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Early Carboniferous granitoids, distributed in the Yining and Central Tianshan blocks, Chinese western Tianshan, are important for deciphering their tectonic contexts and evolutionary history of the South Tianshan Ocean. Here we present LA-ICP-MS zircon U-Pb ages, in situ Hf isotopic data, and whole-rock geochemical data of the monzogranites and syenogranites from the Kalejun Mountains, southern part of the Yining Block, aiming to constrain their petrogenesis and geodynamic background. The results reveal that these monzogranites and syenogranites were emplaced at 356 Ma and 344 Ma, respectively. Geochemically, they are characterized by high SiO2 (68.74–75.76 wt.%) and K2O (4.58–6.18 wt%), low MgO (0.14–0.76 wt.%) and P2O5 (0.04–0.24 wt.%) contents. In addition, they are depleted in Ba, Sr, Eu, Ti, Nb, and Zr, and enriched in Rb, Cs, Th, and U. These features indicate that the Kalejun granites are high-silica I-type granites. The low positive εHf(t) values (+1.1 to +8.2) and old T D M 2 H f model ages (1294 to 827 Ma) of the studied zircons imply that the parental magma of these granites were derived from the reworking of Proterozoic basement with minor involvement of juvenile materials. Combined with the Late Devonian to Early Carboniferous magmatic activities in the Yining and Central Tianshan blocks (e.g. the discovery of A-type bubble rhyolites and high-Mg andesites), it is suggested that the Kalejun granites were likely related to the roll-back of the South Tianshan oceanic slab. Finally, we argue that the subduction of South Tianshan Ocean probably terminated at the end of the Early Carboniferous. [ABSTRACT FROM AUTHOR]

Late Paleozoic volcanic rocks are well exposed in the Yining Block, NW China, and are predominately composed of andesites, rhyolites and volcaniclastics as well as minor basalts. Study of the petrology, whole‐rock geochemistry and zircon U‐Pb dating for the Early Carboniferous alkaline basalts from Wusun Mountain, western Yining Block, constrains their petrogenesis and tectonic evolution. The alkaline basalts consist mainly of plagioclases, mostly albite and labradorite, as well as clinopyroxenes and olivines; zircon U‐Pb dating indicates their formation at ca. 350 Ma. Geochemically, the basaltic samples have low SiO2 contents, and high TiO2, Al2O3 and alkaline contents, coupled with high Na2O/K2O ratios, displaying an alkaline basalt affinity. They show remarkable LILE enrichment and HFSE depletion. Meantime, these samples have relatively high TFe2O3, MgO, and Mg# values as well as Ni and Cr, relatively high Sm/Yb and U/Th, suggesting origination from a mantle source metasomatized by slab fluids. They formed in a transitional tectonic setting from arc to intraplate, showing a typical affinity of back‐arc basin basalts. The alkaline basalts were likely generated in a nascent back‐arc extension setting resulting from slab rollback of the southern Tianshan oceanic lithosphere. A bi‐directional subduction model seems more reasonable for the evolution of the southern Tianshan Ocean. These new data will provide a new tectonic model for Late Paleozoic tectonic evolution of the western Yining Block. [ABSTRACT FROM AUTHOR]

Massive Late Palaeozoic magmatic rocks are well developed along the northern margin of the Chinese western Tianshan. Previous studies mainly focused on the Carboniferous to Permian magmatism, and the Devonian magmatic rocks were rarely reported. Thus, this study presents new zircon U-Pb dating, whole-rock geochemistry and Lu-Hf isotopic data for the Late Devonian granitic plutons from the Kekesala area of the Chinese western Tianshan, aiming to elucidate their ages, petrogenesis, and tectonic settings. The Kekesala granitic plutons comprise granodiorites, monzogranites and syenitic granites. Zircon U-Pb dating results show they were emplaced in Late Devonian (ca. 372 Ma). Geochemically, the granodiorites and monzogranites are characterized by high-K calc-alkaline I-type series, and have low Ni and Cr, and weakly positive εHf(t) values, interpreted to be predominantly derived from partial melting of a lower crust with minor addition of mantle-derived materials; The syenitic granites with medium-K calc-alkaline features, exhibit high Sr and low Y and Yb, likely originated from partial melting of a subducted slab involving some mantle peridotites. The Kekesala I-type granitic plutons provide robust evidence for the existence of a subduction regime for the northern part of the Chinese western Tianshan in the Late Devonian. Based on the studied results, together with available data, we conclude that initial subduction of the North Tianshan Ocean began at least in the Middle Ordovician and terminated at the beginning of the Late Carboniferous rather than in the Middle Silurian. [ABSTRACT FROM AUTHOR]

The Carboniferous is an important period for understanding tectonic evolutionary history and subduction processes of Chinese western Tianshan orogen. Here, we present results of petrologic, geochemical, and in situ LA‐ICP‐MS zircon U–Pb and Hf isotope data from an Early Carboniferous mafic dike–syenitic granite association in Atengtao Mountain, Yili Block, aiming to constrain their ages and petrogenesis and tectonic significance. Zircon U–Pb dating results reveal that the mafic dikes and syenitic granites were coevally emplaced at ca. 345–349 Ma. Geochemically, the mafic dikes contain high MgO, Nb, TiO2, and Ta contents, low SiO2 contents, and high Na2O/K2O ratios, showing Nb‐enriched affinities. Additionally, they are enriched in LILEs, relatively depleted in HFSEs, and positive εHf(t) values (+1.2 to +8.7), likely representing melts derived from partial melting of a depleted mantle wedge metasomatized by subducted slab‐derived fluids, with minor involvement of asthenospheric components. Compared with mafic dikes, the coeval syenitic granites display calc‐alkaline I‐type features and have high SiO2, Al2O3, and low MgO, Mg# (<40), Ni, and Cr contents, considered to have been derived from the reworking of the Precambrian basement with an input of mantle‐derived components. These mafic dike–syenitic granite associations likely formed in an arc‐related setting rather than postcollision or mantle plume setting. In addition, pronouncedly higher zircon saturation temperature of the syenitic granites, compared with the coeval I‐type granitoids from western Tianshan, imply the occurrence of a thermal anomaly in this period (ca. 345 Ma). With these studied results, together with previously published data, we argue that a slab break‐off model was likely responsible for the mafic dike–syenitic granite association, and related rocks, in the western Yili Block during Early Carboniferous. [ABSTRACT FROM AUTHOR]

As an important part of the Central Asian Orogenic Belt (CAOB), Chinese western Tianshan contains voluminous Late Palaeozoic volcanic rocks. Here, we present geochronological, geochemical, and in situ Lu–Hf isotopic data from the Atengtao sanukitic high‐Mg andesites (HMAs) of the western Yili Block. LA‐ICP‐MS zircon U–Pb analyses indicate that the Atengtao high‐Mg andesites were generated in the Early Carboniferous (346 ± 2 Ma). All the studied rock samples are characterized by high MgO (3.30–5.45 wt.%), SiO2 (53.25–60.10 wt.%), Cr (90.3–157 ppm), and Ni (31.0–46.7 ppm) contents, with geochemical characteristics analogous to those of sanukitoids of the Setouchi Volcanic Belt (SVB), SW Japan, and Bieluagaxi area, West Junggar. The Atengtao sanukitic HMAs are enriched in LILE and LREE but depleted in HFSE, similar to those of typical arc‐related magmatic rocks. They are also characterized by high Nb (11.4–15.8 ppm) concentrations, high Th/La (0.3) and Th/Yb (2.6–4.0) ratios, and varying zircon εHf(t) values (−2.3 to +4.3). These features are suggested to result from the partial melting of a relatively enriched mantle wedge metasomatized by subducting oceanic slab‐derived sediments. Considering the occurrence of sanukitic HMAs, combined with the contemporaneous special rock assemblages (such as slab‐derived adakite, Nb‐enrich basalt, A‐type granite/rhyolite, and bimodal volcanic rocks) found in the western part of Yili Block, we propose that the generation of the Carboniferous sanukitic HMAs in Atengtao Mountain were most likely related to the slab break‐off following the southern Tianshan Ocean slab northward subduction beneath the Yili–Central Tianshan Block. This mechanism not only produces intense magmatism with compositional diversity but also gives rise to a local extension in the western part of Yili Block. The slab break‐off model may play an important role in the crustal growth of the CAOB in Phanerozoic time. [ABSTRACT FROM AUTHOR]

West Junggar is located at the southwest margin of the Central Asian Orogenic Belt and includes Silurian pillow basalts of the Mayilashan Formation. The petrogenesis and tectonic setting of these pillow basalts are important for the understanding of the tectonic evolution and metallogeny of the West Junggar area. This paper presents geochronological, geochemical, and whole‐rock Sr–Nd–Pb isotope data from the pillow basalts of the Mayilashan Formation. Zircon LA‐ICP‐MS U–Pb dating of a pillow basalt, which is in conformable contact with the chert, suggests that they were erupted at 437.2 ± 2.2 Ma marking the timing of generation of these rocks as Middle Silurian. Geochemically, all the pillow basalts bear the signature of ocean island basalt (OIB), and are characterized by alkaline affinity with high concentrations of TiO2 (3.28–4.12 wt.%), LILE and LREE enrichment and HREE depletion ((La/Yb)N = 5.5–7.3), with very weak Eu anomalies (Eu/Eu* = 0.96–1.06), and no obvious Nb, Ta, or Ti negative anomalies. Their Sr–Nd–Pb isotopic compositions ((87Sr/86Sr)I = 0.7037–0.7051, εNd(t) = 1.9–2.9, 206Pb/204Pbi = 17.74–18.22, 207Pb/204Pbi = 15.48–15.52, and 208Pb/204Pbi = 36.49–37.86) show Dupal‐like isotopic signature of ophiolites in the southern Paleo‐Asian Ocean. These characteristics indicate that the magmas were derived from a deep OIB reservoir, that is, a depleted but slightly heterogeneous asthenospheric mantle source with ~5–15% partial melting of garnet and spinel lherzolite. Our obtained results, in conjunction with previous published data, allow us to suggest that the alkaline pillow basalts formed in a seamount within an intraoceanic setting, where a larger number of seamounts with different ages occurred in the Paleo‐Asian Ocean. [ABSTRACT FROM AUTHOR]

Late Carboniferous to Early Permian granitic rocks are widely distributed in the Western Junggar (Xinjiang, NW China), but their petrogenesis and tectonic contexts remain controversial. In this paper, we present new zircon U–Pb age, major element, trace element data for the Huangliangzi pluton from the southern West Junggar. The pluton mainly consists of granodiorite porphyry, biotite monzonitic granite porphyry, and quartz monzonite diorite porphyry. Laser‐ablation inductively‐coupled mass‐spectrometry (LA‐ICP‐MS) zircon U–Pb obtained the age of 321.7 ± 1.3 Ma, indicating the granodiorite porphyry was emplaced in the early Late Carboniferous, coeval with abundant magmatic rocks in the region. Geochemically, these rocks are moderately peraluminous high‐K calc‐alkalic and characterized by relatively high SiO2 (64.31–66.69 wt.%), Al2O3 (15.82–16.73 wt.%), and Sr (379–489 ppm) contents and low MgO (1.08–2.46 wt.%; Mg# = 39–55), Y (7.61–9.64 ppm), and Yb (0.95–1.23 ppm) contents, along with positive Eu anomalies (Eu/Eu* = 1.01–1.34) and high Sr/Y (47.7–57.1) ratios. These are compositional features of adakites that are commonly assumed to have been produced through partial melting of subducted oceanic crust. In addition, the adakitic rocks are relatively enriched in light rare‐earth elements (LREEs), large ion lithophile elements (LILEs: e.g., Rb, Ba, Sr, and K), and depleted in high‐field‐strength elements (HFSEs: e.g., Nb, Ta, and Ti) and are also characterized by high εNd(t) value and low initial (87Sr/86Sr)i ratio. The most plausible mechanism for the Huangliangzi adakitic porphyries is the partial melting of subducted oceanic crust interacting with a mantle wedge. Combined with the geological setting and previous studies, therefore, we suggest that the southern West Junggar was in a subduction‐dominated island‐arc setting in the early Late Carboniferous, and multistage subduction–accretionary orogeny may be the main mechanism for the difference between the north and the south subduction duration in the Western Junggar. [ABSTRACT FROM AUTHOR]

The Yining Massif, sandwiched between the Junggar and Tarim plates, has received much attention because of its special position and complex tectonic evolution, as well as a significant breakthrough in geological prospecting. Moreover, a lot of studies have focused on two suites of volcanic rocks of the Early Carboniferous Dahalajunshan and Late Carboniferous Yishijilike formations in the Yining Massif. Recently, an increasing number of results have shown that two suites of volcanic rocks have obvious differences in lithochemistry and geochemistry and might have formed in an arc and intracontinental rift settings, respectively. Furthermore, the latest results of Sr–Nd isotopes indicate that the initial (87Sr/86Sr)i ratio is less than 0.7119 for all samples in the two formations. But the (87Sr/86Sr)i of andesites in the Dahalajunshan Formation is obviously higher than that of the Yishijilike Formation. However, those of dacites and rhyolites are just the opposite. The (143Nd/144Nd)i of all kinds of rocks from the Dahalajunshan Formation is less than 0.5126, and that of basalts in Yishijilike Formation is also less than 0.5126. However, the results of the andesites and rhyolites are higher than 0.5126. In short, the parameters of (87Sr/86Sr)i, (143Nd/144Nd)i, εNd(t), TDM (Ga), and εSr(t) are different obviously between the two suites, showing progressive change from basic to acid rocks in the two formations (gradual increase and decrease), but the changed direction is just the opposite. Consequently, it illustrates that there is a significant distinction in composition and petrogenesis between the Dahalajunshan and Yishijilike formations. The Dahalajunshan Formation volcanic rocks might be derived from an enriched mantle, whereas the volcanic rocks in the Yishijilike Formation are related to the evolution of continental crust. In other words, the differentiation of Sr–Nd isotopes provides a reference information for studying the petrogenesis and tectonic setting of the two suites of volcanic rocks. [ABSTRACT FROM AUTHOR]

Zircon U–Pb geochronological and geochemical analyses are reported for a suite of the early Carboniferous volcanic rocks from West Junggar (Northwest China), southern Central Asian Orogenic Belt (CAOB), with the aim to investigate the sources, petrogenesis, and tectonic implications. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U–Pb analysis from an andesite yielded concordant weighted mean206Pb/238U age of 345 ± 3 Ma, indicating the presence of early Carboniferous volcanic rocks in West Junggar. The early Carboniferous volcanic rocks consist of basalt, basaltic andesite, and andesite. Geochemically, all the samples bear the signature of ocean island basalt (OIB), and are characterized by alkaline affinity with minor variations in SiO2compositions (45.13–53.05 wt.%), high concentrations of Na2O + K2O (5.08–8.89 wt.%) and TiO2(1.71–3.35 wt.%), and LREE enrichment and HREE depletion ((La/Yb)N = 7.1–12.4), with weak Eu anomalies (Eu/Eu* = 0.9–1.1) and no obvious Nb, Ta, and Ti negative anomalies. These features suggest that the early Carboniferous volcanic rocks were derived from an OIB-related source that consists of oceanic lithosphere with ~1–3% degree partial melting of garnet lherzolite. From these observations, in combination with previous work, we conclude that the early Carboniferous alkaline volcanic rocks in Karamay region formed by upwelling of asthenospheric mantle through a slab window in a forearc setting during consumption of the West Junggar Ocean. Meanwhile, seamounts, which formed in the Late Devonian and were accreted and subducted in Karamay arc, also brought geological effects in the subduction zone. [ABSTRACT FROM AUTHOR]

The tectonic setting of the West Qinling orogenic belt (QOB) during the Middle–Late Triassic remains a subject of debate. Petrogenesis of adakitic granodiorite plays a critical role in determining the nature of the lower continental crust and mantle dynamics during orogenic processes in the region. The Tadong adakitic granodiorite pluton in the western part of the West QOB is an important element of this system. Its petrogenesis can place severe constraints on the nature of the lower continental crust and mantle dynamics during the formation of the orogenic belt. U–Pb dates obtained through zircon laser-ablation inductively coupled mass spectrometry indicate that the Tadong pluton was emplaced at 220.2 ± 2.5 Ma, coeval with abundant magmatic rocks in the region. This indicates a prominent magmatic event in the western part of West Qinling during the Late Triassic. Geochemically the granodiorites are metaluminous to peraluminous high-K calc-alkalic and characterized by relatively high SiO2(63.84–67.91 wt.%), Al2O3(15.39–16.54 wt.%), and Sr (435.08–521.64 ppm), and low MgO (1.16–1.88 wt.%; Mg# = 38–46), Y (5.49–8.84 ppm) and Yb (0.34–0.91 ppm) contents, variable Eu anomalies (Eu/Eu* = 0.87–1.1), and high Sr/Y (51.72–84.45) ratios. These are compositional features of adakites that are commonly assumed to have been produced through partial melting of subducted oceanic basalt. In addition, the adakitic rocks are relatively enriched in light rare earth elements, large ion lithophile elements (Rb, Ba, Sr, Th, and K), and depleted in high field strength elements. However, petrological, geochronological, and geochemical characteristics indicate that the adakitic rocks were most likely formed by partial melting of a thickened mafic lower crust. Therefore, we suggest that the Tadong adakitic granodiorites were produced in a syn-collisional regime and associated with asthenospheric upwelling triggered by slab break-off or gravitational instability. This mechanism was responsible for generating the Late Triassic magmatism of West Qinling. [ABSTRACT FROM PUBLISHER]

U–Pb zircon geochronological, geochemical, and whole-rock Sr–Nd isotopic analyses are reported for a suite of Karamay A-type granites from the Central Asian Orogenic Belt (CAOB) in the western Junggar region of northern Xinjiang, Northwest China, with the aim of investigating the sources and petrogenesis of A-type granites. The Karamay pluton includes monzogranite and syenogranite. Laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U–Pb dating yielded a concordant weighted mean206Pb/238U age of 304 ± 5 Ma (n = 11), defining a late Carboniferous magmatic event. Geochemically, the rock suite is characterized by high SiO2, FeOt/MgO, total alkalies (K2O + Na2O), Zr, Nb, Y, Ta, Ga/Al, and rare earth elements (REEs) (except for Eu), and low contents of MgO, CaO, and P2O5, with negative Ba, Sr, P, Eu, and Ti anomalies. These features indicate an A-type affinity for the Karamay granitic intrusions. Isotopically, they display consistently depleted Sr–Nd isotopic compositions (initial87Sr/86Sr = 0.7014–0.7022, ϵNd(t) = +5.6–+7.0). Geochronological, geochemical, and isotopic data suggest that the Karamay A-type granites were derived from remelting juvenile lower crust, followed by fractional crystallization. The Karamay A-type granites as well as widespread late Carboniferous magmatism in the western Junggar region of the southwestern CAOB may have been related to ridge subduction and a resultant slab window. This further demonstrates the importance of the late Palaeozoic granitic magmatism in terms of vertical crustal growth in northern Xinjiang. [ABSTRACT FROM AUTHOR]

Abstract: The Darbut Ophiolitic Complex consists of ultramafic rocks, cumulates, pillow lavas and abyssal radiolarian cherts, and occurs in the Sartuohai–Suluqiaoke area which is situated in the eastern part of the West Junggar (NW China), Southern Altaids. In the present study, we report new geochronological and geochemical data obtained for gabbro and basalt blocks embedded in the Darbut Ophiolitic Complex. Zircon U–Pb analyses from one representative gabbro sample by LA-ICP-MS yielded a weighted mean age of 391±6Ma, showing that it was emplaced in the Middle Devonian. The samples bear N-MORB, E-MORB, and arc-like geochemical signatures. They are tholeiitic in composition with low concentrations of Na2O+K2O varying from 1.36 to 4.09wt.%, Mg and Ti depleted, large ion lithophile elements (LILEs) enriched, with insignificant negative Eu. They also show negative Nb–Ta anomalies and high positive ε Nd(t) values, with relative high La/Nb, Ba/Nb, Ba/La, Ba/Th and Zr/Nb ratios. We interpret that these volcanic rocks were derived from a slightly metasomatized depleted mantle source in a back-arc basin setting, which corresponds to 10–30% partial melting of a depleted spinel lherzolite mantle. The data presented here in combination with previously published data suggest a northwestward subduction model for the West Junggar. During the period of the Early Devonian to Early Carboniferous, the West Junggar was dominated by normal northwestward subduction, and the ridge subduction commenced in the Late Carboniferous. [Copyright &y& Elsevier]

Abstract: The Huangyangshan pluton occurs in the Kalamaili region which is situated in the central part of the Central Asian Orogenic Belt, East Junggar, Xinjiang (NW China). The granitoid rocks are composed of medium-grained biotite (richterite, arfvedsonite) alkali-feldspar granite, fine grained arfvedsonite alkali-feldspar granite and microgranular enclaves. The granites have a pronounced A-type affinity: they are metaluminous to weakly peraluminous and calc-alkaline to alkaline in composition with high concentrations of Na2O+K2O varying from 8.4 to 9.2wt.%, high FeOt/MgO and 10,000Ga/Al ratios, low abundances of CaO, MgO and TiO2, enrichment in some LILEs (such as Rb and Th) and HFSEs (such as Zr, Y and REEs except Eu), depletion in Sr and Ba. Moreover, they display characteristic tetrad REE patterns and non-CHARAC trace element behavior, which is well demonstrated in highly differentiated rocks with strong hydrothermal interaction. The U–Pb zircon LA-ICP-MS ages of the host rocks and enclaves are 311±5Ma and 300±6Ma, respectively. The similar of these two ages suggests that host rocks and enclaves formed at a same time. Furthermore, the time span closely corresponds to known ages of post-collisional A-type granitoids of the Junggar terrane. Geochemical, geochronological and isotopic data (ε Nd(T) in the range +5.2 to +6.6 and I Sr mostly in the range 0.7031–0.7041) suggest that the Huangyangshan intrusions, and the enclaves are of mixed origin and are most probably formed by the interaction between the lower crust- and mantle-derived magmas in the Late Carboniferous post-collisional tectonic setting (A2 type granite). The magma for the Huangyangshan granites was derived by partial melting of an enriched subcontinental lithospheric mantle (SCLM) that was modified by slab-derived components from an earlier subduction event, this melting resulted from heat supplied from the asthenosphere through an opening created during the break-off of an oceanic slab. This further proves the important contribution of the Late Paleozoic granitic magmatism in terms of vertical crustal growth in northern Xinjiang. [Copyright &y& Elsevier]

Graphical abstract Highlights • New zircon U-Pb ages for the Bieluagaxi sanukitic dikes are ca. 319–315 Ma. • The sanukitic dikes are divided into two groups according to MgO contents. • A multi-stage subduction-accretionary orogeny model is suitable for West Junggar. Abstract Sanukitic dikes, mainly consisting of pyroxene diorite porphyrite, diorite porphyry, quartz diorite porphyrite and quartz diorite, were widely distributed in the Bieluagaxi area, southern West Junggar. In this contribution, we present new LA-ICP-MS zircon U-Pb ages, major and trace elements, and Sr-Nd-Hf isotopes for these dioritic dikes. These rocks formed in the early Late Carboniferous (ca. 319–315 Ma), coeval with abundant magmatic rocks in the region, and exhibit high MgO, Cr and Ni concentrations and K/Na ratios, and also show strong enrichment in large ion lithophile elements relative to high field strength elements, with pronounced negative Nb, Ta, and Ti anomalies, analogues to those of Cenozoic sanukitoids of the Setouchi Volcanic Belt. Compositionally, the sanukitic dikes are divided into two groups. Group 1 have MgO contents greater than 6 wt% (6.18–9.34 wt%), with Mg# values ranging from 58.2 to 73.7. They also have relatively low SiO 2 (51.7–55.7 wt%) and Sr (356 ppm in average) contents, and low Sr/Y (15.1–25.4) ratios, but high concentrations of Cr (6.2–490 ppm) and Ni (12.8–163 ppm). Compared to the Group 1, the Group 2 samples have slightly lower MgO (2.12–5.58 wt%; Mg# = 45.8–68.5), Cr (10.1–329 ppm) and Ni (2.84–136 ppm), but relatively higher SiO 2 (58.6–65.7 wt%) and Sr (304–521 ppm) concentrations and Sr/Y (19.2–41.0) ratios, making them akin to adakitic rocks elsewhere. These dikes also exhibit depleted Sr-Nd-Hf isotopic signatures, with (87Sr/86Sr) i = 0.70353–0.70480, εNd(t) = +5.03 to +7.61, εHf(t) = +10.9 to +15.3. Geochemical and Sr-Nd-Hf isotopic data suggest that the Group 1 rocks are similar to the typical sanukitoids of the Setouchi Volcanic Belt, and were likely derived from partial melting of a depleted mantle source with subducted sediment melts. While the Group 2 rocks show a remarkable geochemical affinity with the Northwestern Karamay sanukitoids, and were derived from partial melting of a depleted mantle source metasomatized by slab-derived adakitic melts and fluids. Combined with the identified and reported subduction-related magmatism, i.e., adakites, sanukitoids, Nb-enriched basalts, lagged arc volcanic rocks, and I-type granitoids in the Western Junggar region and taking into consideration the previous achievements, therefore, we consider a multi-stage subduction-accretionary orogeny model may account for the difference of subduction duration between the northern segment and southern segment of Western Junggar. [ABSTRACT FROM AUTHOR]