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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]