Middle to Late Ordovician arc system in the Kyrgyz Middle Tianshan : From arc-continent collision to subsequent evolution of a Palaeozoic continental margin

D. V. ALEXEIEV; A. KRÖNER; E. HEGNER; Y. ROJAS-AGRAMONTE; Yu S. BISKE; J. WONG; H. Y. GENG; E. A. IVLEVA; M. MÜHLBERG; A. V. MIKOLAICHUK; D. LIU

doi:10.1016/j.gr.2016.02.003

Middle to Late Ordovician arc system in the Kyrgyz Middle Tianshan : From arc-continent collision to subsequent evolution of a Palaeozoic continental margin

D. V. ALEXEIEV^*, A. KRÖNER, E. HEGNER, Y. ROJAS-AGRAMONTE, Yu S. BISKE, J. WONG, H. Y. GENG, E. A. IVLEVA, M. MÜHLBERG, A. V. MIKOLAICHUK, D. LIU

^*Corresponding author for this work

Research output: Journal Publications › Journal Article (refereed) › peer-review

86 Citations (Scopus)

Abstract

New geological, geochronological and isotopic data reveal a previously unknown arc system that evolved south of the Kyrgyz Middle Tianshan (MTS) microcontinent during the Middle and Late Ordovician, 467–444 Ma ago. The two fragments of this magmatic arc are located within the Bozbutau Mountains and the northern Atbashi Range, and a marginal part of the arc, with mixed volcanic and sedimentary rocks, extends north to the Semizsai metamorphic unit of the southern Chatkal Range. A continental basement of the arc, indicated by predominantly felsic volcanic rocks in Bozbutau and Atbashi, is supported by whole-rock Nd- and Hf-in-zircon isotopic data. ε_Nd(t) of + 0.9 to − 2.6 and ε_Hf(t) of + 1.8 to − 6.0 imply melting of Neo- to Mesoproterozoic continental sources with Nd model ages of ca. 0.9 to 1.2 Ga and Hf crustal model ages of ca. 1.2 to 1.7 Ga. In the north, the arc was separated from the MTS microcontinent by an oceanic back-arc basin, represented by the Karaterek ophiolite belt. Our inference of a long-lived Early Palaeozoic arc in the southwestern MTS suggests an oceanic domain between the MTS microcontinent and the Tarim craton in the Middle Ordovician. The time of arc-continent collision is constrained as Late Ordovician at ca. 450 Ma, based on cessation of sedimentation on the MTS microcontinent, the age of an angular unconformity within the Karaterek suture zone, and the age of syncollisional metamorphism and magmatism in the Kassan Metamorphic Complex of the southern Chatkal Range. High-grade amphibolite-facies metamorphism and associated crustal melting in the Kassan Metamorphic Complex restricts the main tectonic activity in the collisional belt to ca. 450 Ma. This interpretation is based on the age of a synkinematic amphibolite-facies granite, intruded into paragneiss during peak metamorphism. A second episode of greenschist- to kyanite–staurolite-facies metamorphism is dated between 450 and 420 Ma, based on the ages of granitoid rocks, subsequently affected or not affected by this metamorphism. The latest episode is recorded by greenschist-facies metamorphism in Silurian sandstones and granodiorites and by retrogression of the older, higher-grade rocks. This may have occurred at the Silurian to Devonian transition and reflects reorganization of a Middle Palaeozoic convergent margin. Late Ordovician collision was followed by initiation of a new continental arc in the southern MTS. This arc was active in the Early Silurian, latest Silurian to Middle Devonian, and Late Carboniferous, whereas during the Givetian through Mississippian (ca. 385–325 Ma) this area was a passive continental margin. These arcs, previously well constrained west of the Talas-Ferghana Fault, continued eastwards into the Naryn and Atbashi areas and probably extended into the Chinese Central Tianshan. The disappearance of a major crustal block with transitional facies on the continental margin and too short a distance between the arc and accretionary complex suggest that plate convergence in the Atbashi sector of the MTS was accompanied by subduction erosion in the Devonian or Early Pennsylvanian. This led to a minimum of 50–70 km of crustal loss and removal of the Ordovician arc as well as the Silurian and Devonian forearcs in the areas east of the Talas-Ferghana Fault.

Original language	English
Pages (from-to)	261-291
Number of pages	31
Journal	Gondwana Research
Volume	39
Early online date	7 Mar 2016
DOIs	https://doi.org/10.1016/j.gr.2016.02.003
Publication status	Published - Nov 2016
Externally published	Yes

Bibliographical note

We thank Mikhail Ghes', Rena Maksumova, and Rinella Rinenberg for discussion and consultations, which helped to coordinate our field study. We are grateful to Vladimir Kiselev for providing a zircon concentrate of sample Ki5 and to Nadejda Priyatkina for detrital zircon data on a sample from the Kembel Complex. The help of Anatoliy Rybin, Director of the Research Station of the Russian Academy of Sciences in Bishkek, in organising fieldwork in Kyrgyzstan is much appreciated. Chao Yuan of the Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, kindly arranged for chemical analysis of several whole-rock samples in this study, and Yin Tong, Institute of Geology, CAGS, kindly provided a chemical analysis of sample A12026-3. Chun Yang of the Beijing SHRIMP Centre prepared perfect zircon mounts, and Xiao-Chao Che and Liqin Zhou provided the zircon CL images. Jianfeng Gao of the Canadian Geological Survey, Ottawa, provided an unpublished Excel-based program to construct the Hf evolution diagrams of Fig. 15 . We are grateful to Dmitriy Konopelko, two anonymous reviewers and Associated Editors Yunpeng Dong and Inna Safonova for thorough reviews and important comments that helped to improve the manuscript.

Funding

This study was financially supported by the Russian Science Foundation (RNF) project No. 14-27-00058 , RFBR grants 11-05-91332 and 13-05-91151 to DVA, by Deutsche Forschungsgemeinschaft (DFG) grant KR590/90-1 to AK, grant RO4174/1-2 to YRA, and grant 3.38.137.2014 from St-Petersburg University to Yu.B. E.H. acknowledges financial support of the Munich Radiogenic Isotope Facility by the Geo-Department , and YRA acknowledges the Prometeo Project of the Secretariat for Higher Education, Science, Technology and Innovation of the Republic of Ecuador . This paper represents a contribution to the research assignment No. 0135-2014-0002 of GIN RAS “The role of accretionary and collisional processes in the formation of the western segment of the Central Asian fold belt and the Urals”. It is also part of a collaborative study between Mainz University and the University of Hong Kong, funded jointly by the German Exchange Service (DAAD) and the Hong Kong Research Council.

Keywords

Arc-continent collision
Kyrgyzstan
Middle Tianshan
Nd–Hf isotopes
Palaeozoic
U–Pb zircon dating

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10.1016/j.gr.2016.02.003

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ALEXEIEV, D. V., KRÖNER, A., HEGNER, E., ROJAS-AGRAMONTE, Y., BISKE, Y. S., WONG, J., GENG, H. Y., IVLEVA, E. A., MÜHLBERG, M., MIKOLAICHUK, A. V., & LIU, D. (2016). Middle to Late Ordovician arc system in the Kyrgyz Middle Tianshan : From arc-continent collision to subsequent evolution of a Palaeozoic continental margin. Gondwana Research, 39, 261-291. https://doi.org/10.1016/j.gr.2016.02.003

@article{6060ed160a1c4fca84e2018f49c489e1,

title = "Middle to Late Ordovician arc system in the Kyrgyz Middle Tianshan : From arc-continent collision to subsequent evolution of a Palaeozoic continental margin",

abstract = "New geological, geochronological and isotopic data reveal a previously unknown arc system that evolved south of the Kyrgyz Middle Tianshan (MTS) microcontinent during the Middle and Late Ordovician, 467–444 Ma ago. The two fragments of this magmatic arc are located within the Bozbutau Mountains and the northern Atbashi Range, and a marginal part of the arc, with mixed volcanic and sedimentary rocks, extends north to the Semizsai metamorphic unit of the southern Chatkal Range. A continental basement of the arc, indicated by predominantly felsic volcanic rocks in Bozbutau and Atbashi, is supported by whole-rock Nd- and Hf-in-zircon isotopic data. εNd(t) of + 0.9 to − 2.6 and εHf(t) of + 1.8 to − 6.0 imply melting of Neo- to Mesoproterozoic continental sources with Nd model ages of ca. 0.9 to 1.2 Ga and Hf crustal model ages of ca. 1.2 to 1.7 Ga. In the north, the arc was separated from the MTS microcontinent by an oceanic back-arc basin, represented by the Karaterek ophiolite belt. Our inference of a long-lived Early Palaeozoic arc in the southwestern MTS suggests an oceanic domain between the MTS microcontinent and the Tarim craton in the Middle Ordovician. The time of arc-continent collision is constrained as Late Ordovician at ca. 450 Ma, based on cessation of sedimentation on the MTS microcontinent, the age of an angular unconformity within the Karaterek suture zone, and the age of syncollisional metamorphism and magmatism in the Kassan Metamorphic Complex of the southern Chatkal Range. High-grade amphibolite-facies metamorphism and associated crustal melting in the Kassan Metamorphic Complex restricts the main tectonic activity in the collisional belt to ca. 450 Ma. This interpretation is based on the age of a synkinematic amphibolite-facies granite, intruded into paragneiss during peak metamorphism. A second episode of greenschist- to kyanite–staurolite-facies metamorphism is dated between 450 and 420 Ma, based on the ages of granitoid rocks, subsequently affected or not affected by this metamorphism. The latest episode is recorded by greenschist-facies metamorphism in Silurian sandstones and granodiorites and by retrogression of the older, higher-grade rocks. This may have occurred at the Silurian to Devonian transition and reflects reorganization of a Middle Palaeozoic convergent margin. Late Ordovician collision was followed by initiation of a new continental arc in the southern MTS. This arc was active in the Early Silurian, latest Silurian to Middle Devonian, and Late Carboniferous, whereas during the Givetian through Mississippian (ca. 385–325 Ma) this area was a passive continental margin. These arcs, previously well constrained west of the Talas-Ferghana Fault, continued eastwards into the Naryn and Atbashi areas and probably extended into the Chinese Central Tianshan. The disappearance of a major crustal block with transitional facies on the continental margin and too short a distance between the arc and accretionary complex suggest that plate convergence in the Atbashi sector of the MTS was accompanied by subduction erosion in the Devonian or Early Pennsylvanian. This led to a minimum of 50–70 km of crustal loss and removal of the Ordovician arc as well as the Silurian and Devonian forearcs in the areas east of the Talas-Ferghana Fault.",

keywords = "Arc-continent collision, Kyrgyzstan, Middle Tianshan, Nd–Hf isotopes, Palaeozoic, U–Pb zircon dating",

author = "ALEXEIEV, {D. V.} and A. KR{\"O}NER and E. HEGNER and Y. ROJAS-AGRAMONTE and BISKE, {Yu S.} and J. WONG and GENG, {H. Y.} and IVLEVA, {E. A.} and M. M{\"U}HLBERG and MIKOLAICHUK, {A. V.} and D. LIU",

note = "We thank Mikhail Ghes', Rena Maksumova, and Rinella Rinenberg for discussion and consultations, which helped to coordinate our field study. We are grateful to Vladimir Kiselev for providing a zircon concentrate of sample Ki5 and to Nadejda Priyatkina for detrital zircon data on a sample from the Kembel Complex. The help of Anatoliy Rybin, Director of the Research Station of the Russian Academy of Sciences in Bishkek, in organising fieldwork in Kyrgyzstan is much appreciated. Chao Yuan of the Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, kindly arranged for chemical analysis of several whole-rock samples in this study, and Yin Tong, Institute of Geology, CAGS, kindly provided a chemical analysis of sample A12026-3. Chun Yang of the Beijing SHRIMP Centre prepared perfect zircon mounts, and Xiao-Chao Che and Liqin Zhou provided the zircon CL images. Jianfeng Gao of the Canadian Geological Survey, Ottawa, provided an unpublished Excel-based program to construct the Hf evolution diagrams of Fig. 15 . We are grateful to Dmitriy Konopelko, two anonymous reviewers and Associated Editors Yunpeng Dong and Inna Safonova for thorough reviews and important comments that helped to improve the manuscript.",

year = "2016",

month = nov,

doi = "10.1016/j.gr.2016.02.003",

language = "English",

volume = "39",

pages = "261--291",

journal = "Gondwana Research",

issn = "1342-937X",

publisher = "Elsevier Inc.",

}

ALEXEIEV, DV, KRÖNER, A, HEGNER, E, ROJAS-AGRAMONTE, Y, BISKE, YS, WONG, J, GENG, HY, IVLEVA, EA, MÜHLBERG, M, MIKOLAICHUK, AV & LIU, D 2016, 'Middle to Late Ordovician arc system in the Kyrgyz Middle Tianshan : From arc-continent collision to subsequent evolution of a Palaeozoic continental margin', Gondwana Research, vol. 39, pp. 261-291. https://doi.org/10.1016/j.gr.2016.02.003

TY - JOUR

T1 - Middle to Late Ordovician arc system in the Kyrgyz Middle Tianshan : From arc-continent collision to subsequent evolution of a Palaeozoic continental margin

AU - ALEXEIEV, D. V.

AU - KRÖNER, A.

AU - HEGNER, E.

AU - ROJAS-AGRAMONTE, Y.

AU - BISKE, Yu S.

AU - WONG, J.

AU - GENG, H. Y.

AU - IVLEVA, E. A.

AU - MÜHLBERG, M.

AU - MIKOLAICHUK, A. V.

AU - LIU, D.

N1 - We thank Mikhail Ghes', Rena Maksumova, and Rinella Rinenberg for discussion and consultations, which helped to coordinate our field study. We are grateful to Vladimir Kiselev for providing a zircon concentrate of sample Ki5 and to Nadejda Priyatkina for detrital zircon data on a sample from the Kembel Complex. The help of Anatoliy Rybin, Director of the Research Station of the Russian Academy of Sciences in Bishkek, in organising fieldwork in Kyrgyzstan is much appreciated. Chao Yuan of the Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, kindly arranged for chemical analysis of several whole-rock samples in this study, and Yin Tong, Institute of Geology, CAGS, kindly provided a chemical analysis of sample A12026-3. Chun Yang of the Beijing SHRIMP Centre prepared perfect zircon mounts, and Xiao-Chao Che and Liqin Zhou provided the zircon CL images. Jianfeng Gao of the Canadian Geological Survey, Ottawa, provided an unpublished Excel-based program to construct the Hf evolution diagrams of Fig. 15 . We are grateful to Dmitriy Konopelko, two anonymous reviewers and Associated Editors Yunpeng Dong and Inna Safonova for thorough reviews and important comments that helped to improve the manuscript.

PY - 2016/11

Y1 - 2016/11

N2 - New geological, geochronological and isotopic data reveal a previously unknown arc system that evolved south of the Kyrgyz Middle Tianshan (MTS) microcontinent during the Middle and Late Ordovician, 467–444 Ma ago. The two fragments of this magmatic arc are located within the Bozbutau Mountains and the northern Atbashi Range, and a marginal part of the arc, with mixed volcanic and sedimentary rocks, extends north to the Semizsai metamorphic unit of the southern Chatkal Range. A continental basement of the arc, indicated by predominantly felsic volcanic rocks in Bozbutau and Atbashi, is supported by whole-rock Nd- and Hf-in-zircon isotopic data. εNd(t) of + 0.9 to − 2.6 and εHf(t) of + 1.8 to − 6.0 imply melting of Neo- to Mesoproterozoic continental sources with Nd model ages of ca. 0.9 to 1.2 Ga and Hf crustal model ages of ca. 1.2 to 1.7 Ga. In the north, the arc was separated from the MTS microcontinent by an oceanic back-arc basin, represented by the Karaterek ophiolite belt. Our inference of a long-lived Early Palaeozoic arc in the southwestern MTS suggests an oceanic domain between the MTS microcontinent and the Tarim craton in the Middle Ordovician. The time of arc-continent collision is constrained as Late Ordovician at ca. 450 Ma, based on cessation of sedimentation on the MTS microcontinent, the age of an angular unconformity within the Karaterek suture zone, and the age of syncollisional metamorphism and magmatism in the Kassan Metamorphic Complex of the southern Chatkal Range. High-grade amphibolite-facies metamorphism and associated crustal melting in the Kassan Metamorphic Complex restricts the main tectonic activity in the collisional belt to ca. 450 Ma. This interpretation is based on the age of a synkinematic amphibolite-facies granite, intruded into paragneiss during peak metamorphism. A second episode of greenschist- to kyanite–staurolite-facies metamorphism is dated between 450 and 420 Ma, based on the ages of granitoid rocks, subsequently affected or not affected by this metamorphism. The latest episode is recorded by greenschist-facies metamorphism in Silurian sandstones and granodiorites and by retrogression of the older, higher-grade rocks. This may have occurred at the Silurian to Devonian transition and reflects reorganization of a Middle Palaeozoic convergent margin. Late Ordovician collision was followed by initiation of a new continental arc in the southern MTS. This arc was active in the Early Silurian, latest Silurian to Middle Devonian, and Late Carboniferous, whereas during the Givetian through Mississippian (ca. 385–325 Ma) this area was a passive continental margin. These arcs, previously well constrained west of the Talas-Ferghana Fault, continued eastwards into the Naryn and Atbashi areas and probably extended into the Chinese Central Tianshan. The disappearance of a major crustal block with transitional facies on the continental margin and too short a distance between the arc and accretionary complex suggest that plate convergence in the Atbashi sector of the MTS was accompanied by subduction erosion in the Devonian or Early Pennsylvanian. This led to a minimum of 50–70 km of crustal loss and removal of the Ordovician arc as well as the Silurian and Devonian forearcs in the areas east of the Talas-Ferghana Fault.

AB - New geological, geochronological and isotopic data reveal a previously unknown arc system that evolved south of the Kyrgyz Middle Tianshan (MTS) microcontinent during the Middle and Late Ordovician, 467–444 Ma ago. The two fragments of this magmatic arc are located within the Bozbutau Mountains and the northern Atbashi Range, and a marginal part of the arc, with mixed volcanic and sedimentary rocks, extends north to the Semizsai metamorphic unit of the southern Chatkal Range. A continental basement of the arc, indicated by predominantly felsic volcanic rocks in Bozbutau and Atbashi, is supported by whole-rock Nd- and Hf-in-zircon isotopic data. εNd(t) of + 0.9 to − 2.6 and εHf(t) of + 1.8 to − 6.0 imply melting of Neo- to Mesoproterozoic continental sources with Nd model ages of ca. 0.9 to 1.2 Ga and Hf crustal model ages of ca. 1.2 to 1.7 Ga. In the north, the arc was separated from the MTS microcontinent by an oceanic back-arc basin, represented by the Karaterek ophiolite belt. Our inference of a long-lived Early Palaeozoic arc in the southwestern MTS suggests an oceanic domain between the MTS microcontinent and the Tarim craton in the Middle Ordovician. The time of arc-continent collision is constrained as Late Ordovician at ca. 450 Ma, based on cessation of sedimentation on the MTS microcontinent, the age of an angular unconformity within the Karaterek suture zone, and the age of syncollisional metamorphism and magmatism in the Kassan Metamorphic Complex of the southern Chatkal Range. High-grade amphibolite-facies metamorphism and associated crustal melting in the Kassan Metamorphic Complex restricts the main tectonic activity in the collisional belt to ca. 450 Ma. This interpretation is based on the age of a synkinematic amphibolite-facies granite, intruded into paragneiss during peak metamorphism. A second episode of greenschist- to kyanite–staurolite-facies metamorphism is dated between 450 and 420 Ma, based on the ages of granitoid rocks, subsequently affected or not affected by this metamorphism. The latest episode is recorded by greenschist-facies metamorphism in Silurian sandstones and granodiorites and by retrogression of the older, higher-grade rocks. This may have occurred at the Silurian to Devonian transition and reflects reorganization of a Middle Palaeozoic convergent margin. Late Ordovician collision was followed by initiation of a new continental arc in the southern MTS. This arc was active in the Early Silurian, latest Silurian to Middle Devonian, and Late Carboniferous, whereas during the Givetian through Mississippian (ca. 385–325 Ma) this area was a passive continental margin. These arcs, previously well constrained west of the Talas-Ferghana Fault, continued eastwards into the Naryn and Atbashi areas and probably extended into the Chinese Central Tianshan. The disappearance of a major crustal block with transitional facies on the continental margin and too short a distance between the arc and accretionary complex suggest that plate convergence in the Atbashi sector of the MTS was accompanied by subduction erosion in the Devonian or Early Pennsylvanian. This led to a minimum of 50–70 km of crustal loss and removal of the Ordovician arc as well as the Silurian and Devonian forearcs in the areas east of the Talas-Ferghana Fault.

KW - Arc-continent collision

KW - Kyrgyzstan

KW - Middle Tianshan

KW - Nd–Hf isotopes

KW - Palaeozoic

KW - U–Pb zircon dating

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U2 - 10.1016/j.gr.2016.02.003

DO - 10.1016/j.gr.2016.02.003

M3 - Journal Article (refereed)

AN - SCOPUS:84962157669

SN - 1342-937X

VL - 39

SP - 261

EP - 291

JO - Gondwana Research

JF - Gondwana Research

ER -

Middle to Late Ordovician arc system in the Kyrgyz Middle Tianshan : From arc-continent collision to subsequent evolution of a Palaeozoic continental margin

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