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The Bayingobi basin is located in the middle of Central Asia Orogenic Belt, at the intersection of Paleo‐Asian Ocean and Tethys Ocean, as well as the junction of multiple tectonic plates. This unique tectonic setting underpins the basin's intricate history of tectonic activity. To unravel the multifaceted tectono‐thermal evolution within the southwestern region of the basin and to elucidate the implications of sandstone‐hosted uranium mineralization, granitic and clastic rock samples were collected from the Zongnai Mts. uplift and Yingejing depression, and apatite fission track (AFT) dating and thermal history simulation analysis were performed. AFT dating findings reveal that the apparent ages of all samples fall within the range of 244 Ma to 112 Ma. In particular, the bedrock of the Zongnai Mts. and Jurassic detrital apatite fission tracks have undergone complete annealing, capturing the uplift‐cooling age. Meanwhile, the AFT ages of Cretaceous detrital rocks are either equivalent to or notably exceed the age of sedimentary strata, signifying the cooling age of the provenance. A comprehensive examination of AFT ages and palaeocurrent direction analyses suggests that the Cretaceous source in the Tamusu area predominantly originated from the central and southern sectors of the Zongnai Mts. uplift. However, at a certain juncture during the Late Early Cretaceous, the Cretaceous provenance expanded to include the northern part of the Zongnai Mts. uplift. Based on the results of thermal history simulations and previous studies, it is considered that the Tamusu area has undergone four distinct tectonic uplift events since the Late Paleozoic. The first is the Late Permian to Early Triassic (260–240 Ma), which is associated with the closure of the Paleo‐Asian Ocean and the accretionary orogeny within the Alxa region. The second uplift event took place in the Early Jurassic (190–175 Ma) and corresponded to intraplate orogeny following the closure of the Paleo‐Asian Ocean. The third uplift event is the Late Jurassic to Early Cretaceous (160–120 Ma), which is linked to the East Asia's position as the convergence center of multiple tectonic plates during this period. The fourth uplift event is linked to the Late Early Cretaceous (112–100 Ma), driven either by the westward subduction of the eastern Pacific plate or the mantle upwelling resulting from the Bangong–Nujiang oceanic lithosphere subduction and slab break‐off. The primary stress orientation for the first three tectonic uplift phases approximated a nearly SN direction, while the fourth stage featured a principal stress direction of NW. The fourth tectonic uplift event of the Late Early Cretaceous and basaltic eruption thermal event during this period likely exerted a significant influence on the formation of the Tamusu sandstone‐hosted uranium deposit. [ABSTRACT FROM AUTHOR]

The Tianshan range, a Paleozoic orogenic belt in Central Asia, has undergone multiple phases of tectonic activities characterized by the N–S compression after the early Mesozoic, including the far‐field effects of the Cenozoic Indian–Asian collision. However, there are limited reports on the tectonic deformation and initiation of Triassic intracontinental deformation in the Tianshan range. Understanding this structural context is crucial for interpreting the early intracontinental deformation history of the Eurasian continent during the early Mesozoic. Growth strata and syn‐tectonic sediments provide a rich source of information on tectonic activities and have been extensively used in the studies of orogenic belts. Based on detail fieldwork conducted in this study, the middle–late Triassic Kelamayi Formation of the northern Kuqa Depression in the southern Tianshan fold‐thrust belt has been identified as the typical syn‐tectonic growth strata. The youngest detrital zircon component in two lithic sandstone samples from the bottom and top of the Kelamayi growth strata yielded U‐Pb ages of 223.4 ± 3.1 and 215.5 ± 2.9 Ma, respectively, indicating that the maximum depositional age of the bottom and top of the Kelamayi growth strata is 226–220 and 218–212 Ma. The geochronological distribution of detrital samples from the Early–Middle Triassic and Late Triassic revealed abrupt changes, suggesting a new source supply resulting from tectonic activation in the Tianshan range. The coupling relationship between the syn‐tectonic sedimentation of the Kelamayi Formation and the South Tianshan fold‐thrust system provides robust evidence that the Triassic intracontinental deformation of the South Tianshan range began at approximately 226–220 Ma (during the Late Triassic) and ended at approximately 218–212 Ma. These findings provide crucial constraints for understanding the intraplate deformation in the Tianshan range during the Triassic. [ABSTRACT FROM AUTHOR]

The Rudny Altai is a western segment of the Altai orogenic belt. Its geological richness makes its geoheritage exploration an urgent matter. Investigations in the Loktevsky District (Altai Region, Russian Federation) have led to the finding of three notable localities, which are proposed as geosites. Field investigations and both qualitative and semi-quantitative (scoring by criteria) studies were carried out to characterize and value the geoheritage properties of these localities. The Neverovsky palaeoreef is a relatively large geosite, representing a Frasnian reef developed on a volcanic edifice. The Zolotukha section and the Razdolnoe section are smaller geosites representing deep-marine facies of the Giventian–Frasnian transition and the late Frasnian, respectively. Seven geoheritage types are established in the Neverovsky palaeoreef, and four geoheritage types are established in the other two geosites. Examination of rarity, accessibility, vulnerability, and other properties allows the ranking of the Neverovsky palaeoreef globally and the other two geosites regionally. The three proposed geosites need special geoconservation measures (especially regarding their rich fossil content). The palaeoreef can be used for the promotion of local tourism. [ABSTRACT FROM AUTHOR]

The Junggar Basin was an intracontinental basin enclosed by multiple orogenies in the Mesozoic. Unravelling the provenances development in the western Junggar Basin enclosed by the West Junggar Orogenic Belt (WJOB) and Tianshan Orogenic Belt (TSOB) would elucidate the exhumation history of these orogenic belts during the post-orogenic period. The TSOB includes Central Tianshan which includes a continental block with the Precambrian to early Palaeozoic metamorphic basements, while the WJOB includes Palaeozoic accretionary complexes. Given their contrasting geological histories, we use detrital garnets, metamorphic ilmenites, epidotes, and Precambrian zircons to distinguish the TSOB and detrital Cr-spinel to distinguish the WJOB. Combined with sedimentary analysis, palaeocurrents, heavy mineral data, seismic profiles, and zircon U-Pb geochronology, here we reconstruct a four-phase source-to-sink model. During the syn-rift phase, the southern basin was stably fed by the TSOB in the Triassic, evidenced by high Garnet-zircon index and stable single-peak Carboniferous detrital zircon age spectra. During the post-rift sag basin phase, the source-to-sink system experienced a significant change, because detrital zircon age spectra change into multiple peaks. During the transpressional basin phase, the WJOB replaced the TSOB as the dominant provenance in the late Middle Jurassic and the TSOB became the dominant provenance again in the Late Jurassic. Syndepositional volcanic materials provided a large amount of sediments. During the sag basin phase, lake transgression happened and the TSOB provenance could not reach the northern basin. We concluded that the WJOB experienced transpression and obvious denudation in the late Middle Jurassic, and the TSOB uplifted under transpression in the Late Jurassic. The transpression controlled the change of major provenances. The aridification in the Late Jurassic was recorded by the decrease in the Zircon-Tourmaline-Rutile index and the increase in epidotes and magnetites. The humidification in the Early Cretaceous was responded to by lake transgression and sediment recycling. [ABSTRACT FROM AUTHOR]

Uplift and amalgamation of the highelevation (>3000 m) Tian Shan and Pamir ranges in Central Asia restricts westerly atmospheric flow and thereby limits moisture delivery to the leeward Taklimakan Desert in the Tarim Basin (<1500 m), the second largest modern sand dune desert on Earth. Although some research suggests that the hyper-arid conditions observed today in the Tarim Basin developed by ca. 25 Ma, stratigraphic evidence suggests the first erg system did not appear until 12.2 Ma. To address this controversy and to understand the tectonic influences on climate in Central Asia, we studied a continuous, 3800-m-thick stratigraphic section deposited from 15.1 to 0.9 Ma now exposed within the western Kepintagh fold-and-thrust belt in the southern Tian Shan foreland. We present new detrital zircon data (n = 839), new carbonate oxygen (δ18Oc) and carbon (δ13Cc) stable isotope compositions (n = 368), structural modeling, and stratigraphic observations, and combine these data with recently published magnetostratigraphy and regional studies to reconstruct the history of deposition, deformation, and climate change in the northwestern Tarim Basin. We find that basins along the southern (this study) and northern (i.e., Ili Basin) margins of the Tian Shan were likely receiving similar westerly precipitation by 15 Ma (δ18Oc = ~-8‰) and had similar lacustrine-playa environments at ca. 13.5 Ma, despite differences in sedimentary provenance. At ca. 12 Ma, an erg desert formed adjacent to the southern Tian Shan in the northwestern Tarim Basin, coincident with a mid- to late Miocene phase of deformation and exhumation within both the Pamir and southern Tian Shan. Desertification at ca. 12 Ma was marked by a negative δ18Oc excursion from -7.8 ± 0.4‰ to -8.7 ± 0.7‰ in the southern Tian Shan foreland (this study), coeval with a negative δ18Oc excursion (~-11 to -13‰) in the Tajik Basin, west of the Pamir. These data suggest that only after ca. 12 Ma did the Pamir-Tian Shan create a high-elevation barrier that effectively blocked westerly moisture, forming a rain shadow in the northwestern Tarim Basin. After 7 Ma, the southern Tian Shan foreland migrated southward as this region experienced widespread deformation. In our study area, rapid shortening and deformation above two frontal foreland faults initiated between 6.0 and 3.5 Ma resulted in positive δ13Cc excursions to values close to 0‰, which is interpreted to reflect exhumation in the Tian Shan and recycling of Paleozoic carbonates. Shortening led to isolation of the study site as a piggy-back basin by 3.5 Ma, when the sediment provenance was limited to the exhumed Paleozoic basement rocks of the Kepintagh fold belt. The abrupt sedimentologic and isotopic changes observed in the southern Tian Shan foreland appear to be decoupled from late Cenozoic global climate change and can be explained entirely by local tectonics. This study highlights how tectonics may overprint the more regional and global climate signals in active tectonic settings. [ABSTRACT FROM AUTHOR]

The closing time of the Paleo-Asian Ocean (PAO) has long been in the focus of research as well as of controversial debates. The Paleozoic A-type granites distributed in the Beishan Orogenic Belt (BOB) at the southern margin of the Central Asian Orogenic Belt (CAOB) provide pivotal clues to constrain the closure of the PAO. In this paper, the newly recognized Duhongshan A-type granites from the middle Huaniushan arc in the BOB (zircon LA-ICP-MS U-Pb ages of ca. 376–374 Ma) are thoroughly studied. The rocks have high SiO2, K2O contents with peralkaline character, and display high Zr + Nb + Ce + Y contents (354–543 ppm), 10,000 × Ga/Al (4.1–4.9), Y/Nb (3.2–5.3), Rb/Nb ratios (8.5–14.1), and a zircon saturation temperature in the range of 877–950 °C, indicative of A2-type granites affinities. The Duhongshan granites display enriched in Th and U; depleted in Ba, Sr, and Ti; with slightly positive whole-rock εNd(t) values (+1.86 to +2.21), indicating an origin related to partial melting of lower crustal material in post-collision extension settings. Combined with previous reported results, we conclude that the granitoids in the middle Huaniushan arc were mostly formed around 424–367 Ma and can be divided into two types based on petrochemistry: (a) A-type granites, which generally have high SiO2 and K2O, derived from the relatively shallow crustal source in post-collision tectonic settings; and (b) adakite and I-type granites, which display high Sr/Y ratios as well as Nb, Ta, and Ti depletion, likely generated from the melting of juvenile crust in active continental margin arcs. Integrating the previous regional investigations, we propose that the Hongliuhe–Niujuanzi–Xichangjing Ocean (HNXO) of the PAO was closed and transformed in the post-collision extensional tectonic stage during the Late Devonian and formed as post-collision magmatism, while the arc magmatism may be related to the subduction of the Liuyuan Ocean, which is located in the Southern HNXO. [ABSTRACT FROM AUTHOR]

In the Phanerozoic, the production of continental crust was associated with convergent geodynamic settings [1] and, therefore, with intracontinental orogenic belts developed after the closure of paleooceans. Evaluation of the proportions of the juvenile crust versus older recycled material is a key parameter for understanding how the crust in orogens formed and evolved. The Mongol–Okhotsk orogenic belt is one of the major structural parts of Central Asia. Its central (Transbaikalian) part contains well-reserved fragments of an island-arc system, as well as the entire spectrum of accretionary prism formations, allowing us to evaluate the proportions of juvenile versus recycled sedimentary material in the crust of this orogen. In this part of the belt, the most representative fragments of the juvenile crust are volcanogenic–sedimentary sequences of the Late Paleozoic Kamenka and Urtui formations. The former is an indicator of a subduction zone along the northwestern margin of the Mongol–Okhotsk Ocean, with a dip beneath the Siberian Paleocontinent, whereas the latter marks the subduction zone along the southeastern margin, with a dip beneath the Argun superterrane. The entire spectrum of compositions for volcanism of the Kamenka Formation, from basalts to rhyolites, is characterized by positive values of ɛNd(254 Ma) = +1.4–(+3.8) and by TNd(DM) = 896–920 Ma. Basalts of the Urtui Formation also have positive values of ɛNd(350 Ma) = +1.7–(+6.0) at TNd(DM) = 773–939 Ma. This gives us grounds to evaluate the characteristics of the juvenile crust of the Mongol–Okhotsk orogenic belt: it is characterized by positive ɛNd(t) and by model ages TNd(DM) < 1000 Ma. The composition of metasedimentary rocks from the accretionary wedge of the Mongol–Okhotsk orogenic belt is considerably dominated by older recycled crustal material, the likely source of which is Late Riphean rock complexes of the Argun superterrane. [ABSTRACT FROM AUTHOR]

Late Mesozoic carbonatites of Central Asia are developed within the Central Asian Orogenic Belt and adjacent territories of the Siberian and North China platforms. In terms of their structural position, age, geochemical characteristics, and other parameters, they differ from other carbonatite occurrences of Central Asia and are distinguished as the Late Mesozoic carbonatite province in Central Asia. The province includes separate areas of carbonatite magmatism, the geological position of which is determined by the relation with Late Mesozoic rift zones of intracontinental Asia. The carbonatites were formed within a relatively narrow time range (between 150 and 118 Ma) at the early evolution stages of these zones. The carbonatite-bearing complexes of the province are represented by subolcanic and volcanic associations of silicate rocks, carbonatites, magmatic non-silicate rocks (phosphates, sulfates, and others), as well as products of hydrothermal activity. The carbonatites are characterized by diverse composition and include calciocarbonatites, magnesiocarbonatites, and ferrocarbonatites. The silicate rocks are dominated by K–Na and K intermediate rocks. All these rocks have similar geochemical features determined by the elevated contents of LREE, Sr, Ba, and Pb, at low Nb and Ta contents. The typomorphic minerals of carbonatites of the province, in addition to carbonates, are fluorite, Ba and Sr sulfates or carbonates, LREE F-carbonates, and apatite. Unaltered carbonatites are enriched in 18О and 13С relative to mantle values, but in general fall within the compositional range of carbonatites around the world. Hydrothermal and supergene processes modified the mineral composition of carbonatites, which was accompanied by a change of the initial Sr, O, and C isotope composition. The Sr and Nd isotope composition of rocks of carbonatite complexes of the province in general depends on the age of the basement of a definite volcanic area. Carbonatites and associated silicate rocks have close isotope characteristics, but carbonatites usually show relative enrichment in (87Sr) and depletion in radiogenic neodymium (143Nd). The formation of the Late Mesozoic carbonatite province is related to the activity of mantle plumes, which controlled the Late Mesozoic magmatism in Central Asia. The plumes obviously were accompanied by fluid flows enriched in СО2, F, and S. This caused the enrichment of lithospheric mantle in volatile components, as well as REE, Sr, Ba, and K, which were extracted by a fluid en route to the surface. Subsequent melting of metasomatized mantle produced parental melts of carbonate-bearing rock complexes. [ABSTRACT FROM AUTHOR]

East Junggar is an important part of the Central Asia Orogenic Belt and has developed a multi‐epoch and multi‐type metallogenic system. Yundukala is a recently discovered large intrusion‐related Au–Cu–Co deposit. The No. 1 main mineralization zone mainly occurs in the contact area between fine‐grained diorite and basalt. Massive and vein mineralization have developed there, but the ore‐bearing stratum, ore‐bearing intrusive rocks, and metallogenic ages are not clear. Zircon SHRIMP U–Pb dating of the porphyritic diorite and fine‐grained diorite yields ages of 416.1 ± 3.9 Ma and 411.1 ± 7.5 Ma, respectively. The dioritoid intruded into the ore‐bearing stratum, indicating that this formation is part of the Early Palaeozoic strata rather than the Middle Devonian Beishan Formation. The Re–Os isochron age of the chalcopyrite in the massive mineralization is 402.6 ± 5.2 Ma; thus, the massive mineralization is related to fine‐grained diorite and formed in the Early Devonian. Six sulphides and four sulphides from the vein mineralization yield Re–Os isochron ages of 352.8 ± 1.8 Ma and 354 ± 23 Ma, respectively, and the limited vein mineralization was formed during 353–354 Ma. The massive and vein mineralizations in the Yundukala deposit were formed in the Early Devonian and Early Carboniferous. [ABSTRACT FROM AUTHOR]

Reconstructing the tectonic architecture of the southern Altaids is of great importance to piece together the continental growth history of the Central Asian continent. In this paper, we address the subduction‐accretion process of the Paleo‐Tianshan Ocean, one branch of the South Tianshan Ocean, in the southern Altaids, through a detailed geological and geochemical investigation of the Wulanmoren Accretionary Complex (WAC). The WAC is composed of ophiolitic mélanges, ocean plate stratigraphy mélanges, and turbiditic coherent units. In this study, we present key geological, petrological, and geochemical evidence indicating back‐arc and ocean island affinity of the igneous rocks of the WAC. Zircon U‐Pb dates of these rocks ages range between 380.2 ± 1.3 and 302.0 ± 5.3 Ma. The sedimentary matrix units of the mélanges were deposited in the Early Devonian (∼405 Ma) to the Late Triassic (∼222 Ma), rather than Silurian strata as previously thought. However, the ages of some detrital zircons in the sedimentary matrix are Precambrian, pointing to a complex evolution involving multiple ocean island terrains and island arcs of different ages that accreted from the mid‐Paleozoic to the Early Mesozoic. Plain Language Summary: Well‐exposed rock outcrops of the Wulanmoren Accretionary Complex (WAC) offer an ideal opportunity to solve the enigma of the evolutionary history of the Paleo‐Tianshan Ocean (PTO) of Central Asia. We report field observations, geochemistry, and geochronology of the WAC in the southern Altaids, pointing to multiple tectonic settings of ages spanning from the Early Devonian (∼405 Ma) to the Late Triassic (∼222 Ma). These reconstructions suggest closure time of the PTO occurred post‐Triassic. Based on detrital zircons provenance analysis, we propose a multi‐island ocean model to explain the tectonic evolution of the PTO in the time period studied. Key Points: The Wulanmoren Accretionary Complex was composed of ophiolitic mélanges, ocean plate stratigraphy mélanges, and coherent unitsThe Late Paleozoic MORB‐like and OIB‐type basalts, and ∼222 Ma coherent units indicate closure of the Paleo‐Tianshan Ocean occurred post‐TriassicThe southern Paleo‐Asian Ocean was an archipelago with several subduction systems which is similar to the modern southwest Pacific [ABSTRACT FROM AUTHOR]

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Mantle intrusive rocks (lamproites and basalts) were collected from different units of the Uzbek Tian Shan, Central Asia to investigate xenoliths and xenocrysts aiming at tracking the shallow or deep nature of the mantle source. Whole-rock geochemistry and petrography revealed that these rocks are mostly of basaltic composition and may contain various exotic materials. These rocks originate from composite mantle magmas; they often result from the mixing between an evolved primary melt and more primitive melts, as indicated by the composition and textures of clinopyroxenes. Olivine, orthopyroxene and spinel mineral geochemistry from xenocrysts and lherzolitic xenoliths is consistent with a shallow mantle source (spinel lherzolite). Trace element content of clinopyroxenes shows LREE depletion supporting the removal of the magma from an undepleted sub-continental lithospheric mantle. The latter one is heterogenous, though and some parts recorded evidence of intense metasomatism. The upwelling asthenospheric magmas, emplacing in trans-lithospheric structures, were probably directly transferred into the crust or just below the crust, without significantly changing the geochemical composition of the sub-continental lithospheric mantle. [ABSTRACT FROM AUTHOR]

As the largest Phanerozoic accretionary orogenic belt in the world, the Central Asian Orogenic Belt (CAOB) experienced multiple episodes of tectonic and magmatic activities in association with extensive gold mineralization during the early Paleozoic. The newly discovered Baiyinha'er gold deposit in the southwestern CAOB exemplifies a typical structure-controlled gold mineralization due tectonic compression related to oceanic–continental subduction during the closure of the Paleo-Asian Ocean. A sequence of gold-bearing quartz veins and diorite porphyry dykes are emplaced along faults and fractures in a deformed quartz diorite batholith and its host rocks. Gold mineralization is closely associated with the emplacement of quartz veins that were formed in the same stress as the diorite porphyry dykes. They are the results of continued N–S compression. Zircon U–Pb dating yielded identical ages of 433–432 Ma for the diorite porphyry dykes and their host quartz diorite batholith. Furthermore, geochemical analysis reveals that the dioritic rocks (both the batholith and the dykes) belong to a magmatic arc related to the closure of the Paleo-Asian Ocean. The tectonic–magmatic–mineralization processes in the Baiyinha'er and contiguous areas are ascribed to the prolonged oceanic-continental subduction during the closure of the Paleo-Asian Ocean in the early Silurian. Oceanic subduction beneath the Bainaimiao arc led to generation of arc magmatism, forming the quartz diorite pluton in the Baiyinha'er and contiguous areas. Subduction-related tectonic compression resulted in faulting and fracturing of the solidified diorite intrusion and subsequent emplacement of the dioritic magmas along the faults and fractures. Continued and co-axial N–S compression induced new faults and fractures that host the gold-bearing quartz veins. [ABSTRACT FROM AUTHOR]

The Luobei Complex in Northeast (NE) China lies in the northern Heilongjiang Complex and comprises a sequence of low-temperature–high-pressure metamorphic rocks distributed along the N–S-oriented suture zone between the Jiamusi and Songliao blocks. However, the timing of formation and tectonic setting of the Luobei Complex remain poorly constrained. Here, we present petrological, geochronological, and geochemical data for metasedimentary rocks from the Luobei Complex to elucidate its origin and tectonic setting. The Luobei Complex is characterised by the occurrence of serpentinite, blueschist, greenschist, amphibolite, and marble, which form lenses or interlayers in a matrix of two-mica schist, albite schist, quartz schist, and granitic gneiss. Zircon U–Pb dating of four metasedimentary rocks yields consistent Late Triassic maximum depositional ages (ca. 214 Ma). Detrital zircons from the Luobei Complex yield ages ranging from 1889 to 202 Ma, with age peaks at 504, 350, 265, and 214 Ma. The ages prior to 350 Ma exist in both the Jiamusi Block and the Central Asia Orogenic Belt (CAOB), indicating that the syn-deposition of Luobei Complex, meanwhile, the lack of ages younger than 350 Ma suggests that the Jiamusi Block rifted eastward from the CAOB. Geochemical data indicate that the studied metasedimentary rocks were formed in a continental island arc setting. These results, together with the Early Jurassic metamorphism reported by previous studies, constrain the timing of final collision to Late Triassic–Early Jurassic after subduction of the Jiamusi Block beneath the Songliao Block. Combining our new results with previous findings, we propose a new tectonic model: (1) during the latest Carboniferous to Late Triassic, the Jiamusi Block rifted from the CAOB as a result of Mongol–Okhotsk oceanic plate subduction; and (2) during the Late Triassic and Early Jurassic, the Jiamusi Block was reunited with the Songliao Block, and the Heilongjiang Complex formed, as a result of Paleo-Pacific plate subduction. [ABSTRACT FROM AUTHOR]

The southern Altaids is of critical significance for a better understanding of the orogenic architecture and continental growth in Central Asia. The tectonic setting of the South Tianshan, a typical Paleozoic accretionary orogen within the southern Altaids, is controversial. This study reports new structural relations, geochemistry, and geochronology of previously assigned Late Silurian–Early Devonian strata in the Karaghol area of the South Tianshan. The constituent rocks are pillow basalts, ribbon cherts, limestones, siliceous mudstones, and turbiditic sandstones. Field relations show that these rocks are characterized by fault-bound tectonic slices and mélanges with typical block-in-matrix structures. The pillow basalts show N-MORB, E-MORB, and OIB geochemical fingerprints, and our new LA-ICP-MS zircon U–Pb dates indicate that the maximum eruption age of the OIB-type basalts was ca. 386 Ma, whereas the Maximum Depositional Ages (MDAs) of the turbiditic sandstones were ca. 369 Ma and 355 Ma. The age spectra of the detrital zircons, which define prominent peaks at ca. 370 Ma, ca. 420 Ma, ca. 770 Ma, ca. 960 Ma with subordinate Proterozoic ages, are a good match with the igneous ages of intermediate to felsic magmatism in the Yili–Central Tianshan arc. We conclude that the previously assigned Late Silurian–Early Devonian strata in the Karaghol area are mostly dismembered structural components and mélanges that belonged to an accretionary complex of Late Devonian to Early Carboniferous age, into which fragments of a Late Devonian seamount along with South Tianshan oceanic crustal rocks were likely emplaced during north-dipping subduction in the Early Carboniferous. This well-documented accretionary orogen in the Chinese South Tianshan is a key constraint on the accretionary orogenesis of the southern Altaids. [ABSTRACT FROM AUTHOR]

The final subduction and suture of the Paleo-Asia Ocean (PAO) are controversial, and the key to this question is to locate the latest subduction/final suture of the accretionary type orogenic belt. Previous studies mainly focused on the Tianshan, Beishan, Alxa, and Solonker Orogens for this issue. As a Phanerozoic orogenic belt located further south of the Beishan-Alxa Tectonic Belts, the Dunhuang Orogenic Belt (DOB) is becoming a research hotspot for revealing the evolutionary history of the southernmost Central Asia Orogenic Belt (CAOB). The youngest subduction-related arc magmatism is pivotal for constraining the lower limit of subduction of a lost ocean. This study presents integrated investigations of field observation, whole-rock geochemistry, and geochronology, targeting diabase dykes, intermediate-acid magmatic rocks, and garnet-bearing metabasite samples in the middle part of the DOB. LA-ICP-MS U-Pb dating of zircon yielded episodic magmatism of ca. 274–273 Ma for Xiaohongshan granite and Dongbatu syenogranite, ca. 250 Ma for Keziletage syenite, ca. 243–239 Ma for diabase and granitic dykes in the Kalatashitage area and Mogutai syenogranite, and maximum deposition age of ca. 262 Ma for pyroclastic rock in the Kalatashitage area. Most of those Permian-Triassic magmatic rocks show continental arc-related geochemical features during the subduction stage. The negative εHf(t) values and ancient TDM2 model ages of zircon indicate they were mainly derived from the partial melting of ancient crustal materials. The hornblende 40Ar/39Ar ages of ca. 258–250 Ma of the garnet-bearing metabasite samples also reflect a high heat flow setting during this period possibly triggered by arc activities. These Permian-Triassic magmatic and thermal records in the DOB are similar to contemporaneous records in surrounding South Tianshan-Alxa-Beishan orogens. We suggest that the final subduction of the PAO in the DOB possibly at least lasted to the Middle Triassic. [ABSTRACT FROM AUTHOR]

To understand the origin of curved subduction zones has been one of the major challenges in plate tectonics. The Mongol-Okhotsk Orogen in Central Asia is characterized by the development of a U-shaped oroclinal structure that was accompanied by the continuous subduction of the Mongol-Okhotsk oceanic plate. Therefore, it provides a natural laboratory to understand why and how a subduction system became tightly curved. In this study, we provide the first structural observation around the hinge of the Mongolian Orocline (the Zag zone in Central Mongolia), with an aim to constrain the oroclinal geometry and to link hinge zone structures with the origin of the orocline. Our results show that rocks in the Zag zone are characterized by the occurrence of a penetrative foliation that is commonly subparallel to bedding. Both bedding and dominant fabric in the Zag zone are steeply dipping, and their strike orientations in a map view follow a simple curve around the hinge of the Mongolian Orocline, thus providing the first structural constraint for 3D geometry of the orocline. A secondary penetrative fabric parallel to the axial plane of the orocline was not observed, indicating a low degree of orogen-parallel shortening during oroclinal bending. Combining with available geological and geophysical data, we conclude that the Mongolian Orocline was developed in a period of Permian to Jurassic, and its origin was linked to the subduction of the Mongol-Okhotsk oceanic slab. We consider that the low-strain oroclinal bending likely resulted from the along-strike variation in trench retreat, which was either triggered by the negative buoyancy of the Mongol-Okhotsk oceanic slab, or driven by the relative rotation of the Siberian and North China cratons. Our results shed a light on 3D geometry and geodynamic mechanisms of large-scale oroclinal bending in an accretionary orogen. [ABSTRACT FROM AUTHOR]

Compositional changes in successively erupted felsic rocks can be used to infer physical changes in lower crustal conditions and to enhance the understanding of the tectonic regime. This study presents geochronological, geochemical and isotopic data for two I-type granitic plutons in the Sonid Left Banner of the Central Asian Orogenic Belt. Our new data, together with compiled I-type granitoid data, reveal the presence of magma compositional transition at ∼305 Ma in the Baolidao arc-accretion belt. The early stage granitoids (330–305 Ma) are medium-K calc-alkaline with higher Sr/Y ratios. The late stage granitoids (305–270 Ma) are high-K calc-alkaline with lower Sr/Y ratios. The two-stage granitoids have roughly similar predominately positive Sr−Nd−Hf isotope values, but with a decreasing trend from the early to late stages. Geochemical data indicate that the early stage granitoids were generated by dehydration melting of juvenile mafic crust at amphibole-dominated depths. In contrast, the late stage granitoids were produced by dehydration melting of a mixed lithology containing juvenile K-rich mafic lower crust and supracrustal materials at the plagioclase-stable crustal level. We propose that the compositional transition of these granitoids can be linked with different slab behaviors of the northward subducting Paleo-Asian oceanic plate, and also with the back-arc tectonic settings. [ABSTRACT FROM AUTHOR]

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In Central Asia, the Carboniferous is a crucial period in the formation of the Tianshan Belt and associated bending of the Kazakhstan tectonic collage. In order to reveal Carboniferous magmatic events of the region and their tectonic implications, we conducted field investigations, zircon U–Pb dating, whole-rock geochemical and Sr–Nd isotopic studies on the Early Carboniferous Dahalajunshan Formation and Late Carboniferous Yishijilike Formation volcanic rocks of the Wusun Mountain Range (southern Yili-Central Tianshan Block). Volcanic rocks of the Dahalajunshan Formation consist of calc-alkaline basalt, andesite and dacite, yielding new zircon U–Pb ages of ~ 350 Ma. They have positive whole-rock εNd(t) values (+ 0.5 to + 1.6). In contrast, the Yishijilike Formation volcanic rocks dominantly comprise alkaline and calc-alkaline bimodal suites that erupted at ~ 337 Ma to 313 Ma and have higher whole-rock εNd(t) values (+ 2.3 to + 4.3). These two episodes of Carboniferous magmatism were correlated with partial melting of depleted mantle that metasomatized by slab-derived fluids. The late Carboniferous Wusun Mountain magmatic belt shows characteristics of a back-arc system that evolved due to trench retreat relative to the southern margin of the Yili-Central Tianshan Block. This mechanism induced an extensional regime with gradually depleting magma sources. The asymmetric retreat of the paleo-subduction zones of the South Tianshan Ocean and Junggar Ocean relative to the Yili-Central Tianshan Block was hence a vital driving force for the bending of the Kazakhstan Orocline. [ABSTRACT FROM AUTHOR]

Early Palaeozoic evolution of the Kazakhstan orocline in the Central Asian Orogenic Belt (CAOB) is key to reconstructing the Palaeozoic tectonic framework in Central Asia. This study presents field mapping, geochemistry, and geochronological data from the Wulasitai area of northern West Junggar to constrain the subduction polarity and major tectonic events in the Chingiz arc of the Kazakhstan orocline during the Early Palaeozoic. The mapping area outcrops imbricated coherent turbidite slices and mélanges that consist of chert, limestone, silt, sandstone, and conglomerate blocks in mudstone matrix, representing an OPS (Ocean Plate Stratigraphy) mélange in an accretionary complex. Existing fossil ages from these blocks range from the Ordovician to Silurian, while our new detrital zircon U-Pb samples from the turbiditic matrix yield maximum depositional ages (MDTs) from 428 ± 2 Ma to 450 ± 1 Ma. Detrital zircon ages of ~510 to 430 Ma in the mélange suggest the Chingiz arc to the south of the study area as a major sediment source, providing an indirect constraint on the polarity of subduction. We suggest that the northern part of the Chingiz arc may be underlain by southward subduction, with the accretionary complex located on the Wulasitai area of the northern West Junggar. The Wulasitai mélange is overlain depostionally by volcanic rocks carrying depleted HFSE and enriched LILE, LREE. The andesite and tuff are dated to 415 ± 5 Ma, 414 ± 3 Ma, and 402 ± 6 Ma, which we interpret as reflecting the development of the volcanic arc onto the previous subduction complex. This model implies the generation of the arc (accretion arc) as the slab rolling back and trench retreating, which may play an important role in the evolutionary history of CAOB. [ABSTRACT FROM AUTHOR]

The tectonic evolutionary history between the Xing'an Block (XB) and Songnen Block (SB) in the eastern Central Asia Orogenic Belt (CAOB) has been hotly debated. In this study, we present a series of new data to provide a better constraint on the magmatic process during plate subduction and its implications for the regional tectonic evolution of XB and SB, even the CAOB. The whole-rock geochemistry and zircon U-Pb chronology of syenogranite in the Chaihe area of the Great Xing'an Range have been carried out. The dating results show that the syenogranite was formed in the Late Carboniferous during the 303.1-316.1 Ma. The SiO2 content of dated samples is around between 65.43%~75.88%, while the total alkali content (K2O+Na2O) is 7.23%~10.19%, the content of MgO (0.07%~0.63%) and the value of Mg# is 0.14~0.36. Moreover, they have right-inclined REE distribution patterns [(La/Yb)N = 1.23-15.61] with slight negative or inappreciable Eu anomalies (δEu = 0.06-0.49). All samples were enriched in LILEs (e.g., Rb and K) and depleted in HFSEs (e.g., Nb, Ta and Ti). Based on these data, combined with their trace element characteristics, we conclude that these rocks in our study area were likely derived from partial melting of the crust. Combining with regional tectonic evolution studies and our petrological and geochemical studies, we propose that they formed in a post-collisional extensional tectonic setting that developed after the amalgamation of the Xing'an and Songnen blocks and closure of the Nenjiang Ocean between them during the Late Carboniferous. [ABSTRACT FROM AUTHOR]

Studies carried out by the authors show that the uplift of Central Asia situated between the eastern Alpine–Himalayan and western Altai–Stanovoy orogenic belts formed in the neotectonic epoch. Major elements of the neotectonic structure and compiled upper mantle sections showing the difference in P-wave velocities from the standard values for the corresponding depths are analyzed. It is found that underthrusting of the high-velocity uppermost mantle of the Indian Platform beneath the Himalayas produced deformational thickening and a significant decrease in the density of the lithosphere. This led to uplift of the Himalayas, Karakorum, Hindu Kush, Pamirs, Southern and Western Tibet, and Western Kunlun, accelerating in the Pliocene–Quaternary. The seismic velocities are lowered under the rest of Central Asia except for some peripheral mountain systems. Two intramantle plumes are identified. The Tibetan plume is traced from depths of ~1600 km. The upper mantle alterations initiated by this plume were the main source of the Tibet uplift. The Khangai Plume is traced from depths of ~1250 km. The Khangai plume, together with its Khentei branch, caused the formation of the Khangai and Khentei Highlands and Neogene–Quaternary basaltic volcanism. The influence of sublithosheric flows spreading out of the Tibetan and Khangai plumes, as well as the Ethiopian–Afar superplume, caused a decrease in the density of the upper mantle, Neogene–Quaternary flexural deformation, and Pliocene–Quaternary uplift of the Central and Eastern Tien Shan, Gobi Altai, and partly, Mongolian Altai. The seismic wave velocities in the upper mantle are increased under the Western Tien Shan, Junggar Alatau, Gorny Altai, Western Sayan, and northwestern Mongolian Altai. The source of deformation and uplift is the collisional interaction of lithospheric blocks, while the magnitudes of uplift are lower than in mountain systems with a decreased density of the upper mantle. [ABSTRACT FROM AUTHOR]

Along the present-day circum-Pacific subduction girdle, seamount subduction is known to have significant effects on subduction dynamics including on seismicity and arc magmatism. Because seamount subduction should have occurred throughout much of Earth history, its effects on orogenesis in the overriding plate should be identifiable in ancient orogens. In this study, we investigate the Paleozoic South Tianshan orogen of Central Asia, for which abundant evidence of seamount subduction exists, further bolstered by the continuation of a long-lived plume-induced large igneous province on the subsequently accreted Tarim craton. We find that semi-continuous seamount subduction from ca. 400 to 330 Ma temporarily shut down arc magmatism, and once the seamounts were completely subducted, then arc magmatism resumed and eclogites were quickly exhumed. If such an orogenic fingerprint of seamount subduction can be identified in ancient orogens, a much more complete picture of plumesubduction interaction and its influence on both crustal and mantle processes can be developed. [ABSTRACT FROM AUTHOR]

The Central Asian Orogenic Belt, as the largest accretionary orogen on Earth, is an ideal candidate to study the geodynamics of convergent plate boundaries through a prolonged period. The evolution of this orogen has been explained by different tectonic models, which incorporated one, or a combination, of the following mechanisms: lateral stacking of arc systems along major shear zones, arc amalgamation, oroclinal bending, and trench migration. Here we elucidate major mechanisms responsible for the tectonic evolution of the Central Asian Orogenic Belt, focusing on the Chinese Tianshan Orogen in the southern Central Asian Orogenic Belt. Structural observations from the ~50-km-long Gangou section show evidence of polyphase deformation. The earliest episode of orogenparallel sinistral shearing, constrained to the Early Devonian (ca. 399 Ma) by syn-deformational intrusions, was possibly controlled by oblique subduction. This was followed by an episode of ~NE-SW contractional deformation, dated at ca. 356 Ma (40Ar/39Ar age of syn-deformational hornblende), and likely associated with an episode of trench advance. The third stages of deformation during the latest Carboniferous and Permian involved ~NE-SW contraction, orogen-parallel extension, and dextral transpression. Our new geochronological data constrain the timing of orogen-parallel extension to ca. 303-293 Ma, and confirm that dextral activation along shear zones occurred during the Permian. The results highlight the role of trench migration, oblique tectonics, and syn-collisional orogen-parallel extension in the build-up of the Central Asian Orogenic Belt, and contribute to the pre-collisional reconstruction of this orogenic system. [ABSTRACT FROM AUTHOR]

Studies of volcanic rocks in orogenic troughs of Eastern Kazakhstan were carried out. The troughs were formed at late-orogenic stages of evolution of Hercynian Altai collision system. Volcanic rocks are represented by basalts, andesites, dacites and rhyolites. Based on geochemical and isotopic data, the basalts and andesites derived from mafic magmas that formed as a result of partial melting of garnet peridotites in the upper mantle under the orogen. U–Pb zircon data prove two volcanic stages: more-scaled Middle Carboniferous (~311 Ma) and less-scaled Early Permian (297–290 Ma). Basalts and andesites in lower parts of the orogenic troughs and independent dacite-rhyolite structures were formed at the Middle Carboniferous stage. Parental mafic magmas were formed as a result of partial melting of mantle substrates in local transtensional zones along large shear faults. The formation of dacites and rhyolites could have been caused by partial melting of crustal substrates under effect of mafic magmas. Transtensional movements in the lithosphere of orogenic belts may indicate the beginning of collapse of orogens. A smaller volume of basalts and andesites formed at the Early Permian stage. Geochemical data prove the independent episode of partial melting in upper mantle. Synchronous basalts and andesites also appeared at wide territory in Tian Shan, Central Kazakhstan, and Central and Southern Mongolia. Early Permian volcanism indicates general extension of the lithosphere at the postorogenic stages. Large-scaled Early Permian mafic and granitoid magmatism in Central Asia has been interpreted in recent years as the Tarim Large Igneous Province caused by Tarim mantle plume activity. Thus, the extension of the lithosphere and associated volcanism in the Early Permian can be an indicator of the onset of the plume–lithosphere interaction process. [ABSTRACT FROM AUTHOR]

The Paleozoic granitoids of the Urgamal pluton in the crystalline basement of the northwestern part of the Dzabkhan Terrain are considered. The age of these granitoids, 463 ± 2 Ma, was determined by the U–Pb method (ID-TIMS). The Urgamal pluton is located on the border of the Dzabkhan Terrain with the Early Caledonian formations of the Ozernaya Zone. The pluton was emplaced after the the Dzabkhan Terrain had converged with the paleo-oceanic and island arc complexes of the Ozernaya Zone. The granitoids are therefore attributed to post-accretionary formations occurring in the Early Caledonian superterrain of Central Asia. Intrusive complexes similar in age and structural position are known in the Caledonian Ozernaya Zone, Sangilen Block, Tuva-Mongolian Terrain, and the Olkhon Terrain of the framing of the East Siberian Platform. Geological settings of these complexes allow the time of integration of the Early Caledonian superterrain of Central Asia and the Siberian Platform to be estimated. [ABSTRACT FROM AUTHOR]

As one of the largest Phanerozoic orogens in the world, the Central Asian Orogenic Belt (CAOB) is a natural laboratory for studies of continental dynamics and metallogenesis. This paper summarizes the research progresses of the accretionary processes and metallogenesis of the CAOB since the People's Republic of China was founded, and puts forward the prospect for future research. During the early period (1950s–1970s), several geological theories were applied to explain the geological evolution of Central Asia. In the early period of China's reform and opening-up, the plate tectonics theory was applied to explain the evolution of the northern Xinjiang and Xingmeng regions, and the opinion of subduction-collision between Siberian, Kazakhstan, and China-North Korea-Tarim plates was proposed. The idea of the Solonker-Yanbian suture zone was established. In the 1990s, the study of the CAOB entered a period of rapid development. One school of scholars including geologists from the former Soviet Union proposed a multi-block collision model for the assemblage of the CAOB. In contrast, another school of scholars, led by a Turkish geologist, Celal Şengör, proposed that the Altaids was formed through the growth and strike-slip duplicates of a single island arc, and pointed out that the Altaids is a special type of collisional orogen. During this period, Chinese geologists carried out a lot of pioneering researches on ophiolites and high-pressure metamorphic rocks in northern China, and confirmed the main suture zones accordingly. In 1999, the concept of "Central Asian metallogenic domain" was proposed, and it became one of the three major metallogenic domains in the world. Since the 21st century, given the importance for understanding continental accretion and metallogenic mechanism, the CAOB has become the international academic forefront. China has laid out a series of scientific research projects in Central Asia. A large number of important scientific research achievements have been spawned, including the tectonic attribution of micro-continents, timing and tectonic settings of ophiolites, magmatic arcs, identification and anatomy of accretionary wedges, regional metamorphism-deformation, (ultra)high-pressure metamorphism, ridge subduction, plume-plate interaction, archipelagic paleogeography and spatio-temporal framework of multiple accretionary orogeny, continental growth, accretionary metallogenesis, structural superposition and transformation, etc. These achievements have made important international influences. There still exist the following aspects that need further study: (1) Early evolution history and subduction initiation of the Paleo-Asian Ocean; (2) The accretionary mechanism of the extroversion Paleo-Asian Ocean; (3) The properties of the mantle of the Paleo-Asian Ocean and their spatiotemporal distribution; (4) The interaction between the Paleo-Asian Ocean and the Tethys Ocean; (5) Phanerozoic continental growth mechanism and its global comparison; (6) Accretionary metallogenic mechanism of the Central Asian metallogenic domain; and (7) Continental transformation mechanism. [ABSTRACT FROM AUTHOR]

The Initial Upper Paleolithic (IUP) is one of the most important phases in the recent period of the evolution of humans. During a narrow period in the first half of Marine Isotope Stage 3 laminar industries, accompanied by developed symbolism and specific blade technology, emerged over a vast area, replacing different variants of the Middle Paleolithic. In western Eurasia, the earliest appearance of IUP technology is seen at the Boker Tachtit site, dated ca. 50 ka cal BP. The earliest evidence of IUP industries in the Balkans and Central Europe, linked to the spread of Homo sapiens , has been dated to around 48 ka cal BP. A key area of IUP dispersals are the mountains and piedmont of southern Siberia and eastern Central Asia. One of the reference assemblages here is Kara-Bom, an open-air site in the Siberian Altai. Three major settlement phases are distinguished in the sediment sequence. In this paper, we present the results of new radiocarbon determinations and Bayesian models. We find that the latest phase of the IUP, Upper Paleolithic 1 ('UP1') is bracketed between 43 and 35 ka cal BP (at 95.4% probability). The earliest IUP phase, 'UP2', begins to accumulate from ca. 49 ka cal BP and ends by ca. 45 ka cal BP. The Middle Paleolithic 'MP2' assemblages all fall prior to 50 ka cal BP. We can detect a spatial distribution of dates from the geographic core of the IUP beyond the Altai where it appears around 47–45 ka cal BP. The current distribution of dates suggests a west–east dispersal of the IUP technocomplex along the mountain belts of Central Asia and South Siberia. [ABSTRACT FROM AUTHOR]

The uplift history of the Pamir-Tian Shan orogens remains debated, and is crucial to understanding the aridification of Central Asia. To address this question, we performed inverse modeling of the westward-flowing Vakhsh River along the Alai Valley between the Pamir and Tian Shan orogens. We validated the application of this method in reconstructing uplift history of mountains with complex climatic and tectonic settings. The modeled results reveal three episodes of accelerated uplift of the Vakhsh River drainage at ca. 10–7 Ma, ca. 5 Ma, and 2–0 Ma. The late Miocene rapid uplift at rates of 0.6–0.8 mm/yr of the Vakhsh River drainage occurred at ca. 10–7 Ma. Rock uplift, coeval with compressional deformation and exhumation around the Alai Valley, was likely driven by crustal shortening during the Pamir-Tian Shan convergence. Narrowing of the Alai Valley started to impact westerly atmospheric flow, leading to incipient rain shadow responsible for emergence of desert in the proximal leeward Tarim Basin. Accelerated uplift at ca. 5 Ma and 2–0 Ma at rates of 1.0–1.4 mm/yr and 1.7–2.3 mm/yr, increased surface elevations to near modern heights (3.5–5 km) that largely blocked the westerlies, causing enhanced aridification in the Tarim Basin. Our modeling results highlight the important role of mountain building in shaping late Cenozoic climate in Central Asia. [Display omitted] • Study examines the uplift history of the Pamir-Tian Shan convergence zone. • Applies river channel profile inversion method • River inverse modeling can be used in complex climatic and tectonic settings. • Three episodes of accelerated rock uplift has occurred in the late Cenozoic. • Highlights mountain building as a key mechanism for Central Asia aridification [ABSTRACT FROM AUTHOR]

The Altai‐Junggar‐Tianshan collage in southern Altaids is an important metallogenic domain in Central Asia that contain world‐class copper‐iron‐nickel deposits. As an accretionary‐type metallogenic system, the metallogenic processes of the Altai‐Junggar‐Tianshan collage is essential in understanding the genetic mechanism of ore deposits in general. Here in this paper we present a brief introduction to the project on the western part of the Southern Altaids, entitled "The deep structure and metallegenic processes of the North China accretionary metallogenic systems". This project mainly focuses on the deep structure and metallogenic background of the Altai‐Junggar‐Tianshan collage by integrated studies from field geology, structural mapping, geochemistry and geophysical exploration. Multiple new geological and geophysical methods will be applied to make transparency of the Kalatongke and Kalatage ore clusters. This will update our understanding of the geodynamic processes of metallogenesis and lead to the development and foundation of new metallogenic theories in accretionary orogens. [ABSTRACT FROM AUTHOR]

The early Mesozoic marked an important transition from collisional orogeny to post‐orogenic extension at the northern margin of the North China Craton (NCC). In this study, we undertook zircon U‐Pb dating and whole‐rock major‐ and trace‐element geochemical analyses of early Mesozoic granitic rocks in the Chifeng area to establish their geochronological framework, petrogenesis, and implications for the tectonic evolution of the eastern Central Asia Orogenic Belt (CAOB). Zircon U‐Pb dating results show that these rocks were emplaced in three stages during the Triassic: (1) syenogranites during 250–248 Ma, (2) granodiorites during 244–243 Ma, and (3) monzogranites and granodiorites during 232–230 Ma. These Triassic granitoids belong to the high‐K calc‐alkaline series and are evolved I‐type granites. They have high SiO2 and low MgO contents with enrichments in light rare‐earth elements, Zr, Hf, Rb, Th, and U, and depletions in Ba, Nb, Ta, Sr, and Eu. These geochemical data indicate that the granitoids were derived from partial melting of a lower‐crustal source under relatively low‐pressure conditions and subsequently underwent extensive fractional crystallization. Considering both the geochemical data and regional geological information, we propose that the 250–248 Ma syenogranites were emplaced in an extensional environment linked to slab break‐off after closure of the Paleo‐Asian Ocean (PAO) along the Solonker‐Xra Moron‐Changchun suture zone. The 244–243 Ma granodiorites were formed in a compressional orogenic setting during collision between the Erguna‐Xing'an‐Songliao composite block and the NCC. The 232–230 Ma granodiorites and monzogranites were emplaced during the transition from compressional orogeny to post‐orogenic extension. Overall, the early Mesozoic tectonic evolution of the Chifeng area can be divided into three main stages: (1) closure of the Paleo‐Asian Ocean and extension related to slab break‐off during the Early Triassic; (2) continuous collisional compression during the Middle Triassic after closure of the PAO; and (3) post‐orogenic extension during the Late Triassic, most probably due to lithospheric delamination after amalgamation of the Erguna‐Xing'an‐Songliao composite block and the NCC. [ABSTRACT FROM AUTHOR]

A great number of magmatic Cu‐Ni deposits (including Kalatongke in Xinjiang and Hongqiling in Jilin) are distributed over a distance of almost 3000 km across the Tianshan‐Xingmeng Orogenic Belt, from Tianshan Mountains in Xinjiang in the west, to Jilin in eastern China in the east. These deposits were formed during a range of magmatic episodes from the Devonian to the Triassic. Significant magmatic Cu‐Ni‐Co‐PGE deposits were formed from the Devonian period in the Nalati arc (e.g. Jingbulake Cu‐Ni in Xinjiang), Carboniferous period in the Puerjin‐Ertai arc (e.g. Kalatongke Cu‐Ni‐Co‐PGE in Xinjiang), Carboniferous period in the Dananhu‐Touquan arc (e.g. Huangshandong, Xiangshan and Tulaergen in estern Tianshan, Xinjiang) to Triassic period in the Hulan arc (e.g. Hongqiling Cu‐Ni in Jilin). In addition to the overall tectonic, geologic and distribution of magmatic Cu‐Ni deposits in the Tianshan‐Xingmeng Orogenic Belt, the metallogenic setting, deposit geology and mineralization characteristics of each deposit mentioned above are summarized in this paper. Geochronologic data of Cu‐Ni deposits indicate that, from west to east, the metallogenic ages in the Tianshan‐Xingmeng Orogenic Belt changed with time, namely, from the Late Caledonian (∼440 Ma), through the Late Hercynian (300–265 Ma) to the Late Indosinian (225–200 Ma). Such variation could reflect a gradual scissor type closure of the paleo Asian ocean between the Siberia Craton and the North China Craton from west to east. [ABSTRACT FROM AUTHOR]

• Rift-related anorogenic magmatism of the Yenisey Ridge correlated with the breakup of Columbia and Rodinia supercontinents. • Age correlation supports long-lived connection between southwestern Siberia and North Atlantic cratons in the Proterozoic. • Intraplate magmatism compatible with paleogegrahic location of southern Siberia adjacent to northern Laurentia. The tectonic evolution of the Siberian Cratonic margins offers important clues for global paleogeographic reconstructions, within the complex continental collage of Central Asia. The Yenisey Ridge fold–and–thrust belt at the western margin of the Siberian Craton forms part of the Central Asian Orogenic Belt (CAOB) and is a key to understand the Precambrian tectonic evolution of the Siberian Craton and crustal growth in the CAOB, the world's largest Phanerozoic accretionary orogenic belt. Here we report the occurrence of A-type granites with geochemical features indicating intraplate setting from the Yenisey Ridge and provide evidence for rift-related magmatism. Zircon SHRIMP U–Pb analyses coupled with in situ U–Th–Pb geochronology of monazite constrain the timing of emplacement of the rift–related granitoids and suggest two consequential breakup events. The magmatic events at 1380 Ma and 800–720 Ma along the western margin of the Siberian Craton and other continental blocks can be associated with the breakup of the Precambrian supercontinents Nuna-Columbia (1.8–1.3 Ga) and Rodinia (1.2–0.7 Ga). These pre-Grenville and post-Grenville episodes of regional crustal evolution are correlated with the synchronous successions and similar style of rocks along the Arctic margin of Nuna–Columbia and Rodinia and supports the spatial proximity of Siberia and North Atlantic cratons (Laurentia and Baltica) over the long period 1.38–0.72 Ga. Our data confirm the proposed Neoproterozoic paleogeographic reconstructions of Columbia and Rodinia as constrained from the large igneous province (LIP) record. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • HP-LT eclogitic schists of the Atbashi Complex are overlain by late Kasimovian strata. • The minimum age of HP-LT metamorphism in the Atbashi Complex is late Kasimovian (ca. 305 Ma). • South Tianshan Ocean closed in the Late Pennsylvanian. • Young ages of HP-LT rocks reflect incorrect interpretation of analytical data. Abstract The proposed Triassic age of oceanic subduction and high-pressure/low-temperature (HP-LT) metamorphism in the South Tianshan orogen (STS) of the southwestern Central Asian Orogenic Belt needs to be re-examined on the basis of field relationship and precise age dating. Our biostratigraphic study in the Atbashi Range of southern Kyrgyzstan indicates that sedimentary strata unconformably overlie the HP-LT metamorphic rocks within the Turkestan suture zone and have a late Kasimovian (ca. 305 Ma) age. This constrains the minimum age of eclogite metamorphism in the HP-LT metamorphic complex. A Late Pennsylvanian to early Permian (Asselian) hinterland basin overlaps the margins of the Middle and South Tianshan and the ophiolitic suture between them, thus leaving no space for an oceanic basin in the northern STS in the late Permian or Triassic. In the south, overlap assemblages stitching the STS with the Tarim Craton consist of late Asselian to early Sakmarian limestones and early Permian rhyolites. Early Permian (ca. 295–265 Ma) post-collisional A-type granites and sub-alkaline plutons are widespread in the STS and are not affected by thrust deformation. These facts indicate that thrust packages of the STS were stacked together and welded to the margin of the Tarim Craton by the early Permian. The widespread occurrence of early Permian sub-alkaline granites is also not compatible with an oceanic accretionary wedge setting in the STS during the Permian or Triassic. Permian and Triassic zircon ages for subduction-related HP-LT metamorphic rocks and ophiolitic gabbro from the Atbashi and Djandjir ranges reported in two recent papers contradict geological relationships. A review of reported analytical data shows that anomalously young ages in all studied samples are based on geologically meaningless single zircon analyses and/or discordant data, which cannot be used for age calculation. The suggestion that an oceanic basin in the STS remained open and subduction continued until the Middle Triassic is erroneous because of insufficient consideration of basic regional geological relationships and incorrect interpretations of analytical results. [ABSTRACT FROM AUTHOR]

Abstract There are long–standing uncertainties over the deep crustal composition and basement nature of the Chinese Altai and Junggar orogens of the southwestern Central Asian Orogenic Belt (CAOB). Zircon Lu Hf isotopic tracer techniques applied to granitoids are helpful in distinguishing old from young deep crustal compositions. This study aims to characterize the basement nature (ancient & juvenile) of the Chinese Altai and East Junggar orogens using Hf isotopic mapping of granitoids (510–200 Ma). Zircon Hf isotopic data (18 new and 79 published samples) indicate that the study area can be divided into six Hf isotopic provinces on the basis of T DM C ages: Province I, >1.4 Ga; II, 1.4–1.2 Ga; III, 1.2–1.0 Ga; IV, 1.0–0.8 Ga; V, 0.8–0.6 Ga; and VI, 0.6–0.4 Ga. Provinces I, II, and III occur mainly in the central (units 2 and 3) and southern (unit 4) Altai orogen, and have slightly positive zircon ε Hf (t) values of +0.5 to +9.1 with slightly old T DM C ages of 1.53–0.81 Ga. Provinces IV and V are mainly distributed in the northern (unit 1) and southernmost (unit 5) Altai orogen, with zircon ε Hf (t) values of +7.5 to +11.1 and young T DM C ages of 0.84–0.60 Ga. In contrast, Province VI (East Junggar orogen) has zircon ε Hf (t) values of +11.6 to +14.9, with much younger T DM C ages of 0.59–0.35 Ga, except for the small Taheir area with a negative ε Hf (t) value of −2.5 and an older T DM C age of 2.5 Ga. There is a sharp contrast between the deep crustal compositions of the Altai and Junggar orogens, which are ancient in central Altai and relatively juvenile in East Junggar. This confirms that significant Neoproterozoic–Phanerozoic continental crustal growth occurred in the southern Altai and Junggar orogens, with juvenile crust occupying ~78% of the study area, and that the CAOB is a site of significant Phanerozoic continental growth. The distribution of juvenile and ancient crust in the Altai and East Junggar orogens provides new evidence for the tectonic division of the two orogens by the Erqis fault zone, and explains the heterogeneity of crustal growth in the southwestern CAOB. Highlights • Hf isotopic mapping determines six provinces in the Altai and East Junggar orogens. • These provinces indicate distinct basements between the two orogens. • Crustal growth is heterogeneous and its proportion reaches to ~78% in the study area. [ABSTRACT FROM AUTHOR]

Abstract Microcontinents with Precambrian basement have played an important role in the accretionary and amalgamation history of the Central Asian Orogenic Belt (CAOB). However, their geological evolution is only poorly constrained due to restricted exposure of the Precambrian rocks, which were extensively overprinted mainly by Paleozoic tectonic, metamorphic and magmatic events. In the present study, in situ zircon U–Pb age and Hf isotopic data of 64 Paleozoic and early Mesozoic (from 499 to 217 Ma) as well as 14 Mesoproterozoic and Neoproterozoic (from 1555 to 871 Ma) granitic samples from four major arc terranes of the Beishan orogen (southernmost CAOB) were compiled in order to assess the nature of their crustal basement as well as the subsequent Paleozoic tectonic evolution. Zircon ε Hf (t) values and calculated Hf model ages are similar for all arc terranes with Hf model age peaks at approximately 1.0–0.8 Ga and 2.0–1.8 Ga. We suggest that all of these Paleozoic arc terranes formed on a single, uniform Precambrian continental terrane. Furthermore, this continental terrane shows typical characteristics of Mesoproterozoic (~1.4 Ga) juvenile crustal growth, which may have been part of an extensive Mesoproterozoic continental terrane, now tectonically fragmented and located over a distance of more than a thousand kilometers in the southern CAOB. Among the cratons bordering the CAOB, Baltica displays most similarities with this continental terrane, while a Mesoproterozoic correlation with the Tarim Craton is rather questionable. [ABSTRACT FROM AUTHOR]

Abstract: The South Tien Shan (STS) belt results from the last collision event in the western Central Asian Orogenic Belt (CAOB). Understanding its formation is of prime importance in the general framework of the CAOB. The Atbashi Range preserves high‐P (HP) rocks along the STS suture, but still, its global metamorphic evolution remains poorly constrained. Several HP units have been identified: (a) a HP tectonic mélange including boudins of mafic eclogites in a sedimentary matrix, (b) a large (>100 km long) high‐P metasedimentary unit (HPMU) and (c) a lower blueschist facies accretionary prism. Raman Spectroscopy on carbonaceous material combined with phengite and chlorite multiequilibria and isochemical phase diagram modelling indicates that the HPMU recorded homogeneous P–T conditions of 23–25 kbar and 560–570°C along the whole unit. 40Ar/39Ar dating on phengite from the HPMU ranges between 328 and 319 Ma at regional scale. These ages are interpreted as (re‐) crystallization ages of phengite during Tmax conditions at a pressure range of 20–25 kbar. Thermobarometry on samples from the HP tectonic mélange provides similar metamorphic peak conditions. Thermobarometry on the blueschist to lower greenschist facies accretionary prism indicates that it underwent P–T conditions of 5–6 kbar and 290–340°C, highlighting a 17–20 kbar pressure gap between the HPMU‐tectonic mélange units and the accretionary prism. Comparison with available geochronological data suggests a very short time span between the prograde path (340 Ma), HP metamorphic peak (330 Ma), the Tmax (328–319 Ma) and the final exhumation of the HPMU (303–295 Ma). Extrusion of the HPMU, accommodated by a basal thrust and an upper detachment, was driven by buoyant forces from 70–75 km up to 60 km depth, which directly followed continental subduction and detachment of the HPMU. At crustal depths, extrusion was controlled by collisional tectonics up to shallow levels. Lithological homogeneity of the HPMU and its continental‐derived character from the North Tien Shan suggest this unit corresponds to the hyper‐extended continental margin of the Kazakh continent, subducted southward below the north continental active margin of the Tarim craton. Integration of the available geological data allows us to propose a general geodynamic scenario for Tien Shan during the Carboniferous with a combination of (a) N‐dipping subduction below the Kazakh margin of Middle Tien Shan until 390–340 Ma and (b) S‐dipping subduction of remaining Turkestan marginal basins between 340 and 320 Ma. [ABSTRACT FROM AUTHOR]

Oxygen fugacity is a key parameter in controlling the petrogenesis of mafic-ultramafic rocks and their associated sulfide mineralization, especially in convergent settings. This study uses new and previously published experimental data on olivine-sulfide pairs to reparameterize an expression for oxygen barometry using the distribution coefficient KDFeNi for Fe-Ni exchange between olivine and sulfide. We derive a new expression, ΔQFM = (9.775 + 0.416 ∙ CNi − KDFeNi)/4.308, where ΔQFM denotes divergence from the fayalite-magnetite-quartz buffer. The revised oxygen barometry has been applied to the Permian magmatic Ni-Cu deposits in the Central Asian Orogenic Belt, NW China. The Ni-Cu deposits in the East Tianshan—North Tianshan, Central Tianshan, and Beishan—are considered as a single mineral system, whereas the spatially separated deposits in the East Junggar are considered as a separate system. The deposit of the East Tianshan group exhibits a large range of oxygen fugacity (QFM − 2 to ~QFM + 1) and Ni tenor (metal concentration in pure sulfide, ~ 5 to 16 wt%). The Poyi and Huangshannan deposits contain high-Ni tenor sulfides, varying from 12 to 16 wt%. The relatively high Fo values (> 85 mol%) and Ni contents (> 2000 ppm) in olivine of these deposits indicate that the high-Ni tenor sulfides were segregated from less differentiated high-Ni magmas that also had relatively high oxygen fugacity (~QFM + 1). The remaining Ni-Cu deposits in the East Tianshan—the Huangshandong, Huangshanxi, Hulu, Tulaergen, Tudun, and Xiangshanzhong deposits—have intermediate Ni tenors (5-8 wt%). These sulfides correspond to intermediate Fo values (80-84 mol%) and Ni contents (700-1400 ppm) in the coexisting olivine, illustrating that they were segregated from magmas with lower Ni contents thought to be the result of a large amount (15-20%) of olivine fractionation at depth. These magmas are more reduced (− 2 < ΔQFM < + 0.3) than the less evolved magmas (~QFM + 1). It is shown that the ΔQFM value calculated for the deposits in East Tianshan decreases with decreasing Fo value, indicating that the host magmas became gradually reduced during evolution, which can be explained by primarily oxidizing magma progressively assimilating crustal material containing reducing agents, such as carbon. The Kalatongke deposit in the East Junggar belt, with the lowest Ni tenors in sulfides (3-5 wt%) and low Fo values in olivine (< 78 mol%), was derived from relatively oxidizing magmas (~QFM + 1) that had experienced significant olivine plus clinopyroxene and plagioclase fractionation at depth. We propose that the variation in oxygen fugacity and Ni tenor in the Permian Ni-Cu deposits in the Central Asian Orogenic Belt is the result of gradual contamination and a variable degree of fractional crystallization. [ABSTRACT FROM AUTHOR]

The largest mountain belt in Central Asia (∼9 million km2) is called the Altaids. It was assembled between ∼750 and ∼130 Ma ago around the western and southern margins of the Siberian Craton, partly on an older collisional system (the 'Urbaykalides'). Geological, geophysical, and geochemical data-mostly high-resolution U-Pb ages-document the growth of only three arc systems in Central and Northwest Asia during this time period, an interval throughout which there were no major arc or continental collisions in the area. While the Altaids were being constructed as a Turkic-type orogen, continental crust grew in them by 1/3 of the global total. The Altaids thus added some 3 million km2 to the continental crust over a period of 0.6 billion years, typical of Phanerozoic crustal growth rates. [ABSTRACT FROM AUTHOR]

The Paleo Asian Ocean underwent a protracted closure history during Late Paleozoic. Here we investigate the magmatic evolution during this process based on a detailed study in the Baiyinwula region along the Uliastai continental margin. The major rock types in this area are Late Carboniferous-Early Permian volcanic sequences and coeval intrusions. We identified four stages of magmatic evolution based on the diverse assemblages and their precise isotopic ages. The first stage is represented by andesites with a zircon 206 Pb/ 238 U age of ca. 326 ± 12 Ma. These rocks are metaluminous to weakly peraluminous, high-K calc-alkaline, and possess high Na 2 O/K 2 O ratios in the range of 1.23 to 2.45. They also display enrichment of large ion lithophile elements (LILE) and depletion of high field strength elements (HFSE), with markedly positive zircon ε Hf (t) varying from 8.1 to 15.6.The geochemical features of these andesites are similar to those of typical arc volcanic rocks. The second stage includes granodiorites emplaced at 318.6 + 1.8 Ma. The rocks are high-K calc-alkaline with A/CNK values ranging from 0.95 to 1.06, and show enrichment in LILE and depletion in HFSE. They show geochemical affinities to adakites, with high Sr and low Y and Yb contents, indicating magma derivation from thickened lower crust. Zircon grains from these rocks display positive initial ε Hf ( t ) values ranging from 11.1 to 14.6 with corresponding two-stage Hf model ages ( T DM2 ) of 394–622 Ma. The third stage consists of syenogranite together with a volcanic suite ranging in composition from rhyolite todacite, which formed during 303.4 ± 1.2 to 285.1 ± 2.2 Ma. They possess elevated silica and alkali contents, high FeOt/MgO and Ga/Al ratios, low Al 2 O 3 , MgO and CaO contents, and high Rb, Y, Nb, Ce, Zr, Y, and Ga contents, strong negative Ba, Sr and Eu anomalies, showing I- to A-type granitic affinities. Zircons in these rocks show elevated Hf isotopic compositions (ε Hf ( t ) = 9.9 to 14.6) with T DM2 varying from 324 to 673 Ma. The fourth magmatic pulse is represented by K-feldspar granite with zircon U-Pb ages from 283.2 ± 1.9 Ma to 280.0 ± 1.4 Ma, and typical alkalic A-type granite geochemistry. These rocks possess positive ε Hf ( t ) values in the range of 9.7 to15.2, and a restricted range of Hf model age from 327 to 684 Ma. The magmatic rocks from the four stages show comparable ε Hf ( t ) and T 2DM , suggesting that the magmas were derived from the same evolving mantle-derived source. We propose a tectonic model linking the evolution of the magmatism with the closure of the Paleo Asian Ocean that involved the following stages. The andesites were formed during the initial oceanic subduction stage with magma sourced from the metasomatized lithospheric mantle. Stage 2 adakite-like rocks were derived from subduction-induced thickened crust. Subsequent slab rollback resulted in asthenospheric upwelling and melting of residual juvenile crust to generate the I- and A- type syenogranite, rhyolite and dacite suite, finally followed by the A-type K-feldspar granite. [ABSTRACT FROM AUTHOR]

The detrital zircon geochronological record of Permian-Triassic clastic rocks of the Beishan region in the southern Central Asian orogenic belt indicates a pattern of cyclical, successive Paleozoic accretion events. Comparison of zircon age spectra derived from two individual arc terranes reveals similar age patterns offset by 30-40 m.y. Detrital samples with a provenance interpreted as the southern arc terrane indicate magmatic peaks at 275, 370, and 430 Ma with a 50 m.y. hiatus from 350 to 300 Ma. Samples with a provenance interpreted as the northern arc terrane exhibit a similar pattern yet with consistently earlier component peaks at 310, 400, and 445 Ma with a 40 m.y. hiatus from 380 to 340 Ma. This is interpreted to reflect that subduction developed successively between terranes and progressed until Silurian-Devonian sequential docking of the arcs along separate suture zones. Detrital geochronology of accreted sediments (single peak at 445 Ma) within the northern suture, with coincident tuff and pillow basalt U-Pb zircon ages of 409 ± 2.9 and 416.6 ± 15.0 Ma, respectively, may redefine a principal phase of amalgamation as Devonian, over previously interpreted ages in the Carboniferous-Permian. Initiation and cessation of arc magmatism are shown to correlate with regional phases of ophiolite generation and emplacement, respectively. This supports regional models that ophiolite belts in the Central Asian orogenic belt correlate with suture zones developed from multiple contemporaneous subduction systems between arcs. We explore whether a pericratonic archipelago of crustal slivers around the Tarim craton may have initiated successive arc formation. [ABSTRACT FROM AUTHOR]

Enhanced aridification of Central Asia driven by the combined effects of orogenic surface uplift, Paratethys retreat, changes in atmospheric moisture transport and global cooling is one of the most prominent Cenozoic climate change events of the Northern Hemisphere. Deciphering regional long-term patterns of Central Asian hydrology is, therefore, a key element in understanding the role of Northern Hemisphere mid-latitude drying in the global hydrological system. This study characterizes long-term palaeoenvironmental conditions between the late Oligocene and early Miocene in south-eastern Kazakhstan based on stable isotopes, elemental geochemistry and laser ablation uranium-lead geochronology from alluvial, fluvial and pedogenic deposits. Sedimentary facies and geochemical weathering indices suggest an increased surface and groundwater discharge fed by orographically enhanced precipitation in the Tien Shan hinterland. In contrast, pedogenic stable isotope data and elevated rates of magnesium fixation in clay minerals mirror enhanced rates of evaporation in the vadose zone due to protracted aridification. This study posits that pronounced surface uplift of the Tien Shan Mountains during the Oligocene-Miocene transition promoted regionally increased orographic precipitation and the development of fluvial discharge systems. [ABSTRACT FROM AUTHOR]

The Central Asian Orogenic Belt (CAOB) is regarded to have undergone multiple phases of intracontinental deformation during the Meso-Cenozoic. Located in a key position along the southern CAOB, the Alxa Tectonic Belt (ATB) connects the northernmost Tibetan Plateau with the Mongolian Plateau. In this paper we apply apatite U-Pb and fission track thermochronological studies on varieties of samples from the southwestern ATB, in order to constrain its thermal evolution. Precambrian bedrock samples yield late Ordovician-early Silurian (~ 430–450 Ma) and late Permian (~ 257 Ma) apatite U-Pb ages; the late Paleozoic magmatic-sedimentary samples yield relatively consistent early Permian ages from ~ 276 to 290 Ma. These data reveal that the ATB experienced multiple Paleozoic tectono-thermal events, as the samples passed through the apatite U-Pb closure temperature (~ 350–550 °C). We interpret these tectonic events to record the long-lived subduction-accretion processes of the Paleo-Asian Ocean during the formation of the southern CAOB, with possible thermal influence of the Permian Tarim mantle plume. Apatite fission track (AFT) data and thermal history modelling reveal discrete low-temperature thermal events for the ATB, inducing cooling/reheating through the AFT partial annealing zone (~ 120–60 °C). During the Permian, the samples underwent rapid cooling via exhumation or denudation from deep crustal levels to temperatures < 200 °C. Subsequent thermal events in the Triassic were thought to be associated with the final amalgamation of the CAOB or the closure of the Paleotethys. During the Jurassic-Cretaceous the study area experienced heating by burial, followed by renewed cooling, which may be related with the construction and subsequent collapse of the Mongol-Okhotsk Orogeny, or the Lhasa-Eurasia collision and subsequent slab break-off. These results indicate that the ATB may have been stable after late Cretaceous in contrast to the Qilian Shan and Tianshan. Finally, our results indicate differential exhumation scenario occurred across the southwestern ATB during the Cretaceous. [ABSTRACT FROM AUTHOR]

The North Tianshan and East Junggar belts in north Xinjiang, China, are two key terranes for the Paleozoic tectonic reconstruction of the Central Asian Orogenic Belt (CAOB). However, their Carboniferous paleogeographic setting and arc-basin relationships remain disputed. To better-constrain these problems, we carried out an investigation on the provenance of Carboniferous sandstones from the Yaomoliang Formation in East Junggar and the Qijiaojing Formation in North Tianshan. Modal and geochemical analyses reveal that the sediments are mainly derived from arc-related terranes. Detrital zircon U-Pb age spectra show distinct differences between the East Junggar and North Tianshan belts. The upper Yaomoliang Formation has a Late Carboniferous depositional age (ca. 315 Ma) with a single peak spectrum of detrital zircon ages, which is similar with zircon ages from the igneous rocks and associated accretionary complexes in East Junggar belt, suggesting that it was probably derived from the East Junggar arc. The samples from the Qijiaojing Formation have Early Carboniferous depositional ages (ca. 330 Ma to 354 Ma). Their complicated detrital zircon age peaks resemble the detrital and igneous zircon ages from the Harlik-Dananhu arc, implying that their source terrane could be the Harlik-Dananhu arc, as revealed by the near-source petrographic and arc-derived geochemical features. In combination with our results and the published data, we suggest two distinctive Carboniferous arc-basin systems, the Kelamaili Ocean-related arc-basin which is characterized by the northward subduction beneath the East Junggar arc, and the Bogda intra-arc basin which evolved from splitting the previous Harlik-Dananhu arc by the rollback of the subducting North Tianshan oceanic plate. The sedimentary provenance evidence reveals that the Kelamaili Ocean has not closed until ca. 315 Ma. The multiple arc-basin systems in North Xinjiang indicate an archipelago-type subduction and accretionary scenario in the evolution of southwestern CAOB during the Carboniferous. [ABSTRACT FROM AUTHOR]

The Tuva-Mongolian terrane of the Central Asian Orogenic Belt is a composite structure with a Vendian-Cambrian terrigenous-carbonate cover. The Sangilen block in the southern part of the belt is a smaller composite structure, in which tectono-stratigraphic complexes of different age that were produced under various conditions were amalgamated in the course of Early Paleozoic tectonic cycle. The P-T parameters of the Early Paleozoic metamorphism in the western part of the Sangilen block corresponded to the amphibolite facies. The gneisses of the Erzin Complex contain relict granulite-facies mineral assemblages. The granulites are dominated by metasediments typical of deep-water basins on passive continental margins. The only exception is granulites of the Lower Erzin tectonic nappe of the Chinchlig thrust system: these rocks are metatholeiites, tonalites, and trondhjemites, whose REE patterns are similar to those of MORB. The composition of these granulites and their high Sm/Nd ratios indicate that the rocks were derived from juvenile crust that had been formed in an environment of a mature island arc or backarc basin. It is reasonable to believe that these rocks are fragments of the Late Riphean basement of the Sangilen block. The average Pb/U zircon age of the garnet-hypersthene granulites is 494 ± 11 Ma. With regard for the zircon age of the postmetamorphic granitoids, the granulite-facies metamorphism occurred within the age range of 505-495 Ma. The peak metamorphic temperature reached 910-950°C, and the pressure was 3-4 kbar, which corresponds to ultrahigh-temperature/low-pressure (UHT-LP) metamorphism. The garnet-hypersthene orthogranulites were formed at a temperature that decreased to ~850°C and pressure that increased to ~5.5-7 kbar. It can be hypothesized that the earlier UHT-LP granulites were produced at an elevated heat flux and were later (in the course of continuing collision) overlain by a relatively cold tectonic slab, and this leads to a certain temperature decrease and pressure increase. This relatively cold slab could consist of fragments of the Vendian elevated-pressure metamorphic belt whose development terminated at the Vendian-Cambrian boundary before the onset of the Early Paleozoic regional metamorphism. [ABSTRACT FROM AUTHOR]

The article focuses on the study using Detrital Zircon Geochronology conducted on sandstones from Kaishantun (KST) Formation and Kedao (KD) Group in Yanbian Area, to ascertain the final closure of the Paleo-Asian Ocean (PAO) in the eastern segment of Central Asian Orogenic Belt (CAOB) in North East China. Tables and Diagrams are presented to support the study.

The modern geodynamic transformations of the Amur geoblock are related to the activation of pull-apart-strike-slip and simple strike-slip movements. These movements resulted in the formation of destruction zones along ancient transregional fault systems (Nenjiang-Selemdzha, Lermontovka-Belogorsk, West Turan, Khingan, Tan Lu, and others) and young NW- and WE-trending fractures with distinctly expressed shearing displacements. These processes are fixed by earthquakes, focal magmatism, pulsed degassing of the Earth's interior, and fluid discharge. High-permeability structures confined to the juncture of the destruction zones and young fractures served as the deep degassing drainage systems. These structures are traced by decompaction fields and anomalies of He and other gases. The most contrasting Varvarovka anomaly is located in the northeastern flank of the Yerkovtsy brown coal deposit. The paleogene coal-bearing rocks studied in the Yuzhny quarry within this deposit are characterized by high contents of noble, rare metals, and rare-earth elements, which frequently exceed their average abundances by ten orders of magnitude. Based on assay analysis, the Au content in the coals varies from trace amounts to 4.6 ppm. [ABSTRACT FROM AUTHOR]

Based on the results of Sm-Nd isotopic geochemical and U-Th-Pb geochronological LA-ICP-MS studies, it has been established that the formation of metamorphic rock protoliths of the Stanovoi Complex in the western Dzhugdzhur-Stanovoi Superterrane of the Central Asian Foldbelt took place over the following time spans: 2750-2860 Ma (Ilikan Group of the Ilikan Zone), 1890-1910 Ma (Bryanta Group of the Bryanta Zone), and ~2.0 Ga (Kupuri and Zeya groups of the Kupuri and Zeya zones, respectively). It has been shown that the western part of the Dzhugdzhur-Stanovoi Superterrane was formed ~1.9 Ga ago, as a result of collision of the Neoarchean Ilikan Terrane, the Paleoproterozoic island arc, and the Paleoproterozoic Kupuri-Zeya Terrane. The data make it possible to consider the Kurul'ta, and Zverevo blocks of the Stanovoi Structural Suture and the Ilikan Terrane of the Dzhugdzhur-Stanovoi Superterrane of the Central Asian Foldbelt as constituents of a common terrane. [ABSTRACT FROM AUTHOR]

An early extensive Neoproterozoic (ca. 900 Ma) continental magmatic arc system covering hundreds of kilometers has been reported to occur in the South Beishan Orogenic Belt (SBOB) and the Central Tianshan (CTA) in the southern Central Asian Orogenic Belt (CAOB). However, evidence for coeval high-grade metamorphism and thus the formation of an accretionary orogen in the framework of Rodinia is ambiguous or absent. This study provides new petrological, geochemical and geochronological data for garnet-bearing schists (quartz + garnet + biotite + plagioclase ± muscovite) from the SBOB in order to constrain its Neoproterozoic metamorphic history. The metamorphic zircon rims are either unzoned or display sector zoning in CL-images and reveal REE patterns with flat HREE patterns and negative Eu anomalies, which are interpreted to be in chemical equilibrium with garnet and plagioclase. The zircon U-Pb dating yields concordant U-Pb ages of 900 ± 3 Ma, 897 ± 2 Ma and 898 ± 4 Ma for the metamorphic zircon rims. The inherited detrital zircon cores of one sample display a concordant U-Pb age of 1397 ± 5 Ma that is consistent with the timing of formation for the extensive Mesoproterozoic continental arc in the SBOB and CTA. Based on phase equilibrium geothermobarometry and average P-T thermobarometric calculations, minimum amphibolite-facies P-T conditions are estimated to be >600 °C at pressure >0.6 GPa, which is thought to have been overprinted by subsequent Paleozoic metamorphism. However, the Ti-in-zircon thermometer still reveals temperatures of up to 840 °C using the composition of metamorphic zircon rims, suggesting former ca. 900 Ma granulite-facies peak metamorphic temperatures. The combined petrological and geochronological evidence in conjunction with the continental affinity of the regional metamorphic rocks suggests that the SBOB and the eastern CTA experienced an early Neoproterozoic accretionary orogenesis during the final assembly stage of Rodinia. [ABSTRACT FROM AUTHOR]