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Article: Carboniferous mantle-derived felsic intrusion in the Chinese Altai, NW China: implications for geodynamic change of the accretionary orogenic belt

TitleCarboniferous mantle-derived felsic intrusion in the Chinese Altai, NW China: implications for geodynamic change of the accretionary orogenic belt
Authors
KeywordsAccretionary orogenic belt
Caob
Chinese altai
Geochemistry
Geochronology
Issue Date2012
PublisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/jcr
Citation
Gondwana Research, 2012, v. 22 n. 2, p. 681-698 How to Cite?
Abstract
This paper reports whole-rock Sr-Nd and zircon U-Pb and Hf isotopic compositions, as well as major and trace element data, for the granodiorites and their mafic microgranular enclaves (MMEs) in the Tuokesalei area, northwestern Chinese Altai. The granodiorites are characterized by peraluminous compositions (A/CNK=1.01-1.45), with relatively high SiO 2 (64.4 to 70.9wt.%) and low MgO (0.75 to 1.97wt.%) contents. These rocks possess low total rare earth element (REE) contents (67-187ppm) with weakly negative Eu anomalies and mantle-like whole-rock Nd-Sr isotopic compositions (ε Nd(t)=+2.5 to +4.5; ( 87Sr/ 86Sr) i=0.7038 to 0.7048) and zircon ε Hf(t) values (+5.93 to +12.9). The MMEs contain abundant magmatic amphiboles and needle-like apatites, have low SiO 2 (51.7 to 54.3wt.%) and high MgO (2.86 to 3.75wt.%) and REE contents (162-298ppm), and are characterized by moderately negative Eu anomalies (Eu/Eu*=0.40-0.60) and slightly depleted to enriched LREE ((La/Nd) N=0.74-1.41) and flat HREE ((Gd/Yb) N=1.16-1.39) patterns. The MMEs have whole-rock Nd-Sr isotopic compositions (ε Nd(t)=+2.6 to +2.7, ( 87Sr/ 86Sr) i=0.7034-0.7050) similar to those of the host granodiorites. Their similarities in crystallization age, mineral assemblage and isotopic composition document that the MMEs may represent an early crystallized phase, which was broken into pieces and brought to the shallow level during the host magma ascent and emplacement. Their precursor magmas were probably derived from an oceanic lithospheric mantle, which was characterized by pronounced Nd-Ta depletions. Mineral compositions of MMEs suggest that amphibole was a major early fractional mineral, which effectively differentiated the mantle-derived basaltic liquids to silica-rich melts. Zircon U-Pb dating yielded an age of 313±5Ma for the host granodiorites and 313±13Ma for their MMEs. The geochemical data of this study records an important episode of magmatism in an environment transitional from a subduction-related regime to a post-tectonic extension. Results of this study suggest that the accretionary orogenic process did not completely terminate until the Late Carboniferous to Permian in this region. © 2011 International Association for Gondwana Research.
Persistent Identifierhttp://hdl.handle.net/10722/151350
ISSN
2013 Impact Factor: 8.122
2013 SCImago Journal Rankings: 3.898
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorCai, Ken_US
dc.contributor.authorSun, Men_US
dc.contributor.authorYuan, Cen_US
dc.contributor.authorXiao, Wen_US
dc.contributor.authorZhao, Gen_US
dc.contributor.authorLong, Xen_US
dc.contributor.authorWu, Fen_US
dc.date.accessioned2012-06-26T06:20:57Z-
dc.date.available2012-06-26T06:20:57Z-
dc.date.issued2012en_US
dc.identifier.citationGondwana Research, 2012, v. 22 n. 2, p. 681-698en_US
dc.identifier.issn1342-937Xen_US
dc.identifier.urihttp://hdl.handle.net/10722/151350-
dc.description.abstractThis paper reports whole-rock Sr-Nd and zircon U-Pb and Hf isotopic compositions, as well as major and trace element data, for the granodiorites and their mafic microgranular enclaves (MMEs) in the Tuokesalei area, northwestern Chinese Altai. The granodiorites are characterized by peraluminous compositions (A/CNK=1.01-1.45), with relatively high SiO 2 (64.4 to 70.9wt.%) and low MgO (0.75 to 1.97wt.%) contents. These rocks possess low total rare earth element (REE) contents (67-187ppm) with weakly negative Eu anomalies and mantle-like whole-rock Nd-Sr isotopic compositions (ε Nd(t)=+2.5 to +4.5; ( 87Sr/ 86Sr) i=0.7038 to 0.7048) and zircon ε Hf(t) values (+5.93 to +12.9). The MMEs contain abundant magmatic amphiboles and needle-like apatites, have low SiO 2 (51.7 to 54.3wt.%) and high MgO (2.86 to 3.75wt.%) and REE contents (162-298ppm), and are characterized by moderately negative Eu anomalies (Eu/Eu*=0.40-0.60) and slightly depleted to enriched LREE ((La/Nd) N=0.74-1.41) and flat HREE ((Gd/Yb) N=1.16-1.39) patterns. The MMEs have whole-rock Nd-Sr isotopic compositions (ε Nd(t)=+2.6 to +2.7, ( 87Sr/ 86Sr) i=0.7034-0.7050) similar to those of the host granodiorites. Their similarities in crystallization age, mineral assemblage and isotopic composition document that the MMEs may represent an early crystallized phase, which was broken into pieces and brought to the shallow level during the host magma ascent and emplacement. Their precursor magmas were probably derived from an oceanic lithospheric mantle, which was characterized by pronounced Nd-Ta depletions. Mineral compositions of MMEs suggest that amphibole was a major early fractional mineral, which effectively differentiated the mantle-derived basaltic liquids to silica-rich melts. Zircon U-Pb dating yielded an age of 313±5Ma for the host granodiorites and 313±13Ma for their MMEs. The geochemical data of this study records an important episode of magmatism in an environment transitional from a subduction-related regime to a post-tectonic extension. Results of this study suggest that the accretionary orogenic process did not completely terminate until the Late Carboniferous to Permian in this region. © 2011 International Association for Gondwana Research.en_US
dc.languageengen_US
dc.publisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/jcren_US
dc.relation.ispartofGondwana Researchen_US
dc.subjectAccretionary orogenic belten_US
dc.subjectCaoben_US
dc.subjectChinese altaien_US
dc.subjectGeochemistryen_US
dc.subjectGeochronologyen_US
dc.titleCarboniferous mantle-derived felsic intrusion in the Chinese Altai, NW China: implications for geodynamic change of the accretionary orogenic belten_US
dc.typeArticleen_US
dc.identifier.emailCai, K: caikd@hku.hken_US
dc.identifier.emailSun, M: minsun@hku.hken_US
dc.identifier.emailZhao, G: gzhao@hkucc.hku.hk-
dc.identifier.authoritySun, M=rp00780en_US
dc.identifier.authorityZhao, G=rp00842en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1016/j.gr.2011.11.008en_US
dc.identifier.scopuseid_2-s2.0-84863864922en_US
dc.identifier.hkuros205433-
dc.identifier.volume22-
dc.identifier.issue2-
dc.identifier.spage681-
dc.identifier.epage698-
dc.identifier.isiWOS:000307602000025-
dc.publisher.placeNetherlandsen_US
dc.identifier.scopusauthoridWu, F=40561925600en_US
dc.identifier.scopusauthoridLong, X=14012199100en_US
dc.identifier.scopusauthoridZhao, G=7403296321en_US
dc.identifier.scopusauthoridXiao, W=7202456615en_US
dc.identifier.scopusauthoridYuan, C=35241599200en_US
dc.identifier.scopusauthoridSun, M=25932315800en_US
dc.identifier.scopusauthoridCai, K=14011943800en_US
dc.identifier.citeulike10164745-

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