Tectonic Evolution of the West Bogeda: Evidences from Zircon U-Pb Geochronology and Geochemistry Proxies, NW China

: The Bogeda Shan (Mountain) is in southern part of the Central Asian Orogenic Belt (CAOB) and well preserved Paleozoic stratigraphy, making it an ideal region to study the tectonic evolution of the CAOB. However, there is a long-standing debate on the tectonic setting and onset uplift of the Bogeda Shan. In this study, we report detrital zircon U-Pb geochronology and whole-rock geochemistry of the Permian sandstone samples, to decipher the provenance and tectonic evolution of the West Bogeda Shan. The Lower-Middle Permian sandstone is characterized by a dominant zircon peak age at 300–400 Ma, similar to the Carboniferous samples, suggesting their provenance inheritance and from North Tian Shan (NTS) and Yili-Central Tian Shan (YCTS). While the zircon record of the Upper Permian sandstone is characterized by two major age peaks at ca. 335 Ma and ca. 455 Ma, indicating the change of provenance after the Middle Permian and indicating the uplift of Bogeda Shan. The initial uplift of Bogeda Shan was also demonstrated by structural deformations and unconformity occurring at the end of Middle Permian. The bulk elemental geochemistry of sedimentary rocks in the West Bogeda Shan suggests the Lower-Middle Permian is mostly greywacke with maﬁc source dominance, and tectonic setting changed from the continental rift in the Early Permian to post rift in the Middle Permian. The Upper Permian mainly consists of litharenite and sublitharenite with maﬁc-intermediate provenances formed in continental island arcs. The combined evidences suggest the initial uplift of the Bogeda Shan occurred in the Late Permian, and three stages of mountain building include the continental rift, post-rift extensional depression, and continental arc from the Early, Middle, to Late Permian, respectively.


Introduction
The Central Asian Orogenic Belt (CAOB) is located between the Siberia Craton to the north and the Tarim and North China Craton to the south. It is regarded as the largest (extending 7000 km from west to east) accretionary orogenic belt on Earth. It was formed by a series of amalgamation events of several micro-continents and island arcs during the Late Carboniferous to Permian periods ( Figure 1a) [1][2][3]. The Tian Shan forms the southern part of the CAOB, with an average elevation of ca. 2000 m and summits >7000 m. It is the key orogenic belt to study the tectonic evolution of the The Late Paleozoic witnessed significant climate and tectonic changes in Northwest China, including the Bogeda region. Despite previous research on the tectonic evolution of Bogeda Shan, the timing of initial uplift and its tectonic setting are still enigmatic. Some authors first suggested that a small-scale orogeny occurred in the Bogeda area during the Carboniferous [10], based on zircon U-Pb geochronology, while the initial uplift of the West Bogeda Shan occurred in the Late Permian [11,12]. However, other researchers suggested that the first significant uplift of Bogeda Shan occurred during the Early to Middle Jurassic, according to the configuration of sedimentary units [13][14][15]. Besides, the The Late Paleozoic witnessed significant climate and tectonic changes in Northwest China, including the Bogeda region. Despite previous research on the tectonic evolution of Bogeda Shan, the timing of initial uplift and its tectonic setting are still enigmatic. Some authors first suggested that a small-scale orogeny occurred in the Bogeda area during the Carboniferous [10], based on zircon U-Pb geochronology, while the initial uplift of the West Bogeda Shan occurred in the Late Permian [11,12]. However, other researchers suggested that the first significant uplift of Bogeda Shan occurred during the Early to Middle Jurassic, according to the configuration of sedimentary units [13][14][15]. Besides, the Late Jurassic has been considered as the most critical stage for the Bogeda Shan uplift [16][17][18]. As to Minerals 2020, 10, 341 3 of 24 the tectonic setting, two contrasting viewpoints exist, i.e., a continental rift or an island arc, and are still highly debated [19].
It is widely accepted that the Bogeda Shan was uplifted during the Mesozoic, but the onset time remains largely controversial. Therefore, this study aims to illustrate the provenances, tectonic setting, and evolution of the West Bogeda Shan during the Permian based on the integrated analyses of petrology, detrital zircon U-Pb geochronology, and bulk geochemistry of sedimentary rocks from the Lower to Upper Permian. The timing of the initial uplift of the Bogeda Shan will be revealed with all these analyses.

Geological Setting and Stratigraphy
The study area of Bogeda Shan belongs to the NTS Belt which is composed of volcanic arcs, intra-arc basin, and accretionary complex in relation to the final closure of the Northern Tianshan Ocean [20]. The NTS Belt can be further divided into the Bogeda-Harlik Belt in the north and Juelotage Belt in the south. The Bogeda Shan is a part of the Bogeda-Harlik Belt and extends >250 km in the east-west direction (Figure 1b). It is the geographical boundary of the two largest basins in northwest China, with the Junggar Basin in the north and Turpan-Hami Basin in the south. The Paleozoic orogenic movements formed the high topography of Bogeda Shan due to India-Asia collision during the early Cenozoic [21][22][23]. The central part of the Bogeda Shan consists of Carboniferous sedimentary rocks (Lower Carboniferous composed by marine volcanic ignimbrite and bimodal volcanic lava, while Upper Carboniferous is dominated by felsic ignimbrite and marine basaltic lava), while the north and south parts are composed mainly by Mesozoic and Cenozoic sediments. The lithology of the East Bogeda Shan is more variable than in the western part, and the latter was formed during the Early Carboniferous (Mississippian) [24][25][26][27]. The Dalongkou section investigated in this study is distributed in the Fukang Depression in the West Bogeda Shan, with the clear exposure of the Permian and Triassic strata for field work (Figure 1c).
The Permian strata at the anterior of West Bogeda Shan are made up of the following eight central units: the Shirenzigou Formation (P 1 s), Tashkula Formation (P 1 t) in the Lower Permian, Ulupo Formation (P 2 w), Jingjingzigou Formation (P 2 j), Lucaogou Formation (P 2 l) and Hongyanchi Formation (P 2 h) in the Middle Permian, as well as Quanzijie Formation (P 3 q) and Wutonggou Formation (P 3 wt) in the Upper Permian ( Figure 2). The paleontologic record suggest the depositional environments in the anterior region of the West Bogeda Shan were normal marine and shelf depositions during the Carboniferous to Early Permian ( Figure 2), with sandstone and siltstone representing the primary lithologies. In the Middle Permian, the depositional environment changed to terrestrial and lacustrine facies, resulting in a variable lithology of sandstone, siltstone, mudstone, and oil-bearing mudstone. The Upper Permian strata is composed of conglomerate and sandstone deposited in alluvial fan and braided river environment [28][29][30][31][32][33].

Sampling and Analytical Methods
This study collected new data on the samples from the Upper Permian, and a total of eleven sandstone samples were collected from the Dalongkou section (43°57′21″N, 88°51′44″E) with the thickness of 117.53 m (Figure 3a,b). Among them, seven sandstone samples were chosen for zircon U-Pb dating, and eleven samples for whole-rock geochemistry analyses. The samples are mainly from quartz-rich medium to fine grained sandstone (Figure 3h,i), with poor to moderate sorting and roundness (Figure 3c,d).

Zircon U-Pb Geochronology
The samples for detrital zircon U-Pb dating were prepared following the previous procedures [34,35]. The sandstone samples were first crushed with the agate mortar. Then, the grain size fraction of 63-125 μm was separated by the wet-sieving method. After wet sieving, tribromomethane liquid (CHBr3) was used to separate heavy minerals, followed by magnetic separation. Later, detrital zircon grains were then identified and picked out from non-magnetic or weak magnetic minerals under a binocular microscope. About 200-300 grains of zircon were randomly selected, pasted on adhesive tapes, and enclosed in epoxy resin followed by polishing to yield a smooth flat surface. Before being ablated by a laser, cathodoluminescence (CL) images were used to check the internal structures of zircons by the electron microprobe of JEOL JXA-8230 (JEOL, Tokyo, Japan).

Sampling and Analytical Methods
This study collected new data on the samples from the Upper Permian, and a total of eleven sandstone samples were collected from the Dalongkou section (43 • 57 21 N, 88 • 51 44 E) with the thickness of 117.53 m (Figure 3a,b). Among them, seven sandstone samples were chosen for zircon U-Pb dating, and eleven samples for whole-rock geochemistry analyses. The samples are mainly from quartz-rich medium to fine grained sandstone (Figure 3h,i), with poor to moderate sorting and roundness (Figure 3c,d).

Zircon U-Pb Geochronology
The samples for detrital zircon U-Pb dating were prepared following the previous procedures [34,35]. The sandstone samples were first crushed with the agate mortar. Then, the grain size fraction of 63-125 µm was separated by the wet-sieving method. After wet sieving, tribromomethane liquid (CHBr 3 ) was used to separate heavy minerals, followed by magnetic separation. Later, detrital zircon grains were then identified and picked out from non-magnetic or weak magnetic minerals under a binocular microscope. About 200-300 grains of zircon were randomly selected, pasted on adhesive tapes, and enclosed in epoxy resin followed by polishing to yield a smooth flat surface. Before being ablated by a laser, cathodoluminescence (CL) images were used to check the internal structures of zircons by the electron microprobe of JEOL JXA-8230 (JEOL, Tokyo, Japan).
The measurements of zircon U-Pb ratios were performed at Tong University using a 193 nm excimer laser (Resonetics M50L) (Resonetics, Nashua, NH, USA) coupled with a quadrupole inductively coupled plasma mass spectrometry (ICP-MS, Agilent 7900, Agilent, Santa Clara, CA, USA). The zircon grains were ablated with a laser spot size of 26 µm at the repetition of 6 Hz and the fluence of 4 J cm −2 . Masses 206, 207, 208, 232, 235, and 232 were acquired by the ICP-MS. Reference zircon materials 91500 and Plešovice were measured periodically to carry out U-Pb age external calibration and monitor the measurements. The U-Pb isotope ratios and the corresponding ages were calibrated using UranOS software [36]. The brief calibration procedure included blank subtraction, calculation of ratio of means, instrumental drift correction, and normalization by primary reference material (91500). The uncertainties of U-Pb isotopes ratios and ages were propagated in the calibration and results were reported with 2σ uncertainties [36]. As we did not acquired mass 204, the common Pb correction was performed using the Stacey-Kramers method on the basis of the measured 206 Pb/ 238 U ages [37]. To minimize the uncertainty due to some poor-quality ages, U-Pb ages with discordance larger than 10% were excluded from the following discussion. The discordance of 206 Pb/ 238 U age less than 1.4 Ga is defined as 100*(1-206 Pb/ 238 U/ 207 Pb/ 235 U) and the discordance of 206 Pb/U 238 age greater than 1.4 Ga is defined as 100*(1-206 Pb/ 238 U/ 207 Pb/ 206 Pb) [38]. The weighted mean ages of reference zircons 91500 and Plešovice are 1062.8 ± 9.9 Ma and 336.1 ± 3.1 Ma, respectively (Figure 6a), which are consistent with the reference ages within the uncertainties [39][40][41].  The measurements of zircon U-Pb ratios were performed at Tong University using a 193 nm excimer laser (Resonetics M50L) (Resonetics, Nashua, NH, USA) coupled with a quadrupole inductively coupled plasma mass spectrometry (ICP-MS, Agilent 7900, Agilent, Santa Clara, CA, USA). The zircon grains were ablated with a laser spot size of 26 μm at the repetition of 6 Hz and the fluence of 4 J cm −2 . Masses 206, 207, 208, 232, 235, and 232 were acquired by the ICP-MS. Reference zircon materials 91500 and Plešovice were measured periodically to carry out U-Pb age external calibration and monitor the measurements. The U-Pb isotope ratios and the corresponding ages were calibrated using UranOS software [36]. The brief calibration procedure included blank subtraction, calculation

Major and Trace Elemental Analysis
For the measurements of major and trace elemental compositions in the bulk samples, eleven samples were first ground by an agate mortar, and then organic matter was removed in a muffle furnace at the temperature of 600 • C. A mixture of 1:1 HF and HNO 3 acids was added to the samples and kept in dissolution bombs in an oven of 190 • C for 48 h for digestion. After the digestion, 30% HNO 3 was added to the samples before putting into the oven for at least 12 h at 190 • C. The completely digested samples were measured for major and trace elements by ICP-OES (IRIS Advantage) and ICP-MS (Agilent 7900), respectively. Four kinds of geo-standards (BCR-2, BHVO-2, AGV-2, and GSP-2) [42] were used for the analytic quality control, which yields the analytical uncertainties less than 5%. The Si concentration was calculated by assuming the total content of major oxides and trace elements is 100% according to previous research [43]. All of the above sample preparations and measurements were conducted at the State Key Laboratory of Marine Geology, Tongji University, Shanghai, China.

Detrital Zircon U-Pb Geochronology
To examine the sediment provenances of the West Bogeda Shan from the Carboniferous to Triassic periods, all available detrital zircon U-Pb ages from previous studies are compiled and presented in Table S1 [24,32,[44][45][46][47]. The U-Pb ages of the Upper Permian detrital zircons from seven sandstone samples were measured in the present study. Most of the zircon grains have oscillatory zoning and are generally euhedral to subhedral on the CL images ( Figure 4), suggesting that these zircons from the Upper Permian originated mostly from acidic magmatic rocks. The Th/U ratios of these zircons are mostly >0.1, further diagnostic of their magmatic origin ( Figure 5) [48]. Results of all samples within 90-110% concordance (or less than 10% discordance) are plotted in the U-Pb concordia diagrams (Appendix A), and the data with concordance <90% and >110% are excluded during subsequent analysis.

Major and Trace Elements
The compositions of major and trace elements of eleven sandstone samples from the West Bogeda Shan are given in Table 1. Geochemical data of samples from the Lower-Middle Permian were collected from previous studies [8,50,51] and presented in Table S2.

Major and Trace Elements
The compositions of major and trace elements of eleven sandstone samples from the West Bogeda Shan are given in Table 1. Geochemical data of samples from the Lower-Middle Permian were collected from previous studies [8,50,51] and presented in Table S2.

Provenance Variation of Sedimentary Rocks in the West Bogeda Shan
Detrital zircon geochronology has been used as a proxy for sedimentary provenance analysis due to zircon's stability during weathering and transporting [52,53]. Detrital zircon U-Pb ages of the Upper Permian samples have two notable age peaks at ca. 335 Ma and ca. 455 Ma (Figure 7a), whereas only one main age population was observed for the Carboniferous to Middle Permian samples (Figure 7b). Therefore, we infer that the sediment provenances in the West Bogeda Shan were derived from relatively homogeneous sources with a narrow zircon age population in the Carboniferous to Middle Permian periods, but obviously changed to multiple sources during the Late Permian and Triassic. Detrital zircons collected from the Upper Carboniferous to Middle Permian with major peaks at ca. 342.0 Ma, ca. 310.2 Ma and ca. 311.7 Ma, respectively (Figure 7b). Detrital zircons with ages of 360-320 Ma and 320-300 Ma may source from the magmatic belts of the YCTS and NTS, respectively [8]. The paleocurrents in the Permian and Triassic were mainly north directed, implying that the source of the detrital zircon grains was suited to the south in the Tian Shan area (Figure 7c) [8,15,51,54]. Therefore, the Carboniferous volcanic rocks in the NTS and magmatic belt of YCTS are considered as the sources of deposits in the Upper Carboniferous to Middle Permian [55]. Two major age peaks at ca. 330.2 Ma and ca. 448.0 Ma could be identified for Upper Permian deposits and three major age peaks for Lower Triassic deposits at ca. 245.9 Ma, ca. 314.7 Ma and ca. 458.1 Ma, which may indicate the initial uplift of Bogeda Shan and could be the source of the Junggar Basin [55]. This could also be demonstrated by poorly-sorted and rounded conglomerate and pebbly sandstone of Late Permian age, suggesting that the deposits were near the source area without long distance of transporting (Figure 3f).
Moreover, as shown in the Dickinson diagram (Figure 8 age peaks at ca. 330.2 Ma and ca. 448.0 Ma could be identified for Upper Permian deposits and three major age peaks for Lower Triassic deposits at ca. 245.9 Ma, ca. 314.7 Ma and ca. 458.1 Ma, which may indicate the initial uplift of Bogeda Shan and could be the source of the Junggar Basin [55]. This could also be demonstrated by poorly-sorted and rounded conglomerate and pebbly sandstone of Late Permian age, suggesting that the deposits were near the source area without long distance of transporting (Figure 3f).  [8,44]; Data for Triassic are from [56]. (c) Paleocurrent of Lower Permian [57], Middle Permian [58] and Upper Permian to Lower Triassic [15]. N is total measured grains, and n is grains with 90-110% concordance.
Moreover, as shown in the Dickinson diagram (Figure 8 [8,44]; Data for Triassic are from [56]. (c) Paleo-current of Lower Permian [57], Middle Permian [58] and Upper Permian to Lower Triassic [15]. N is total measured grains, and n is grains with 90-110% concordance.  Rare earth elements (REEs) and high-field-strength elements (HFSEs) such as Nb, Ta, Zr, and Hf are relatively conservative during sediment weathering, transport, and post-depositional processes, and thus are treated as reliable tracers for sediment provenances [60,61]. Even though the REE could be affected by grain size and chemical weathering, provenance composition plays a key role on the REE geochemistry of sediments [62]. Chondrite-normalized REE patterns of Permian samples ( Figure  9), show the enrichment of light REE (LREE) relative to the heavy REE (HREE) [63]. The LREE/HREE Rare earth elements (REEs) and high-field-strength elements (HFSEs) such as Nb, Ta, Zr, and Hf are relatively conservative during sediment weathering, transport, and post-depositional processes, and thus are treated as reliable tracers for sediment provenances [60,61]. Even though the REE could be affected by grain size and chemical weathering, provenance composition plays a key role on the REE geochemistry of sediments [62]. Chondrite-normalized REE patterns of Permian samples (Figure 9), show the enrichment of light REE (LREE) relative to the heavy REE (HREE) [63]. The LREE/HREE ratios of the Lower, Middle, and Upper Permian samples have ranges of 5.0-10.0, 4.5-5.7, and 5.8-8.9, respectively. Relatively negative Eu anomalies (Eu/Eu* generally <0.7) are observed in the samples from the Lower-Middle Permian (Figure 9a,b), while the Upper Permian samples have weak or no Eu anomalies (Eu/Eu* around 0.9) (Figure 9c). This could further indicate the provenance variation occurred from Lower-Middle Permian to Upper Permian [60].

Source Rock Composition and Paleoclimate
In sedimentary rocks, accessory minerals such as zircon, monazite, and apatite are rich in REEs. Generally, felsic rocks have higher LREE/HREE ratios and strong Eu depletions, whereas mafic rocks display relatively low LREE/HREE ratios and moderate Eu anomalies [63]. The Lower-Middle Permian sandstone samples have higher LREE/HREE ratios and weak negative Eu anomalies, while the Upper Permian samples have weak or no Eu anomalies (Figure 9). This observation apparently suggests that the Permian sedimentary rocks in the West Bogeda Shan might have been were derived from the multiple sources, albeit with the dominance of mafic components. All these observations of bulk geochemistry suggest a provenance change from the Early-Middle to Late Permian. We therefore argue that the Middle Permian could be the crucial period for the variations of sediment provenance and tectonic setting in the West Bogeda Shan, which is synchronous with the tectonic evolutions of Bogeda Shan during the Late Carboniferous (Pennsylvanian) and Early Permian periods [64], corresponding to the tectonic setting of the Harlik-Dananhu arc [65]. Sediments deposited in the basins where the West Bogeda Shan is currently located during the Late Carboniferous and Early Permian witnessed the tectonic evolution at that time.

Source Rock Composition and Paleoclimate
In sedimentary rocks, accessory minerals such as zircon, monazite, and apatite are rich in REEs. Generally, felsic rocks have higher LREE/HREE ratios and strong Eu depletions, whereas mafic rocks display relatively low LREE/HREE ratios and moderate Eu anomalies [63]. The Lower-Middle Permian sandstone samples have higher LREE/HREE ratios and weak negative Eu anomalies, while the Upper Permian samples have weak or no Eu anomalies (Figure 9). This observation apparently suggests that the Permian sedimentary rocks in the West Bogeda Shan might have been were derived from the multiple sources, albeit with the dominance of mafic components.
Ratios of Zr/Sc and Th/Sc are useful proxies for identifying the effects of sedimentary recycling and source compositions of sedimentary rocks [60,66]. The large variations but overall positive correlations of Zr/Sc and Th/Sc ratios suggest the variable provenance rock compositions of the West of Bogeda Shan, rather than sedimentary recycling (Figure 10a). The plot of REE versus La/Yb suggests that the Permian samples in the West Bogeda Shan are dominated by sedimentary rocks (Figure 10b). Meanwhile, the lithology of sedimentary rock in the Lower-Middle Permian is different from that of the Upper Permian. The Lower-Middle Permian was mostly composed of greywacke, while shale was subordinate. The Upper Permian was dominated by sublitharenite ( Figure 10c). Based on the plot of Hf versus La/Th, the sedimentary rocks in the West Bogeda originated from mixed mafic sources during the Early-Middle Permian but changed to a mixture of mafic and acidic arc sources in the Upper Permian (Figure 10d) [67]. Similarly, the discrimination plot of Co/Th versus La/Sc [19,45,63] suggests that most of the Permian sandstones are classified into mafic volcanic and andesitic sources, although some of the Lower-Middle Permian samples are of felsic volcanic origins (Figure 10e). The combined analyses all demonstrate that most of the Permian sedimentary rocks inherit mafic detritus in the West Bogeda Shan. Besides, the sedimentary rocks in the Early-Middle Permian formed in an arid climate, and then were transferred to a humid climate zones along with the increasing chemical maturity in the Upper Permian (Figure 10f). This could be demonstrated by widely distributed bivalve and plant fragments in the Upper Permian sandstones (Figure 3d,j,k).
andesitic sources, although some of the Lower-Middle Permian samples are of felsic volcanic origins (Figure 10e). The combined analyses all demonstrate that most of the Permian sedimentary rocks inherit mafic detritus in the West Bogeda Shan. Besides, the sedimentary rocks in the Early-Middle Permian formed in an arid climate, and then were transferred to a humid climate zones along with the increasing chemical maturity in the Upper Permian (Figure 10f). This could be demonstrated by widely distributed bivalve and plant fragments in the Upper Permian sandstones (Figure 3d,j,k).

Rapid Change in Lithology and Depositional Environment
The lithology and depositional environment of West Bogeda area experienced a multiphase evolution during the Permian. During the Late Carboniferous and Early Permian, the depositional environment of West Bogeda area was dominated by semi-deep to deep marine environment, and gravity flow deposits was the main lithology [33,57]. At the end of the Early Permian, the shallow water deposited sandstone directly overlying on the mudstone. The depositional environment transitioned from deep water environment to shallow water environment [73,74]. Further, the depositional environment was transferred from marine to nonmarine environment in the Middle Permian with the main lithology of fine sandstone, mudstone and oil-bearing mudstone. Meanwhile, deformation during the Middle Permian and unconformity contact of Middle and Upper Permian could be found in the area (Figure 3e), which may relate to the uplift of West Bogeda Shan. The deposits of Late Permian age are mainly composed of purplish-reddish conglomerate in P 3 q (Figure 3f,g) and pebbly sandstone in P 3 wt (Figure 3h,i) with poorly-sorted and rounded pebbles. They are typical molasse formations and close to the source area. Combined with our field works and previous studies [31,57], the depositional environment of Upper Permian was alluvial fan and braided river, which was significantly different from Lower-Middle Permian. The rapid change of lithology and environment also suggest the initial uplift of the West Bogeda Shan during the Late Permian.

Tectonic Setting and Basin Evolution in the West Bogeda Shan
Discrimination diagrams for tectonic setting of siliciclastic sediments and sedimentary rocks are mostly based on geochemical compositions such as the contents of major and trace elements and their ratios [75][76][77]. To analyze the tectonic settings of the West Bogeda Shan, proxies of DF1 and DF2 are defined based on major elements components according to previous researches [78,79]. The discrimination diagram of DF1 versus DF2 suggests that the tectonic setting of the West Bogeda Shan in the Early Permian was dominated by a continental rift, and partly changed to island arc in the Middle Permian (Figure 11a) towards an active continental margin and continental island arc in the Late Permian (Figure 11b).  [79]). Symbols are the same as those in Figure 10.  [79]). Symbols are the same as those in Figure 10.
Abundant evidences of abrupt changes of depositional environments, provenance area and source rock composition and development of bimodal volcanic-sedimentary rock series corroborate to the hypothesized rift setting during the Early Permian [27,30]. The discrimination results based on the trace element compositions, such as La-Th-Sc and Th-Sc-Zr/10 ternary diagrams also suggest that almost all sedimentary rocks in the West Bogeda Shan were derived from mafic sources in the Permian. Meanwhile, a continental island arc is the preferred tectonic setting at the epoch of the Late Permian ( Figure 12; Table 2). Figure 11. Tectonic discrimination diagrams with major elements of clastic rocks from Carboniferous to Upper Permian. (a) Discriminant-function multi-dimensional diagram for high and low silica clastic sediments from three tectonic settings (equation for DF1 and DF2 based on Surendra P.Verma et. al. [78]. (b) Discriminant-function multi-dimensional diagram for high and low silica clastic sediments from three plots of discriminant scores along Function 1 versus Function 2, to discriminate rocks suites of West Bogeda Shan (equation for DF1 and DF2 based on Mukul R. Bhatia [79]). Symbols are the same as those in Figure 10.   In summary, the combination of detrital zircon geochronology, whole-rock geochemical and sedimentary characters suggest that the initial uplift of Bogeda Shan occurred in the Late Permian. Combined with previous studies, three tectonic phases characterized the basin evolution from a continental rift, post-rift extensional depression to continental arc (initial uplift).

Inheritance from Upper Carboniferous (Lower Permian)
The tectonic setting of Bogeda Shan during the Carboniferous has been long debated [80]. Geochemical data suggests that it was not an island arc as proposed by Sébastien Laurent-Charvet et al. [81] but could have been a continental rift during the Carboniferous and Early Permian. Geochemical investigations of volcanic rocks and turbiditic deposits as well as gravimetric and magnetic data suggest that Turpan Block and Junggar Block were separated in the end of the Early Permian due to extension and rift of the Bogeda area [56,58,82]. The rift setting was also demonstrated by a series of coarse clastic rocks with intercalations of pillow lava-vesicular basalt [57]. Then, the extension of the belt started to rollback, which formed the Paleo-Bogeda Shan. The combined evidences shown above indicate that the tectonic setting of continental rift in the Early Permian is similar to the Late Carboniferous setting (Figure 13a) [27,30]. The tectonic setting transformed from continental rift to inland arc was a result of the collision of the Junggar and Tarim Blocks at the end of the Early Permian. From this collision, the tectonic setting of West Bogeda Shan changed to intracontinental tectonic evolution stage, and the original terrain of West Bogeda formed (Figure 13b). At the end of the Early Permian, most parts of the terrain were still a submarine environment, while only small parts were lifted up [32,74,[83][84][85].
Minerals 2020, 10, x FOR PEER REVIEW 17 of 25 distribution of bimodal volcanic rocks in the Bogeda Shan [73] and some submarine olistostrome in the West Bogeda Shan [30]. Deformation and unconformity at the end of the Middle Permian also implies the onset tectonic evolution of the West Bogeda Shan. The integrated data from lithological observation and sedimentary geochemical analyses indicates that the provenance characteristics, geochemical composition, and tectonic setting of rocks in the Permian obviously changed from the Early-Middle to Late Permian. Meanwhile, according to previous studies, the powerful intracontinental collision occurred between the Junggar and Tarim Blocks occurred and initiated West Bogeda Shan uplift in the Late Permian (Figure 13d) [32,88]. Thus, During early Middle Permian, depositional environment and tectonic setting were relatively stable, without intensive deformation and only some small scale of tectonic activities in the West Bogeda Shan [32,86]. Due to the relaxation of the compression and rebound of crust deformation, the island arc in the West Bogeda area received a large volume of sediments [54]. With a large sediment supply and incessant basement subsidence, the West Bogeda Shan basin closed during the Middle Permian (Figure 13c) [15,87]. Hence, the tectonic setting was post-rift extensional depression in the Middle Permian. This observation is consistent with some previous studies that reported the wide distribution of bimodal volcanic rocks in the Bogeda Shan [73] and some submarine olistostrome in the West Bogeda Shan [30]. Deformation and unconformity at the end of the Middle Permian also implies the onset tectonic evolution of the West Bogeda Shan.

Initial Uplift of West Bogeda (Upper Permian)
The integrated data from lithological observation and sedimentary geochemical analyses indicates that the provenance characteristics, geochemical composition, and tectonic setting of rocks in the Permian obviously changed from the Early-Middle to Late Permian. Meanwhile, according to previous studies, the powerful intracontinental collision occurred between the Junggar and Tarim Blocks occurred and initiated West Bogeda Shan uplift in the Late Permian (Figure 13d) [32,88]. Thus, this study confirms the previous recognition that the initial uplift of the Bogeda Shan happened in the Late Permian. Meanwhile, the depositional environment, sediment provenance and depositional center greatly changed as a response to the uplift of the Bogeda Shan.

Conclusions
This study presents the data of detailed zircon U-Pb geochronology and whole-rock geochemical compositions of Permian sandstones from the West Bogeda Shan, and discusses the provenances, source rock compositions, tectonic settings and basin evolution history. Several conclusions are summarized here.
(1) Detrital zircon U-Pb chronology suggests the sediments in the Lower-Middle Permian were inherited from the Carboniferous, showing one dominant age population with NTS and YCTS as the main source. However, two or three age populations are notable in the West Bogeda Shan during the periods of Middle Permian to Triassic, suggesting changing sediment provenances. REE series, especially Eu anomalies, also indicate the changes of sediment provenance in the Upper Permian.
(2) The sedimentary rocks in the West Bogeda originated from the mafic-dominant sources during the Early-Middle Permian but changed to lithologies are mixture of mafic and acidic arc sources in the Upper Permian. Besides, the Lower-Middle Permian dominated by wacke and the Upper Permian by litharenite and sublitharenite. The different source rock compositions between the Lower-Middle Permian and the Upper Permian resulted from the complex tectonic evolution of the Bogeda Shan in the Upper Permian.
(3) The provenance, lithology, and depositional environment were significantly changed from the Late Carboniferous to Late Permian. Strata deformation and unconformity also occurred at the end of Middle Permian, which was closely related to the uplift of West Bogeda Shan. Three stages characterized the tectonic evolution of the West Bogeda Shan, showing the continental rift in the Early Permian (inherited from the Upper Carboniferous), post-rift extensional depression in the Middle Permian, and continental arc in the Late Permian. With the initial uplift of Bogeda Shan in the Upper Permian, the depositional environment and sediment provenance changed significantly.