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Article: Xenolith evidence for polybaric melting and stratification of the upper mantle beneath South China

TitleXenolith evidence for polybaric melting and stratification of the upper mantle beneath South China
Authors
KeywordsLithospheric thinning
Mantle x-enoliths
Metasomatism
Polybaric melting
South China
Issue Date2002
PublisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/jseaes
Citation
Journal Of Asian Earth Sciences, 2002, v. 20 n. 8, p. 937-954 How to Cite?
AbstractMantle xenoliths from Hainan and Qilin, South China have been studied to constrain the nature of the upper mantle and mantle processes beneath a continental margin. The extremely low Ti (160-245 ppm) contents in clinopyroxenes from some spinel Iherzolites, indicative of high degrees of partial melting are inconsistent with the relatively high clinopyroxene modes (7.4-13%) in these samples. This inconsistency could be due to polybaric melting that started in the garnet stability field, then, after the breakdown of garnet to pyroxene and spinel, continued in the spinel stability field. Polybaric melting, due to adiabatic decompression of upwelling mantle, would leave a residual mantle in which the degree of depletion decreases with depth. The predicted stratified lithospheric mantle is evidenced by the negative correlation between the forsterite content in olivine and the equilibration temperature, proportional to the depth in the lithosphere from which the xenolith was derived. The lower part of the lithospheric mantle beneath South China consists predominantly of fertile and moderately depleted peridotites, which are either devoid of LREE enrichment, or show the trace element signature of incipient metasomatism, and plot within the Phanerozoic mantle domain. In contrast, the upper part of the mantle contains harzburgite and cpx-poor Iherzolite, which are strongly affected by metasomatism of melt/fluid of highly variable composition. The anomalously high orthopyroxene mode (up to 47%) makes some of these refractory samples compositionally similar to the Proterozoic/Archean mantle. Their low equilibrium temperature (800-900 °C) points to the presence of old lithospheric relicts in the uppermost mantle beneath South China. Such lithosphere architecture may have resulted from partial replacement of Archean-Proterozoic lithosphere by asthenosphere that rose adiabatically subsequent to lithospheric thinning during the Cenozoic. © 2002 Elsevier Science Ltd. All rights reserved.
Persistent Identifierhttp://hdl.handle.net/10722/72751
ISSN
2015 Impact Factor: 2.647
2015 SCImago Journal Rankings: 1.393
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorXu, YGen_HK
dc.contributor.authorSun, Men_HK
dc.contributor.authorYan, Wen_HK
dc.contributor.authorLiu, Yen_HK
dc.contributor.authorHuang, XLen_HK
dc.contributor.authorChen, XMen_HK
dc.date.accessioned2010-09-06T06:44:46Z-
dc.date.available2010-09-06T06:44:46Z-
dc.date.issued2002en_HK
dc.identifier.citationJournal Of Asian Earth Sciences, 2002, v. 20 n. 8, p. 937-954en_HK
dc.identifier.issn1367-9120en_HK
dc.identifier.urihttp://hdl.handle.net/10722/72751-
dc.description.abstractMantle xenoliths from Hainan and Qilin, South China have been studied to constrain the nature of the upper mantle and mantle processes beneath a continental margin. The extremely low Ti (160-245 ppm) contents in clinopyroxenes from some spinel Iherzolites, indicative of high degrees of partial melting are inconsistent with the relatively high clinopyroxene modes (7.4-13%) in these samples. This inconsistency could be due to polybaric melting that started in the garnet stability field, then, after the breakdown of garnet to pyroxene and spinel, continued in the spinel stability field. Polybaric melting, due to adiabatic decompression of upwelling mantle, would leave a residual mantle in which the degree of depletion decreases with depth. The predicted stratified lithospheric mantle is evidenced by the negative correlation between the forsterite content in olivine and the equilibration temperature, proportional to the depth in the lithosphere from which the xenolith was derived. The lower part of the lithospheric mantle beneath South China consists predominantly of fertile and moderately depleted peridotites, which are either devoid of LREE enrichment, or show the trace element signature of incipient metasomatism, and plot within the Phanerozoic mantle domain. In contrast, the upper part of the mantle contains harzburgite and cpx-poor Iherzolite, which are strongly affected by metasomatism of melt/fluid of highly variable composition. The anomalously high orthopyroxene mode (up to 47%) makes some of these refractory samples compositionally similar to the Proterozoic/Archean mantle. Their low equilibrium temperature (800-900 °C) points to the presence of old lithospheric relicts in the uppermost mantle beneath South China. Such lithosphere architecture may have resulted from partial replacement of Archean-Proterozoic lithosphere by asthenosphere that rose adiabatically subsequent to lithospheric thinning during the Cenozoic. © 2002 Elsevier Science Ltd. All rights reserved.en_HK
dc.languageengen_HK
dc.publisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/jseaesen_HK
dc.relation.ispartofJournal of Asian Earth Sciencesen_HK
dc.subjectLithospheric thinningen_HK
dc.subjectMantle x-enolithsen_HK
dc.subjectMetasomatismen_HK
dc.subjectPolybaric meltingen_HK
dc.subjectSouth Chinaen_HK
dc.titleXenolith evidence for polybaric melting and stratification of the upper mantle beneath South Chinaen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=1367-9120&volume=20&spage=937&epage=954&date=2002&atitle=Xenolith+evidence+for+polybaric+melting+and+stratification+of+the+upper+mantle+beneath+South+Chinaen_HK
dc.identifier.emailSun, M:minsun@hku.hken_HK
dc.identifier.authoritySun, M=rp00780en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1016/S1367-9120(01)00087-6en_HK
dc.identifier.scopuseid_2-s2.0-0037112672en_HK
dc.identifier.hkuros81932en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0037112672&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume20en_HK
dc.identifier.issue8en_HK
dc.identifier.spage937en_HK
dc.identifier.epage954en_HK
dc.identifier.isiWOS:000179368800006-
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridXu, YG=48961542800en_HK
dc.identifier.scopusauthoridSun, M=25932315800en_HK
dc.identifier.scopusauthoridYan, W=16159355700en_HK
dc.identifier.scopusauthoridLiu, Y=48961202900en_HK
dc.identifier.scopusauthoridHuang, XL=8083983300en_HK
dc.identifier.scopusauthoridChen, XM=49160969600en_HK

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