Oblique wedge extrusion of UHP/HP complexes in the Late Triassic: structural analysis and zircon ages of the Atbashi Complex, South Tianshan, Kyrgyzstan

Sang, Miao; Xiao, Wenjiao; Bakirov, Apas; Orozbaev, Rustam; Sakiev, Kadyrbek; Zhou, Kefa

doi:10.1080/00206814.2016.1241163

Cited by 34 publications

(45 citation statements)

References 46 publications

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“…However, the subduction polarity of the South Tianshan Ocean has long been controversial. Southward subduction (Charvet et al, ; Jourdon et al, ) and northward subduction (Gao et al, ; Gao et al, ; Sang et al, ; Xiao, Huang, Han, Sun, & Li, ; Xiao et al, ; L. Zhang et al, 2007) have both been proposed. Furthermore, the timing of the final closure of the South Tianshan Ocean is likewise a subject open to debate since.…”

Section: Tectonic Backgroundmentioning

confidence: 99%

“…Therefore, as a necessary complement to our previous work on the structure, petrotectonics and geochronology of the Atbashi Complex (Sang et al, ; Sang et al, ), the objects of this paper are to present new whole‐rock major and trace elements and zircon U–Pb isotope compositions of the Atbashi basic UHP/HP rocks, in order to better understand the evolution of the Kyrgyz South Tianshan Oceanic slab, as one of the major means of constructing the subduction and emplacement history of a major exhumed tectonic slab.…”

Section: Tectonic Backgroundmentioning

confidence: 99%

“…Geological map of the Tianshan orogenic collage in Kyrgyzstan showing the major Palaeozoic Ili‐Central Tianshan magmatic arc and the South Tianshan Accretionary Complex with emphasis on the Atbashi Ridge (modified after Sang et al, ). Positions of Figures , and are marked [Colour figure can be viewed at wileyonlinelibrary.com]…”

Section: Introductionmentioning

confidence: 99%

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Unravelling a Devonian–Triassic seamount chain in the South Tianshan high‐pressure/ultrahigh‐pressure accretionary complex in the Atbashi area (Kyrgyzstan)

2020

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Seamounts are common occurrences on the extant oceanic floors of the earth, and accreted single seamounts are also widely distributed on the modern active margins, but recognition of single seamounts is an uneasy job in the ancient orogens, and the detection of a chain of accreted seamounts is even harder, therefore understanding the multiple accretion of ancient seamounts is nearly negligible. A combined analysis of geochronology and geochemistry was conducted on the basic eclogitic rocks from the Atbashi Accretionary Complex in the Kyrgyz South Tianshan, in a bid to unravel the accretion process of a chain of seamounts in the Paleo‐Asian Ocean in the southern Altaids. A set of reliable U–Pb zircon ages of 397.6 ± 8 Ma age for a basaltic andesite, 353 ± 8 Ma for a gabbro, and 317.1 ± 9 Ma for a diorite were obtained in this study. Both unmetamorphosed basic rocks and eclogites carry geochemical signatures of plume‐derived seamounts that were influenced by their respective mantle source. Taken together with previously published age data, the spatial and temporal features of these Atbashi rocks indicate the timing and sequence of formation, subduction, and extrusion of the South Tianshan oceanic remnants in the Early/Middle Devonian to Late Triassic. The integrated data indicate the existence of a seamount chain composed of Early/Middle Devonian–Late Triassic seamounts in the Atbashi Complex. The paleogeographic pattern and analysis of these fragments derived from the ocean‐type seamounts enable the reconstruction of tectonic models of that portray, magmatism, mantle‐derived plumes, subduction and exhumation of this Devonian–Triassic ocean floor.

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Section: Tectonic Backgroundmentioning

confidence: 99%

Section: Tectonic Backgroundmentioning

confidence: 99%

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Unravelling a Devonian–Triassic seamount chain in the South Tianshan high‐pressure/ultrahigh‐pressure accretionary complex in the Atbashi area (Kyrgyzstan)

2020

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“…The Atbashi Range constitutes a palaeo‐subduction prism represented by different structural units described from north to south along the Ak‐Talaa Valley (Figure b–d) (Alekseev, Aristov, & Degtyarev, ; Bakirov, ; Bakirov & Kotov, ; Biske, Zubtov, & Porshnyakov, ; Hegner et al., ; Loury et al., ; Sang et al., , ): An accretionary prism: This prism is composed of metapelites and calcschists locally including lenses of metabasites and is overthrust onto the MTS sedimentary series. A dismembered nonmetamorphic ophiolite composed of pillow‐basalts, flaser gabbros, plagiogranites, serpentinites and cherts: This ophiolite constitutes a fragment of the oceanic lithosphere overthrust towards the north onto the accretionary prism. Conodonts in cherty sequences constrained the age of the ophiolite as Early to Late Devonian (Pragian to Famennian; Alekseev et al., ). An eclogite facies tectonic mélange (“HP mélange”) containing decametre‐scale mafic eclogitic boudins within a metasedimentary matrix: It was overthrust onto the ophiolite in the Ak‐Talaa area.…”

Section: Geological Settingmentioning

confidence: 99%

Tectonometamorphic evolution of the Atbashi high‐Punits (KyrgyzCAOB, Tien Shan): Implications for the closure of the Turkestan Ocean and continental subduction–exhumation of the South Kazakh continental margin

Loury

Rolland

Guillot

et al. 2018

Journal Metamorphic Geology

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

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“…The authors further propose that porphyry-type Cu-Au mineralization should have a high potential at the deep sites of the Tawuerbieke district. Sang et al (2017) present an example of oblique wedge extrusion of ultra-high-pressure (UHP)/Highpressure (HP) rocks in the Atbashi accretionary complex of the Kyrgyz South Tianshan. Their field mapping and structural analysis demonstrate that the Atbashi EclogiteBlueschist Complex is situated in a complicated duplex formed by a northerly dextral transpression system and a southerly sinistral transtension system.…”

Section: Introductionmentioning

confidence: 99%

Tectonics, magmatism, and mineralization of Circum–Balkash–Junggar area in the Central Asian Orogenic Belt

Xiao

Shen

Chen

2017

International Geology Review

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Oblique wedge extrusion of UHP/HP complexes in the Late Triassic: structural analysis and zircon ages of the Atbashi Complex, South Tianshan, Kyrgyzstan

Cited by 34 publications

References 46 publications

Unravelling a Devonian–Triassic seamount chain in the South Tianshan high‐pressure/ultrahigh‐pressure accretionary complex in the Atbashi area (Kyrgyzstan)

Unravelling a Devonian–Triassic seamount chain in the South Tianshan high‐pressure/ultrahigh‐pressure accretionary complex in the Atbashi area (Kyrgyzstan)

Tectonometamorphic evolution of the Atbashi high‐Punits (KyrgyzCAOB, Tien Shan): Implications for the closure of the Turkestan Ocean and continental subduction–exhumation of the South Kazakh continental margin

Tectonics, magmatism, and mineralization of Circum–Balkash–Junggar area in the Central Asian Orogenic Belt

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