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Article: Constraining the mid-crustal channel flow beneath the Tibetan Plateau: Data from the Nielaxiongbo gneiss dome, SE Tibet

TitleConstraining the mid-crustal channel flow beneath the Tibetan Plateau: Data from the Nielaxiongbo gneiss dome, SE Tibet
Authors
Keywordsgneiss dome
leucogranite
mid-crustal channel flow
middle crustal layer
Nielaxiongbo
SE Tibet
South Tibetan Detachment System
Issue Date2012
PublisherTaylor & Francis Inc. The Journal's web site is located at http://www.tandf.co.uk/journals/TIGR
Citation
International Geology Review, 2012, v. 54 n. 6, p. 615-632 How to Cite?
AbstractGneiss domes involving the South Tibetan Detachment System provide evidence for crustal extension simultaneous with shortening. The Nielaxiongbo gneiss dome is composed of a metamorphic complex of granitic gneiss, amphibolite, and migmatite; a ductilely deformed middle crustal layer of staurolite-or garnet-bearing schist; and a cover sequence of weakly metamorphosed Triassic and Lower Cretaceous strata. The middle crust ductilely deformed layer is separated from both the basement complex and the cover sequence by lower and upper detachments, respectively, with a smaller detachment fault occurring within the ductilely deformed layer. Leucogranites crosscut the basement complex, the lower detachment, and the middle crustal layer, but do not intrude the upper detachment or the cover sequence. Three deformational fabrics are recognized: a N-S compressional fabric (D1) in the cover sequence, a north-and south-directed extensional fabric (D2) in the upper detachment and lower tectonic units, and a deformation (D3) related to the leucogranite intrusion. SHRIMP zircon U-Pb dating yielded a metamorphic age of 514 million years for the amphibolite and a crystallization age of 20 million years for the leucogranite. Hornblende from the amphibolite has an 40Ar/ 39Ar age of 18 0.3 million years, whereas muscovites from the schist and leucogranite yielded 40Ar/ 39Ar ages between 13.5 0.2 and 13.0 0.2 million years. These results suggest that the basement was consolidated at 510 Ma and then exhumed during extension and silicic plutonism at 20 Ma. Continuing exhumation led to cooling through the 500C Ar closure temperature in hornblende at 18 Ma to the 350C Ar closure temperature in muscovite at 13 Ma. The middle crustal ductilely deformed layer within gneiss domes of southern Tibet defines a southward-extruding ductile channel, marked by leucogranites emplaced into migmatites and amphibolites. We propose a model involving thinned upper crust for the initial extension of the Tibetan Plateau in the early Miocene. © 2012 Copyright Taylor and Francis Group, LLC.
Persistent Identifierhttp://hdl.handle.net/10722/151368
ISSN
2015 Impact Factor: 2.365
2015 SCImago Journal Rankings: 1.248
ISI Accession Number ID
Funding AgencyGrant Number
National Basic Research Programme of China2009CB421001
National Science Foundation of China40872140
40921062
111 ProjectB07011
National Science and Engineering Research Council of Canada
Funding Information:

This study was supported by research grants from the National Basic Research Programme of China (2009CB421001), National Science Foundation of China (40872140, 40921062), the 111 Project (B07011), and the National Science and Engineering Research Council of Canada. We are grateful to the geological team of the Tibetan Geological Survey for assistance in the field, and we thank Keith Taylor for technical assistance in the Argon Isotope Laboratory at Dalhousie University.

References

 

DC FieldValueLanguage
dc.contributor.authorYan, DPen_HK
dc.contributor.authorZhou, MFen_HK
dc.contributor.authorRobinson, PTen_HK
dc.contributor.authorGrujic, Den_HK
dc.contributor.authorMalpas, Jen_HK
dc.contributor.authorKennedy, Aen_HK
dc.contributor.authorReynolds, PHen_HK
dc.date.accessioned2012-06-26T06:21:14Z-
dc.date.available2012-06-26T06:21:14Z-
dc.date.issued2012en_HK
dc.identifier.citationInternational Geology Review, 2012, v. 54 n. 6, p. 615-632en_HK
dc.identifier.issn0020-6814en_HK
dc.identifier.urihttp://hdl.handle.net/10722/151368-
dc.description.abstractGneiss domes involving the South Tibetan Detachment System provide evidence for crustal extension simultaneous with shortening. The Nielaxiongbo gneiss dome is composed of a metamorphic complex of granitic gneiss, amphibolite, and migmatite; a ductilely deformed middle crustal layer of staurolite-or garnet-bearing schist; and a cover sequence of weakly metamorphosed Triassic and Lower Cretaceous strata. The middle crust ductilely deformed layer is separated from both the basement complex and the cover sequence by lower and upper detachments, respectively, with a smaller detachment fault occurring within the ductilely deformed layer. Leucogranites crosscut the basement complex, the lower detachment, and the middle crustal layer, but do not intrude the upper detachment or the cover sequence. Three deformational fabrics are recognized: a N-S compressional fabric (D1) in the cover sequence, a north-and south-directed extensional fabric (D2) in the upper detachment and lower tectonic units, and a deformation (D3) related to the leucogranite intrusion. SHRIMP zircon U-Pb dating yielded a metamorphic age of 514 million years for the amphibolite and a crystallization age of 20 million years for the leucogranite. Hornblende from the amphibolite has an 40Ar/ 39Ar age of 18 0.3 million years, whereas muscovites from the schist and leucogranite yielded 40Ar/ 39Ar ages between 13.5 0.2 and 13.0 0.2 million years. These results suggest that the basement was consolidated at 510 Ma and then exhumed during extension and silicic plutonism at 20 Ma. Continuing exhumation led to cooling through the 500C Ar closure temperature in hornblende at 18 Ma to the 350C Ar closure temperature in muscovite at 13 Ma. The middle crustal ductilely deformed layer within gneiss domes of southern Tibet defines a southward-extruding ductile channel, marked by leucogranites emplaced into migmatites and amphibolites. We propose a model involving thinned upper crust for the initial extension of the Tibetan Plateau in the early Miocene. © 2012 Copyright Taylor and Francis Group, LLC.en_HK
dc.languageengen_US
dc.publisherTaylor & Francis Inc. The Journal's web site is located at http://www.tandf.co.uk/journals/TIGRen_HK
dc.relation.ispartofInternational Geology Reviewen_HK
dc.subjectgneiss domeen_HK
dc.subjectleucograniteen_HK
dc.subjectmid-crustal channel flowen_HK
dc.subjectmiddle crustal layeren_HK
dc.subjectNielaxiongboen_HK
dc.subjectSE Tibeten_HK
dc.subjectSouth Tibetan Detachment Systemen_HK
dc.titleConstraining the mid-crustal channel flow beneath the Tibetan Plateau: Data from the Nielaxiongbo gneiss dome, SE Tibeten_HK
dc.typeArticleen_HK
dc.identifier.emailZhou, MF: mfzhou@hkucc.hku.hken_HK
dc.identifier.emailMalpas, J: jgmalpas@hku.hken_HK
dc.identifier.authorityZhou, MF=rp00844en_HK
dc.identifier.authorityMalpas, J=rp00059en_HK
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1080/00206814.2010.548153en_HK
dc.identifier.scopuseid_2-s2.0-84859135400en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-84859135400&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume54en_HK
dc.identifier.issue6en_HK
dc.identifier.spage615en_HK
dc.identifier.epage632en_HK
dc.identifier.isiWOS:000303563500001-
dc.publisher.placeUnited Statesen_HK
dc.identifier.scopusauthoridYan, DP=36683417500en_HK
dc.identifier.scopusauthoridZhou, MF=7403506005en_HK
dc.identifier.scopusauthoridRobinson, PT=55153718300en_HK
dc.identifier.scopusauthoridGrujic, D=7004566643en_HK
dc.identifier.scopusauthoridMalpas, J=7006136845en_HK
dc.identifier.scopusauthoridKennedy, A=7401653640en_HK
dc.identifier.scopusauthoridReynolds, PH=7201378946en_HK

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