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Article: Genesis of Carboniferous volcanic rocks in the eastern Junggar: Constraints on the closure of the Junggar Ocean

TitleGenesis of Carboniferous volcanic rocks in the eastern Junggar: Constraints on the closure of the Junggar Ocean
Authors
KeywordsCaob
Eastern Junggar
Geochemistry
Isotope
Subduction
Volcanic Rocks
Zhaheba
Issue Date2006
PublisherChinese Academy of Sciences, Institute of Geology and Geophysics. The Journal's web site is located at http://www.ysxb.ac.cn/ysxb/ch/index.aspx
Citation
Acta Petrologica Sinica, 2006, v. 22 n. 1, p. 31-40 How to Cite?
AbstractZhaheba Carboniferous volcanic rocks mainly composed of basalts and basaltic andesites occur within Upper Carboniferous Batamayi Group, north of Zhaheba ophiolite in the eastern Junggar. These rocks have relatively high Mg # (64 - 73) values, moderate TiO 2 (<0.85%), Al 2O 3 (13.75% - 16.88%), but low CaO (4.51% - 7.28%) and FeO T (5.82% - 7.71%) contents, showing characteristics of primitive magmas. These rocks have relatively high Na 2 O/K 2O ratios (>1) and alkali contents (Na 2O + K 2O) = 4.3% - 7.1%). They are enriched in LILEs but relatively depleted in HFSEs, with strong negative Nb-Ta anomalies, showing typical characteristics of subduction zone. These samples are slightly enriched in LREEs ((La/Yb) N = 1.0 - 2.1) and possess weak Eu and Ce anomalies (0.94 - 1.08, 1.00 - 1.06, respectively), without significant fractionations of HREEs (Gd N/Yb N = 1.1 - 1.3). Furthermore, they have high radioactive Sr (I Sr = 0.705282 - 0.705420) and low radioactive Nd (ε Nd (t) = + 6.59 - + 7.58). These characteristics, along with their low contents of Th (<0.55 × 10 -6) and Pb (<3.52 × 10 -6) and high ratio of Ce/Pb (4 - 79), preclude the possibility for involvement of continental crust, suggesting that they were most likely produced in a subduction-related environment. Their high Ce/Th (18 - 32), Ce/Pb, Ba/Rb (21 - 76), Ba/ Th (>179), ε Nd (t) values and lack of obvious Ce anomalies indicate that there was no significant involvement of subducted sediment during their genesis. Moreover, their trace elements and Nd-Sr isotope compositions are consistent with their origination from a mantle wedge metasomatised by slab-derived fluid. Different from typical arc-related magmas, however, most Zhaheba samples show negative Pb anomalies and relatively high Ce/Pb ratios, which can probably be ascribed to Pb-poor fluid derived from an amphibolite-facies slab in high temperatures. These characteristics indicate that an intra-oceanic subduction environment existed in the eastern Junggar, and that the Junggar Ocean must close after the Late Carboniferous.
Persistent Identifierhttp://hdl.handle.net/10722/151188
ISSN
2015 Impact Factor: 1.234
2015 SCImago Journal Rankings: 0.892
References

 

DC FieldValueLanguage
dc.contributor.authorLong, XPen_US
dc.contributor.authorSun, Men_US
dc.contributor.authorYuan, Cen_US
dc.contributor.authorXiao, WJen_US
dc.contributor.authorChen, HLen_US
dc.contributor.authorZhao, YJen_US
dc.contributor.authorCai, KDen_US
dc.contributor.authorLi, JLen_US
dc.date.accessioned2012-06-26T06:18:27Z-
dc.date.available2012-06-26T06:18:27Z-
dc.date.issued2006en_US
dc.identifier.citationActa Petrologica Sinica, 2006, v. 22 n. 1, p. 31-40en_US
dc.identifier.issn1000-0569en_US
dc.identifier.urihttp://hdl.handle.net/10722/151188-
dc.description.abstractZhaheba Carboniferous volcanic rocks mainly composed of basalts and basaltic andesites occur within Upper Carboniferous Batamayi Group, north of Zhaheba ophiolite in the eastern Junggar. These rocks have relatively high Mg # (64 - 73) values, moderate TiO 2 (<0.85%), Al 2O 3 (13.75% - 16.88%), but low CaO (4.51% - 7.28%) and FeO T (5.82% - 7.71%) contents, showing characteristics of primitive magmas. These rocks have relatively high Na 2 O/K 2O ratios (>1) and alkali contents (Na 2O + K 2O) = 4.3% - 7.1%). They are enriched in LILEs but relatively depleted in HFSEs, with strong negative Nb-Ta anomalies, showing typical characteristics of subduction zone. These samples are slightly enriched in LREEs ((La/Yb) N = 1.0 - 2.1) and possess weak Eu and Ce anomalies (0.94 - 1.08, 1.00 - 1.06, respectively), without significant fractionations of HREEs (Gd N/Yb N = 1.1 - 1.3). Furthermore, they have high radioactive Sr (I Sr = 0.705282 - 0.705420) and low radioactive Nd (ε Nd (t) = + 6.59 - + 7.58). These characteristics, along with their low contents of Th (<0.55 × 10 -6) and Pb (<3.52 × 10 -6) and high ratio of Ce/Pb (4 - 79), preclude the possibility for involvement of continental crust, suggesting that they were most likely produced in a subduction-related environment. Their high Ce/Th (18 - 32), Ce/Pb, Ba/Rb (21 - 76), Ba/ Th (>179), ε Nd (t) values and lack of obvious Ce anomalies indicate that there was no significant involvement of subducted sediment during their genesis. Moreover, their trace elements and Nd-Sr isotope compositions are consistent with their origination from a mantle wedge metasomatised by slab-derived fluid. Different from typical arc-related magmas, however, most Zhaheba samples show negative Pb anomalies and relatively high Ce/Pb ratios, which can probably be ascribed to Pb-poor fluid derived from an amphibolite-facies slab in high temperatures. These characteristics indicate that an intra-oceanic subduction environment existed in the eastern Junggar, and that the Junggar Ocean must close after the Late Carboniferous.en_US
dc.languageengen_US
dc.publisherChinese Academy of Sciences, Institute of Geology and Geophysics. The Journal's web site is located at http://www.ysxb.ac.cn/ysxb/ch/index.aspxen_US
dc.relation.ispartofActa Petrologica Sinicaen_US
dc.subjectCaoben_US
dc.subjectEastern Junggaren_US
dc.subjectGeochemistryen_US
dc.subjectIsotopeen_US
dc.subjectSubductionen_US
dc.subjectVolcanic Rocksen_US
dc.subjectZhahebaen_US
dc.titleGenesis of Carboniferous volcanic rocks in the eastern Junggar: Constraints on the closure of the Junggar Oceanen_US
dc.typeArticleen_US
dc.identifier.emailLong, X: longxp@gig.ac.cnen_US
dc.identifier.emailSun, M: minsun@hku.hk-
dc.identifier.emailYuan, C: yuanchao@HKUCC-COM.hku.hk-
dc.identifier.emailLi, J: jwli-cug@hotmail.com-
dc.identifier.authoritySun, M=rp00780en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.scopuseid_2-s2.0-33745053428en_US
dc.identifier.hkuros120042-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-33745053428&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume22en_US
dc.identifier.issue1en_US
dc.identifier.spage31en_US
dc.identifier.epage40en_US
dc.publisher.placeChinaen_US
dc.identifier.scopusauthoridLong, XP=14012199100en_US
dc.identifier.scopusauthoridSun, M=25932315800en_US
dc.identifier.scopusauthoridYuan, C=35241599200en_US
dc.identifier.scopusauthoridXiao, WJ=7202456615en_US
dc.identifier.scopusauthoridChen, HL=8620950800en_US
dc.identifier.scopusauthoridZhao, YJ=14013151400en_US
dc.identifier.scopusauthoridCai, KD=14011943800en_US
dc.identifier.scopusauthoridLi, JL=26643194200en_US
dc.customcontrol.immutablesml 130311-

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