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Article: Metasomatic mantle source and crustal contamination for the formation of the Neoproterozoic mafic dike swarm in the northern Yangtze Block, South China

TitleMetasomatic mantle source and crustal contamination for the formation of the Neoproterozoic mafic dike swarm in the northern Yangtze Block, South China
Authors
KeywordsCrustal contamination
Mafic dikes
Metasomatic mantle source
Neoproterozoic
Yangtze Block
Issue Date2010
PublisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/lithos
Citation
Lithos, 2010, v. 115 n. 1-4, p. 177-189 How to Cite?
AbstractIn the Huangling region of the northern Yangtze Block, South China, the 820-Ma Huangling felsic pluton was intruded by ∼ 800-Ma mafic dikes. These dikes are composed of fine- to medium-grained diabase, porphyritic diabase and olivine gabbro. Quartz xenocrysts occur locally in the olivine gabbro. The rocks are alkaline to sub-alkaline in composition and have SiO2 ranging from 43.3 to 57.2 wt.%, MgO from 3.7 to 9.2 wt.% and total alkali from 3.0 to 7.3 wt.%. They exhibit LREE enrichment ((La/Yb)n = 3.3-28.5) with slightly negative Eu anomalies (Eu/Eu* = 0.6-1.0). Their primitive mantle-normalized trace element patterns are characterized by enrichment of large-ion lithophile elements (Rb, Ba, Th and U), depletion of high-field-strength elements (Nb, Ta, Zr and Hf) and positive Pb and negative Ti anomalies. They have relatively high initial 87Sr/86Sr ratios ranging from 0.7052 to 0.7080 and variably negative εNd(t) values from - 4.2 to - 10.9. The rocks have a large range of whole-rock εHf values (- 0.35 to - 11.34) and a relatively narrow range of Pb isotope ratios (206Pb/204Pb = 16.96 to 17.97, 207Pb/204Pb = 15.41 to 15.58, and 208Pb/204Pb = 38.08 to 39.66). Initial 87Sr/86Sr ratios correlate negatively with 206Pb/204Pb ratios, whereas 143Nd/144Nd and 208Pb/204Pb ratios and εHf values correlate positively with 206Pb/204Pb ratios. These features are indicative of an EM2 source region, suggesting a lithospheric mantle source modified by subducted components during the Neoproterozoic. The quartz xenocrysts and linear isotopic variations indicate strong crustal contamination during magma emplacement. The energy-constrained assimilation and fractional crystallization (EC-AFC) modeling calculations reveal that the parental magmas were contaminated by continental crust, including Archaean amphibolites, granitic gneisses, metasedimentary rocks and granitic rocks. The mafic dikes are 20 myrs younger than the Huangling felsic pluton, which was produced by partial melting of a thickened continental crust, suggesting that the mafic dikes were a consequence of post-orogenic extension. The Huangling region may have originally been located at the centre of the Yangtze Block. The possible heat source for the generation of the Huangling felsic pluton and mafic dikes was asthenospheric wedging resulting from oceanic slab subduction beneath the northern margin of the Yangtze Block. This conclusion rules out the possibility that the Yangtze Block was located in the central part of the Rodinia supercontinent. The block was more likely situated along the margin of Rodinia. © 2009 Elsevier B.V. All rights reserved.
Persistent Identifierhttp://hdl.handle.net/10722/129172
ISSN
2015 Impact Factor: 3.723
2015 SCImago Journal Rankings: 2.920
ISI Accession Number ID
Funding AgencyGrant Number
National Science Foundation of China40873027
90714002
Special Fund for Basic Scientific Research of Central Colleges
China University of Geosciences(Wuhan)
State Key Lab of Mineral Deposit Geochemistry, CAS200802
University of Hong Kong
Funding Information:

This work was substantially supported by a research grant from National Science Foundation of China (project 40873027, 90714002), the Special Fund for Basic Scientific Research of Central Colleges, China University of Geosciences(Wuhan) a grant from the State Key Lab of Mineral Deposit Geochemistry, CAS (200802) and a 973 project matching grant from the University of Hong Kong. We are grateful to Fu Xiao for the XRF analyses and Gao Jian-Feng for the ICP-MS analyses. Reviews by Nelson Eby, Franco Pirajno and an anonymous referee improved an early draft of this paper and are gratefully acknowledged.

References

 

DC FieldValueLanguage
dc.contributor.authorZhao, JHen_HK
dc.contributor.authorZhou, MFen_HK
dc.contributor.authorJianPing, Zen_HK
dc.date.accessioned2010-12-23T08:33:15Z-
dc.date.available2010-12-23T08:33:15Z-
dc.date.issued2010en_HK
dc.identifier.citationLithos, 2010, v. 115 n. 1-4, p. 177-189en_HK
dc.identifier.issn0024-4937en_HK
dc.identifier.urihttp://hdl.handle.net/10722/129172-
dc.description.abstractIn the Huangling region of the northern Yangtze Block, South China, the 820-Ma Huangling felsic pluton was intruded by ∼ 800-Ma mafic dikes. These dikes are composed of fine- to medium-grained diabase, porphyritic diabase and olivine gabbro. Quartz xenocrysts occur locally in the olivine gabbro. The rocks are alkaline to sub-alkaline in composition and have SiO2 ranging from 43.3 to 57.2 wt.%, MgO from 3.7 to 9.2 wt.% and total alkali from 3.0 to 7.3 wt.%. They exhibit LREE enrichment ((La/Yb)n = 3.3-28.5) with slightly negative Eu anomalies (Eu/Eu* = 0.6-1.0). Their primitive mantle-normalized trace element patterns are characterized by enrichment of large-ion lithophile elements (Rb, Ba, Th and U), depletion of high-field-strength elements (Nb, Ta, Zr and Hf) and positive Pb and negative Ti anomalies. They have relatively high initial 87Sr/86Sr ratios ranging from 0.7052 to 0.7080 and variably negative εNd(t) values from - 4.2 to - 10.9. The rocks have a large range of whole-rock εHf values (- 0.35 to - 11.34) and a relatively narrow range of Pb isotope ratios (206Pb/204Pb = 16.96 to 17.97, 207Pb/204Pb = 15.41 to 15.58, and 208Pb/204Pb = 38.08 to 39.66). Initial 87Sr/86Sr ratios correlate negatively with 206Pb/204Pb ratios, whereas 143Nd/144Nd and 208Pb/204Pb ratios and εHf values correlate positively with 206Pb/204Pb ratios. These features are indicative of an EM2 source region, suggesting a lithospheric mantle source modified by subducted components during the Neoproterozoic. The quartz xenocrysts and linear isotopic variations indicate strong crustal contamination during magma emplacement. The energy-constrained assimilation and fractional crystallization (EC-AFC) modeling calculations reveal that the parental magmas were contaminated by continental crust, including Archaean amphibolites, granitic gneisses, metasedimentary rocks and granitic rocks. The mafic dikes are 20 myrs younger than the Huangling felsic pluton, which was produced by partial melting of a thickened continental crust, suggesting that the mafic dikes were a consequence of post-orogenic extension. The Huangling region may have originally been located at the centre of the Yangtze Block. The possible heat source for the generation of the Huangling felsic pluton and mafic dikes was asthenospheric wedging resulting from oceanic slab subduction beneath the northern margin of the Yangtze Block. This conclusion rules out the possibility that the Yangtze Block was located in the central part of the Rodinia supercontinent. The block was more likely situated along the margin of Rodinia. © 2009 Elsevier B.V. All rights reserved.en_HK
dc.languageengen_US
dc.publisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/lithosen_HK
dc.relation.ispartofLithosen_HK
dc.subjectCrustal contaminationen_HK
dc.subjectMafic dikesen_HK
dc.subjectMetasomatic mantle sourceen_HK
dc.subjectNeoproterozoicen_HK
dc.subjectYangtze Blocken_HK
dc.titleMetasomatic mantle source and crustal contamination for the formation of the Neoproterozoic mafic dike swarm in the northern Yangtze Block, South Chinaen_HK
dc.typeArticleen_HK
dc.identifier.emailZhou, MF:mfzhou@hkucc.hku.hken_HK
dc.identifier.authorityZhou, MF=rp00844en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1016/j.lithos.2009.12.001en_HK
dc.identifier.scopuseid_2-s2.0-76349125548en_HK
dc.identifier.hkuros177730en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-76349125548&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume115en_HK
dc.identifier.issue1-4en_HK
dc.identifier.spage177en_HK
dc.identifier.epage189en_HK
dc.identifier.isiWOS:000276042700013-
dc.publisher.placeNetherlandsen_HK
dc.identifier.scopusauthoridZhao, JH=49061691300en_HK
dc.identifier.scopusauthoridZhou, MF=7403506005en_HK
dc.identifier.scopusauthoridJianPing, Z=49061165000en_HK
dc.identifier.citeulike6474727-

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