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Article: Geochronology, petrogenesis and tectonic significance of peraluminous granites from the Chinese Altai, NW China

TitleGeochronology, petrogenesis and tectonic significance of peraluminous granites from the Chinese Altai, NW China
Authors
KeywordsCrustal structure
Emplacement
Geochronology
Granite
Igneous geochemistry
Issue Date2011
PublisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/lithos
Citation
Lithos, 2011, v. 127 n. 1-2, p. 261-281 How to Cite?
AbstractThe Paleozoic granites in the Chinese Altai are important for the study of tectonic evolution and crustal growth in the Central Asian Orogenic Belt (CAOB). Four representative peraluminous granitic intrusions were selected for systematic studies of zircon U-Pb and Hf isotopic compositions and whole-rock geochemical and Nd-Sr isotopic analyses. These rocks have high ASI (Alumina Saturation Index, Al 2O 3/(CaO+Na 2O+K 2O)=1.01-1.46 molecular ratios), with 0.6-5.6wt.% of normative corundum, and are characterized by moderately negative Eu anomalies (Eu/Eu*=0.38-0.98) and strong depletion in Ba, Nb and Sr elements. Our data suggest that these intrusions were emplaced from 419 to 393Ma, consistent with a period of intensive magmatic activities and high temperature metamorphism in the Chinese Altai. While in situ zircon Hf isotopic analyses for these granites give predominantly positive ε Hf(t) values (+0.8 to +12.8), a few inherited zircons yield negative ε Hf(t) values from -12.5 to -1.53. The U-Pb age and Hf isotopic data of these inherited zircons are similar to that of the widespread metasediments. In addition, the peraluminous granitic rocks have near-zero or negative ε Nd(t) values (-3.3 to -0.5) and relatively high initial 87Sr/ 86Sr ratios (0.7079-0.7266), distinct from those of the I-type granites in the study region, but similar to the Early Paleozoic Habahe sediments. These isotopic compositions suggest that the newly accreted metasediments of Habahe Group may be the major source rock of the peraluminous granites. The geochemical compositions indicate that their precursor magmas were derived from a relatively shallow crustal level (P≤5kbar) and zircon saturation temperatures suggest that these granitic intrusions were emplaced at 672-861°C. The peraluminous granitic magmas were generated by dehydration melting of newly accreted materials, which were possibly brought to at least middle crustal depth by subduction-related processes in an active margin, and were subsequently molten by strikingly high ambient temperature probably caused by upwelling of the hot asthenosphere associated with ridge subduction in the Paleozoic. © 2011 Elsevier B.V.
Persistent Identifierhttp://hdl.handle.net/10722/151332
ISSN
2015 Impact Factor: 3.723
2015 SCImago Journal Rankings: 2.920
ISI Accession Number ID
Funding AgencyGrant Number
National Basic Research Program of China2007CB411308
Hong Kong Research Grants CouncilHKU704307P
National Natural Science Foundation of China40721063
40772130
40803009
HKU CRCG
Hong Kong-Germany Joint Research Scheme
HKU
Funding Information:

This study was supported by the National Basic Research Program of China (2007CB411308), Hong Kong Research Grants Council (HKU704307P), the National Natural Science Foundation of China (40721063, 40772130 and 40803009), the HKU CRCG Research Grants and Hong Kong-Germany Joint Research Scheme. We thank Biao Song, Liewen Xie, Yueheng Yang, Jianfeng Gao, Ying Liu, Guangqian, Hu, Jinlong Ma, Xianglin Tu and Xirong hang for laboratory assistance. We are grateful to Nelson Eby and two anonymous reviewers for their critical reviews and comments that significantly improved this manuscript. A HKU postgraduate studentship to Keda CAI is gratefully acknowledged.

References

 

DC FieldValueLanguage
dc.contributor.authorCai, Ken_US
dc.contributor.authorSun, Men_US
dc.contributor.authorYuan, Cen_US
dc.contributor.authorZhao, Gen_US
dc.contributor.authorXiao, Wen_US
dc.contributor.authorLong, Xen_US
dc.contributor.authorWu, FYen_US
dc.date.accessioned2012-06-26T06:20:45Z-
dc.date.available2012-06-26T06:20:45Z-
dc.date.issued2011en_US
dc.identifier.citationLithos, 2011, v. 127 n. 1-2, p. 261-281en_US
dc.identifier.issn0024-4937en_US
dc.identifier.urihttp://hdl.handle.net/10722/151332-
dc.description.abstractThe Paleozoic granites in the Chinese Altai are important for the study of tectonic evolution and crustal growth in the Central Asian Orogenic Belt (CAOB). Four representative peraluminous granitic intrusions were selected for systematic studies of zircon U-Pb and Hf isotopic compositions and whole-rock geochemical and Nd-Sr isotopic analyses. These rocks have high ASI (Alumina Saturation Index, Al 2O 3/(CaO+Na 2O+K 2O)=1.01-1.46 molecular ratios), with 0.6-5.6wt.% of normative corundum, and are characterized by moderately negative Eu anomalies (Eu/Eu*=0.38-0.98) and strong depletion in Ba, Nb and Sr elements. Our data suggest that these intrusions were emplaced from 419 to 393Ma, consistent with a period of intensive magmatic activities and high temperature metamorphism in the Chinese Altai. While in situ zircon Hf isotopic analyses for these granites give predominantly positive ε Hf(t) values (+0.8 to +12.8), a few inherited zircons yield negative ε Hf(t) values from -12.5 to -1.53. The U-Pb age and Hf isotopic data of these inherited zircons are similar to that of the widespread metasediments. In addition, the peraluminous granitic rocks have near-zero or negative ε Nd(t) values (-3.3 to -0.5) and relatively high initial 87Sr/ 86Sr ratios (0.7079-0.7266), distinct from those of the I-type granites in the study region, but similar to the Early Paleozoic Habahe sediments. These isotopic compositions suggest that the newly accreted metasediments of Habahe Group may be the major source rock of the peraluminous granites. The geochemical compositions indicate that their precursor magmas were derived from a relatively shallow crustal level (P≤5kbar) and zircon saturation temperatures suggest that these granitic intrusions were emplaced at 672-861°C. The peraluminous granitic magmas were generated by dehydration melting of newly accreted materials, which were possibly brought to at least middle crustal depth by subduction-related processes in an active margin, and were subsequently molten by strikingly high ambient temperature probably caused by upwelling of the hot asthenosphere associated with ridge subduction in the Paleozoic. © 2011 Elsevier B.V.en_US
dc.languageengen_US
dc.publisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/lithosen_US
dc.relation.ispartofLithosen_US
dc.subjectCrustal structureen_US
dc.subjectEmplacementen_US
dc.subjectGeochronologyen_US
dc.subjectGraniteen_US
dc.subjectIgneous geochemistryen_US
dc.titleGeochronology, petrogenesis and tectonic significance of peraluminous granites from the Chinese Altai, NW Chinaen_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.lithos.2011.09.001en_US
dc.identifier.scopuseid_2-s2.0-80053630397en_US
dc.identifier.hkuros204301-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-80053630397&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume127en_US
dc.identifier.issue1-2en_US
dc.identifier.spage261en_US
dc.identifier.epage281en_US
dc.identifier.isiWOS:000298070600017-
dc.publisher.placeNetherlandsen_US
dc.identifier.scopusauthoridWu, F=40561925600en_US
dc.identifier.scopusauthoridLong, X=14012199100en_US
dc.identifier.scopusauthoridXiao, W=7202456615en_US
dc.identifier.scopusauthoridZhao, G=7403296321en_US
dc.identifier.scopusauthoridYuan, C=35241599200en_US
dc.identifier.scopusauthoridSun, M=25932315800en_US
dc.identifier.scopusauthoridCai, K=14011943800en_US
dc.identifier.citeulike9824268-

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