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Article: Petrostructural and Geochronological Constraints on Devonian Extension-Shortening Cycle in the Chinese Altai: Implications for Retreating-Advancing Subduction

TitlePetrostructural and Geochronological Constraints on Devonian Extension-Shortening Cycle in the Chinese Altai: Implications for Retreating-Advancing Subduction
Authors
KeywordsCentral Asian Orogenic Belt
crustal extension
low-pressure/high-temperature metamorphism
retreating subduction
tectonic switching
Issue Date2022
Citation
Tectonics, 2022, v. 41, n. 9, article no. e2021TC007195 How to Cite?
AbstractStructural and metamorphic effects of a Devonian extension-shortening cycle in the NW Chinese Altai were investigated using combined structural-petrological analysis and zircon and monazite U-Pb geochronology. Structural observations revealed a ubiquitous, sub-horizontal metamorphic fabric (S1), which was originally sub-parallel with horizontal bedding (S0) of supracrustal Devonian volcanic-sedimentary basins. This metamorphic fabric is defined by a sillimanite-bearing migmatitic gneissosity associated with extensional shear bands and a cordierite-bearing schistosity in the orogenic lower and middle crust, respectively. Staurolite relics preserved in the S1 fabric are interpreted as relics of older, higher pressure Barrovian-type metamorphism. These structural-metamorphic features are correlated with decompression and heating and interpreted as reflecting a crustal-scale extensional phase. S1 was folded to form N-S-oriented upright antiforms cored by migmatites and locally transposed by steep S2 foliation during a ∼W-E-directed shortening (in current coordinates). Andalusite and cordierite overgrew the migmatitic S2 foliation attesting to decreasing pressure associated with vertical extrusion of migmatites in cores of F2 antiforms. New U-Pb age data from subhorizontally foliated migmatites suggest that the D1 extension started at least before ∼410 Ma. Age data of syn-D2 granite intrusions and dykes constrain the D2 shortening starting soon after D1 extension and ending at ∼378 Ma. Combined with regional data, cycles of extensional and contractional tectonic regimes can be defined, which also show eastward migration along-strike of the Altai range. Such extension-shortening cycles could result from alternating retreating and advancing subduction, which governed the evolution of the Altai accretionary system from the Ordovician until the Carboniferous.
Persistent Identifierhttp://hdl.handle.net/10722/326627
ISSN
2023 Impact Factor: 3.3
2023 SCImago Journal Rankings: 1.662
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorKong, Lingzhu-
dc.contributor.authorJiang, Yingde-
dc.contributor.authorSchulmann, Karel-
dc.contributor.authorZhang, Jian-
dc.contributor.authorWeinberg, Roberto F.-
dc.contributor.authorSun, Min-
dc.contributor.authorWang, Sheng-
dc.contributor.authorShu, Tan-
dc.contributor.authorNing, Jun-
dc.date.accessioned2023-03-31T05:25:20Z-
dc.date.available2023-03-31T05:25:20Z-
dc.date.issued2022-
dc.identifier.citationTectonics, 2022, v. 41, n. 9, article no. e2021TC007195-
dc.identifier.issn0278-7407-
dc.identifier.urihttp://hdl.handle.net/10722/326627-
dc.description.abstractStructural and metamorphic effects of a Devonian extension-shortening cycle in the NW Chinese Altai were investigated using combined structural-petrological analysis and zircon and monazite U-Pb geochronology. Structural observations revealed a ubiquitous, sub-horizontal metamorphic fabric (S1), which was originally sub-parallel with horizontal bedding (S0) of supracrustal Devonian volcanic-sedimentary basins. This metamorphic fabric is defined by a sillimanite-bearing migmatitic gneissosity associated with extensional shear bands and a cordierite-bearing schistosity in the orogenic lower and middle crust, respectively. Staurolite relics preserved in the S1 fabric are interpreted as relics of older, higher pressure Barrovian-type metamorphism. These structural-metamorphic features are correlated with decompression and heating and interpreted as reflecting a crustal-scale extensional phase. S1 was folded to form N-S-oriented upright antiforms cored by migmatites and locally transposed by steep S2 foliation during a ∼W-E-directed shortening (in current coordinates). Andalusite and cordierite overgrew the migmatitic S2 foliation attesting to decreasing pressure associated with vertical extrusion of migmatites in cores of F2 antiforms. New U-Pb age data from subhorizontally foliated migmatites suggest that the D1 extension started at least before ∼410 Ma. Age data of syn-D2 granite intrusions and dykes constrain the D2 shortening starting soon after D1 extension and ending at ∼378 Ma. Combined with regional data, cycles of extensional and contractional tectonic regimes can be defined, which also show eastward migration along-strike of the Altai range. Such extension-shortening cycles could result from alternating retreating and advancing subduction, which governed the evolution of the Altai accretionary system from the Ordovician until the Carboniferous.-
dc.languageeng-
dc.relation.ispartofTectonics-
dc.subjectCentral Asian Orogenic Belt-
dc.subjectcrustal extension-
dc.subjectlow-pressure/high-temperature metamorphism-
dc.subjectretreating subduction-
dc.subjecttectonic switching-
dc.titlePetrostructural and Geochronological Constraints on Devonian Extension-Shortening Cycle in the Chinese Altai: Implications for Retreating-Advancing Subduction-
dc.typeArticle-
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1029/2021TC007195-
dc.identifier.scopuseid_2-s2.0-85139113977-
dc.identifier.volume41-
dc.identifier.issue9-
dc.identifier.spagearticle no. e2021TC007195-
dc.identifier.epagearticle no. e2021TC007195-
dc.identifier.eissn1944-9194-
dc.identifier.isiWOS:000848243800001-

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