Search

The East Junggar is a key to understanding the accretionary history of the southern Altaids. However, the tectonic setting and amalgamation history of the East Junggar during the Carboniferous–Permian remain controversial. Here we report new field, geochronological and geochemical data for the Carboniferous–Permian volcanic and sedimentary rocks from the Jiangjun unit and the Hongliugou ophiolitic complex of East Junggar to constrain its tectonic evolution. Carboniferous volcanic rocks, with zircon and apatite U–Pb ages from 337 ± 2 to 303 ± 32 Ma, display arc-related geochemical characteristics. Carboniferous–Permian sedimentary rocks predominantly contain Carboniferous–Permian detrital zircons and have maximum depositional ages from 318 ± 5 to 281 ± 6 Ma. Provenance analysis indicates that the sediments from the west Jiangjun unit were sourced from the Yemaquan arc and those from the east Jiangjun unit may be sourced solely from a new intra-oceanic arc. Integrated data indicate that Carboniferous–Permian strata in the Jiangjun unit were formed in the intra-oceanic arc setting that remained until the middle Permian. These analyses suggest an amalgamation process of multiple convergence and accretion for the southern Altaids during the formation of NE Pangaea in the late Paleozoic. [ABSTRACT FROM AUTHOR]

The Central Asian Orogenic Belt involves amalgamation of numerous magmatic arcs, accretionary complexes and continental fragments during long-lived subduction and accretion. However, the nature of key microcontinental terranes, as well as their continuity, remains unclear. This study conducted outcrop observation, heavy mineral assemblage, whole-rock geochemistry, detrital zircon U–Pb dating and Lu–Hf isotope analysis on sandstones in the Beishan orogenic belt. The findings from field observations, petrographic analysis and weathering indices show that the tectonic setting of the sandstone is a forearc sedimentary basin. The maximum depositional ages (MDAs) of sandstones are 503.8 ± 6.9 Ma and 431.9 ± 6.0 Ma. The provenance of the sandstone is complex, which probably originates from the Shuangyingshan and Hanshan blocks. By comparing the detrital zircon U–Pb ages with adjacent terranes such as Central Tianshan, Dunhuang and Tarim, it was observed that the Shuangyingshan block shares similar provenance with the Dunhuang terrane, while the Mazongshan–Hanshan shows affinity to the Central Tianshan terrane. This study highlights the complex nature of sediment provenance in the Beishan orogenic belt, influenced by tectonic processes involving thrusting, accretionary complexes and the presence of multiple terranes. [ABSTRACT FROM AUTHOR]

Subduction processes of Eastern Tianshan are crucial to understanding the mechanism of the orogenic evolution of the southern Altaids. To identify whether the tectonic setting of the Late Carboniferous or later was continuous subduction, we present a systematic study on Late Carboniferous magmatic rocks exposed continuously in time and space in the Weiya area, which were mainly derived from crustal materials with involvement of mantle-derived materials in a subduction-related setting. Our newly discovered 319 Ma A-type granites imply an extensional environment; 306 Ma diorites were derived from thickened crust. Combined with published data, we propose that rollback of the southward-subducted North Tianshan oceanic plate induced subduction retreating and tectonic extension in the Yamansu–Central Tianshan arc from 324 to 318 Ma. It was followed by advancing subduction from 315 to 301 Ma, during which the crust of the arc was thickened, and much more crustal material was involved in subduction-related magmatism. In the Early Permian, the arc was in an extensional environment followed by a change in the movement direction of the subducting plate, rather than in a post-orogenic setting. The final closure of the North Tianshan Ocean was likely completed in the Middle Triassic. Supplementary material: Field photographs and photomicrographs, zircon U–Pb and Lu–Hf isotopic data, whole-rock major and trace element data, and compiled geochronological and Lu–Hf isotopic data are available at https://doi.org/10.6084/m9.figshare.c.7038686 Thematic collection: This article is part of the Processes of Pangea construction collection available at: https://www.lyellcollection.org/topic/collections/processes-of-pangea-construction [ABSTRACT FROM AUTHOR]

Mantle heterogeneity has revealed systematic differences in Pb isotopic compositions between the Indian Ocean-South Atlantic mantle in the Southern Hemisphere and the Pacific Ocean-North Atlantic mantle in the Northern Hemisphere. This large-scale difference in mantle isotopes in the Southern Hemisphere is known as the DUPAL anomaly, but its origin remains controversial. Based on a systematic review of the Nd-Pb isotopic evolution of the Tethyan mantle domain, this study identified the long-term presence of the DUPAL anomaly in this domain since the early Paleozoic, characterized by long-term and high mantle thorium/uranium (Th/U) ratios. By comparing the Nd-Pb isotopic compositions of the Tethyan mantle domain with the Panthalassic-Pacific mantle domain (the Paleo-Asian, Paleo-Pacific, and modern Pacific oceans), it is shown that the mantle initially had low Th/U features due to early Earth crust-mantle differentiation, with the crust having high Th/U ratios. As such, the mantle initially had uniformly low Th/U ratios that were inherited throughout the Panthalassic-Pacific mantle domain. However, the plate tectonics and continental collisions in the Tethyan domain affected its characteristics, leading to the long-term and large-scale DUPAL anomaly. During the opening of and subduction in the Tethys Ocean, Gondwanaland fragmentation and frequent continent-continent collisions led to long-term and extensive crust-mantle interactions and the continuous input of high-Th/U mantle sources, which thus modified the mantle. This process formed not only the unique DUPAL anomaly in the Tethyan mantle domain, but also the Tethyan tectonic domain dominated by continental collisions. Moreover, the high DUPAL anomaly in the Proto- and Paleo-Tethyan mantle domains records the effects of mantle plumes, which might have occurred primarily during the formation of the Proto- and Paleo-Tethys oceans during the early evolution of the Tethyan domain. Therefore, the inherent coupling of mantle domain properties and plate tectonic mechanisms provides important insights for understanding plate tectonics and geodynamic processes in the Tethyan domain.

The Central Asian Orogenic Belt represents a Late Paleozoic archipelago, but crustal growth and the reworking and exhumation of the individual microcontinental massifs remain poorly constrained. Here, we use the Axi epithermal deposit to examine continental preservation and exhumation in the Central Asian Orogenic Belt of the Chinese Western Tianshan region. Zircon U–Pb dating and geochemistry demonstrate that the andesitic host rock formed via the incremental addition of magma in an Andean-type magmatic arc setting at 362, 354 and 342 Ma. Pyrite Re–Os data and textural evidence reveal two mineralization events at 355 and 332 Ma. Zircon (U–Th)/He data reveal temperatures of c. 180°C until 317.8 ± 9.8 Ma, which is interpreted to record the timing of exhumation of the andesite and gold ore bodies prior to their burial by Carboniferous-age sediments. Further sedimentary concealment continued until the Late Mesozoic when the system was re-exhumed between 148.6 ± 8.6 and 120.0 ± 13 Ma at a rate of c. 9.8 m Ma−1, as shown by apatite (U–Th)/He data. Collectively, the geochronology/thermochronology data show that the Chinese Western Tianshan region records a transition from compressional to extensional tectonism during the Late Paleozoic and Late Mesozoic. The shallow epithermal mineralization was protected from erosion by post-mineralization deposition. Supplementary material: Trace element and zircon U–Pb data for the andesitic host are available at https://doi.org/10.6084/m9.figshare.c.6640014 [ABSTRACT FROM AUTHOR]

Cenozoic uplift in the Tianshan played an important role in driving Proto‐Paratethys Sea retreat and Asian aridification. However, most paleoclimate studies have focused on the Pamir‐Tianshan corridor, and frequently overlook the role of the entire Tianshan range in modifying the Central Asian climate during Cenozoic uplift. When and how Cenozoic deformation of Tianshan was initiated and propagated are intensively debated which makes its role in contributing to climate change in Central Asia more ambiguous. To address this issue, this study presents new detrital zircon U‐Pb and detrital apatite U‐Pb and fission track age data from Cenozoic sedimentary successions (54–0 Ma) in the northern margin of the Tarim Basin and integrates these data with published provenance data from adjacent regions. Our results show that deformation/uplift of the Baicheng‐Kuqa Depression and the South Tianshan occurred at ∼41–37 Ma and ∼24 Ma, when topographic growth of South Tianshan began to block the flow of sediment from the north. Continued uplift of the South Tianshan completely blocked fluvial transport from the Central Tianshan‐Yili Block by ∼10 Ma, as shown by the paucity of 380–310 Ma detrital zircons/apatites. Far‐field, north‐directed compressive stress resulting from the India‐Asia collision began to propagate toward the South Tianshan and its foreland during the Late Eocene, and continued to propagate into the South Tianshan and northward at the ∼24 Ma and 10 Ma. Finally, we suggest a two‐stage of aridification in the Tarim Basin which can be linked to two stages (∼24 and 10 Ma) of growth of the Tianshan. The Tarim Basin and the Taklimakan Desert are located in Central Asia, between the Tibetan Plateau to the south and the Tianshan orogenic belt to the north. This region is a crucial area for exploring the primary drivers of Cenozoic desertification. We performed a systematic zircon and apatite provenance study (including detrital apatite and zircon U‐Pb dating, and detrital apatite fission track analysis) in Cenozoic strata from the northern margin of the Tarim Basin. Our results reveal pulsed deformation of the South Tianshan that initiated at ∼41–37 Ma with two subsequent pulses at ∼24 Ma and ∼10 Ma, the timing of which suggests a close link to the two‐step aridification (∼24 and 10 Ma) of the Tarim Basin. We suggest that the pulsed Cenozoic rise and growth of the South Tianshan played a crucial role in blocking westerly winds, restricting moisture from reaching the Tarim Basin, and driving Cenozoic aridification of the Tarim Basin. Initiation of the Cenozoic uplift of the South Tianshan occurred in the Late EoceneFurther uplift of the South Tianshan completely blocked fluvial transport from the north by ∼10 MaPulsed growth of Tianshan play a dominant role in the two‐step aridification of the Tarim Basin Initiation of the Cenozoic uplift of the South Tianshan occurred in the Late Eocene Further uplift of the South Tianshan completely blocked fluvial transport from the north by ∼10 Ma Pulsed growth of Tianshan play a dominant role in the two‐step aridification of the Tarim Basin

Full‐waveform inversion of surface waves can provide high‐resolution S‐wave velocity (Vs) of the shallow subsurface and is becoming a popular shallow‐seismic method. We propose a misfit function based on instantaneous‐phase coherency, which can measure the amplitude‐unbiased coherency between measured and synthetic data. The instantaneous‐phase coherency was once the key component that was used in the phase‐weight stacking technology to enhance the weak but coherent signals. Using synthetic data, we show that our full‐waveform inversion approach based on the proposed misfit function is robust in reconstructing subsurface anomalies from data contaminated by random noise. We also show that our misfit function is robust against the errors in the estimated source wavelets. We then choose to use published field data acquired at an archaeological site as a benchmark dataset to test the performance of our full‐waveform inversion in a real environment. Subsurface structures identified in our inversion results are verified by an independent archaeological excavation, while the results from conventional full‐waveform inversion are dominated by artefacts. The results of synthetic tests and field data experiments demonstrate the robustness of our full‐waveform inversion approach in reconstructing the shallow subsurface structure from field data, where amplitude information of recorded wavefield may not be correctly recorded.

The Central Tianshan Block is one of numerous microcontinental blocks within the Central Asian Orogenic Belt (CAOB) that overlies Precambrian basement rocks. Constraining the evolution of these ancient basement rocks is central to understanding the accretionary and collisional tectonics of the CAOB, and their place within the Rodinia supercontinent. However, to date, the timing and tectonic settings in which the basement rocks in the Central Tianshan Block formed are poorly constrained, with only sparse geochemical and geochronological data from granitic rocks within the northern segment of the block. Here, we present a systematic study combining U-Pb geochronology, whole-rock geochemistry, and the Sr-Nd isotopic compositions of newly-identified granitic gneisses from the Bingdaban area of Central Tianshan Block. The analyzed samples yield a weighted mean Neoproterozoic 206Pb/238U ages of 975–911 Ma. These weakly-peraluminous granitic rocks show a common geochemical I-type granite affinity. The granitic gneisses are calc-alkaline and enriched in large ion lithophile elements (LILEs) and light rare earth elements (LREEs), but they are depleted in high field strength elements (HFSEs); these characteristics are similar to those of typical subduction-related magmatism. All samples show initial (87Sr/86Sr)(t)ratios between 0.705136 and 0.706745. Values for ƐNd(t)in the granitic gneisses are in the range from −5.7 to −1.2, which correspond to Nd model ages of 2.0–1.7 Ga, indicating a role for Mesoproterozoic to Paleoproterozoic rocks in the generation of the granitic protoliths. The documented geochemical features indicate that the protoliths for the gneisses have a similar petrogenesis and magmatic source, which may reflect partial melting of thickened crust with the addition of small amounts of mantle-derived material. The Central Tianshan Block probably constitute part of an exterior orogen that developed along the margin of the Rodinian supercontinent during the Early Neoproterozoic and underwent a transition from subduction to syn-collision compression at 975–911 Ma.

The accretionary complex (AC) in the North Qilian belt comprises coherent and chaotic units consisting of bedded cherts, pelagic mudstone, shale, turbidites, basalt, limestone, blueschist, eclogite lenses and ophiolitic mélange. Cherts from the Donggoukou and Biandukou outcrops in the north of the blueschist belt contain abundant Middle Ordovician radiolarians together with rare conodonts. Well-preserved radiolarians also occur in cherts associated with high-pressure/low-temperature rocks in the Baijingsi AC outcrop. Conodonts of Floian–Dapingian age and Middle Ordovician radiolarians also occur in the Shihuigou AC. Geochemical analysis of 23 cherts reveals variable SiO2 contents (74.56–97.16 wt%) and high mean Al/(Al + Fe + Mn) ratios ranging from 0.35 to 0.85, indicating a non-hydrothermal origin. Ce/Ce* and LaN/YbN ratios of 0.70–1.22 and 0.67–1.59 respectively are high and variable, similar to those of associated muddy siltstone (0.59–0.96 and 1.14–1.55, respectively), suggesting near-trench deposition with associated terrigenous input. Together with the metamorphic ages of blueschists and eclogites, the North Qilian belt AC formed by accretion of ocean plate stratigraphic successions in response to subduction of the Proto-Tethyan Ocean prior to 450 Ma. Supplementary material: Appendices 1-6 are available at: https://doi.org/10.6084/m9.figshare.c.5418275 Thematic collection: This article is part of the Fold-and-thrust belts collection available at: https://www.lyellcollection.org/cc/fold-and-thrust-belts [ABSTRACT FROM AUTHOR]

West Junggar is a key area for understanding intra-oceanic plate subduction and the final closure of the Junggar Ocean. Knowledge of the Carboniferous tectonic evolution of the Junggar Ocean region is required for understanding the tectonic framework and accretionary processes in West Junggar, Central Asian Orogenic Belt. A series of Early Carboniferous volcanic and intrusive rocks, namely, basaltic andesite, andesite, dacite, and diorite, occur in the Mayile area of southern West Junggar, northwestern China. Our new LA-ICPMS zircon U-Pb geochronological data reveal that diorite intruded at 334 (±1) Ma, and that basaltic andesite was erupted at 334 (±4) Ma. These intrusive and volcanic rocks are calc-alkaline, display moderate MgO (1.62%–4.18%) contents and Mg# values (40–59), and low Cr (14.5×10−6–47.2×10−6) and Ni (7.5×10−6–34.6×10−6) contents, and are characterized by enrichment in light rare-earth elements and large-ion lithophile elements and depletion in heavy rare-earth elements and high-field-strength elements, meaning that they belong to typical subduction-zone island-arc magma. The samples show low initial 87Sr/86Sr ratios (range of 0.703649–0.705008), positive εNd(t)values (range of 4.8–6.2 and mean of 5.4), and young TDMNd model ages ranging from 1016 to 616 Ma, indicating a magmatic origin from depleted mantle involving partial melting of 10%–25% garnet and spinel lherzolite. Combining our results with those of previous studies, we suggest that these rocks were formed as a result of northwestward subduction of the Junggar oceanic plate, which caused partial melting of sub-arc mantle. We conclude that intra-oceanic arc magmatism was extensive in West Junggar during the Early Carboniferous.

Compressive stress generated at collision fronts can propagate over long distances, inducing deformation within the continent's interior. Nevertheless, the factors governing the partitioning of intracontinental deformation remain enigmatic. The Altai Mountains serve as a type‐example of ongoing intracontinental deformation. Here, we investigate the crustal architecture of the Chinese Altai Mountains, using receiver functions obtained from newly deployed dense seismic nodal arrays. The new seismic results reveal distinct crustal features, including (a) a negative polarity discontinuity beneath Chinese Altai Mountains, suggesting a low‐velocity layer; (b) a north‐dipping mid‐crustal structure beneath the suture zone between East Junggar and Chinese Altai, indicating underthrusting of East Junggar's lower crust beneath the Chinese Altai Mountains; (c) a double Moho structure beneath East Junggar, revealing a high‐velocity lower crustal layer. In conjunction with constraints from previous multi‐disciplinary regional studies, the double Moho structures are interpreted as mafic restite from Late Paleozoic magma underplating. The addition of mafic materials can significantly enhance the rheological strength of East Junggar's crust, causing it to function as an indenter that thrust beneath the Chinese Altai Mountains during the subsequent convergence process. As a consequence, significant deformation occurs in the Chinese Altai region, resulting in the emergence of decollements, as evident by the negative polarity discontinuity. The presence of pre‐existing decollements makes the Altai Mountains region more susceptible to deformation, thereby facilitating the concentration of intracontinental deformation. These findings illuminate the evolution history of the Chinese Altai Mountains and highlight the great impacts of ancient tectonics on intracontinental deformation partitioning. The factors that control how deformation is distributed within mountains located within continents are still not fully understood. In this study, we focused on the Altai Mountains to bring clarity to this topic. We used a new kind of seismic data to create images of the underground structures in the East Junggar‐Altai area. By combining information from previous studies in the region, we built a picture of how this area has changed since the Late Paleozoic era. During the Late Paleozoic period, the East Junggar region's crust became stronger due to a process involving molten rock moving upward and hardening beneath it. As a result, it was pushed below the Altai Mountains in a convergence event. This convergence caused extensive changes in the Altai Mountains' crust, creating a weakened section near the surface. The crustal properties and structures formed from ancient tectonic activities during the Paleozoic era have been preserved over time. This has made the Altai Mountains particularly prone to experiencing more recent deformations within the continent. Our findings emphasize how important ancient tectonic events are in determining how deformation is spread within continents. High‐resolution images of crustal structures of the East Junggar‐Altai area were obtained from newly deployed dense seismic arraysNew constraints have emerged in the evolutionary history of the Chinese Altai‐East Junggar regions since the Late PaleozoicInherited crustal structures and properties arose from the Paleozoic tectonics govern the partitioning of the intracontinental deformation High‐resolution images of crustal structures of the East Junggar‐Altai area were obtained from newly deployed dense seismic arrays New constraints have emerged in the evolutionary history of the Chinese Altai‐East Junggar regions since the Late Paleozoic Inherited crustal structures and properties arose from the Paleozoic tectonics govern the partitioning of the intracontinental deformation

Alxa occupies a crucial position between the Tianshan–Beishan orogen to the west and the Solonker suture to the east and is important in our understanding of the accretionary orogenesis of the southern Altaids. To unravel the tectonic history of the Alxa region, we undertook an integrated study of the field geology, geochemistry and geochronology of magmatic rocks and an accretionary complex. Six granites and one rhyolite from the Zhusileng–Hangwula arc show a peraluminous, high-K calc-alkaline composition and one gabbro is tholeiitic. They show patterns rich in incompatible elements and negative Nb–Ta anomalies on primitive mantle-normalized trace element spider diagrams. Laser ablation inductively coupled plasma mass spectrometry zircon U–Pb dating reveals 348–329 and 267–250 Ma magmatic events. These data indicate that the Zhusileng–Hangwula arc was a Japan-type island arc from the late Paleozoic to Early Triassic. The Engger Us mélange comprises pillow basalts with a normal-type mid-ocean ridge basalt composition, tuffs, cherts, siliceous mudstones, limestones and turbidites, which are tectonically juxtaposed by a block-in-matrix structure. This mélange is interpreted as a Carboniferous–Permian accretionary complex. These new data, combined with previous studies, confirm that the Palaeo-Asian Ocean subducted bidirectionally in the Alxa region in the Carboniferous–Early Triassic. A consistent divergent subduction system existed from Alxa to Solonker before the terminal closure of the Palaeo-Asian Ocean in the Mid- to Late Triassic. Supplementary material: Major and trace element data and zircon U-Pb age results of all the samples are available at: https://doi.org/10.6084/m9.figshare.c.4962230 [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.

Numerous continents have rifted and drifted away from Gondwana to repeatedly open ocean basins over the past ∼500 million years. These Gondwana-derived continents drifted towards and collided with components of the Eurasian continent to successively close the preexisting oceans between the two. Plate tectonics satisfactorily describes the continental drift from Gondwana to Eurasia but does not define the geodynamic mechanism of continuously rifting to collisions of continents in the Tethyan Realm. After reappraisal of geological records of the rift, collision and subduction initiation from the surface and various geophysical observations from depth, we propose that Eurasia-directed subducting oceanic slabs would have driven Tethyan system in the Phanerozoic. The Eurasia-directed subduction would have dragged the passive Gondwana margin to rift and drift northwards, giving birth to new oceans since the Paleozoic. The closure of preexisting oceans between the Gondwana-derived continents and Eurasia led to continental collisions, which would have induced the initiation of oceanic subduction in the Tethyan Realm. Multiple episodic switches between collision-subduction-rift repeatedly led to the separation of continental fragments from Gondwana and dragged them to drift towards Eurasia. The final disappearance of Neo-Tethys would have induced collision of the Gondwana-derived continents with the Eurasian continent, giving rise to the Cenozoic Alpine-Zagros-Himalayan collisional system. Therefore, the Eurasia-directed oceanic subduction would have acted as a ‘one-way train’ that successively transferred the ruptured Gondwana continental fragments in the south, into the terminal in the north. In this regard, the engine of this “Tethyan one-way train” is the negative buoyancy of subducting oceanic slabs.

The Kangurtag belt in the Eastern Tianshan, connecting the Dananhu Arc with the Central Tianshan Arc, contains diagnostic rocks of accretionary origin, and thus provides key information about the evolution of the North Tianshan Ocean. The Southern Kangurtag belt is composed of two types of mélange. Type I mélange consists of Enriched Mid‐Ocean Ridge Basalt‐type pillow basalts, draped by biohermal limestones and carbonate‐siliceous sediments of a slope facies, and siliceous argillites from a hemipelagic‐pelagic environment that together make up a seamount assemblage. In Type II mélange, Normal Mid‐Ocean Ridge Basalt and ribbon cherts were dismembered and entrained in a clastic matrix, showing a “block‐in‐matrix” structure. Detrital zircons of four sandstones from Devonian and Carboniferous strata within the mélanges have a predominant age population of 410–430 Ma and a distinct Proterozoic cluster around 1.4–1.6 Ga. The εHf(t) values of Phanerozoic zircons range from −25.1 to +8.6. Such age patterns, typical of the Central Tianshan Arc, and the Hf isotopic data indicate that these sedimentary successions were deposited on the northern margin of the Central Tianshan Arc. The youngest detrital zircon age of 317 Ma provides an upper limit for the time of formation of the Southern Kangurtag accretionary complex. Therefore, we suggest that the Southern Kangurtag belt comprises an accretionary complex that developed during southward subduction of the North Tianshan Ocean beneath the Central Tianshan Arc. This subduction began in the Early Ordovician and may have lasted until the Late Carboniferous–Permian. Two types of mélange are recognized in the Southern Kangurtag accretionary complexComposition and detrital zircon U‐Pb‐Hf isotopic data from sandstones indicate that they were deposited on the margin of the Central TianshanSouthward subduction of the North Tianshan Ocean may have lasted until the Late Carboniferous‐Permian

•Four ophiolitic mélanges in the Junggar region, southern Altaids were studied.•Ophiolitic mélanges juxtapose ophiolite suites with multi-stage magmatic rocks.•Ophiolitic mélanges underwent dismembering by multi-stage deformations.•Mélanges record processes from mid-ocean ridge to supra- and post-subduction zones.

•Lüliangshan Cu deposit in the North Qaidam belt is an ophiolite-hosted VMS deposit.•Ore-hosting rocks generated in a ridge-proximal environment during early-stage subduction.•Formation of the Cu deposit is related to forearc spreading in the early Cambrian.

The timing of final subduction and closure of the Paleo‐Asian Ocean (PAO) is controversial. Located in a key position within the southern Central Asian Orogenic Belt, the Alxa Tectonic Belt (ATB) provides a crucial window to evaluate the final subduction processes of the PAO. This study presents field and geochronological data for Permian volcano‐sedimentary rocks from the southwestern ATB. Field observations revealed a syntectonic unconformity between the Middle and Upper Permian strata. Detrital zircon U‐Pb analyses show a major peak at ~273 Ma and a subordinate peak at ~440 Ma for the Middle Permian sample. The Upper Permian samples show consistently unimodal age spectra with single peaks at ~261 and ~263 Ma, respectively. The Permian zircons from the analyzed samples yield predominately positive εHf(t) values, indicating major juvenile magmatic processes mixed with limited recycled Precambrian basement. The diagnostic zircon U‐Pb‐Hf isotopic characteristics and ubiquitous intermediate and felsic volcanic detritus in these rocks indicate rapid sediments accumulation sourced from a proximal magmatic terrane in a suprasubduction zone environment. The Paleozoic zircon U‐Pb age peaks from this study are comparable to those for the Permian arc‐related sediments along the Solonker Suture Zone, thus linking the Alxa active margin with the northern margin of the North China Craton during Middle‐Late Permian times. Our study thus provides key constraints for the final subduction processes of the PAO, documented within the ATB, before the terminal amalgamation of the southern Central Asian Orogenic Belt. Syndepositional volcanism and tectonism exist within Permian volcano‐sedimentary rocks in the southwestern Alxa Tectonic BeltSedimentological, compositional, and zircon U‐Pb‐Hf isotopic data point to a subduction zone setting in Alxa area until Late PermianPermian subduction and accretion processes existed along the southern Central Asian Orogenic Belt

The pattern and timing of collision between India and Eurasia have long been a major concern of the international community. However, no consensus has been reached hitherto. To explore and resolve the disagreements in the Himalayan study, in this paper we begin with the methodology and basic principles for the anatomy of composition and nature of convergent margins, then followed by an effort to conduct a similar anatomy for the India-Eurasia collision. One of the most common patterns of plate convergence involves a passive continental margin, an active continental margin and intra-oceanic basins together with accreted terranes in between. The ultimate configuration and location of the terminal suture zone are controlled by the basal surface of the accretionary wedge, which may show fairly complex morphology with Z-shape and fluctuant geometry. One plausible method to determine the terminal suture zone is to dissect the compositions and structures of active continental margins. It requires a focus on various tectonic elements belonging to the upper plate, such as accretionary wedges, high-pressure (HP)-ultra-high-pressure (UHP) metamorphic rocks, Barrovian-type metamorphic rocks and basement nappes, together with superimposed forearc basins. Such geological records can define the extreme limits and the intervening surface separating active margin from the passive one, thus offering a general sketch for the surface trace of the terminal suture zone often with a cryptic feature. Furthermore, the occurrence of the cryptic suture zone in depth may be constrained by geophysical data, which, in combination with outcrop studies of HP-UHP metamorphic rocks, enables us to outline the terminal suture zone. The southern part of the Himalayan orogen records complicated temporal and spatial features, which are hard to be fully explained by the classic “two-plate-one-ocean” template, therefore re-anatomy of the compositions and nature for this region is necessitated. Taking advantage of the methodology and basic principles of plate convergence anatomy and synthesizing previous studies together with our recent research, we may gain new insights into the evolution of the Himalayan orogeny. (1) The Yarlung-Zangbo ophiolite is composed of multiple tectonic units rather than a single terminal suture zone, and a group of different tectonic units were juxtaposed against each other in the backstop of the Gangdese forearc. (2) The Tethyan Himalayan Sequence (THS) contains mélanges with typical block-in-matrix structures, uniform southwards paleocurrents and age spectra of detrital zircons typical of Eurasia continent. All of these facts indicate that the THS belonged to Eurasia plate before the terminal collision, emplaced in the forearc of the Gangdese arc. (3) The Greater Himalayan Crystalline Complex (GHC) and Lesser Himalayan Sequence (LHS) comprise complex components including eclogites emplaced into the GHC and the upper part of the LHS. Judging from the fact that HP-UHP metamorphic rocks are exhumed and emplaced in the upper plate, the GHC and the upper part of the LHS where eclogite occur should be assigned to the upper plate, lying above the terminal subduction zone surface. It is the very surface along which the continuous subduction of the India subcontinent occurred, therefore acting as the terminal, cryptic suture. From the suture further southward, the bulk rock associations of the LHS and Sub-Himalayan Sequence (Siwalik) show little affinity of mélange, probably belonging to the foreland system of the India plate. By the anatomy of tectonic features of all the tectonic units in the Himalayan orogen as well as the ages of the subduction-accretion related deformation, we conclude that the terminal India-Eurasia collision occurred after 14 Ma, the timing of the metamorphism of the eclogites emplaced into the upper plate. The development of rifts stretching in N-S direction in Tibet and tectonic events with the transition from sinistral to dextral movements in shear zones, such as the Ailaoshan fault in East Tibet, can coordinately reflect the scale and geodynamic influence of the India-Eurasia convergence zone. By conducting a detailed anatomy of the southern Himalayas, we propose a new model for the final collision-accretion of the Himalayan orogeny. Our study indicates that the anatomy of structures, composition, and tectonic nature is the key to a better understanding of orogenic belts, which may apply to all the orogenic belts around the world. We also point out that several important issues regarding the detailed anatomy of the structures, compositions and tectonic nature of the Himalayan orogeny in future.

The Tianshan orogenic belt, part of the Central Asian Orogenic Belt, offers an opportunity to examine the complexities of an orogenic system that records long‐term intracontinental deformation. The Tianshan have been reactivated multiple times since the Mesozoic, but the mechanisms and driving forces of these various orogenic events are not well constrained. Moreover, the spatial exhumation pattern of the entire Tianshan remains poorly studied. We present new zircon and apatite (U‐Th)/He and apatite fission track thermochronological data for samples from the northwestern part of the Chinese Western Tianshan. They indicate three distinctive phases of rapid cooling in the late Carboniferous‐early Permian, Late Triassic‐Early Jurassic, and Cretaceous. The first phase can be linked to uplift and exhumation related to the subduction/closure of the Paleo‐Asian Ocean, while the episodic cooling during the Late Triassic‐Early Jurassic (250–190 Ma) and Cretaceous (115–80 Ma) are interpreted as related to uplift and exhumation associated with strike‐slip deformation and Mesozoic clockwise or anticlockwise rotation of the Junggar basin. Our new data, in concert with a compilation of previously published data from elsewhere in the region, reveal that the Tianshan underwent a greater amount of exhumation in the southern section, and less exhumation took place to the north. All available data also support the notion that the exhumation process has been essentially the same in tectonic blocks along strike since late Paleozoic. During the Cenozoic, the Tianshan experienced large‐scale, rapid exhumation starting in the late Miocene (12–10 Ma) and not the early Miocene as has been previously proposed. Pulsed exhumation episodes in the Tianshan orogenic belt are interpreted as the result of differential rotation of local crustal blocksThe late Paleozoic to Cenozoic regional exhumation was greatest in southwest Tianshan and lessened progressively to the north and eastNew data and regional compilation show that the late Oligocene deformation event was local and did not result in regional exhumation Pulsed exhumation episodes in the Tianshan orogenic belt are interpreted as the result of differential rotation of local crustal blocks The late Paleozoic to Cenozoic regional exhumation was greatest in southwest Tianshan and lessened progressively to the north and east New data and regional compilation show that the late Oligocene deformation event was local and did not result in regional exhumation

The Altai is an enigmatic, relatively young mountain belt with sharp relief (up to 4,500 m high) that developed thousands of kilometers away from the nearest current plate margins. The Fuyun area, at the interface between the southern margin of the Chinese Altai and the Junggar Basin, represents a key locality for understanding the Meso‐Cenozoic deformation and exhumation history of the Altai. The complex structural architecture of the Fuyun area suggests that multiple deformation events affected the area, which ultimately led to the exhumation of the Altai. Furthermore, the area hosts orogenic‐type mineralization, suggesting a history of fluid alteration. However, in contrast to the well‐constrained Palaeozoic history, the timing of Meso‐Cenozoic deformation, metasomatism and exhumation has not been comprehensively studied. This study presents new apatite U‐Pb, trace element and fission track data for the Fuyun area and integrates these with previous studies for the Altai to shed more light on the Meso‐Cenozoic tectonic history. The apatite U‐Pb dates, associated with LREE‐depleted trace element profiles, suggest that a phase of Middle–Late Jurassic (∼170–160 Ma) metasomatism affected the Keketuohai area, which is potentially linked to the timing of rare‐metal mineralization. The apatite fission track results and thermal history models reveal rapid early Late Cretaceous (∼100–75 Ma) cooling linked to tectonic exhumation throughout the Chinese Altai, associated with distant plate‐margin processes. In addition, samples taken in vicinity to the frontal thrusts of the Altai record evidence for Cenozoic partial resetting of the apatite fission track system. The Altai Mountains are a high elevation, sharp relief mountain belt within central Asia. Despite their location thousands of kilometers from the present day plate margin, the Altai preserve young mountains induced by tectonic forces originating at the plate boundaries. Integrating new low‐temperature data with existing studies reveals extensive uplift of the Altai during the Late Cretaceous, induced by the reactivation of major structures. A subsequent pulse of Cenozoic uplift further developed the topography observed today. In addition to mountain building, alteration of crystalline rocks associated with mineralization has also been observed. The chemical signatures within apatite grains suggests they grew from a fluid that altered the crystalline rocks, which may have links to nearby economic mineralization. The Fuyun area records Jurassic metasomatism in apatites corresponding to the timing of hydrothermal rare‐metal mineralizationLate Cretaceous rapid cooling is preserved throughout the Altai, coeval with km‐scale deposition of coarse sediments in adjacent basinsThe Altai shows partial fission track resetting in the Cenozoic during India‐Eurasia convergence, where exhumation has outpaced denudation The Fuyun area records Jurassic metasomatism in apatites corresponding to the timing of hydrothermal rare‐metal mineralization Late Cretaceous rapid cooling is preserved throughout the Altai, coeval with km‐scale deposition of coarse sediments in adjacent basins The Altai shows partial fission track resetting in the Cenozoic during India‐Eurasia convergence, where exhumation has outpaced denudation

The Altaids is generally considered to be the largest Phanerozoic accretionary orogen on Earth, but it is unclear whether it was associated with extensive continental crustal growth and whether there is a link between the crustal growth and ore mineralization. This paper reviews whole-rock Nd and zircon Hf isotope data for felsic–intermediate–mafic igneous rocks in the Altaids and presents Nd + Hf isotopic contour maps for this region. The maps highlight the 3D lithospheric compositional architecture of the Altaids and make it possible to quantitatively evaluate the crustal growth and its relationship with ore deposits. The Altaids hosts ∼4 107 350 km2and ∼184 830 750 km3(assuming a crustal thickness of 40–50 km) juvenile crust (ϵNd(t) > 0), accounting for 58% by isotope-mapped area (∼7 010 375 km2) of almost all outcrops of the Altaids (∼8 745 000 km2) and formed during 1000–150 Ma (mainly 600–150 Ma). The juvenile crustal, slightly juvenile-reworked crustal and slightly reworked crustal provinces controlled the Cu–Au, the Pb–Zn–Ag and the Li–Be, Nb–Ta and W–Sn ore deposits. According to the crustal architecture and background of deep compositions, we propose that the ore deposits can be grouped into three types: juvenile crust-related, mixed-source (or slightly juvenile crust)-related and reworked crust-related. This highlights the close relationship between accretion, continental growth and mineralization, and will facilitate exploration for specific ore-deposit types in the Altaids.Nd + Hf isotopic mapping of igneous rocks demonstrates voluminous Phanerozoic continental growth and its crustal architecture in the Altaids, which control the distribution of the ore deposits and allow the deposits to be grouped into three types: juvenile crust-, mixed source-, and reworked crust-related. This highlights the relationship between continental growth and mineralization.

This study provides new constraints on the mantle transition zone (MTZ) structure under the Tian Shan orogenic belt in the context of the double‐sided subduction of the Junggar lithosphere and the Tarim lithosphere. The 410‐ and 660‐km discontinuities bordering the MTZ under the Tian Shan and its adjacent areas are mapped by stacking 68,361 receiver functions from 4,122 events recorded by 100 broadband seismic stations. Regional and large‐scale 3‐D velocity models are used to explain the effect of the laterally heterogeneous velocity anomalies. We identify a thickened MTZ of about 9.3 km under the eastern Tian Shan and the Darbut belt. This thickening indicates a lower temperature, which is correlated with the broken‐off subducted lithosphere or the delamination of the eastern Tian Shan lithosphere. We document the thinning of the MTZ caused by the depressed 410‐km discontinuity and the uplifted 660‐km discontinuity across the Tian Shan orogenic belt, Junggar Basin and Tarim Basin. This thinning corresponds to a+ 100 K thermal anomaly in the MTZ, and we suggest that it may have been produced by thermal upwelling originating from the lower mantle. The slightly thinned MTZ beneath the Altai Mountains was caused by the uplift of these two discontinuities, which is related to the high‐velocity anomalies in the upper mantle and MTZ. In contrast, the thinned MTZ below the easternmost segment of the Tian Shan orogenic belt, formed by the depression of 6.5 km for the 410‐km discontinuity may indicate the presence of small‐scale mantle upwelling. The tectonic activity of the Tian Shan orogenic belt is affected by the bidirectional subduction of the Junggar and Tarim lithosphere. However, the deep dynamic processes of the eastern Tian Shan has long been poorly constrained by independent seismological evidence. Based on the seismic data collected by 100 broadband seismic stations, the high‐resolution results of mantle transition zone (MTZ) structure were mapped using P‐wave receiver functions. The results reveal a thick MTZ under the eastern Tian Shan and Darbut belt caused by the uplifted 410 discontinuity, which may be related to delaminated lithosphere root or broken‐off lithosphere. The depressed 410‐km and uplifted 660‐km discontinuities across Tian Shan, Junggar Basin and Tarim Basin may originate from the thermal upwelling of the lower mantle. Our results provide valuable insight into the dynamic processes of plate subduction and mantle convection under the eastern Tian Shan orogenic belt. The 410‐ and 660‐km discontinuities under the eastern Tian Shan were mapped using receiver functions with high resolutionThe thickening of mantle transition zone (MTZ) under Tian Shan and Darbut belt is associated with delaminated lithosphere root or broken‐off lithosphereThe thinning of MTZ across Tian Shan, Junggar Basin and Tarim Basin may originate from the thermal upwelling of the lower mantle The 410‐ and 660‐km discontinuities under the eastern Tian Shan were mapped using receiver functions with high resolution The thickening of mantle transition zone (MTZ) under Tian Shan and Darbut belt is associated with delaminated lithosphere root or broken‐off lithosphere The thinning of MTZ across Tian Shan, Junggar Basin and Tarim Basin may originate from the thermal upwelling of the lower mantle

The Kanguer Subduction Complex in the Eastern Tianshan is critical to understanding the tectonic evolution of the southern Altaids as it marks the terminal suture along which the Paleo‐Asian Ocean was consumed. However, the nature and timing of this final collision, as well as the mechanism of shearing and related magmatism, remain enigmatic. The Kanguer Subduction Complex demonstrates obvious sinistral transtensional and dextral compressional deformation in different tectonic events along the Qiugemingtash Shear Zone in Huangshan area. Three sets of asymmetric plunging folds (e.g., basin‐like, S‐shaped and Z(W)‐shaped) were recognized in the sedimentary rocks. Locally, the folds are offset by dextral strike‐slip faults, indicating that they were formed by dextral shearing. The Huangshandong mafic‐ultramafic complex experienced brittle dextral shearing partitioned around the margins of the intrusion. Detrital zircon U‐Pb dates for deformed sedimentary rocks have maximum deposit ages (MDA) of 251 and 290 Ma, respectively, and syn‐compressional shearing conjugate granitic dikes that intruded into the deformed sedimentary rocks yield crystallization ages of 249 and 245 Ma, respectively. These ages reveal that the extensional and/or transtensional sedimentary basins formed between ca. 290–249 Ma, and dextral compressional shearing started ca. 249 Ma. Combining deformed units with transtensional basins and mantle‐derived magmatism, we suggest that ocean‐ridge subduction induced a sinistral transtensional regime in a forearc/intraarc setting related to the Tuva‐Mongol Orocline in the Permian. The oblique convergence between the Tarim Craton and southern Altaids triggered the Qiugemingtash dextral compressional shearing in the Early Triassic (ca. 249 Ma). Asymmetric plunging folds and brittle dextral deformation at the margin of rhomb‐shaped Huangshandong complex in Kanguer Subduction ComplexOcean‐ridge subduction in the Tuva‐Mongol Orocline led to fore‐arc/intra‐arc transtension and mantle‐derived intrusions during 290–249 MaOblique convergence triggered the dextral compressional shearing in southern Altaids in ca. 249 Ma Asymmetric plunging folds and brittle dextral deformation at the margin of rhomb‐shaped Huangshandong complex in Kanguer Subduction Complex Ocean‐ridge subduction in the Tuva‐Mongol Orocline led to fore‐arc/intra‐arc transtension and mantle‐derived intrusions during 290–249 Ma Oblique convergence triggered the dextral compressional shearing in southern Altaids in ca. 249 Ma

The Neo‐Tethys subduction and subsequent Arabia‐Eurasia continental collision invoked widespread Cenozoic tectono‐magmatism throughout the Iranian Plateau. We herein develop a new method to image the shallow crustal S‐wave velocity (Vs) structure by joint inversion of multifrequency waveforms and horizontal‐to‐vertical ratios around the direct P phase in P‐wave receiver functions. Synthetic tests demonstrate the validity of our method in constraining the absolute Vsvalues beneath single stations down to ∼12‐km depth. By applying this method to a seismic array of 63 stations with an average spacing of ∼10 km along the main profile, we construct a detailed shallow crustal Vsmodel across the northwestern Iranian Plateau. The model is characterized by distinct high‐ and low‐velocity anomalies beneath the Iranian hinterland and the Zagros foreland fold‐and‐thrust belt, respectively. In combination with geological observations and laboratory data, the imaged high‐velocity anomalies (with Vsof 3.2–3.9 km/s) may denote arc to intraplate magmatism beneath Central Iran and Alborz to the north, whereas the low‐velocity anomalies (with Vsof ∼1.65 km/s) probably represent the marl/shale layers in Late Cretaceous and Paleocene beneath Zagros. The magmatic rocks at the Iranian hinterland exhibit strong variations in absolute Vs, reflecting different bulk compositions with more mafic inland. The shale/marl layers could have acted as décollements to accommodate crustal deformation. Our observations underline both the key role of lithology‐controlled layering in sedimentary deformation at the Zagros fold‐and‐thrust belt and the change in compositions and forming‐environments of magmatic rocks at the Iranian hinterland. Accurate velocity models of the shallow crust, especially in plate convergence zones, provide constraints on tectonic deformation and related mechanisms at shallow depths. However, existing seismic methods for imaging shallow crustal structures usually require dense and uniform ray‐path coverage, leading to limited application in areas with irregular distribution of stations and/or events. In this study, we propose inverting for shallow crustal velocity structures beneath single stations by using multifrequency signals around the direct P phase in receiver functions. The method is suitable for both the single‐station case and tectonically inactive regions. We applied the method to construct a detailed shallow crustal velocity model in northwestern Iran. The new model provides a more detailed view of the shallow crustal features of this tectonically complex region and helps to elucidate the Cenozoic tectono‐magmatic activities related to the Neo‐Tethys subduction and subsequent continental collision. Frequency‐dependent signals around the direct P phase in receiver functions enable a better recovery of shallow crustal VsstructuresThe inland change in compositions of magmatic rocks may reflect a shift from continent arc to intraplate magmatism in northwestern IranThe lithology‐controlled layering plays a key role in sedimentary deformation at the Zagros fold‐and‐thrust belt Frequency‐dependent signals around the direct P phase in receiver functions enable a better recovery of shallow crustal Vsstructures The inland change in compositions of magmatic rocks may reflect a shift from continent arc to intraplate magmatism in northwestern Iran The lithology‐controlled layering plays a key role in sedimentary deformation at the Zagros fold‐and‐thrust belt

One of the most largest known and important metallogenic provinces in China is East Tianshan, where seven major types of Late Paleozoic metal deposits have been recognized: (1) porphyry-type Cu-Mo-(Au) ore deposits, (2) volcanic Fe-Cu deposits, (3) orogenic lode gold deposits, (4) magmatic Cu-Ni sulfide deposits, (5) epithermal gold deposits, (6) volcanic hydrothermal Cu deposits, and (7) skarn Cu-Ag deposits. Tectonically, the development of these Late Paleozoic metal mineral deposits was closely associated with the subduction and closure of the ancient Tianshan ocean intervening between the Tarim craton and the Junggar-Kazakhstan block. In the Late Devonian to Early Carboniferous, the northern margin of the Tarim craton existed as a passive-type continental margin, whereas the ancient Tianshan ocean was subducted beneath the southern margin of the Junggar-Kazakhstan block, resulting in the formation of the Dananhu-Tousuquan magmatic arc and associated porphyry-type Cu-Mo-(Au) deposits. In the Middle Carboniferous, the ancient Tianshan ocean began to subduct beneath the northern margin of the Tarim craton, leading to the formation of the Aqishan-Yamansu magmatic arc and associated volcanic Fe-Cu deposits. In the Late Carboniferous, the ancient Tianshan ocean was closed, and a continent-arc collision occurred, leading to the formation of the Tianshan orogen. Following the collision was an extensional event, which was associated with the emplacement of large amounts of ultramafic-mafic complexes and the formation of a number of large- to medium-scale magmatic copper-nickel ore deposits along the Kangger suture zone. In the Early Permian, East Tianshan entered into a post-collision stage, associated with the widespread emplacement of granitoid bodies and eruption of within-plate volcanism, which led to the formation of volcanic hydrothermal copper deposits, skarn-type Cu-Ag deposits, post-orogenic gold deposits, and epithermal gold deposits in East Tianshan.

The enhanced preservation potential of continental material during continental convergence is thought to be responsible for the episodic continental growth process. However, the mechanism of preservation potential variation is unclear. In this study, we use a novel high‐density passive‐source seismic approach to image the whole‐crust architecture of the juvenile continent in southern Altaids. Two arcuate crust fragments are found between Paleozoic island‐arc belts, which indicate the relicts of inter‐arc oceanic basins. The results show that the trapped oceanic basins make up a large proportion of the juvenile continental crust and that the reduction in subduction erosion due to its incomplete subduction can explain a period of rapid continental growth revealed by previous zircon studies. We suggest that a large number of ocean basins may be trapped during supercontinent formation, and they play a critical role in continental material preservation and continental episodic growth. The growth of the continental crust is an episodic process associated with the supercontinental circle, but a specific mechanism to explain it is still lacking. Here, we combined the seismic images with magnetic and geological data to reveal that two trapped oceanic basins form parts of the lower crust in southern Altaids. These oceanic basins are trapped in the gaps between continents and arcs because their boundaries are rarely having a jigsaw puzzle‐like fit. During this process, the continental crust grows significantly due to the addition of oceanic basins and the associated decrease in subduction erosion. We proposed that numerous oceanic basins could be captured during the formation of supercontinents, leading to peaks in continental crust growth. We present a new high‐resolution image of the crustal structures of the Eastern Junggar using the receiver function methodCombing geomagnetic and geological data to identify trapped oceanic basins and reconstruct their trapping processInvestigating the contribution of trapped ocean basins to continental growth and the implications for global continental episodic growth We present a new high‐resolution image of the crustal structures of the Eastern Junggar using the receiver function method Combing geomagnetic and geological data to identify trapped oceanic basins and reconstruct their trapping process Investigating the contribution of trapped ocean basins to continental growth and the implications for global continental episodic growth

Subduction zones provide important constraints on reconstruction of tectonic configurations and convergent geodynamics. The timing and evolution of the subduction zones at the interaction between the Paleo‐Asian and Tethyan Oceans remain ambiguous, casting significant uncertainty on the reconstructions of proto‐Asia and subduction dynamics. Here, we report new petrologic and geochronologic data of a high‐grade metamorphic complex in the Dunhuang area, NW China, together with thermodynamic modeling, geothermobarometry, and second ion mass spectrometry U‐Pb chronology to reveal the complex metamorphic structure and history of the Paleozoic subduction‐exhumation channel at the intersection of the Paleo‐Asian and Tethyan domains. The subduction zone contains a diverse collection of eclogite, high‐pressure (HP) granulites, amphibolites, and metasedimentary rocks with a broad spectrum of P‐T‐tpaths, which were buried and exhumed at different depths at ∼463–411 Ma. Our first dating of the oldest (∼463 Ma) HP granulite extends the orogenic period earlier to the Middle Ordovician. The uneven change in subduction gradients from ∼18°C/km to ∼10°C/km illustrates the thermal evolution of the subduction zone from infancy to maturity. A dramatic drop of the gradient at ∼420 Ma suggests a potential short‐term switch of the subduction dynamics from “hot” to “cool,” possibly due to plate geometry reorganization in response to slab roll‐back. Our data demonstrate that the Dunhuang Complex was chaotically mixed and juxtaposed at different levels in the subduction‐exhumation channel. The southward younging and increase in depth of the HP metamorphism indicate that the Dunhuang Complex was formed by north‐dipping subduction of the Proto‐Tethyan Ocean from the Early Paleozoic. The exhumed metamorphic complex in the Dunhuang area, NW China, provides primary evidence of how a deep subduction zone was constructed and evolved during the interaction between the Paleo‐Asian and Tethyan Oceans. Knowledge of these tectonic relations is essential to reconstruct the history of accretion of proto‐Asia. Our new petrologic and geochronologic data from the Dunhuang Complex reveal the metamorphic history of Paleozoic subduction‐exhumation. We report the oldest Ordovician (∼463 Ma) high‐pressure granulite and demonstrate that the regional thermal gradient during subduction ranged from ∼18°C/km to ∼10°C/km between ∼463 and ∼411 Ma. These results make the Dunhuang Complex one of the finest natural exposures on Earth that highlights how fast and how much a thermal gradient of subduction can evolve over time. Diverse P‐T‐tpaths of these high‐grade metamorphic rocks indicate that the Dunhuang Complex was a Paleozoic accretionary forearc that was produced by km‐scale mixing and tectonic juxtaposition of diverse rocks in a subduction‐exhumation channel during closure of the Tethyan Ocean. The T/Pgradient of the Dunhuang Complex varied unevenly from ∼18°C/km to ∼10°C/km between the Middle Ordovician and Early DevonianA dramatic drop of the gradient at ∼420 Ma highlights a potential short‐term change in the subduction dynamics in response to slab roll‐backDiverse P‐T‐tpaths indicate a Paleozoic accretionary forearc produced by km‐scale mixing and juxtaposition of rocks in a subduction channel The T/Pgradient of the Dunhuang Complex varied unevenly from ∼18°C/km to ∼10°C/km between the Middle Ordovician and Early Devonian A dramatic drop of the gradient at ∼420 Ma highlights a potential short‐term change in the subduction dynamics in response to slab roll‐back Diverse P‐T‐tpaths indicate a Paleozoic accretionary forearc produced by km‐scale mixing and juxtaposition of rocks in a subduction channel

Comprehensive studies of the tectonic nature and the formation age of the Dashui complex in the Eastern Tianshan‐Beishan Orogen may address and help to better understand the complicated accretionary tectonics of the southern Altaids. Based on our detailed geological mapping, structural analysis, and understanding of new geochemistry and detrital zircon U‐Pb dating of critical samples, the Dashui complex can be subdivided into one mélange (Central Zone) and two units of forearc basin and slope basin (Northern and Southern Zones). The Northern Zone is composed of debris flows and turbidites. The Central Zone has a “block‐in‐matrix” structure, and the blocks of basalts have E‐MORB or N‐MORB geochemical signatures. The Southern Zone is characterized by debris flows. Therefore, we name these rocks Dashui subduction complex. Detrital zircons from the three zones show a major single age peak at ca. 460–420 Ma and a minor age peak at ca. 280–260 Ma, and the maximum depositional ages from north to south are: 264, 244 and 246 Ma, respectively, indicate that the Dashui subduction complex developed independently within an overall intra‐oceanic arc until ca. 244 Ma, and there must have been a large‐scale tectonic separation between the Central Tianshan Arc to the north and the Shuangyingshan Arc to the south. The structural geometry and kinematics of the Dashui complex and adjacent areas indicate that this complex likely experienced syn‐subduction thrusting and strike‐slip deformation. In particular, the late Xingxingxia strike‐slip faulting finally juxtaposed the Central Tianshan, Mazongshan, and Shuangyingshan arcs. In the southern margin of the Altaids, the tectonic framework and evolution characteristics are significantly different between the east part in Solonker and the west part in South Tianshan. The newly‐defined Dashui subduction complex in the Tianshan‐Beishan Orogen is a key to understanding the east‐west junction of the southern margin of the Altaids. We focused on the rock assemblages, structural styles, and geochemical characteristics of critical samples of the Dashui complex, and identified that the Dashui complex was not composed of the successive stratigraphic unit, but rather consist of one mélange and two coherent units, which were relics of forearc basin, accretionary complex and slope basin from north to the south formed by the subduction of the Tianshan‐Beishan Oceans. The detrital zircon ages of the different three zones of the Dashui complex indicated that the complex developed independently within an overall intra‐oceanic arc until ca. 244 Ma. Combined with the above data and the structural analysis of the Dashui complex and the adjacent areas, we proposed that the Xingxingxia strike‐slip faulting finally juxtaposed the Central Tianshan, Mazongshan and Shuangyingshan arcs and forming a unique amalgamation style in the southern Altaids after 244 Ma. The Dashui subduction complex is divisible into three zones: one typical OPS mélange zone and two coherent unit zonesThe Dashui subduction complex was apparently independent until 244 MaThe Xingxingxia strike‐slip fault finally juxtaposed the Central Tianshan, Mazongshan, and Shuangyingshan arcs in the southern Altaids The Dashui subduction complex is divisible into three zones: one typical OPS mélange zone and two coherent unit zones The Dashui subduction complex was apparently independent until 244 Ma The Xingxingxia strike‐slip fault finally juxtaposed the Central Tianshan, Mazongshan, and Shuangyingshan arcs in the southern Altaids

Tracing the closure of oceans with irregular margins and the formation of an orocline are crucial for understanding plate reconstruction and continental assembly. The eastern Central Asian Orogenic Belt, where the Mongol-Okhotsk orocline is situated, is one of the world's largest magmatic provinces. Using a large data set of U-Pb zircon ages, we updated the timing of many published igneous rocks, which allowed us to recognize tightly ‘folded’ linear Carboniferous-Jurassic magmatic belts that wrap around the Mongol-Okhotsk suture and their migrations both sutureward and suture-parallel. The new successive magmatic belts reveal a rollback, scissor-like (or zipper-like) closure of the Mongol-Okhotsk Ocean that was fundamentally controlled by coeval subduction rollback and rotation of the Siberian and Mongolian-Erguna blocks. This study also demonstrates the complex mechanisms and processes of the closure of an ocean with irregular margins and the formation of a consequent orocline.A large data-set of ages of magmatic rocks reveals tightly 'curved' linear magmatic belts and their migrations towards the central suture, which indicates a scissor-like closure of the Mongol-Okhotsk Ocean. These well-documented relations help us better understand the closure process of an ocean with irregular margins and the formation of curved mountain belts.

The Jaz Murian Basin in Southeast Iran is a forearc basin that sits on top of the western Makran subduction zone. A recent seismic deployment inside the western Jaz Murian Basin documents extremely strong reverberations between the free surface and the top of the basement. These strong multiples, which hamper studies of deeper structures, carry precious information on the structure of the basin. Here we combine three independent measurements, including teleseismic P/S‐wave coda autocorrelations, P‐wave polarization analysis and receiver functions, to image the architecture of the western Jaz Murian Basin. The S‐wave velocity structure beneath each station is constrained by teleseismic P‐wave polarization analysis and a simple grid search method. In addition, both P‐ and S‐wave reflections are extracted to measure the Poisson's ratio and the thickness of sediments, in addition to P‐ and/or S‐wave velocities. We find that the sedimentary cover has an average thickness of ∼3 km with very low S‐wave velocities around 1.2 km/s. The estimated Vp/Vs ratios are relatively high between 2.23 and 2.52, suggesting that the western Jaz Murian Basin contains unconsolidated recently deposited sediments. Passive imaging studies usually suffer from a limited spatial resolution owing to lower frequency content and sparser acquisition compared to active source seismic experiments. On the other hand, the former are easier to perform for a fraction of the cost of the latter. In this study, we exploit teleseismic body waves recorded by our recently deployed temporary array in the western Jaz Murian forearc basin, southeast Iran. Our results reveal the detailed structure of the western Jaz Murian sedimentary basin, mostly filled with unconsolidated sediments, possibly originating from lake deposition. We extract energetic P‐ and S‐wave reflections from the coda of teleseismic P and S wavesWe combine these reflections with measurements of P wave polarization to resolve the structure of the western Jaz Murian sedimentary basinThe nature of the sediments inside the Jaz Murian Basin and of the basement provides insight into the recent tectonic regime in that region We extract energetic P‐ and S‐wave reflections from the coda of teleseismic P and S waves We combine these reflections with measurements of P wave polarization to resolve the structure of the western Jaz Murian sedimentary basin The nature of the sediments inside the Jaz Murian Basin and of the basement provides insight into the recent tectonic regime in that region

Previous studies concluded that a Trans‐Tethyan oceanic subduction zone existed prior to Paleogene India‐Eurasia collision, when the ocean lacked intervening continental slivers. In this paper, we present the first report of Early Cretaceous shortening and 152.8 Ma alkali magmatism in the continental sliver Longzi block, a ca. 750 km E‐W by ca. 130 km N‐S tract of the NE Himalaya within the Himalaya orogen. The Longzi block contains overturned south‐vergent folds in Triassic‐Lower Cretaceous strata intruded by 136–123 Ma mafic‐dioritic‐dacite dikes, which constrain the time of Early Cretaceous shortening. Triassic strata with NW Australian affinity and Late Jurassic conglomerates derived from northern India record the pre‐rift history. Evidence for the rifting includes 152.8–145 Ma alkali intrusive rocks, a Late Jurassic unconformity, rapid changes in sediment thickness, and the water depth during deposition of Upper Jurassic strata. The rifting event was coeval with the formation of 152–155 Ma oceanic crust in the NE Indian Ocean and of a Late Jurassic submarine escarpment with 1,200 m of sediments offshore of NW Australia. These data show that the Longzi block was part of westernmost Argoland, a continental sliver that rifted from East Gondwana. The Longzi block subsequently collided with a N‐dipping Trans‐Tethyan intra‐oceanic subduction zone in the Early Cretaceous to generate the relevant shortening, long before the Paleocene continent‐continent collision along the Yarlung‐Tsangpo suture zone. This rift‐collision in the Himalayan region reflects the Mesozoic archipelagic paleogeography in eastern Neotethys, which was preceded by ocean closure, and the two‐stage collision of India‐Eurasia in the Cenozoic. This study presents the first report of Early Cretaceous shortening and 152.8 Ma alkali magmatism in the Longzi block, a continental sliver between India and Eurasia in the NE Himalaya. Folds in Triassic‐Lower Cretaceous strata were intruded by 136–123 Ma dikes, suggesting Early Cretaceous shortening. This shortening counters the currently accepted model that the NE Himalaya experienced only an extension in the northern Indian passive margin at that time. In Mt. Kala (Chinese Tibet), 152.8 Ma alkali intrusive rocks are coeval with an unconformity, rapid changes in sediment thickness and depositional water depth in the Himalayan rocks, and with 152–155 Ma oceanic crust in the NE Indian Ocean. These relations demonstrate that the NE Himalaya contains evidence of Late Jurassic rifting. The Longzi block contains NW Australian‐affinity Triassic strata and Indian‐affinity Late Jurassic conglomerates, indicating derivation from East Gondwana before the rifting. These data show that the Longzi block was part of westernmost Argoland that separated from East Gondwana. This continental block had an archipelagic configuration between India and Eurasia in Neotethys that began in the Late Jurassic. Recognition of the Longzi continental sliver improves our understanding of the Mesozoic geodynamics of Neotethys, and confirms the two‐stage India‐Eurasia collision in the Cenozoic. The Longzi block in the NE Himalaya records Early Cretaceous shortening and Late Jurassic alkali magmatismFirst geological evidence demonstrates that the Longzi block is the westernmost fragment of Argoland that was separated from East GondwanaNew archipelagic framework since the Late Jurassic demonstrates Mesozoic geodynamics of Neotethys and Cenozoic two‐stage collision in Tibet The Longzi block in the NE Himalaya records Early Cretaceous shortening and Late Jurassic alkali magmatism First geological evidence demonstrates that the Longzi block is the westernmost fragment of Argoland that was separated from East Gondwana New archipelagic framework since the Late Jurassic demonstrates Mesozoic geodynamics of Neotethys and Cenozoic two‐stage collision in Tibet

The Qilian orogen consists of the North Qilian belt, the Central Qilian block and the South Qilian belt and is regarded as part of the northern margin of the Proto-Tethys Ocean. The tectonic mechanism responsible for the early Paleozoic magma generation in the Qilian orogen is crucial to understanding the ocean-continent configurations and the closure of the Proto-Tethys Ocean. This paper compiles the early Paleozoic mafic and granitic intrusions in the South Qilian belt and the Central Qilian block, to constrain the subduction and accretion of the South Qilian ocean. The early Paleozoic mafic intrusions in the Central Qilian block indicate that the influence of slab-derived fluids dominates their petrogenesis, while the mafic intrusions in the South Qilian belt were mostly affected by involvement of significant sediment-derived melts in their formation. They are supportive of a mélange model, in which melting of mélange diapirs originating at the slab-mantle interface generates fluid-metasomatised magma source in the deep mantle under the Central Qilian block and sediment-derived melts-metasomatised magma source under the Hualong block in the South Qilian belt, consistent with northward subduction of the South Qilian ocean. It is proposed that northward intra-oceanic subduction of the South Qilian Ocean occurred at 530–470 Ma in front of the Hualong block and continued at 470–446 Ma but was then accompanied by the development of a mature volcanic arc. Continuous subduction resulted in accretion of the Hualong block northwards onto the Central Qilian block, and this collision started at ca.446 Ma and lasted to ca.420 Ma. The final closure of the South Qilian ocean was marked by the onset of continental collision between the Qaidam-Quanji block and the amalgamated Hualong-Central Qilian block at ca.440 Ma, and also the cause of the A-type granitoids after final collision occurred at ca.420 Ma.

Abstract: The basement rocks in the Kuluketage area are composed predominately of tonalite-trondhjemite-granodiorite rocks, and occured mainly in Xinger and Korla. U-Pb dating of TTG gneiss near Korla yielded a late Neoarchean weighted mean 207Pb/206Pb age of 2.65 Ga, which is the oldest published age for the TTG rocks in the Kuluketage area and thus suggests that Archean terrane in the area was formed in the late Neoarchean. The Korla gneiss is much younger than the TTG rocks in the northern Altyn Tagh, eastern Tarim Craton, indicating that the oldest terrane of the Tarim Craton was exposed probably in the northern Altyn Tagh. Until late Neoarchean, the Tarim continent extends to the Kuluketage area and finally had generated a relatively large uniform Archean basement within the craton. Zircon Hf isotopic analyses of the TTG gneiss give low ɛHf(t) values (−5 to 1) with Paleoarchean to Mesoarchean two-stage model ages (T DM2) between 3.0 and 3.3 Ga, suggesting that the basement rocks in the northern Tarim Craton were derived dominately from partial melting of Paleoarchean to Mesoarchean juvenile crustal material. The Hf model ages, therefore, indicate that no continent crust older than 3.3 Ga existed in the Kuluketage area.

‘Arc system’ is used here as a collective term for a variety of arcs that occur along continental margins or in oceanic plates; it includes associated units from adjacent plates. Four major arc systems (Mariana-, Japan-, Cordillera- and Alaska-type) can be distinguished along the Circum-Pacific region. Some Japan-type arc systems in ancient orogens (e.g. the Altaids) may have been largely regarded as microcontinents because they have so-called Precambrian basement. Often the Cordillera-type arc systems can be very complicated, and if they are rifted away from the host continent they become more difficult to recognize. Commonly these arc systems interact mutually and with continental marginal sequences, leading to complicated accretionary and collisional orogens. The alternation between Western Pacific archipelagos and the Eastern Pacific active margin is the stereotype of accretionary and collisional orogenesis. More importantly, these four main types of arc systems can be juxtaposed into a final orogenic collage, which is another main expression of accretionary orogenesis. Only some parts of accretionary and collisional orogens can be terminated by attachment of a continent-size craton such as Tarim or even India, and even so the accretionary and collisional processes may continue elsewhere along strike. The significance of the interactions among these arc systems and their final juxtaposition has not been fully appreciated in ancient orogens. The Altaids together with the Circum-Pacific orogens offers a good opportunity to study such accretionary–collisional orogenesis.

The Qinling orogen of central China occupies a key position in East Asia, and is of fundamental importance in unraveling its tectonic evolution. Devonian sedimentary basins are located between the North Qinling arc and the Baishuijiang Devonian-Permian accretionary wedge. Paleocurrent indictors and petrological and geochemical analyses show that turbiditic and coastal sandstones and pyroclasts developed in paleo-forearcs. Sedimentation of conglomerates and associated turbiditic and pyroclastic rocks evidently was related to the development of the North Qinling orogen rather than the South China craton. Gravels in the conglomerates were derived predominantly from the North Qinling and partly from its basement.Northward Devonian subduction and subsequent uplift caused successive forearc depocenters and associated facies belts to migrate southwards synchronously with sedimentation. Transpressive and transtensional faults segmented the basins into discrete half-graben sub-basins. Paleocurrent analysis adjacent to thrust faults demonstrates that thrust sheets crests were truncated by erosion and provided detritus for sub-basins. Shallow-marine and turbiditic depositional systems evolved in complex patterns to produce varied facies frameworks associated with complex subduction accretion. These facts, together with other geological and geochemical data, demonstrate that the North China craton grew southwards by arc-accretion processes from the end of the early Paleozoic to the beginning of the late Paleozoic, long before the integration of the North China and Yangtze cratons.

The Tuwu–Yandong porphyry copper belt lies in the eastern Tianshan mountains, eastern section of the Central Asian orogenic belt. The copper mineralization is mainly hosted in plagiogranite porphyries intruded into early Carboniferous volcanic rocks of the Paleozoic Dananhu island arc between the Tarim and Siberian plates. The plagiogranite porphyries have contents of 65–73 wt% SiO2, 14–17 wt% Al2O3, 0.9–2.2 wt% MgO, 3–16 ppm Y, 0.4–1.40 ppm Yb, 347–920 ppm Sr, and positive Eu anomalies. The rocks also exhibit positive ɛNd(t)values (+5.0 to +9.4) and low initial 87Sr/86Sr values (0.70316–0.70378). Such features are similar to those of adakites derived from partial melting of a subduction-related oceanic slab. The mineralization age is early Carboniferous (350–320 Ma), which is close to that of the porphyries. The close relationship between the Cu mineralization and the porphyry is also indicated by their similar Sr-Nd-Pb isotopic compositions. We suggest that the copper porphyry (magma) system in the Dananhu island arc was formed by direct melting of an obliquely subducting early Carboniferous oceanic slab.The Tuwu–Yandong porphyry copper belt lies in the eastern Tianshan mountains, eastern section of the Central Asian orogenic belt. The copper mineralization is mainly hosted in plagiogranite porphyries intruded into early Carboniferous volcanic rocks of the Paleozoic Dananhu island arc between the Tarim and Siberian plates. The plagiogranite porphyries have contents of 65–73 wt% SiO2, 14–17 wt% Al2O3, 0.9–2.2 wt% MgO, 3–16 ppm Y, 0.4–1.40 ppm Yb, 347–920 ppm Sr, and positive Eu anomalies. The rocks also exhibit positive ɛNd(t)values (+5.0 to +9.4) and low initial 87Sr/86Sr values (0.70316–0.70378). Such features are similar to those of adakites derived from partial melting of a subduction-related oceanic slab. The mineralization age is early Carboniferous (350–320 Ma), which is close to that of the porphyries. The close relationship between the Cu mineralization and the porphyry is also indicated by their similar Sr-Nd-Pb isotopic compositions. We suggest that the copper porphyry (magma) system in the Dananhu island arc was formed by direct melting of an obliquely subducting early Carboniferous oceanic slab.

The Baishan Mo–Re deposit is located in the eastern section of the eastern Tianshan orogenic belt, NW China. The deposit has a grade of 0.06% Mo and a high content of rhenium of 1.4 g/t. Rhenium and osmium isotopes in sulfide minerals from the Baishan deposit are used to determine the age of mineralization. Rhenium concentrations in molybdenite samples are between 74 and 250 μg/g. Analysis of eight molybdenite samples yields an isochron age of 224.8±4.5 Ma (2σ). Pyrite samples have rhenium and osmium concentrations varying in the range 33.4–330.6 ng/g and 0.08–0.81 ng/g, respectively. Isotope data on seven pyrite samples yield an isochron age of 225±12 Ma (2σ) on the 187Re/188Os versus 187Os/188Os plot and an age of 233±14 Ma (2σ) on the 187Os versus 187Re correlation diagram. The ages of molybdenite and pyrite are consistent within the analytical errors. Combined with field observations, the data indicate that Mo–Re mineralization in the Baishan deposit is produced by a magmatic-hydrothermal event in an intracontinental extensional setting after late Paleozoic orogeny. The initial 187Os/188Os ratio of pyrite is 0.3±0.07. The δ34S values of molybdenite vary from +0.5 to +3.6‰. Both data indicate that mineralization is derived mainly from a mantle source.The Baishan Mo–Re deposit is located in the eastern section of the eastern Tianshan orogenic belt, NW China. The deposit has a grade of 0.06% Mo and a high content of rhenium of 1.4 g/t. Rhenium and osmium isotopes in sulfide minerals from the Baishan deposit are used to determine the age of mineralization. Rhenium concentrations in molybdenite samples are between 74 and 250 μg/g. Analysis of eight molybdenite samples yields an isochron age of 224.8±4.5 Ma (2σ). Pyrite samples have rhenium and osmium concentrations varying in the range 33.4–330.6 ng/g and 0.08–0.81 ng/g, respectively. Isotope data on seven pyrite samples yield an isochron age of 225±12 Ma (2σ) on the 187Re/188Os versus 187Os/188Os plot and an age of 233±14 Ma (2σ) on the 187Os versus 187Re correlation diagram. The ages of molybdenite and pyrite are consistent within the analytical errors. Combined with field observations, the data indicate that Mo–Re mineralization in the Baishan deposit is produced by a magmatic-hydrothermal event in an intracontinental extensional setting after late Paleozoic orogeny. The initial 187Os/188Os ratio of pyrite is 0.3±0.07. The δ34S values of molybdenite vary from +0.5 to +3.6‰. Both data indicate that mineralization is derived mainly from a mantle source.

The Western Kunlun Range in northwestern Tibet records a history of enlargement of the Central Asian crust. In the Early Ordovician a south-dipping intra-oceanic subduction-accretion complex was accreted to the Tarim block, forming an Andean-type margin in the Late Ordovician. This margin grew southward (present-day coordinates) in the Early Silurian, with an accretionary complex on its southern side against which the Kudi gneiss-schist complex was attached. Clastic sediments continued to infill forearc/intra-arc basins on the top of the arc-accretionary complexes during Devonian-Carboniferous time. In the Early to Mid-Carboniferous, tectonic and magmatic quiescence is indicated by an absence of volcanic and plutonic rocks in the Kudi area, whereas subduction was still active in the western part of the range in the Gaz area near the present-day Pamir syntaxis. A Late Carboniferous-Permian to Early Mesozoic accretionary arc and forearc developed in front of the Andean-type margin, indicating that north-dipping subduction was renewed in the Late Carboniferous. Final collision of the Karakoram-North Qiangtang block to the western Kunlun orogenic collage by the Mid-Jurassic resulted in closure of Paleo-Tethys. The accretion and development of the Western Kunlun orogen contributed huge quantities of material for the crustal growth of Asia.

The continental crust is unique to the Earth in the solar system, and controversies remain regarding its origin, accretion and reworking of continents. The plate tectonics theory has been significantly challenged in explaining the origin of Archean (especially pre‐3.0 Ga) continents as they rarely preserve hallmarks of plate tectonics. In contrast, growing evidence emerges to support oceanic plateau models that better explain characteristics of Archean continents, including the bimodal volcanics and nearly coeval emplacement of tonalite‐trondjhemite‐granodiorite (TTG) rocks, presence of ∼1600°C komatiites and dominant dome structures, and lack of ultra‐high‐pressure rocks, paired metamorphic belts and ophiolites. On the other hand, the theory of plate tectonics has been successfully applied to interpret the accretion of continents along subduction zones since the late Archean (3.0–2.5 Ga). During subduction processes, the new mafic crust is generated at the base of continents through partial melting of mantle wedge with the addition of H2O‐dominant fluids from subducted oceanic slabs and partial melting of the juvenile mafic crust results in the generation of new felsic crusts. This eventually leads to the outgrowth of continents. Subduction processes also cause softening, thinning, and recycling of continental lithosphere due to the vigorous infiltration of volatile‐rich fluids and melts, especially along weak belts/layers, leading to widespread continental reworking and even craton destruction. Reworking of continents also occurs in continental interiors due to either plate boundary processes or plume‐lithosphere interactions. The effects of plumes have proven to be less significant and cause lower degrees of lithospheric modification than subduction‐induced craton destruction. All solid planets in the solar system have a core‐mantle‐crust structure, but the Earth is a unique planet with felsic continents and plate tectonics. Controversies have long surrounded the origin, growth (accretion) and reworking of continents. The plate tectonics theory has been significantly challenged in explaining the origin of continents as Archean (>2.5 billion years) continents rarely preserve hallmarks of plate tectonics. In contrast, oceanic plateau models can explain the origin of bimodal volcanic and plutonic assemblages, presence of ∼1600°C komatiites and dominant dome structures, and lack of ultra‐high‐pressure rocks, paired metamorphic belts, and ophiolites in Archean continents. The accretion of continents can be successfully interpreted by plate tectonics along subduction zones via partial melting of juvenile mafic crust, which itself is generated at the base of continental crust through partial melting of mantle wedges. Subduction can also cause widespread reworking of continents and even destruction of presumably strong cratons, as manifested by the common occurrence of weakening, thinning, and recycling of continental lithosphere due largely to the vigorous infiltration of volatile‐rich fluids and melts, especially along both lateral and vertical weak zones. Less significant continental reworking also occurs in continental interiors with either plate boundary processes or plume‐lithosphere interactions. Archean continental nuclei likely originated from oceanic plateaus formed by mantle plumes, not from island arcs via oceanic subductionArchean continental nuclei underwent accretion or growth at margins by oceanic subduction, involving juvenile arc formation and accretionContinental reworking occurs ubiquitously, with significant reworking/craton destruction being mainly associated with oceanic subduction Archean continental nuclei likely originated from oceanic plateaus formed by mantle plumes, not from island arcs via oceanic subduction Archean continental nuclei underwent accretion or growth at margins by oceanic subduction, involving juvenile arc formation and accretion Continental reworking occurs ubiquitously, with significant reworking/craton destruction being mainly associated with oceanic subduction

A major current debate in Asian tectonics concerns the time of closure of the Paleo‐Asian Ocean (PAO) and the collision between the Central Asian arcs and the Tarim and North China cratons (NCC). This has led to much uncertainty about the reconstruction of proto‐Asia and tectonic configuration of northeast Pangea. Here we report Triassic provenance change in the foreland of the Alxa Block by field‐based zircon U‐Pb and Hf isotopic analysis. Nonmarine sediments, unconformable on or in fault contact, with the Alxa basement yield Precambrian and Paleozoic–Triassic detrital zircon ages with maximum depositional ages of Middle‐Late Triassic (∼244–224 Ma). Hf isotopic data indicate that Middle Triassic sandstones were sourced from the NCC basement and a continental arc, whereas Late Triassic sediments received an additional input from a juvenile arc. This provenance change in the foreland sedimentation indicates that the final closure of the PAO was in the Middle‐Late Triassic. The Central Asian Orogenic Belt, the world’s largest Phanerozoic accretionary orogen, was constructed by the amalgamation of magmatic arcs and subduction‐accretion complexes during the protracted subduction of the Paleo‐Asian Ocean (PAO). The collision between Central Asian arcs and the Tarim and North China cratons led to the final closure of the PAO and formation of proto‐Asia and northeast Pangea. Constraining when and how the PAO closed is fundamental for a better understanding of the complex history of assembly of this part of Asia and the process from accretion to collision of the accretionary orogen. We conducted geological mapping and provenance analysis of a newly discovered foreland deposition on the Alxa Block in northwest China. The results reveal a provenance change in the Middle‐Late Triassic, which we interpret as a response to collision between the juvenile Central Asian arcs and the North China Craton. Our findings combined with regional data point to final closure of the PAO in the Middle‐Late Triassic. Discovery of Triassic syn‐orogenic sediments in the foreland of the Alxa Block, northwest ChinaDetrital zircon U‐Pb and Lu‐Hf isotopic data indicate that juvenile Central Asian arc detritus arrived in the Alxa foreland by CarnianThe provenance change constrains the time of closure of the Paleo‐Asian Ocean as Middle‐Late Triassic (Ladinian‐Carnian) Discovery of Triassic syn‐orogenic sediments in the foreland of the Alxa Block, northwest China Detrital zircon U‐Pb and Lu‐Hf isotopic data indicate that juvenile Central Asian arc detritus arrived in the Alxa foreland by Carnian The provenance change constrains the time of closure of the Paleo‐Asian Ocean as Middle‐Late Triassic (Ladinian‐Carnian)

Sedimentary rocks provide key information on source‐to‐sink systems and the regional expression of plate tectonics. The abruptly changing provenance signature of sedimentary rocks is commonly ascribed to changes in the source regions, such as continental collision events, the rise of mountain chains, reorganization of river systems and climatic change. However, moving the positions of the sinks (depocenters) geographically can also change the provenance record, but this is rarely considered. Typically, large‐scale strike‐slip faults can transport depocenters for long distances, thus altering the provenance information. In this study, we present a systematic investigation of the provenance changes in the Sikhote‐Alin orogenic belt in the Russian Far East to evaluate this process. The Central Sikhote‐Alin Fault is a margin‐parallel strike‐slip fault that developed along the NE Asian continental margin from the late Mesozoic. Our new detrital zircon U‐Pb data, together with a compilation of geochronological data, indicate two different types of provenance signatures available: the sediments to the west of the fault were mainly derived from the adjacent Central Asian Orogenic Belt, but to the east of the fault, they were mainly supplied from the Korean Peninsula, which is several hundred kilometers away. It is proposed that these different sedimentary rocks were juxtaposed by syn‐ and post‐subduction sinistral displacements along the fault, and were not related to local variations in the source regions. Thus, understanding the shifting positions of depocenters is important when decoding provenance change because lateral displacement is critical for reconstructing regional paleogeography along oblique convergent plate margins. Drainage systems on Earth's continents carry abundant sediments from their sources to sinks. These sediments, which record climatic, topographic, tectonic and river dynamic information during their journeys, are finally preserved as sedimentary rocks. By studying them, geologists can decode the ancient source‐to‐sink systems. Events occurring in the source regions are always emphasized to explain the varying information in the sediments. For example, the rise of mountains can migrate river's watershed and drainage basins, changing the characteristics of materials. Sometimes, however, simply moving positions of the sinks/basins also can achieve similar effects, such as basins moved by large strike‐slip faults. Here, our research in Sikhote‐Alin, Russian Far East shows that the sediments have two age spectrum patterns, indicating two provenance types along the NE Asian margin during the late Mesozoic. We suggest that the two types were juxtaposed by a large‐scale strike‐slip fault during and/or after their deposition. The different provenance features in Sikhote‐Alin was caused by the large‐scale margin‐parallel motion, instead of any variations in the sources. Similar tales were reported in NW America, northeastern Tibetan Plateau and other regions globally. Thus, understanding the shifting positions of sinks/basins is important when interpreting provenance change and reconstructing regional paleogeography. Provenance change along the NE Asian margin was caused by large strike‐slip faults cutting depocenters, not variations in the sourcesMoving geographic positions of depocenters is rarely considered, but need more attentions when analyzing provenance changeLinking large strike‐slip faults and sedimentary records can importantly contribute to plate and geographic reconstructions Provenance change along the NE Asian margin was caused by large strike‐slip faults cutting depocenters, not variations in the sources Moving geographic positions of depocenters is rarely considered, but need more attentions when analyzing provenance change Linking large strike‐slip faults and sedimentary records can importantly contribute to plate and geographic reconstructions

New field relations and U‐Pb ages of detrital zircons from Middle Devonian‐Upper Triassic sedimentary rocks in the South Tianshan constrain the time and style of terminal suturing between the Tarim Craton and the Yili‐Central Tianshan arc. The variety of mélange blocks set within diagnostic thrust‐imbricates demonstrates that basalts, limestones, cherts, and sandstones belong to the Ocean Plate Stratigraphy (OPS) of an accreted oceanic plate. The imbricated OPS structure is further confirmed by our observation of lateral juxtaposition of Lower Carboniferous meta‐sandstones and Upper Carboniferous sandstones. Detrital zircon ages from Middle Devonian to Lower‐Middle Triassic rocks show no input from the Tarim Craton, but rather derivation from the Yili‐Central Tianshan arc or from isolated seamounts/oceanic plateaus within the South Tianshan oceanic plate. The integrated field observations and sediment provenance indicate that these rocks belong to the South Tianshan accretionary complex. The Upper Triassic sandstones show a mixed provenance from the Tarim Craton and the Yili‐Central Tianshan arc suggesting that the final subduction of the South Tianshan oceanic plate lasted until its terminal collision to the Tarim craton in the Late Triassic. Our work not only supports continuous northward subduction of the South Tianshan oceanic plate, but also indicates that the cryptic terminal suture between the Tarim Craton and the Yili‐Central Tianshan arc is situated on the southern boundary of the South Tianshan accretionary complex, providing new constraints on the final amalgamation of the Altaid orogen. This multi‐disciplinary study demonstrates an optimum means of unraveling the complex framework and tectonic evolution of an accretionary orogen. South Tianshan was an accretionary complex belonging to the Yili‐Central Tianshan arc, rather than a passive margin of the Tarim CratonTerminal suture between the Tarim and the Yili‐Central Tianshan is situated in the southern boundary of the South TianshanNorthward subduction of the South Tianshan oceanic plate lasted until the Late Triassic as indicated by a mixed provenance South Tianshan was an accretionary complex belonging to the Yili‐Central Tianshan arc, rather than a passive margin of the Tarim Craton Terminal suture between the Tarim and the Yili‐Central Tianshan is situated in the southern boundary of the South Tianshan Northward subduction of the South Tianshan oceanic plate lasted until the Late Triassic as indicated by a mixed provenance

The Iranian plateau is a natural laboratory for deciphering the lithospheric deformation and deep dynamics in response to the Neo‐Tethyan subduction and subsequent Arabia‐Eurasia continental collision. Here we used S‐wave receiver function data from a dense seismic array to construct the structural image of the lithosphere‐asthenosphere system across the northeastern to eastern Iranian plateau. The lithosphere‐asthenosphere boundary (LAB) is consistently imaged, being relatively flat at 80–90 km depth in eastern Iran, but deepening northward to ∼120 km depth beneath the Kopeh Dagh‐Turan platform boundary with an overall “root‐like” shape in northeastern Iran. A shallower (<45 km) and a deeper Moho (∼50–55 km) are also observed beneath eastern and northeastern Iran, respectively, suggesting similar crustal deformation to mantle lithosphere but different patterns laterally. Moreover, a strong positive velocity discontinuity (PVD) is detected at ∼170 km depth beneath eastern Iran, possibly representing the base of an asthenospheric low‐velocity layer (LVL). Waveform modeling reveals large velocity contrasts of ∼4%–6% over a depth range of less than 30 and 20 km, respectively, across the LAB and the asthenospheric PVD. Combining our new results with geological and petrological constraints, we deduced that the asthenospheric LVL contains a small amount of melt, with sharp boundaries separating from the nearly melt‐free lithosphere above (LAB) and deeper mantle below (PVD). The observed structural variations of the lithosphere‐asthenosphere system across the study region may result from the complex lithospheric deformation in response to the Arabia‐Eurasia collision and effects of multiple tectono‐thermal events associated with the earlier Neo‐Tethyan subduction. Lateral variations of the lithospheric and sub‐lithospheric structures are investigated across northeastern to eastern IranLithospheric responses to the Arabia‐Eurasia convergence vary across the interior of the Iranian plateauHydrous melting possibly occurs in the asthenospheric low‐velocity layer beneath eastern Iran Lateral variations of the lithospheric and sub‐lithospheric structures are investigated across northeastern to eastern Iran Lithospheric responses to the Arabia‐Eurasia convergence vary across the interior of the Iranian plateau Hydrous melting possibly occurs in the asthenospheric low‐velocity layer beneath eastern Iran

Subduction transformation (advancing vs. retreating) may be manifested by compositional variations of arc magmas and may result in oroclinal bending. Identifying relevant chemical and physical processes is crucial for understanding accretionary orogenesis and continental crustal evolution. The Northern Yili Block (NYB) was situated on an active margin associated with subduction of the Junggar Ocean (part of the Paleo‐Asian Ocean) and underwent perplexing accretionary orogenesis in late Paleozoic. Two episodes of subduction‐related granitoid magmatism have been identified, the first in the Late Devonian (374–369 Ma) and the second in the Late Carboniferous (ca. 304 Ma). These two episodes of granitoid magmatism exhibit contrasting features; for example, the first episode shows low εNd(t) (−6 to −2) and εHf(t) (−12 to +3) values, while the second episode displays relatively higher values (−2 to +7 and 0 to +20, respectively), suggesting increase contribution of juvenile components in the magma sources. The calculated zircon saturation temperatures are mostly <800°C for the first episode but increased to >800°C for the second episode. The (La/Yb)Nratios of the two‐episode granitoids vary from 2–17 to 1–9, indicative of the NYB crustal thinning in the Late Carboniferous. In addition, the migrations of the magmatic arc and trench in the NYB took place coevally in the Late Carboniferous and were accompanied by development of an accretionary complex and an immature back‐arc basin. We interpret that the arc magmatic variations and migrations reflect geodynamic transition from the Late Devonian advancing subduction to the Late Carboniferous retreating subduction. The retreating subduction of the Junggar oceanic plate possibly resulted in prominent oroclinal bending of the southern Kazakhstan collage system in the Late Carboniferous. Two episodes of granitoids were derived from mixed sources of the Proterozoic basement and various Paleozoic juvenile materialsThe tectonic transformation occurred in the Northern Yili Block from advancing to retreating subduction in late PaleozoicThe subduction zone transition may account for oroclinal bending in southern limb of the Kazakhstan Orocline in the Late Carboniferous