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Article: Oxygen and hydrogen isotope geochemistry of ultrahigh-pressure eclogites from the Dabie Mountains and the Sulu terrane

TitleOxygen and hydrogen isotope geochemistry of ultrahigh-pressure eclogites from the Dabie Mountains and the Sulu terrane
Authors
KeywordsHydrogen
Isotopes
Oxygen
Issue Date1998
PublisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/epsl
Citation
Earth And Planetary Science Letters, 1998, v. 155 n. 1-2, p. 113-129 How to Cite?
AbstractThe oxygen and hydrogen isotope compositions of mineral separates have been determined for ultrahigh-pressure (UHP) eclogites from Shuanghe in the eastern Dabie Mountains and from Donghai in the western Sulu terrane, East China. The results show a large variation in δ 18O values of garnet and omphacite (-2.6 to +7.0‰ for Shuanghe and -10.4 to +4.8‰ for Donghai) but a small range in phengite SD value (-104 to -73‰). Oxygen isotope equilibrium has been preserved between the eclogite minerals and thus records the metamorphic temperatures of 550-730°C for the Shuanghe eclogites and 650-750°C for the Donghai eclogites. These not only demonstrate that the UHP rocks acquired the unusual δ 18O values prior to eclogite-facies metamorphism by interaction with 18O-depleted fluids, but also precludes the infiltration of external fluids during exhumation as the cause for the O depletion in the eclogites. Ancient meteoric water is assumed to exchange oxygen isotopes with the eclogite precursors on the continental crust prior to plate subduction. The extremely low δ 18O values (-10 to -9‰) and SD values (-104 to -100‰) for the Qinglongshan eclogite may represent the oxygen and hydrogen isotope compositions of ancient meteoric water at some earlier time than subduction. The survival of the oxygen and hydrogen isotopic signature of meteoric water in the UHP eclogites indicates that the eclogites resided at mantle depths only for a short time, otherwise the extremely 18O-depleted eclogites would be re-equilibrated isotopically with the mantle due to diffusion and recrystallization. This suggests restricted fluid mobility and limited crust-mantle interaction during the UHP metamorphism. The consistency of oxygen isotope temperatures between different mineral pairs in this study suggests relatively rapid cooling and ascent for the UHP eclogites in the early stage of their exhumation. However, there are differential exchanges of oxygen and hydrogen isotopes in hydroxyl-bearing minerals (and rutile) with retrograde fluid during exhumation, which has not only resulted in lower oxygen isotope temperatures for mineral pairs containing zoisite and rutile, but also disequilibrium and reversed hydrogen isotope fractionations between phengite, amphibole and zoisite. © 1998 Elsevier Science B.V.
Persistent Identifierhttp://hdl.handle.net/10722/150997
ISSN
2015 Impact Factor: 4.326
2015 SCImago Journal Rankings: 3.628
References

 

DC FieldValueLanguage
dc.contributor.authorZheng, YFen_US
dc.contributor.authorFu, Ben_US
dc.contributor.authorLi, Yen_US
dc.contributor.authorXiao, Yen_US
dc.contributor.authorLi, Sen_US
dc.date.accessioned2012-06-26T06:15:40Z-
dc.date.available2012-06-26T06:15:40Z-
dc.date.issued1998en_US
dc.identifier.citationEarth And Planetary Science Letters, 1998, v. 155 n. 1-2, p. 113-129en_US
dc.identifier.issn0012-821Xen_US
dc.identifier.urihttp://hdl.handle.net/10722/150997-
dc.description.abstractThe oxygen and hydrogen isotope compositions of mineral separates have been determined for ultrahigh-pressure (UHP) eclogites from Shuanghe in the eastern Dabie Mountains and from Donghai in the western Sulu terrane, East China. The results show a large variation in δ 18O values of garnet and omphacite (-2.6 to +7.0‰ for Shuanghe and -10.4 to +4.8‰ for Donghai) but a small range in phengite SD value (-104 to -73‰). Oxygen isotope equilibrium has been preserved between the eclogite minerals and thus records the metamorphic temperatures of 550-730°C for the Shuanghe eclogites and 650-750°C for the Donghai eclogites. These not only demonstrate that the UHP rocks acquired the unusual δ 18O values prior to eclogite-facies metamorphism by interaction with 18O-depleted fluids, but also precludes the infiltration of external fluids during exhumation as the cause for the O depletion in the eclogites. Ancient meteoric water is assumed to exchange oxygen isotopes with the eclogite precursors on the continental crust prior to plate subduction. The extremely low δ 18O values (-10 to -9‰) and SD values (-104 to -100‰) for the Qinglongshan eclogite may represent the oxygen and hydrogen isotope compositions of ancient meteoric water at some earlier time than subduction. The survival of the oxygen and hydrogen isotopic signature of meteoric water in the UHP eclogites indicates that the eclogites resided at mantle depths only for a short time, otherwise the extremely 18O-depleted eclogites would be re-equilibrated isotopically with the mantle due to diffusion and recrystallization. This suggests restricted fluid mobility and limited crust-mantle interaction during the UHP metamorphism. The consistency of oxygen isotope temperatures between different mineral pairs in this study suggests relatively rapid cooling and ascent for the UHP eclogites in the early stage of their exhumation. However, there are differential exchanges of oxygen and hydrogen isotopes in hydroxyl-bearing minerals (and rutile) with retrograde fluid during exhumation, which has not only resulted in lower oxygen isotope temperatures for mineral pairs containing zoisite and rutile, but also disequilibrium and reversed hydrogen isotope fractionations between phengite, amphibole and zoisite. © 1998 Elsevier Science B.V.en_US
dc.languageengen_US
dc.publisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/epslen_US
dc.relation.ispartofEarth and Planetary Science Lettersen_US
dc.subjectHydrogenen_US
dc.subjectIsotopesen_US
dc.subjectOxygenen_US
dc.titleOxygen and hydrogen isotope geochemistry of ultrahigh-pressure eclogites from the Dabie Mountains and the Sulu terraneen_US
dc.typeArticleen_US
dc.identifier.emailLi, Y:yiliang@hkucc.hku.hken_US
dc.identifier.authorityLi, Y=rp01354en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.scopuseid_2-s2.0-0031817342en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0031817342&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume155en_US
dc.identifier.issue1-2en_US
dc.identifier.spage113en_US
dc.identifier.epage129en_US
dc.publisher.placeNetherlandsen_US
dc.identifier.scopusauthoridZheng, YF=36982687100en_US
dc.identifier.scopusauthoridFu, B=35960736900en_US
dc.identifier.scopusauthoridLi, Y=27171876700en_US
dc.identifier.scopusauthoridXiao, Y=7403260575en_US
dc.identifier.scopusauthoridLi, S=23983105000en_US

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