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Article: Two-stage collision-related extrusion of the western Dabie HP-UHP metamorphic terranes, central China: Evidence from quartz c-axis fabrics and structures

TitleTwo-stage collision-related extrusion of the western Dabie HP-UHP metamorphic terranes, central China: Evidence from quartz c-axis fabrics and structures
Authors
KeywordsExtrusion
Mylonite
Quartz c-axis fabrics
Western Dabie orogen, Tectonics
Issue Date2009
PublisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/jcr
Citation
Gondwana Research, 2009, v. 16 n. 2, p. 294-309 How to Cite?
AbstractThe western Dabie orogen (also known as the Hong'an block) forms the western part of the Dabie-Sulu HP-UHP belt, central China. Rocks of this orogen have been subjected to pervasive ductile deformation, and include numerous quartz schists and felsic mylonites cropping out in ductile shear zones. Quartz textures in these mylonites contain important clues for understanding the movement sense of late-collisional extrusion and exhumation of high-pressure-ultrahigh-pressure (HP-UHP) rocks from the lower crustal level to the upper crustal level during Middle Triassic and Early Jurassic. The orientation and distribution of quartz crystallographic axes were used to confirm the regional shear sense across the orogen. The asymmetry of c-axis patterns consistently indicates top-to-the-southeast thrusting across the orogen in early structural stages. Later stages of deformation show different senses of movement in northern and southern parts of the orogen, with top-to-the-northwest sinistral shearing recorded in rocks north of the Xinxian HP-UHP eclogite-facies belt, and top-to-the-southeast dextral shearing south of the same unit. Based on our study on quartz c-axis fabrics and marco- to micro-scale structures, simultaneous southeastward shearing within a large part of the orogen and normal faulting north of the Xinxian HP-UHP unit is explained by upward extrusion in early stages of deformation. The extrusion process has been attributed to syn- and late-collisional processes, accounting for some earlier deformation in the western Dabie orogen such as metamorphic sequences around the core of the Xinxian HP-UHP eclogite-facies unit. Much higher pressure of deformation is also indicated in the aligned glaucophane and omphacite from blueschist and eclogite in the field. An orogen-parallel eastward extrusion of the Xinxian HP-UHP eclogite-facies unit, however, occurred diachronously in later stages of deformation. Therefore, a tectonic model combining an early upward extrusion with a later eastward extrusion is presented. Two different stages and types of extrusion for exhumation of HP-UHP rocks are suitable to all of east central China. Geochronological data shows that the first, upward extrusion occurred during Middle Triassic, the second, eastward extrusion occurred during Late Triassic to Early Jurassic. These two extrusions are correlative with two stages of rapid exhumation of the Dabie HP-UHP rocks, respectively. These two-stage late-collisional (Middle Triassic to Early Jurassic) extrusion events bridge the gap between syn-collisional (Early to Middle Triassic) vertical extrusion and post-collisional (Cretaceous) eastward-directed lateral escape and provide vital clues to understanding the more detailed processes of exhumation of HP-UHP rocks. © 2009 International Association for Gondwana Research.
Persistent Identifierhttp://hdl.handle.net/10722/73031
ISSN
2015 Impact Factor: 8.743
2015 SCImago Journal Rankings: 4.949
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorLi, Sen_HK
dc.contributor.authorKusky, TMen_HK
dc.contributor.authorLiu, Xen_HK
dc.contributor.authorZhang, Gen_HK
dc.contributor.authorZhao, Gen_HK
dc.contributor.authorWang, Len_HK
dc.contributor.authorWang, Yen_HK
dc.date.accessioned2010-09-06T06:47:24Z-
dc.date.available2010-09-06T06:47:24Z-
dc.date.issued2009en_HK
dc.identifier.citationGondwana Research, 2009, v. 16 n. 2, p. 294-309en_HK
dc.identifier.issn1342-937Xen_HK
dc.identifier.urihttp://hdl.handle.net/10722/73031-
dc.description.abstractThe western Dabie orogen (also known as the Hong'an block) forms the western part of the Dabie-Sulu HP-UHP belt, central China. Rocks of this orogen have been subjected to pervasive ductile deformation, and include numerous quartz schists and felsic mylonites cropping out in ductile shear zones. Quartz textures in these mylonites contain important clues for understanding the movement sense of late-collisional extrusion and exhumation of high-pressure-ultrahigh-pressure (HP-UHP) rocks from the lower crustal level to the upper crustal level during Middle Triassic and Early Jurassic. The orientation and distribution of quartz crystallographic axes were used to confirm the regional shear sense across the orogen. The asymmetry of c-axis patterns consistently indicates top-to-the-southeast thrusting across the orogen in early structural stages. Later stages of deformation show different senses of movement in northern and southern parts of the orogen, with top-to-the-northwest sinistral shearing recorded in rocks north of the Xinxian HP-UHP eclogite-facies belt, and top-to-the-southeast dextral shearing south of the same unit. Based on our study on quartz c-axis fabrics and marco- to micro-scale structures, simultaneous southeastward shearing within a large part of the orogen and normal faulting north of the Xinxian HP-UHP unit is explained by upward extrusion in early stages of deformation. The extrusion process has been attributed to syn- and late-collisional processes, accounting for some earlier deformation in the western Dabie orogen such as metamorphic sequences around the core of the Xinxian HP-UHP eclogite-facies unit. Much higher pressure of deformation is also indicated in the aligned glaucophane and omphacite from blueschist and eclogite in the field. An orogen-parallel eastward extrusion of the Xinxian HP-UHP eclogite-facies unit, however, occurred diachronously in later stages of deformation. Therefore, a tectonic model combining an early upward extrusion with a later eastward extrusion is presented. Two different stages and types of extrusion for exhumation of HP-UHP rocks are suitable to all of east central China. Geochronological data shows that the first, upward extrusion occurred during Middle Triassic, the second, eastward extrusion occurred during Late Triassic to Early Jurassic. These two extrusions are correlative with two stages of rapid exhumation of the Dabie HP-UHP rocks, respectively. These two-stage late-collisional (Middle Triassic to Early Jurassic) extrusion events bridge the gap between syn-collisional (Early to Middle Triassic) vertical extrusion and post-collisional (Cretaceous) eastward-directed lateral escape and provide vital clues to understanding the more detailed processes of exhumation of HP-UHP rocks. © 2009 International Association for Gondwana Research.en_HK
dc.languageengen_HK
dc.publisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/jcren_HK
dc.relation.ispartofGondwana Researchen_HK
dc.rightsGondwana Research. Copyright © Elsevier BV.en_HK
dc.subjectExtrusionen_HK
dc.subjectMyloniteen_HK
dc.subjectQuartz c-axis fabricsen_HK
dc.subjectWestern Dabie orogen, Tectonicsen_HK
dc.titleTwo-stage collision-related extrusion of the western Dabie HP-UHP metamorphic terranes, central China: Evidence from quartz c-axis fabrics and structuresen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=1342-937X&volume=&spage=&epage=&date=2009&atitle=Two-stage+collision-related+extrusion+of+the+western+Dabie+HP-UHP+metamorphic+terranes,+central+China:+Evidence+from+quartz+c-axis+fabrics+and+structuresen_HK
dc.identifier.emailZhao, G:gzhao@hkucc.hku.hken_HK
dc.identifier.authorityZhao, G=rp00842en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1016/j.gr.2009.03.003en_HK
dc.identifier.scopuseid_2-s2.0-67650831897en_HK
dc.identifier.hkuros154999en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-67650831897&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume16en_HK
dc.identifier.issue2en_HK
dc.identifier.spage294en_HK
dc.identifier.epage309en_HK
dc.identifier.isiWOS:000269274000013-
dc.publisher.placeNetherlandsen_HK
dc.identifier.scopusauthoridLi, S=8784176300en_HK
dc.identifier.scopusauthoridKusky, TM=35234213100en_HK
dc.identifier.scopusauthoridLiu, X=34975560500en_HK
dc.identifier.scopusauthoridZhang, G=35085644800en_HK
dc.identifier.scopusauthoridZhao, G=7403296321en_HK
dc.identifier.scopusauthoridWang, L=8842240700en_HK
dc.identifier.scopusauthoridWang, Y=36496272800en_HK

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