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• A "porphyroclast" system occurred in the Tuwu area in the late Early Permian. • The dextral shear event within the Kangguer Shear Zone was initiated at ca. 278 Ma. • The event provides constraints to the intracontinental convergence of the East Tianshan. The Kangguer Shear Zone, located in the East Tianshan, is one of the key faults for understanding the final amalgamation processes of the southwestern margin of the Central Asian Orogenic Belt. Magmatism was active in the Tuwu area of the Kangguer Shear Zone during the late Early Permian. LA–ICP–MS U–Pb dating analyses of the magmatic zircons from three monzogranite plutons, a felsic dyke, and a diorite dyke show ages of 286.9±0.78, 282.8±0.62, 281.7±0.89, 278.0±0.61, and 278.1±1.2 Ma, respectively. Detailed field and microscopic observations reveal that these intrusions form a "porphyroclast" system, and this area has undergone ductile dextral strike-slip deformation, with foliations dipping steeply to the south and subhorizontal stretching lineations trending to the east. Further structural analysis indicates that the three monzogranite plutons intruded into the Kangguer Shear Zone and cooled into rigid bodies before regional dextral strike-slip deformation, which limited the deformation that occurred after 282 Ma. The felsic dykes exhibit synkinematic characteristics, and the diorite dyke may have intruded before or at the same time as dextral strike-slip deformation, implying that regional dextral shear was initiated at ca. 278 Ma. These data, combined with previous studies, suggest that the initiation of dextral shear in the Kangguer Shear Zone occurred after the closure of the Kangguer Ocean and was the result of regional nearly N–S compression caused by the convergence of the Tarim Craton and plates north of the Kangguer Shear Zone. [ABSTRACT FROM AUTHOR]

[Display omitted] Evolution of internal or external oceanic domains can bring decisive indications into the mode of formation of supercontinents, which is key to understand the supercontinent cycle. Defining the type of ocean evolving in the Central Asian Orogenic belt (CAOB) is thus critical to better understand the Earth's supercontinental evolution. In this contribution, we provide systematic and combined U-Pb, trace-element in zircon and hafnium-in-zircon analyses of four turbidites of the Altai accretionary wedge. These turbiditic rocks provide constraints into the early Paleozoic subduction-accretionary stages of the Mongolian Accretionary Collage (MAC) and show a major detrital age peak in the Cambro-Ordovician (∼490–500 Ma), with minor Neo- and Paleo-Proterozoic to Archean peaks. The zircon trace-elemental patterns are consistent with derivation mostly from magmatic arc (with granitoids affinity), interpreted as detritus sourced from the Ikh-Mongol continental arc system further north-east (present coordinates). The main detrital zircon peak together with the zircon magmatic arc origin suggest that the subduction-accretionary stage was active from 550 to 430 Ma showing mixed ε Hf (t) values (-20 to + 15). A summary of the detrital zircon ε Hf (t) values from 550 to 430 Ma suggests a continuous increase of ε Hf (t) mean values from + 0.2 to + 6.1 towards younger ages. The younging juvenile trend can be compared to the evolution of external orogeny, therefore consistent with a Pacific-type accretionary system facing an external ocean. At last, the results combined with two paleo-geographic reconstructions from the literature imply that the MAC may have been part of the Peri-Siberian accretionary orogeny in the early Paleozoic. [ABSTRACT FROM AUTHOR]

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

[Display omitted] • Devonian migmatite-granite complex developed a sub-horizontal HT/LP fabric. • Structures across the crust of the Chinese Altai advocate Devonian extension. • Subduction retreat induced crustal extension and promoted metallogenic evolution. Crustal extension due to the retreat of subduction system has been assigned as an important mechanism governing the Devonian tectonic evolution of the Chinese Altai Orogen in central Asia. While the extensional regime has been repeatedly inferred from petro-structural (petrographic and structural) records preserved in the orogenic upper crust sedimentary covers and orogenic middle crust schists, such records have rarely been documented in the deep crustal migmatitic and/or magmatic rocks. This gap is filled in this study by applying combined petro-structural analysis in conjunction with zircon and monazite U-Pb geochronology on representative orogenic lower crustal migmatite-granite complexes. These complexes are characterized by the development of a sub-horizontal foliation associated with extensional melt‐filled shear bands. The foliation commonly contains garnet-sillimanite ± K-feldspar ± cordierite-bearing metamorphic assemblages that are compatible with a low-pressure/high-temperature thermal regime. In addition, such mineral assemblages are usually found to replace pre-existing middle-pressure/middle-temperature Barrovian-type ones, reflecting a tectonic switch from thickening to extension. New monazite and zircon U-Pb age data, together with regional pre-existing ages, suggest that the sub-horizontal high-temperature foliation formed during a period of 420–390 Ma. Combined with previously published data, our data reinforce that a crustal-scale extensional tectonic regime developed in response to retreating of subduction system governed the geodynamic evolution of the Chinese Altai Orogen during Devonian times. This process led to regional anatexis of the pre-existing Ordovician accretionary wedge complex, facilitated the formation of stabilized and vertically stratified continental crust, and promoted the metallogenic evolution in the region during the Devonian. [ABSTRACT FROM AUTHOR]

[Display omitted] • Grenville-age terrane is identified in the Qilian orogen. • The Precambrian basement of the Qilian orogen is divided into four distinct mega-sequences. • ∼475 Ma metamorphism was related to the subduction of the Proto-Tethys Ocean. The Qilian orogen at the northeastern margin of the Tibetan Plateau records a complete history from continental breakup to oceanic basin evolution and back to continental collision during the Neoproterozoic to Paleozoic interval. The Qilian Ocean, as a branch of the Proto-Tethys Ocean, was connected to the Iapetus Ocean but is lesser known than its two more famous counterparts. This paper presents zircon U-Pb and biotite-muscovite 40Ar/39Ar isotope data from the Yemananshan Complex in the western Central Qilian belt to assess the age and provenance of late Mesoproterozoic-early Paleozoic successions in the Qilian orogen. The results indicate the Central Qilian belt is characterized by Late Mesoproterozoic-early Neoproterozoic orogenesis with magmatism from 1200 Ma to 900 Ma and clastic metasedimentary rocks deposited between 1050 and 920 Ma. Statistical analysis of detrital zircon data and auxiliary temporal information from the Qilian orogen affirms the notion that sedimentation occurred in four distinct megasequences: (1) 1950–1850 Ma, the oldest known strata, (2) 1250–920 Ma, during Grenvillian-Sveconorwegian orogenesis, (3) 840–760 Ma, the disintegration of Rodinia, and (4) 650–550 Ma, which is typical of the orogenic belts that sutured the Gondwana continental blocks. Metamorphic zircon and 40Ar/39Ar isotope data indicate early Paleozoic metamorphism at ca. 475 Ma, which overlaps with magmatic activity associated with arc-back-arc basin development in the Central Qilian belt, which was associated with subduction of the Proto-Tethys in eastern Gondwana. [ABSTRACT FROM AUTHOR]

[Display omitted] • The ca. 311 Ma granite was derived from biotite dehydration melting of metagreywacke. • The ca. 283 Ma granite experienced extreme differentiation and melt–fluid interaction. • The granitic rocks record the tectonic transition from syn- to post-collision (ca. 320–280 Ma). • Hf isotopic mapping reveals significant crustal reworking. Peraluminous granitoids can provide crucial insights into crustal reworking. Here we report a geochemical study of two Late Paleozoic peraluminous granitic plutons in the South Tianshan Belt, NW China, to constrain their crustal reworking history. Zircon U-Pb analyses yield ages of 311 ± 4 Ma for the garnet-bearing biotite granite and 283 ± 4 Ma for the garnet-bearing muscovite granite. The garnet-bearing biotite granites exhibit peraluminous affinity (ASI = 1.04–1.11), high CaO/Na 2 O, low Rb/Sr, and negative ε Nd (t) (−8.7 to –7.5) and zircon ε Hf (t) (–8.4 to –0.8) values with ancient crustal model ages, which suggest they were derived from dehydration melting of metagraywacke. The garnet-bearing muscovite granites, containing manganese garnet, show high SiO 2 (72.3–76.8 wt%) and strongly peraluminous (ASI = 1.14–1.22), high Rb/Sr (37.8–128.9), low Zr/Hf (16.61–31.80) and Nb/Ta (3.05–5.71), and exhibit tetrad REE patterns (TE 1 , 3 = 1.05–1.27), which can be ascribed to high-degree fractional crystallization accompanied by the interaction with fluids. They show negative ε Nd (t) values (–8.6 to –6.6) and variable zircon ε Hf (t) values (–4.9 to +2.7), implying ancient crustal with minor juvenile crustal sources. In combination with the occurrence of peraluminous magmatic rocks of the South Tianshan Belt, we propose that the peraluminous magmatic rocks were formed by the partial melting of ancient crustal rocks from the passive continental margin of the Tarim Craton, which represents an important crustal reworking event in the Central Asian Orogenic Belt. [ABSTRACT FROM AUTHOR]

• Fission track technique effectively constrains tectono-thermal events. • 5 cooling-uplifting episodes of 200–170, 170–100, 100–50, 50–18 and 18–0 Ma. • Zircon FT age of ~193–133 Ma reveal the northward subduction of the Tethyan ocean. • Apatite FT age of ~103–29 Ma response to the collision of India–Asia plate.Apatite FT age of ~103–29 Ma response to the collision of India–Asia plate. • These results have certain universality in the Eastern Kunlun Orogenic Belt. The present Tibetan plateau is a collage of several terranes, including the Lhasa, Qiangtang, Songpan-Ganzi and Kunlun-Qaidam terranes. Following closure of the Palaeo- and Neo-Tethyan oceans, the terranes of the Tibetan plateau migrated northward, and the deformation timing of the northern part of the Songpan-Ganze terrane between Golmud and Dulan in the Eastern Kunlun Orogenic Belt (EKOB) is still poorly understood. Fission track (FT) analysis of zircon and apatite from two localities between Golmud and Dulan has yielded new information about the timing of deformation in EKOB. Samples collected from Aikeng and Boguole yielded zircon and apatite FT central age ranges of ~193–133 Ma and ~103–29 Ma respectively. Thermal history modelling of FT data revealed five major episodes of cooling in these regions at ~200–170 Ma, ~170–100 Ma, ~100–50 Ma, ~50–18 Ma, and ~18–0 Ma. Stage one represents the collision between the Qiangtang and Kunlun tectonic blocks and the closure of the Songpan-Ganzi-Bayan Har Triassic turbidite basin. In stage two, the northward subduction of the Neo-Tethys oceanic plate accentuated sediment transport to the actively closing ocean basin between the Lhasa and Qiangtang terranes, the far-field effect of collision caused the cooling of the EKOB. Stage three is characterised by tectonic quiescence, which ended at ~50 Ma due to the collision of India and Asia. In stage four, the establishment of a strike-slip fault system and fold-thrust belt in the EKOB resulted in exhumation. Stage five saw rapid cooling in response to the most recent compressional event associated with fault development in the EKOB. [ABSTRACT FROM AUTHOR]