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Article: Neoproterozoic adakitic plutons in the northern margin of the Yangtze Block, China: Partial melting of a thickened lower crust and implications for secular crustal evolution

TitleNeoproterozoic adakitic plutons in the northern margin of the Yangtze Block, China: Partial melting of a thickened lower crust and implications for secular crustal evolution
Authors
KeywordsAdakites
Crustal evolution
Hannan region
Neoproterozoic
South China
Issue Date2008
PublisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/lithos
Citation
Lithos, 2008, v. 104 n. 1-4, p. 231-248 How to Cite?
AbstractNumerous Neoproterozoic felsic and mafic-ultramafic intrusions occur in the Hannan region at the northern margin of the Yangtze Block. Among these, the Wudumen and Erliba plutons consist of granodiorites and have SHRIMP zircon U-Pb ages of ∼ 735 Ma. The rocks have high K2O (0.8-3.6 wt.%) and Na2O (4.4-6.4 wt.%) and low MgO (0.4-1.7 wt.%). They also have high Sr/Y (32-209) and (La/Yb)n ratios (4.4-38.6). Their εNd values range from - 0.41 to - 0.92 and zircon initial 176Hf/177Hf ratios from 0.282353 to 0.282581. These geochemical features are similar to those of adakitic rocks produced by partial melting of a thickened lower crust. Our new analytical results, combined with the occurrence of voluminous arc-related mafic-ultramafic intrusions emplaced before 740 Ma, lead us to propose that the crustal evolution in the northern margin of the Yangtze Block during Neoproterozoic involved: (1) rapid crustal growth and thickening by underplating of mafic magmas from the mantle which was modified by materials coming from the subducting oceanic slab from ∼ 1.0 to ∼ 0.74 Ga, and (2) partial melting of the thickened lower crust due to a thermal anomaly induced by upwelling of asthenosphere through an oceanic slab window, producing the ∼ 735 Ma adakitic Wudumen and Erliba plutons. Our model suggests that the crustal thickness was more than 50 km at the northern margin of the Yangtze Block at ∼ 735 Ma, and rule out the possibility of a mantle plume impact causing the > 735 Ma magmatism in the region. © 2008 Elsevier B.V. All rights reserved.
Persistent Identifierhttp://hdl.handle.net/10722/72560
ISSN
2015 Impact Factor: 3.723
2015 SCImago Journal Rankings: 2.920
ISI Accession Number ID
Funding AgencyGrant Number
Chinese Academy of Science2005-2-21
National Science Foundation of China40672037/D0204
Funding Information:

We thank A.C. Kerr, P. Castillo and P. T. Robinson for their constructive comments that helped to clarify our discussion. This work was substantially supported by the Chinese Academy of Science (2005-2-21) and National Science Foundation of China (Project 40672037/D0204). We are grateful to A, Kennedy for SHRIMP dating, Xiao Fu for XPF analyses, J.-F. Gao for ICP-MS analyses, Y.H. Yang and X.-F. Zhao for zircon Hf isotope analyses and W. Chen for field assistance. Dr. K.N. Pang is also thanked for his proofreading of the manuscript.

References

 

DC FieldValueLanguage
dc.contributor.authorZhao, JHen_HK
dc.contributor.authorZhou, MFen_HK
dc.date.accessioned2010-09-06T06:42:59Z-
dc.date.available2010-09-06T06:42:59Z-
dc.date.issued2008en_HK
dc.identifier.citationLithos, 2008, v. 104 n. 1-4, p. 231-248en_HK
dc.identifier.issn0024-4937en_HK
dc.identifier.urihttp://hdl.handle.net/10722/72560-
dc.description.abstractNumerous Neoproterozoic felsic and mafic-ultramafic intrusions occur in the Hannan region at the northern margin of the Yangtze Block. Among these, the Wudumen and Erliba plutons consist of granodiorites and have SHRIMP zircon U-Pb ages of ∼ 735 Ma. The rocks have high K2O (0.8-3.6 wt.%) and Na2O (4.4-6.4 wt.%) and low MgO (0.4-1.7 wt.%). They also have high Sr/Y (32-209) and (La/Yb)n ratios (4.4-38.6). Their εNd values range from - 0.41 to - 0.92 and zircon initial 176Hf/177Hf ratios from 0.282353 to 0.282581. These geochemical features are similar to those of adakitic rocks produced by partial melting of a thickened lower crust. Our new analytical results, combined with the occurrence of voluminous arc-related mafic-ultramafic intrusions emplaced before 740 Ma, lead us to propose that the crustal evolution in the northern margin of the Yangtze Block during Neoproterozoic involved: (1) rapid crustal growth and thickening by underplating of mafic magmas from the mantle which was modified by materials coming from the subducting oceanic slab from ∼ 1.0 to ∼ 0.74 Ga, and (2) partial melting of the thickened lower crust due to a thermal anomaly induced by upwelling of asthenosphere through an oceanic slab window, producing the ∼ 735 Ma adakitic Wudumen and Erliba plutons. Our model suggests that the crustal thickness was more than 50 km at the northern margin of the Yangtze Block at ∼ 735 Ma, and rule out the possibility of a mantle plume impact causing the > 735 Ma magmatism in the region. © 2008 Elsevier B.V. All rights reserved.en_HK
dc.languageengen_HK
dc.publisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/lithosen_HK
dc.relation.ispartofLithosen_HK
dc.rightsLithos. Copyright © Elsevier BV.en_HK
dc.subjectAdakitesen_HK
dc.subjectCrustal evolutionen_HK
dc.subjectHannan regionen_HK
dc.subjectNeoproterozoicen_HK
dc.subjectSouth Chinaen_HK
dc.titleNeoproterozoic adakitic plutons in the northern margin of the Yangtze Block, China: Partial melting of a thickened lower crust and implications for secular crustal evolutionen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0024-4937&volume=104&spage=231&epage=248&date=2008&atitle=Neoproterozoic+adakitic+plutons+in+the+northern+margin+of+the+Yangtze+Block,+China:+Partial+melting+of+a+thickened+lower+crust+and+implications+for+secular+crustal+evolutionen_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.2007.12.009en_HK
dc.identifier.scopuseid_2-s2.0-49449110683en_HK
dc.identifier.hkuros153188en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-49449110683&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume104en_HK
dc.identifier.issue1-4en_HK
dc.identifier.spage231en_HK
dc.identifier.epage248en_HK
dc.identifier.isiWOS:000259667400015-
dc.publisher.placeNetherlandsen_HK
dc.identifier.scopusauthoridZhao, JH=49061691300en_HK
dc.identifier.scopusauthoridZhou, MF=7403506005en_HK

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