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Article: Elemental and Sr-Nd-Pb isotopic geochemistry of Mesozoic mafic intrusions in southern Fujian Province, SE China: Implications for lithospheric mantle evolution

TitleElemental and Sr-Nd-Pb isotopic geochemistry of Mesozoic mafic intrusions in southern Fujian Province, SE China: Implications for lithospheric mantle evolution
Authors
KeywordsMafic dykes
Mantle evolution
Mesozoic
SE China
Issue Date2007
PublisherCambridge University Press. The Journal's web site is located at http://journals.cambridge.org/action/displayJournal?jid=GEO
Citation
Geological Magazine, 2007, v. 144 n. 6, p. 937-952 How to Cite?
AbstractAbstract Cretaceous mafic dykes in Fujian province, SE China provide an opportunity to examine the nature of their mantle source and the secular evolution of the Mesozoic lithospheric mantle beneath SE China. The mafic rocks have SiO2 ranging from 47.42 to 55.40 wt %, Al2O3 from 14.0 wt % to 20.4 wt %, CaO from 4.09 to 11.7 wt % and total alkaline (K2O+Na2O) from 2.15 wt % to 6.59 wt %. Two types are recognized based on their REE and primitive mantle-normalized trace element patterns. Type-A is the dominant Mesozoic mafic rock type in SE China and is characterized by enrichment of light rare earth elements (LREE) ((La/Yb)n = 2.85-19.0) and arc-like trace element geochemistry. Type-P has relatively flat REE patterns ((La/Yb)n = 1.68-3.43) and primitive mantle-like trace element patterns except for enrichment of Rb, Ba and Pb. Type-A samples show EMII signatures on the Sr-Nd isotopic diagram, whereas type-P rocks have high initial 143Nd/144Nd ratios (0.5126-0.5128) relative to the type-A rocks (143Nd/144Nd = 0.5124-0.5127). The type-A rocks have 207Pb/204Pb ranging from 15.47 to 15.67 and 206Pb/204Pb from 18.26 to 18.52. All the type-A rocks show a negative correlation between 143Nd/144Nd and 206Pb/204Pb ratios and a positive relationship between 87Sr/86 Sr and206Pb/204Pb ratios, indicating mixing of a depleted mantle source and an EMII component. Geochemical modelling shows that the parental magmas were formed by 5-15 % partial melting of a spinel lherzolite, and contaminated by less than 1 % melt derived from subducted sediment. The type-P magmas were derived from a mantle source unmodified by subduction components. The wide distribution of type-A dykes in SE China suggests that subduction-modified lithospheric mantle was extensive beneath the Cathaysia Block. Geochemical differences between Mesozoic and Cenozoic mafic rocks indicate that lithospheric thinning beneath SE China occurred in two episodes: firstly by heterogeneous modification by subducted components in early Mesozoic times, and later by chemical-mechanical erosion related to convective upwelling of the asthenosphere during Cenozoic times. © 2007 Cambridge University Press.
Persistent Identifierhttp://hdl.handle.net/10722/57263
ISSN
2014 Impact Factor: 2.482
2013 SCImago Journal Rankings: 1.189
References

 

DC FieldValueLanguage
dc.contributor.authorZhao, JHen_HK
dc.contributor.authorHu, Ren_HK
dc.contributor.authorZhou, MFen_HK
dc.contributor.authorLiu, Sen_HK
dc.date.accessioned2010-04-12T01:31:13Z-
dc.date.available2010-04-12T01:31:13Z-
dc.date.issued2007en_HK
dc.identifier.citationGeological Magazine, 2007, v. 144 n. 6, p. 937-952en_HK
dc.identifier.issn0016-7568en_HK
dc.identifier.urihttp://hdl.handle.net/10722/57263-
dc.description.abstractAbstract Cretaceous mafic dykes in Fujian province, SE China provide an opportunity to examine the nature of their mantle source and the secular evolution of the Mesozoic lithospheric mantle beneath SE China. The mafic rocks have SiO2 ranging from 47.42 to 55.40 wt %, Al2O3 from 14.0 wt % to 20.4 wt %, CaO from 4.09 to 11.7 wt % and total alkaline (K2O+Na2O) from 2.15 wt % to 6.59 wt %. Two types are recognized based on their REE and primitive mantle-normalized trace element patterns. Type-A is the dominant Mesozoic mafic rock type in SE China and is characterized by enrichment of light rare earth elements (LREE) ((La/Yb)n = 2.85-19.0) and arc-like trace element geochemistry. Type-P has relatively flat REE patterns ((La/Yb)n = 1.68-3.43) and primitive mantle-like trace element patterns except for enrichment of Rb, Ba and Pb. Type-A samples show EMII signatures on the Sr-Nd isotopic diagram, whereas type-P rocks have high initial 143Nd/144Nd ratios (0.5126-0.5128) relative to the type-A rocks (143Nd/144Nd = 0.5124-0.5127). The type-A rocks have 207Pb/204Pb ranging from 15.47 to 15.67 and 206Pb/204Pb from 18.26 to 18.52. All the type-A rocks show a negative correlation between 143Nd/144Nd and 206Pb/204Pb ratios and a positive relationship between 87Sr/86 Sr and206Pb/204Pb ratios, indicating mixing of a depleted mantle source and an EMII component. Geochemical modelling shows that the parental magmas were formed by 5-15 % partial melting of a spinel lherzolite, and contaminated by less than 1 % melt derived from subducted sediment. The type-P magmas were derived from a mantle source unmodified by subduction components. The wide distribution of type-A dykes in SE China suggests that subduction-modified lithospheric mantle was extensive beneath the Cathaysia Block. Geochemical differences between Mesozoic and Cenozoic mafic rocks indicate that lithospheric thinning beneath SE China occurred in two episodes: firstly by heterogeneous modification by subducted components in early Mesozoic times, and later by chemical-mechanical erosion related to convective upwelling of the asthenosphere during Cenozoic times. © 2007 Cambridge University Press.en_HK
dc.languageengen_HK
dc.publisherCambridge University Press. The Journal's web site is located at http://journals.cambridge.org/action/displayJournal?jid=GEOen_HK
dc.relation.ispartofGeological Magazineen_HK
dc.rightsGeological Magazine. Copyright © Cambridge University Press.en_HK
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.subjectMafic dykesen_HK
dc.subjectMantle evolutionen_HK
dc.subjectMesozoicen_HK
dc.subjectSE Chinaen_HK
dc.titleElemental and Sr-Nd-Pb isotopic geochemistry of Mesozoic mafic intrusions in southern Fujian Province, SE China: Implications for lithospheric mantle evolutionen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0016-7568&volume=144&issue=6&spage=937&epage=952&date=2007&atitle=Elemental+and+Sr-Nd-Pb+isotopic+geochemistry+of+Mesozoic+mafic+intrusions+in+southern+Fujian+Province,+SE+China:+implications+for+lithospheric+mantle+evolutionen_HK
dc.identifier.emailZhou, MF:mfzhou@hkucc.hku.hken_HK
dc.identifier.authorityZhou, MF=rp00844en_HK
dc.description.naturepublished_or_final_versionen_HK
dc.identifier.doi10.1017/S0016756807003834en_HK
dc.identifier.scopuseid_2-s2.0-35648950704en_HK
dc.identifier.hkuros144262-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-35648950704&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume144en_HK
dc.identifier.issue6en_HK
dc.identifier.spage937en_HK
dc.identifier.epage952en_HK
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridZhao, JH=11140043500en_HK
dc.identifier.scopusauthoridHu, R=7202640800en_HK
dc.identifier.scopusauthoridZhou, MF=7403506005en_HK
dc.identifier.scopusauthoridLiu, S=35240550100en_HK

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