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Article: Geochronological and geochemical study of mafic dykes from the northwest Chinese Altai: Implications for petrogenesis and tectonic evolution

TitleGeochronological and geochemical study of mafic dykes from the northwest Chinese Altai: Implications for petrogenesis and tectonic evolution
Authors
KeywordsCAOB
Chinese Altai
Geochemistry
Mafic dykes
Ridge subduction
Issue Date2010
PublisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/jcr
Citation
Gondwana Research, 2010, v. 18 n. 4, p. 638-652 How to Cite?
AbstractFifteen zircons separated from a mafic dyke in the Chinese Altai give a concordant age population with a weighted mean 206Pb/ 238U age of 375.5±4.8Ma, suggesting a Devonian emplacement. On the basis of their mineralogical compositions and textures, the coeval dykes can be divided into gabbroic and doleritic types. They are both sub-alkaline, tholeiitic, characterized by similarly low SiO 2 contents (45.2-52.7wt.%) and total alkaline (K 2O+Na 2O=0.99-4.93wt.%). Rare earth element patterns of the gabbroic dykes are similar to N-MORB (La/Yb N=0.86-1.1), together with their high ε Nd(t) values (+7.6 to +8.1), indicating that their precursor magma was mainly derived from a N-MORB-type depleted asthenospheric mantle. While the REE patterns of the doleritic dykes resemble that of E-MORB (La/Yb N=1.12-2.28), enriched in LILEs and strongly depleted in HFSEs, with relative low ε Nd(t) values (+3.4 to +5.4) and high initial 87Sr/ 86Sr ratios (0.7057-0.7060). The zircon Hf isotopic analysis of the doleritic dykes give ε Hf(t) values from +10.7 to +13.8. These signatures suggest that a depleted mantle wedge metasomatized by slab-derived fluids and/or melts was possibly involved in the generation of the doleritic magma. The refractory peridotite may have been melted with variable degrees caused by upwelling of the hot asthenosphere. The petrogenesis of the mafic dykes suggest a high heat flux as a result of upwelling of the hot asthenosphere and the contrast geochemical signatures can be interpreted by a ridge subduction, which could be an important tectonic control in the accretionary process of the Chinese Altai. © 2010 International Association for Gondwana Research.
Persistent Identifierhttp://hdl.handle.net/10722/139195
ISSN
2014 Impact Factor: 8.235
2014 SCImago Journal Rankings: 4.259
ISI Accession Number ID
Funding AgencyGrant Number
Chinese National 973 Program2007CB411308
Hong Kong Research Grants CouncilHKU704307P
NSFC40725009
Hong Kong University
Funding Information:

This study was financially supported by funds from the Chinese National 973 Program (2007CB411308), the Hong Kong Research Grants Council (HKU704307P), the NSFC (40725009) and Hong Kong University grants. We appreciate Kenny Wong, Xiaoping Xia, Hongyan Geng, Jiyuan Yin, Yingde Jiang, Yujing Wang for field assistance. We thank Biao Song, Liewen Xie, Yueheng Yang, Ying Liu, Xianglin Tu and Xirong Liang for laboratory assistance. We appreciate Mr. Jiangfeng Gao and Dr. Junhong Zhao for scientific discussion. We are very grateful to Prof. Ali Polat and an anonymous reviewer for their critical reviews and constructive comments that significantly improved this manuscript.

References

 

DC FieldValueLanguage
dc.contributor.authorCai, Ken_HK
dc.contributor.authorSun, Men_HK
dc.contributor.authorYuan, Cen_HK
dc.contributor.authorZhao, Gen_HK
dc.contributor.authorXiao, Wen_HK
dc.contributor.authorLong, Xen_HK
dc.contributor.authorWu, Fen_HK
dc.date.accessioned2011-09-23T05:46:32Z-
dc.date.available2011-09-23T05:46:32Z-
dc.date.issued2010en_HK
dc.identifier.citationGondwana Research, 2010, v. 18 n. 4, p. 638-652en_HK
dc.identifier.issn1342-937Xen_HK
dc.identifier.urihttp://hdl.handle.net/10722/139195-
dc.description.abstractFifteen zircons separated from a mafic dyke in the Chinese Altai give a concordant age population with a weighted mean 206Pb/ 238U age of 375.5±4.8Ma, suggesting a Devonian emplacement. On the basis of their mineralogical compositions and textures, the coeval dykes can be divided into gabbroic and doleritic types. They are both sub-alkaline, tholeiitic, characterized by similarly low SiO 2 contents (45.2-52.7wt.%) and total alkaline (K 2O+Na 2O=0.99-4.93wt.%). Rare earth element patterns of the gabbroic dykes are similar to N-MORB (La/Yb N=0.86-1.1), together with their high ε Nd(t) values (+7.6 to +8.1), indicating that their precursor magma was mainly derived from a N-MORB-type depleted asthenospheric mantle. While the REE patterns of the doleritic dykes resemble that of E-MORB (La/Yb N=1.12-2.28), enriched in LILEs and strongly depleted in HFSEs, with relative low ε Nd(t) values (+3.4 to +5.4) and high initial 87Sr/ 86Sr ratios (0.7057-0.7060). The zircon Hf isotopic analysis of the doleritic dykes give ε Hf(t) values from +10.7 to +13.8. These signatures suggest that a depleted mantle wedge metasomatized by slab-derived fluids and/or melts was possibly involved in the generation of the doleritic magma. The refractory peridotite may have been melted with variable degrees caused by upwelling of the hot asthenosphere. The petrogenesis of the mafic dykes suggest a high heat flux as a result of upwelling of the hot asthenosphere and the contrast geochemical signatures can be interpreted by a ridge subduction, which could be an important tectonic control in the accretionary process of the Chinese Altai. © 2010 International Association for Gondwana Research.en_HK
dc.languageengen_US
dc.publisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/jcren_HK
dc.relation.ispartofGondwana Researchen_HK
dc.subjectCAOBen_HK
dc.subjectChinese Altaien_HK
dc.subjectGeochemistryen_HK
dc.subjectMafic dykesen_HK
dc.subjectRidge subductionen_HK
dc.titleGeochronological and geochemical study of mafic dykes from the northwest Chinese Altai: Implications for petrogenesis and tectonic evolutionen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=1342-937X&volume=18&issue=4&spage=638&epage=652&date=2010&atitle=Geochronological+and+geochemical+study+of+mafic+dykes+from+the+northwest+Chinese+Altai:+implications+for+petrogenesis+and+tectonic+evolution-
dc.identifier.emailSun, M:minsun@hku.hken_HK
dc.identifier.emailZhao, G:gzhao@hkucc.hku.hken_HK
dc.identifier.authoritySun, M=rp00780en_HK
dc.identifier.authorityZhao, G=rp00842en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1016/j.gr.2010.02.010en_HK
dc.identifier.scopuseid_2-s2.0-77956493820en_HK
dc.identifier.hkuros193928en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-77956493820&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume18en_HK
dc.identifier.issue4en_HK
dc.identifier.spage638en_HK
dc.identifier.epage652en_HK
dc.identifier.isiWOS:000283006800007-
dc.publisher.placeNetherlandsen_HK
dc.identifier.scopusauthoridCai, K=14011943800en_HK
dc.identifier.scopusauthoridSun, M=25932315800en_HK
dc.identifier.scopusauthoridYuan, C=35241599200en_HK
dc.identifier.scopusauthoridZhao, G=7403296321en_HK
dc.identifier.scopusauthoridXiao, W=7202456615en_HK
dc.identifier.scopusauthoridLong, X=14012199100en_HK
dc.identifier.scopusauthoridWu, F=40561925600en_HK

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