (in Chinese with English abstract). Taylor, S.R., Mclennan, S.M., 1995. The geochemical evolution of the continental crust. Reviews of Geophysics 33(2), 241-265. Tian, G.K., Meng, F.C., Fan, Y.Z., Liu, Q., Duan, X.P., 2016. The characteristics of Early Paleozoic post-orogenic granite in the East Kunlun orogen: a case study of Dagangou granite. Acta Petrologica et Mineralogica 35(3), 371-390(in Chinese with English abstract). Tian, J., Gong, Y.M., Liang, B., Huang, J.C., 1999. Permian-Triassic trace fossils in the Eastern Kunlun orogenic belt. Acta Sedimentologica Sinica 17, 361-366 (in Chinese with English abstract). Tian, S.G., Wang, Z.J., 2001. Stratigraphic sequence of the Early-Middle Permian reef in western East Kunlun Mountains. Acta Geoscientia Sinica 22(3), 243-248 (in Chinese with English abstract). Turner, S., Hawkesworth, C., Liu, J., Rogers, N., Kelley, S., van Calsteren, P., 1993. Timing of Tibetan uplift constrained by analysis of volcanic rocks. Nature 364(6432), 50-54. Vroon, P.Z., Bergen, M.J.V., White, W.M., Varekamp, J.C., 1993. Sr-Nd-Pb isotope systematics of the Banda Arc, Indonesia: Combined subduction and assimilation of continental material. Journal of Geophysical Research Solid Earth 98(B12), 22349–22366.

Wang, B.Z., 2011. The study and investigation on the assembly and coupling petrotectonic assemblage during Paleozoic–Mesozoic period at Qimantage geological corridor domain, China University of Geosciences (Beijing), Beijing, 1-230 (in Chinese with English abstract). Wang, G., Sun, F.Y., Li, B.L., Ao, C., Li, S.J., Zhao, J., Yang, Q.A., 2016. Geochronology, geochemistry and tectonic implication of Early Neoproterozoic monzogranite in Xiarihamu ore district from East Kunlun. Geotectonica Et Metallogenia 40(6), 1247-1260 (in Chinese with English abstract). Wang, G., Sun, F.Y., Li, B.L., Li, S.J., Zhao, J.W., Qian, Y., Ao, C., 2013. Zircon U-Pb Geochronology and Geochemistry of the Early Devonian Syenogranite in the Xiarihamu Ore District from East Kunlun, with Implications for the Geodynamic Setting. Geotectonica Et Metallogenia 37(4), 685-697 (in Chinese with English abstract). Wang, G.C., Wang, Q.H., Jian, P., Zhu, Y.H., 2004. Zircon SHRIMP ages of the Precambrian metamorphic basement rocks and their tectonic significance in the eastern Kunlun Mountains, Qinghai province, China. Earth Science Frontiers 11, 481-490 (in Chinese with English abstract). Wang, G.C., Wei, Q.R., Jia, C.X., Zhang, K.X., Li, D.W., Zhu, Y.H., Xiang, S.Y., 2007. Some ideas of Precambrian geology in the East Kunlun, China. Geological Bulletin of China 26(8), 929-937 (in Chinese with English abstract). Wang, G.C., Zhang, K.X., Cao, K., Wang, A., Xu, Y.D., 2010. Expanding processes of the Qinghai-Tibet Plateau during Cenozoic: an insight from spatio-temporal difference of uplift. Earth Science-Journal of China University of Geosciences 35(5), 713-727 (in Chinese with English abstract). Wang, T., Li, B., Chen, J., Wang, J.S., Li, W.F., Jin, T.T., 2016. Characteristics of chronology and

geochemistry of the early Silurian monzogranite in the Wulonggou area, East Kunlun and its geological significance. Journal of Mineralogy and Petrology 36(2), 62-70 (in Chinese with English abstract). Wang, X.B., Pei, X.Z., Li, R.B., Chen, Y.X., Liu, C.J., Li, Z.C., Yang, S., Sang, J.Z., Chen, G., B, D.W., 2016. LA-ICP-MS zircon U-Pb ages of metamorphic rocks from Xiaomiao Formation in Tatuo area of eastern East Kunlun Mountains and their geological significance. Geological Bulletin of China 35(7), 1144-1157 (in Chinese with English abstract). Wang, X.X., Hu, N.G., Wang, T., Sun, Y.G., Ju, S.C., Lu, X.X., Li, S., Qi, Q.J., 2012. Late Ordovician Wanbaogou granitoid pluton from the southern margin of the Qaidam basin: Zircon SHRIMP U-Pb age, Hf isotope and geochemistry. Acta Petrologica Sinica 28(9), 2950-2962 (in Chinese with English abstract). Wang, Y.B., Yang, H., 2004. Middle Permian paleobiogeography study in east Kunlun, A'nyêmaqên and Bayan Har. Science in China Series D: Earth Sciences 47(12), 1120-1126 (in Chinese with English abstract). Wang, Y.L., Zhou, H.Z., Li, Y.J., Wei, J.H., Li, H., Yu, H., Huang, X.K., Ke, K.J., 2018. Origin of Late Silurian A-type granite in Wulonggou area East Kunlun orogen: zircon U-Pb age, geochemistry, Nd and Hf isotopic constraints. Earth Science 43(4), 1219-1236 (in Chinese with English abstract). Wang, Z.Z., Han, B.F., Feng, C.Y., Li, G.C., 2014. Geochronology, geochemistry and tectonic significance of granites in Baiganhu area, Xinjiang. Acta Petrologica et Mineralogica 33(4), 597-616 (in Chinese with English abstract). Wei, X.L., Zeng, X.P., Gan, C.P., Zhang, D.X., Yu, X.L., 2016. Geochemistry and geological significance of intermediate-acid intrusive rocks in Chaganganuo area, East Kunlun. Northwestern

Geology 49(2), 1-10 (in Chinese with English abstract). White, W.M., Patchett, J., 1984. Hf-Nd-Sr isotopes and incompatible element abundances in island arcs: implications for magma origins and crust-mantle evolution. Earth and Planetary Science Letters 67(2), 167-185. Wu, C., Yin, A., Zuza, A.V., Zhang, J.Y., Liu, W.C., Ding, L., 2016. Pre-Cenozoic geologic history of the central and northern Tibetan Plateau and the role of Wilson cycles in constructing the Tethyan orogenic system. Lithosphere 8(3). Wu, C., Zuza, A.V., Chen, X., Ding, L., Levy, D.A., Liu, C., Liu, W., Jiang, T., Stockli, D.F., 2019. Tectonics of the Eastern Kunlun Range: Cenozoic reactivation of a Paleozoicϋearly Mesozoic orogen. Tectonics 38(5), 1609-1650. Wu, J., Lan, C.L., Li, J.L., 2005. Geochemical characteristics and tectonic setting of volcanic rocks in the Muztag ophiolitic mélange, East Kunlun Mountains, Xinjiang, China. Geological Bulletin of China 24, 1157-1161 (in Chinese with English abstract). Wu, R.C., Gu, X.X., Zhang, Y.M., He, G., Kang, J.Z., Yu, F.C., Feng, L.Q., Xu, J.C., 2017. The sedimentary geochemical records about the tectonic evolution of the East Kunlun Orogenic Belt from early Paleozoic to early Mesozoic. Geoscience 31(4), 716-733 (in Chinese with English abstract). Wu, S.F., Chen, L.B., Ren, W.K., Zhang, H.Q., Wang, S.H., Ding, C.W., 2012. Discovery of rapakivite granite and its geological implication in Qimantage. Journal of Qinghai University (Nature Science Edition) 30(5), 49-54 (in Chinese with English abstract). Wu, Z.H., Ye, P.S., Patrick, B.J., Hu, D.G., Zhao, W.J., Wu, Z.H., 2009. Late Oligocene-Early Miocene thrusting in southern East Kunlun Mountains, northern Tibetan plateau. Journal of Earth

Science 20(2), 381-390 (in Chinese with English abstract). Xia, R., Wang, C., Deng, J., Carranza, E.J.M., Li, W., Qing, M., 2014. Crustal thickening prior to 220Ma in the East Kunlun Orogenic Belt: Insights from the Late Triassic granitoids in the Xiao-Nuomuhong pluton. Journal of Asian Earth Sciences 93, 193-210. Xiao, W.J., Santosh, M., 2014. The western Central Asian Orogenic Belt: a window to accretionary orogenesis and continental growth. Gondwana Research 25(4), 1429-1444. Xiao, W.J., Windley, B.F., Badarch, G., Sun, S., Li, J.L., Qin, K.Z., Wang, Z.H., 2004. Palaeozoic accretionary and convergent tectonics of the southern Altaids: implications for the growth of Central Asia. Journal of the Geological Society 161(3), 339-342. Xiao, W.J., Windley, B.F., Yong, Y., Yan, Z., Yuan, C., Liu, C.Z., Li, J.L., 2009. Early Paleozoic to Devonian multiple-accretionary model for the Qilian Shan, NW China. Journal of Asian Earth Sciences 35(3–4), 323-333. Xiong, F.H., Ma, C.Q., Jiang, H.A., Liu, B., Huang, J., 2014. Geochronology and geochemistry of Middle Devonian mafic dykes in the East Kunlun orogenic belt, Northern Tibet Plateau: Implications for the transition from Prototethys to Paleotethys orogeny. Chemie der Erde 74(2), 225-235. Xiong, F.H., Ma, C.Q., Zhang, J.Y., Liu, B., 2012. The origin of mafic microgranular enclaves and their host granodiorites from East Kunlun, Northern Qinghai-Tibet Plateau: implications for magma mixing during subduction of Paleo-Tethyan lithosphere. Mineralogy and Petrology 104(3-4), 211-224. Xu, X., Song, S.G., Su, L., 2016. Formation age and tectonic significance of the Wanbaogou basalts in the middle East Kunlun orogenic belt. Acta Petrologica et Mineralogica 35(6), 965-980 (in Chinese with English abstract).

Xu, Z.Q., Jiang, M., Yang, J.S., Zhao, G.G., Cui, J.W., Li, H.B., Lu, Q.T., Xue, G.Q., 1999. Mantle diapir and inward intracontinental subduction: A discussion on the mechanism of uplift of the Qinghai-Tibet Plateau. Geological Society of America Special Papers 328, 19-31. Xu, Z.Q., Li, H.B., Yang, J.S., Chen, W., 2001. A large transpression zone at the south margin of the East Kunlun Mountains and oblique subduction. Acta Geologica Sinica (Chinese Edition) 75(2), 156-164 (in Chinese with English abstract). Xu, Z.Q., Yang, J.S., Jiang, M., Li, H.B., Xue, G.Q., Yuan, X.C., Qian, H., 2001. Deep structure and lithospheric shear faults in the East Kunlun-Qiangtang region, northern Tibetan Plateau. Science in China Series D: Earth Sciences 44, 1-9 (in Chinese with English abstract). Xu, Z.Q., Yang, J.S., Li, H.B., Yao, J.X., 2006. The Early Palaeozoic terrene framework and the formation of the high-pressure (HP) and ultra-high pressure (UHP) metamorphic belts at the Central Orogenic Belt (COB). Acta Geologica Sinica (Chinese Edition) 80(12), 1793-1806 (in Chinese with English abstract). Xu, Z.Q., Yang, J.S., Li, H.B., Zhang, J.X., Zeng, L.S., Jiang, M., 2006. The Qinghai-Tibet plateau and continental dynamics: A review on terrain tectonics, collisional orogenesis, and processes and mechanisms for the rise of the plateau. Geology in China 33(2), 221-238 (in Chinese with English abstract). Xu, Z.Q., Yang, J.S., Li, H.Q., Wang, R.R., Cai, Z.H., 2012. Indosinian collision-orogenic system of Chinese continent and its orogenic mechanism. Acta Petrologica Sinica 28(6), 1697-1709 (in Chinese with English abstract). Xu, Z.Q., Yang, J.S., Wu, C.L., Li, H.B., Zhang, J.X., Qi, X.X., Song, S.G., Qiu, H.J., 2006. Timing and mechanism of formation and exhumation of the Northern Qaidam ultrahigh-pressure

metamorphic belt. Journal of Asian Earth Sciences 28(2), 160-173. Yan, K., Li, J., 2010. The palaeoenvironmental implication of Early-Middle Ordovician acritarch communities from South China. Chinese Science Bulletin 55(10), 957-964 (in Chinese with English abstract). Yan, W., Qiu, D.M., Ding, Q.F., Liu, F., 2016. Geochronology, petrogenesis, source and its structural significance of Houtougou monzogranite of Wulonggou Area in Eastern Kunlun orogen. Journal of Jilin University 46(2), 443-460 (in Chinese with English abstract). Yang, G.X., Li, Y.J., Tong, L.L., Wang, Z.P., Le, W., 2017. Oceanic island basalts in ophiolitic melanges of the Central China Orogen: An overview. Geological Journal (Part 2), 1-19 (in Chinese with English abstract). Yang, J.S., Jiang, C.F., Feng, B.G., Zhu, Z.Z., Zhao, M., Shi, X.D., Hu, J.Q., 1986. An outline on the tectonics of the Kunlun region. Bulletin of the Institute of Geology Chinese Academy of Geological Sciences 2, 010 (in Chinese with English abstract). Yang, J.S., Li, H.B., 2006. Contributions of strike-slip faulting to exhumation of ultrahigh pressure metamorphic rocks and the Cretaceous uplift of the northern Qinghai-Tibet plateau. Earth Science Frontiers 13(4), 80-90 (in Chinese with English abstract). Yang, L., Zhou, H.W., Zhu, Y.H., Dai, X., Lin, Q.X., Ma, Z.Q., Jian, K.K., Zhang, M.Y., 2014. Geochemical characteristics and LA-ICP-MS zircon U-Pb ages of intermediate to mafic dyke swarms in Haxiya area, Golmud, Qinghai Province. Geological Bulletin of China 33(6), 804-819 (in Chinese with English abstract). Yang, S., Pei, X.Z., Li, R.B., Liu, C.J., Chen, Y.X., Li, Z.C., Wang, X.B., Sang, J.Z., Chen, G., Deng, W.B., 2016. Provenance analysis and structural implications of Gequ Formation at the Buqingshan

area in the eastern segment of the East Kunlun region. Geological Bulletin of China 35(5), 674-686 (in Chinese with English abstract). Ye, Z.F., Wang, J., Wang, B.Z., Suo, Y.X., Song, T.Z., Ma, Y.S., 2004. Discovery and primarily research of the Early-Middle Devonian strata in mount Bukedaban district in west-middle section of East Kunlun Mts. Northwestern Geology 37(1), 13-18 (in Chinese with English abstract). Yin, A., Dang, Y., Wang, L., Jiang, W., Zhou, S., Chen, X., Gehrels, G.E., McRivette, M.W., 2008. Cenozoic tectonic evolution of Qaidam basin and its surrounding regions (Part 1): The southern Qilian Shan-Nan Shan thrust belt and northern Qaidam basin. Geological Society of America Bulletin 120(7-8), 813-846. Yin, A., Dang, Y., Zhang, M., McRivette, M.W., Burgess, W.P., Chen, X., 2007. Cenozoic tectonic evolution of Qaidam basin and its surrounding regions (part 2): wedge tectonics in southern Qaidam basin and the Eastern Kunlun Range. Geological Society of America Special Papers 433, 369-390. Yin, A., Harrison, T.M., 2000. Geologic evolution of the Himalayan-Tibetan orogen. Annual Review of Earth and Planetary Sciences 28, 211-280. Yin, F.G., Pan, G.T., 2008. The late Paleozoic basin system in the western part of East Kunlun. Acta Geoscientica Sinica 29(1), 31-38 (in Chinese with English abstract). Yu, M., Feng, C.Y., Santosh, M., Mao, J.M., Zhu, Y.F., Zhao, Y.M., Li, D.X., 2017. The Qiman Tagh Orogen as a window to the crustal evolution in northern Qinghai-Tibet Plateau. Earth-Science Reviews 167. Zha, X.F., Ji, W.H., Zhang, H.D., Li, R.S., Zhao, Z.M., Pan, S.J., 2012. A discussion on the deformation phases and tectonic process of the Southern Kunlun accretionary complex belt,in central Qinghai. Geological Bulletin of China 3(47), 971-972 (in Chinese with English abstract).

Zhang, D.X., Wei, X.L., Zeng, X.P., Wang, W., Yu, X.L., Wang, T., Bao, S.B., 2016. Geochemical characteristics and tectonic setting analysis of middle Devonian intermediate-acid intrusive rock in the Gashundawu area, eastern Kunlun belt. Mineral Exploration 7(4), 612-623 (in Chinese with English abstract). Zhang, H.F., Parrish, R., Zhang, L., Xu, W.C., Yuan, H.L., Gao, S., Crowley, Q.G., 2007. A-type granite and adakitic magmatism association in Songpan–Garze fold belt, eastern Tibetan Plateau: Implication for lithospheric delamination. Lithos 97(3), 323-335. Zhang, H.F., Zhang, L., Harris, N., Jin, L.L., Yuan, H.L., 2006. U–Pb zircon ages, geochemical and isotopic compositions of granitoids in Songpan-Garze fold belt, eastern Tibetan Plateau: constraints on petrogenesis and tectonic evolution of the basement. Contributions to Mineralogy and Petrology 152(1), 75-88. Zhang, J.X., Meng, F.C., Wan, Y.S., Yang, J.S., Dong, G.A., 2003. Early Paleozoic tectono-thermal event of the Jinshuikou Group on the southern margin of Qaidam: Zircon U-Pb SHRIMP age evidence. Geological Bulletin of China 22(6), 397-404 (in Chinese with English abstract). Zhang, J.Y., Ma, C.Q., Xiong, F.H., Liu, B., 2012. Petrogenesis and tectonic significance of the Late Permian–Middle Triassic calc-alkaline granites in the Balong region, eastern Kunlun Orogen, China. Geological Magazine 149(5), 892-908 (in Chinese with English abstract). Zhang, J.Y., Ma, C.Q., Xiong, F.H., Liu, B., Li, J.W., Pan, Y.M., 2014. Early Paleozoic high-Mg diorite-granodiorite in the eastern Kunlun Orogen, western China: Response to continental collision and slab break-off. Lithos 210, 129-146. Zhang, K.X., Huang, J.C., Yin, H.F., Wang, G.C., Wang, Y.B., Feng, Q.L., 2000. Application of radiolarians and other fossils in non-Smith strata. Science in China Series D: Earth Sciences 43(4),

364-374. Zhang, K.X., Lin, Q.X., Zhu, Y.H., Yin, H.F., Luo, M.S., Chen, N.S., Wang, G.C., 2004. New paleontological evidence on time determination of the east part of the Eastern Kunlun Mélange and its tectonic significance. Science in China Series D: Earth Sciences 47(10), 865-873. Zhang, L.Y., Ding, L., Pullen, A., Kapp, P., 2015. Reply to comment by W. Liu and B. Xia on “Age and geochemistry of western Hoh-Xil-Songpan-Ganzi granitoids, northern Tibet: Implications for the Mesozoic closure of the Paleo-Tethys ocean”. Lithos 212–215(14), 457-461. Zhang, Q., Wang, C.Y., Liu, D., Jian, P., Qian, Q., Zhou, G.Q., Robinson, P.T., 2008. A brief review of ophiolites in China. Journal of Asian Earth Sciences 32(5), 308-324. Zhang, X.T., Yang, S.D., Yang, Z.J.E., 2007. Geological map of Qinghai Province, China. Geological Publishing House, Beijing. Zhang, Y.L., Hu, D.G., Shi, Y.R., Lu, L., 2010. SHIRMP zircon U-Pb ages and tectonic significance of Maoniushan Formation volcanic rocks in East Kunlun orogenic belt, China. Geological Bulletin of China 29(11), 1614-1618 (in Chinese with English abstract). Zhang, Y.L., Zhang, X.J., Hu, D.G., Shi, Y.R., Lu, L., 2010. SHRIMP zircon U-Pb ages of rhyolite from the Naij Tal group in the east Kunlun orogenic belt. Journal of Geomechanics 16(1), 21-20 (in Chinese with English abstract). Zhao, F.F., Sun, F.Y., Liu, J.L., 2017. Zircon U-Pb geochronology and geochemistry of the gneissic granodiorite in Manite area from East Kunlun, with implications for geodynamic setting. Earth Science 42(6), 927-1044 (in Chinese with English abstract). Zhao, S.J., Li, S.Z., Liu, X., Santosh, M., Somerville, I.D., Cao, H.H., Yu, S., Zhang, Z., Guo, L., 2015. The northern boundary of the Proto-Tethys Ocean: constraints from structural analysis and

U–Pb zircon geochronology of the North Qinling Terrane. Journal of Asian Earth Sciences 113, 560-574. Zhao, Z.G., Yang, B., Huang, X., Zhang, X.H., Xiong, F.H., Jiang, H.A., 2013. Discovery of middle Permian fusulinids in the Changshitou Mountain in the Maduo area, Qinghai province and its geological significance. Journal of Stratigraphy 37(3), 292-296 (in Chinese with English abstract). Zhao, Z.M., Li, R.S., Ji, W., Chen, S.J., 2010. Silurian tectonic-paleogeographic environment in Kunlun Mountain area and its metallogenic significance. Geology in China 37(5), 1284-1304 (in Chinese with English abstract). Zhu, Y.H., Lin, Q.X., Jia, C.X., Wang, G.C., 2006. SHRIMP zircon U-Pb age and significance of Early Paleozoic volcanic rocks in East Kunlun orogenic belt, Qinghai Province, China. Science in China Series D 49(1), 88-96. Zhu, Y.H., Pan, Y.M., Wang, G.C., Lin, Q.X., 2004. Permian volcanic rocks in the Bayan Hala turbidite basin, East Kunlun area. Earth Science-Journal of China University of Geosciences 29(6), 703-710 (in Chinese with English abstract). Zuza, A.V., Yin, A., 2017. Balkatach hypothesis: A new model for the evolution of the Pacific, Tethyan, and Paleo-Asian oceanic domains. Geosphere 13(5), 1664-1712.

Figure Caption Fig. 1. (a) Tectono-magmatic sketch map of the East Kunlun Mountains showing the main tectonic subdivisions from the north to the south (modification based on Zhang et al. (2007)): the North Kunlun Terrane (NKT), South Kunlun Terrane (SKT), Muz Tag-Anemaqen Terrane (MAT) and Hoh Xil-Bayan Har Terrane (HBT). They are separated by the North Kunlun Fault (NKLF), Middle Kunlun Fault (MKLF), South Kunlun Fault (SKLF), Muz Tagh Fault (MTF) and Anemaqen Fault (AMQF) from the north to the south. Age data in different colors aims to easily distinguish different remarkable geologic units including exposed Early Paleozoic, Late Paleozoic and Early Mesozoic data of granitoids, and ophiolites and high-ultrahigh pressure metamorphic rocks. All the age data and their references are listed in the Table S1; (b). Satellite image showing the tectonic framework of East Kunlun Range; (c). U-Pb intrusion ages from the East Kunlun Mountains.

Fig. 2. (a) Simplified geological map showing the distinct geological records from Late Archean to Early Mesozoic within the East Kunlun Mountains; (b) Time scale showing the age of sedimentation, timing of magmatism and metamorphism in the North Kunlun and South Kunlun Terranes; (c) U-Pb ages of detrital zircon from different strata in the East Kunlun Mountains. See text for references. Characteristic geochemical signature of magmatic events is mentioned: CAB: continental arc basalt; IAB island arc basalt; SSZ: supra-subduction zone. Time scale is from Gradstein et al. (2012).

Fig. 3. Generalized stratigraphic columns for the various tectonic-stratigraphic units from the East Kunlun Mountains. Thicknesses of different units are not to scale. Timescale is from Gradstein et al. (2012). See text for details.

Fig. 4. P-T paths of eclogite and garnet amphibolite facies rocks from the East Kunlun high pressure metamorphic belt (Guo et al., 2017). GS: greenschist facies; EA: epidote-amphibolite facies; BS: Blueschist facies; AM: amphibolite facies; GR: granulite facies; HGR: High pressure granulite; Amp-EC: amphibolite eclogite facies; EP-EC: epidote-eclogite facies; Lw-EC: lawsonite eclogite facies; Dry-EC: dry eclogite facies; Coe: Coesite; Qtz: Quartz; Jd: Jade; Ab: albite;

Fig. 5. Discrimination diagram for different mafic-ultramafic rocks (SiO2 ≤ 50 wt. %) from the different terranes based on the Ta/Yb vs. Th/Yb plot (Pearce, 1982), showing a continuous geochemical evolution with time. All the geochemical data and their references are listed in the Table S2. The geochemical variations of different ophiolite types are based on the Dilek and Furnes (2014): P type (plume type); MOR type (mid-ocean ridge type); CM type (Continental Margin type); VA type (volcanic arc type); SSZ type (suprasubduction zone type); Compositional fields: TH, tholeiite; TR, transitional; ALK, alkaline basalt; IAT, island arc tholeiite; CAB, calc-alkaline basalt; SHO, shoshonitic.

Fig. 6. Nb-Yb discrimination diagrams (Pearce et al., 1984), showing a continuous geochemical and geochronological evolution of the felsic rocks (SiO2 > 50 wt. %) from the different terranes. (a). Meso-Neo Proterozoic granitoids; (b). Early Paleozoic granitoids; (c). Late Paleozoic granitoids; (d). Middle Permian-Late Triassic granitoids. All the data and their references are listed in the Table S5. Ocean ridge granites (ORG), within-plate granites (WPG), volcanic arc granites (VAG), syn-collisional granites (Syn-COLG), oceanic arc granites (OAG), and continental arcs (CAG). The

boundary between OAG and CAG is postulated based on the calc-alkaline lava composition from Puerto Rican, Maizuru and Camiguin oceanic island arc. The average upper crust component is from Rudnick and Fountain (1995); the average lower crust component is from Taylor and Mclennan(1995); the average N-MORB component is from Hofmann(1988). The average of E-MORB component is from Sun and McDonough (Sun and McDonough, 1989).

Fig. 7. Zircon U-Pb age data histograms and probability density curves for magmatic intrusions from the NKT, SKT, MAT and HBT. All the age data and their references are listed in the Table S1.

Fig. 8. Plots of εHf (t) vs. U–Pb ages of the igneous rocks (ca. 200 – 1000 Ma) from different terranes in the East Kunlun Range. All the data and their references are listed in the Table S4.

Fig. 9.

143

Nd/144Nd variations versus age (Ma) for Ordovician-Triassic (ca. 500–200 Ma) volcanics

and granitoids from the different terranes in the East Kunlun Range. All the data and their references are listed in the Table S5. DM represents the average εNd (0) value (εNd (0) = 10) for depleted mantle as determined from mid-ocean ridge basalts; CHUR ("chondritic uniform reservoir") stands for present-day reference values (εNd (0) =0) of chondrite (Jacobsen and Wasserburg, 1980). The neodymium isotopes (εNd (t) = 0) can be used to separate mantle and crustal origin. The range of εNd (t) values for the volcanic rocks from the Sunda continental margin arc are based on White and Patchett (1984), and for Mariana and Banda island arcs are based on Ikeda et al. (2016) and Vroon et al.(1993).

Fig. 10. Plot of (a) Sr/Y versus Age and (b) La/Yb versus Age of magmatic rocks (>55 wt % SiO2) from Late Neoproterozoic-Early Mesozoic age (550 Ma – 200 Ma) and Precambrian age (800 – 2000 Ma). Correlating crustal thicknesses are inferred based on the Haschke et al. (2002).

Fig. 11. 3D schematic cross sections to illustrate the major events during the evolution of the East Kunlun Mountains divided into six time snapshots. (a) Stage I: South Kunlun Ocean subducted beneath the SKT in the north, and formed a backarc basin connected with the North Kunlun basement terrane; some basic-ultrabasic rocks associated with the subduction were emplaced into the turbidites in the backarc basin. In the south, the Muz Tagh-Anemaqen island arc chain was formed above the mantle wedge as a result of southward subduction of the oceanic lithosphere. (b) Stage II: the subduction of the backarc oceanic lithosphere caused formation of the North Kunlun continental arc, and following the extinction of backarc basin and initial arc-continental collision between SKT and NKT since early Silurian. (c) Stage III: the collision between NKT and SKT had been sustaining to middle Silurian as a consequence of oblique subduction. The turbidite formation was uplifted and compressed, and the intensive deformation make the deep mafic rocks within the basin occur high-pressure metamorphism. (d) Following the closure of the South Kunlun Ocean, the MAT accreted to the SKT. The collision cause further uplift and deformation of all the terranes. In addition, some oceanic islands associated with the plume were constructed in the Anemaqen ocean basin. During this stage, a magmatism gap of ca. 120 Ma was resulted by a cease of subduction. (e) Stage V: the passive continental margin was transformed into an active margin, and the subduction make the oceanic islands accreted to the margin; the joint effect of flat subduction and slab rollback yields a younger age of intrusion further south. (f) Stage VI: closure of the Anemaqen Ocean cause final

collision between the North Qiangtang Terrane and the MAT.

Fig. 12. Paleogeographic maps that showing the evolution of the East Kunlun Orogen during the Paleozoic: a) Cambrian-middle Ordovician: the elements of the NKT and SKT are widely developed due to bidirectional subduction of South Kunlun Ocean; Qaidam block might dock with Tarim, Alax and North China blocks to develop the Hunia Superterrane (Stampfli et al., 2013), which located close to the equator and in the low Latitude region from the Sinian (Ediacaran) to the Carboniferous (Tang et al., 2000). b) late Ordovician-late Silurian: the plates of Hunia Superterrane assembled at the north of Gondwana Supercontinent due to the progressive shrinking of Proto Tethys Ocean; the North East Kunlun volcanic arcs yielded as a consequence of back arc ocean slab subduction beneath the Qaidam block, and separated from South Kunlun island arcs by Qingshuiquan backarc basin (QSQ B.B.)in the east of East Kunlun Orogen; Muz Tagh-Anemaqen island arcs (MA I.A.s) were scattered in the South Kunlun Ocean, and separated from NKT; c) late Silurian-middle Devonian: the opening of Paleo Tethys-Anemaqen Ocean as a relic of Proto-Tethys leads to the northward drifting of Qaidam block closed to the South China block in the south in the Middle Devonian; and the Qaidam Block had already accreted to the Alax/Hexi Corridorterrane by the Late Devonian as a part of the Paleo-Asia (Song et al., 2013a; Xiao et al., 2009). d) Permian: the MAT accreted onto the continental

margin,

and

leads

to

a

transition

of

subduction

polarity.

The

North

Qiangtang-Qamdo-Simao block as a composite terrane had already separated from South China–Indochina by back-arc spreading since the Carboniferous (Metcalfe, 2013). The paleogeographic data indicates that these blocks was situated at low to intermediate latitudes in the Southern Hemisphere in the Late Carboniferous-Late Permian (Cheng et al., 2013). NQT C.A. =

North Qiman Tagh continental arc; SQT I.A. = South Qiman Tagh island arc; NEK C.A. = North East Kunlun continental arc; SEK I.A. = South East Kunlun island arc;

Table Caption Table 1. Tectonic discrimination of magmatic rocks from the different terranes in the East Kunlun Orogen based on the geochemical features

Table 1. Tectonic discrimination of magmatic rocks from the different terranes in the East Kunlun Orogen based on the geochemical features Terrane

NKT

Cambrian-Middle Silurian

CAG (438–430 Ma)

Tectonic

Late Silurian-Middle

Tectonic

Early Carboniferous-Late

setting

Devonian

setting

Triassic

CAG–OAG

Arc-continent

Continental

(422–407 Ma)

al collision

arc island

OAG–WPG

CAB (439

(261–209

̢394 Ma) Post-collision

(396–391 Ma)

(512–474 Ma);

arc E-MORB̢ CAB̢SHO

CAB-SHO

Partial melting of

(265̢250

lower crust

Ma)

Ma)

Young island

SKT

Ma)

PM̢

N-MORB̢CAB (333–201

E-MORB–OIB–SHO (–526 Ma) OAG

OAG– CAG

Mature island

CAG–WPG

(522̢445

arc

(454–424 Ma)

Ma)

(Arc-continent

Tectonic setting

Rift to subduction

E-MORB–C CAG–OAG

AB

(421–403 Ma)

(419–401

Post-collision OAG (257–225 Ma)

Ma)

Partial melting of E-MORB

al collision)

MAT

OAG (496–436 Ma)



IAT̢CAB̢ SHO (535̢ 430 Ma)

N-MORB̢OIB (332 Oceanic





Ma–Middle Permian)

Oceanic Plateau

island arc







CAG (227–224 Ma)

Collision environment

CAG (219–216 Ma)

Collision environment

WPG (211–203 Ma)

Post-collision

HBT

Dear Editor: We the undersigned declare that this manuscript entitled “A review of the crustal evolution of the East Kunlun Orogen, northern Qinghai-Tibet Plateau” is original, has not been published before and is not currently being considered for publication elsewhere. We would like to draw attention of the Editor to the following publications of one or more of us that refer to aspects of the manuscript presently being submitted. Where relevant copies of such publications are attached. We confirm that the manuscript has been read and approved by all named authors, and that there are no other persons who satisfied the criteria for authorship but are not listed. We further confirm that the order of authors listed in the manuscript has been approved by all of us. We understand that the Corresponding Author is the sole contact for the Editorial process. He/she is responsible for communicating with the other authors about progress, submissions of revisions and final approval of proofs.

Signed by all authors as follows: Yu Miao, Mao Jingwen, Feng Chengyou, Wang Hui, Dick Jeffrey

Declaration of interest statement We declare that we do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted.

Highlights · The East Kunlun orogen is tectonically divided into the North Kunlun Terrane, South Kunlun Terrane, Muz Tagh-Anemaqen Terrane and the Hoh Xil-Bayan Har Terrane. · The North Kunlun Terrane was formed as active continental margin during the Early Paleozoic, and the South Kunlun Terrane was formed as an intra-oceanic island arc in the Mesoproterozoic. The arc-continent collision between them might have occurred in the early-middle Silurian as a consequence of oblique subduction. · The Muz Tagh-Anemaqen Terrane considered as an oceanic island arc was formed by the southward subduction during the Early Paleozoic. · The bilateral arcs amalgamation between the Muz Tagh-Anemaqen Terrane and South Kunlun Terrane is significant for the continental growth and trench seaward movement. · The final closure of the Anemaqen Ocean might have occurred in the Late Triassic.