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Article: Contribution of crustal anatexis to the tectonic evolution of Indian crust beneath Southern Tibet

TitleContribution of crustal anatexis to the tectonic evolution of Indian crust beneath Southern Tibet
Authors
KeywordsAnatexis
Southern tibet
Tectonic evolution
Continental collision
Crustal evolution
Issue Date2011
PublisherGeological Society of America. The Journal's web site is located at http://www.geosociety.org/pubs/
Citation
Geological Society of America Bulletin, 2011, v. 123 n. 1-2, p. 218-239 How to Cite?
AbstractThis geochemical, geochronological, and structural study of intrusive rocks in the Sakya dome of southern Tibet has identified two distinct suites of anatectic granites that carry contrasting implications for the tectonic evolution of the India-Asia collision zone. The northern margin of the dome core was intruded by anastomosing, equigranular two-mica garnet granites between 28.1 ± 0.4 Ma and 22.6 ± 0.4 Ma, coeval with top-to-the-south shear. Trace-element and isotopic (Sr-Nd) characteristics indicate an origin from partial melting of a biotite-bearing source in the Indian crust under conditions of high-fluid-phase activity. These granites thus provide evidence for the melt weakening required by some thermo mechanical models that predict the southward extrusion of a low-viscosity channel during the Oligocene. Evidence for subsequent shear-sense reversal may document initiation of this process. However, a younger suite of porphyritic two-mica granite plutons, emplaced between 14.5 ± 0.9 Ma and 8.81 ± 0.22 Ma, is derived from anatexis of muscovite-bearing metasediments of the High Himalayan Series under fluid-absent conditions. Ar-Ar cooling ages of 144-8.0 Ma from the Sakya dome postdate crystallization of the Oligocene granite suite by 10 m.y. but are coincident with mid-Miocene granite emplacement, suggesting uplift to depths of <10 km by the mid-Miocene. We propose that plate flexural response to Miocene slab steepening was a likely cause of dome uplift, and that this exhumation of midcrustal rocks triggered decompression melting at 15-9 Ma and emplacement of discrete granite plutons into the upper crust under brittle conditions. © 2011 Geological Society of America.
Persistent Identifierhttp://hdl.handle.net/10722/161129
ISSN
2015 Impact Factor: 4.332
2015 SCImago Journal Rankings: 2.299
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorKing, JAen_US
dc.contributor.authorHarris, NBWen_US
dc.contributor.authorArgles, TWen_US
dc.contributor.authorParrish, RRen_US
dc.contributor.authorZhang, H-
dc.date.accessioned2012-08-16T06:38:08Z-
dc.date.available2012-08-16T06:38:08Z-
dc.date.issued2011en_US
dc.identifier.citationGeological Society of America Bulletin, 2011, v. 123 n. 1-2, p. 218-239en_US
dc.identifier.issn0016-7606-
dc.identifier.urihttp://hdl.handle.net/10722/161129-
dc.description.abstractThis geochemical, geochronological, and structural study of intrusive rocks in the Sakya dome of southern Tibet has identified two distinct suites of anatectic granites that carry contrasting implications for the tectonic evolution of the India-Asia collision zone. The northern margin of the dome core was intruded by anastomosing, equigranular two-mica garnet granites between 28.1 ± 0.4 Ma and 22.6 ± 0.4 Ma, coeval with top-to-the-south shear. Trace-element and isotopic (Sr-Nd) characteristics indicate an origin from partial melting of a biotite-bearing source in the Indian crust under conditions of high-fluid-phase activity. These granites thus provide evidence for the melt weakening required by some thermo mechanical models that predict the southward extrusion of a low-viscosity channel during the Oligocene. Evidence for subsequent shear-sense reversal may document initiation of this process. However, a younger suite of porphyritic two-mica granite plutons, emplaced between 14.5 ± 0.9 Ma and 8.81 ± 0.22 Ma, is derived from anatexis of muscovite-bearing metasediments of the High Himalayan Series under fluid-absent conditions. Ar-Ar cooling ages of 144-8.0 Ma from the Sakya dome postdate crystallization of the Oligocene granite suite by 10 m.y. but are coincident with mid-Miocene granite emplacement, suggesting uplift to depths of <10 km by the mid-Miocene. We propose that plate flexural response to Miocene slab steepening was a likely cause of dome uplift, and that this exhumation of midcrustal rocks triggered decompression melting at 15-9 Ma and emplacement of discrete granite plutons into the upper crust under brittle conditions. © 2011 Geological Society of America.-
dc.languageengen_US
dc.publisherGeological Society of America. The Journal's web site is located at http://www.geosociety.org/pubs/en_US
dc.relation.ispartofGeological Society of America Bulletinen_US
dc.subjectAnatexis-
dc.subjectSouthern tibet-
dc.subjectTectonic evolution-
dc.subjectContinental collision-
dc.subjectCrustal evolution-
dc.titleContribution of crustal anatexis to the tectonic evolution of Indian crust beneath Southern Tibeten_US
dc.typeArticleen_US
dc.identifier.emailKing, JA: jessking@hkucc.hku.hken_US
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1130/B30085.1-
dc.identifier.scopuseid_2-s2.0-79251476859-
dc.identifier.hkuros203812en_US
dc.identifier.volume123en_US
dc.identifier.issue1-2-
dc.identifier.spage218en_US
dc.identifier.epage239en_US
dc.identifier.isiWOS:000285696100014-
dc.publisher.placeUnited States-

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