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Article: Structural and geochronological evidence for the leading edge of the Greater Himalayan Crystalline complex in the central Nepal Himalaya

TitleStructural and geochronological evidence for the leading edge of the Greater Himalayan Crystalline complex in the central Nepal Himalaya
Authors
KeywordsMain Central thrust
Tectonic wedging
South Tibet detachment
Collisional tectonics
Issue Date2011
Citation
Earth and Planetary Science Letters, 2011, v. 304, n. 3-4, p. 483-495 How to Cite?
AbstractThe Himalaya is commonly described as a three layer-two fault stack. Namely, a high-grade crystalline core featuring an inverted metamorphic field gradient, the Greater Himalayan Crystalline complex (GHC), is separated from units above and below by shear zones. The Lesser Himalayan Sequence (LHS) underlies the GHC below the Main Central thrust, and the Tethyan Himalayan Sequence (THS) overlies it along the South Tibet detachment. However, the southern Main Central thrust hanging wall consists of a lower unit dominated by a right-way-up metamorphic sequence of biotite ± garnet schists (Bhimphedi Group) and an upper unit with only anchizone metamorphism (Pulchauki Group). The Bhimphedi Group is commonly equated to the GHC, while the Pulchauki Group is well correlated to the THS. However, no shear zone separates these units. We present new structural and geochronological data along the boundary between the GHC and the Bhimphedi Group in the Kathmandu region. These data reveal an ~. 200. m thick Early-Middle Miocene top-north-northeast shear zone that we term the Galchi shear zone. We correlate this shear zone to the South Tibet detachment on the basis of lithological, metamorphic, structural, and chronological criteria. The Galchi shear zone merges with the Main Central thrust to the south, bounding the leading edge of the GHC. This result, combined with recent work in the western Himalaya, suggests that the locally preserved leading edge of the GHC is sub-parallel to the arc of the orogen and the southern Main Central thrust hanging wall is dominated by THS rocks. This orogenic architecture rules out wedge extrusion and channel flow-focused denudation kinematic models for the Himalayan orogen, but is accommodated by tectonic wedging kinematic models, including channel tunneling models with modified timing. © 2011.
Persistent Identifierhttp://hdl.handle.net/10722/224029
ISSN
2015 Impact Factor: 4.326
2015 SCImago Journal Rankings: 3.628

 

DC FieldValueLanguage
dc.contributor.authorWebb, A. Alexander G-
dc.contributor.authorSchmitt, Axel K.-
dc.contributor.authorHe, Dian-
dc.contributor.authorWeigand, Eric L.-
dc.date.accessioned2016-03-18T06:20:45Z-
dc.date.available2016-03-18T06:20:45Z-
dc.date.issued2011-
dc.identifier.citationEarth and Planetary Science Letters, 2011, v. 304, n. 3-4, p. 483-495-
dc.identifier.issn0012-821X-
dc.identifier.urihttp://hdl.handle.net/10722/224029-
dc.description.abstractThe Himalaya is commonly described as a three layer-two fault stack. Namely, a high-grade crystalline core featuring an inverted metamorphic field gradient, the Greater Himalayan Crystalline complex (GHC), is separated from units above and below by shear zones. The Lesser Himalayan Sequence (LHS) underlies the GHC below the Main Central thrust, and the Tethyan Himalayan Sequence (THS) overlies it along the South Tibet detachment. However, the southern Main Central thrust hanging wall consists of a lower unit dominated by a right-way-up metamorphic sequence of biotite ± garnet schists (Bhimphedi Group) and an upper unit with only anchizone metamorphism (Pulchauki Group). The Bhimphedi Group is commonly equated to the GHC, while the Pulchauki Group is well correlated to the THS. However, no shear zone separates these units. We present new structural and geochronological data along the boundary between the GHC and the Bhimphedi Group in the Kathmandu region. These data reveal an ~. 200. m thick Early-Middle Miocene top-north-northeast shear zone that we term the Galchi shear zone. We correlate this shear zone to the South Tibet detachment on the basis of lithological, metamorphic, structural, and chronological criteria. The Galchi shear zone merges with the Main Central thrust to the south, bounding the leading edge of the GHC. This result, combined with recent work in the western Himalaya, suggests that the locally preserved leading edge of the GHC is sub-parallel to the arc of the orogen and the southern Main Central thrust hanging wall is dominated by THS rocks. This orogenic architecture rules out wedge extrusion and channel flow-focused denudation kinematic models for the Himalayan orogen, but is accommodated by tectonic wedging kinematic models, including channel tunneling models with modified timing. © 2011.-
dc.languageeng-
dc.relation.ispartofEarth and Planetary Science Letters-
dc.subjectMain Central thrust-
dc.subjectTectonic wedging-
dc.subjectSouth Tibet detachment-
dc.subjectCollisional tectonics-
dc.titleStructural and geochronological evidence for the leading edge of the Greater Himalayan Crystalline complex in the central Nepal Himalaya-
dc.typeArticle-
dc.description.natureLink_to_subscribed_fulltext-
dc.identifier.doi10.1016/j.epsl.2011.02.024-
dc.identifier.scopuseid_2-s2.0-79953041518-
dc.identifier.volume304-
dc.identifier.issue3-4-
dc.identifier.spage483-
dc.identifier.epage495-

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