Structural styles and zircon ages of the South Tianshan accretionary complex, Atbashi Ridge, Kyrgyzstan: Insights for the anatomy of ocean plate stratigraphy and accretionary processes

Sang, Miao; Xiao, Wenjiao; Orozbaev, Rustam; Bakirov, Apas; Sakiev, Kadyrbek; Pak, Nikolay; Ивлева, Е. А.; Zhou, Kefa; Ao, Songjian; Qiao, Q. Y.; Zhang, Zhixin

doi:10.1016/j.jseaes.2017.07.052

Cited by 43 publications

(62 citation statements)

References 83 publications

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“…Sang et al. () proposed that the so‐called HPMU unit is indistinguishable from the HP tectonic mélange, considering that the HPMU unit consists of blocks of eclogites embedded in a lower grade metasedimentary matrix. By this study, we clearly demonstrate that while the HPMU unit bears a distinct lithology with respect to the HP tectonic Mélange, it also preserves HP assemblages, suggesting that all the lithologies (metasedimentary and metamafic rocks) record HP eclogitic conditions.…”

Section: Discussionmentioning

confidence: 99%

“…() and Sang et al. () to conclude that their source provenance lies in the North Tien Shan, where 450–430 Ma batholiths are widespread. Rojas‐Agramonte et al.…”

Section: Geological Settingmentioning

confidence: 97%

“…() dated metamorphic overgrowths of detrital zircon from a paragneiss of the Tash‐Rabat valley (west of the Atbashi Range, Figure d) and obtained two U–Pb ages of 336 ± 6 Ma and 329 ± 5, while Sang et al. () obtained zircon overgrowth ages as young as c . 250 Ma.…”

Section: Geological Settingmentioning

confidence: 99%

“…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%

“…Mafic eclogite boudins from the HP mélange that crop out in the Ak‐Talaa area have been the main focus of the Atbashi range studies (Figure d; e.g., Hegner et al., ; Loury et al., ; Sang et al., ; Simonov et al., ; Tagiri et al., ). These fragments of mafic eclogites are derived from an oceanic crust with N‐MORB and oceanic island basalt (OIB) protoliths (Simonov et al., ).…”

Section: Geological Settingmentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 99%

“…() and Sang et al. () to conclude that their source provenance lies in the North Tien Shan, where 450–430 Ma batholiths are widespread. Rojas‐Agramonte et al.…”

Section: Geological Settingmentioning

confidence: 97%

Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

See 3 more Smart Citations

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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Ordovician to Early Permian accretionary tectonics of Eastern Tianshan: Insights from Kawabulak ophiolitic mélange, granitoid, and granitic gneiss

Xiao

Windley

et al. 2018

Geological Journal

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There is a broad consensus that the final closure of the Paleo-Asian Ocean lead to the formation of the southern segment of the Central Asian Orogenic Belt. However, the final closure of the Paleo-Asian Ocean remains controversial. To address this issue, a systematical study of geochemical and zircon U-Pb on the Kawabulak ophiolite in the southern Eastern Tianshan was carried out. The Kawabulak ophiolite is an accretionary prism that consists of different lithological tectonic slices and marks the suture zone that welded the Central Tianshan composite arc and the northern passive margin of the Tarim Craton. Zircon U-Pb data show that gabbro blocks of the Kawabulak ophiolite formed at 360.9 ± 3.3 Ma in the northern part and 326.0 ± 3.3 Ma in the southern part, respectively. The geochemistry features of basalts and gabbros show OIB-type, arc/subduction-related affinities, indicating different tectonic setting origins. A granitic gneiss with an arc-related geochemical feature yielded a zircon U-Pb age of 477.2 Ma, indicating the earliest subduction event. The youngest deformed arc-related granitic intrusion (295 Ma) in the Kawabulak prism indicates that the final closure timing of the Paleo-Asian Ocean in Eastern Tianshan is after the Early Permian. The results of our study shed light to the temporal and spatial evolution of the southern Central Asian Orogenic Belt.

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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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Structural styles and zircon ages of the South Tianshan accretionary complex, Atbashi Ridge, Kyrgyzstan: Insights for the anatomy of ocean plate stratigraphy and accretionary processes

Cited by 43 publications

References 83 publications

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

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

Ordovician to Early Permian accretionary tectonics of Eastern Tianshan: Insights from Kawabulak ophiolitic mélange, granitoid, and granitic gneiss

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

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