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Article: Geochemistry of the ~ 430-Ma Jingbulake mafic-ultramafic intrusion in Western Xinjiang, NW China: Implications for subduction related magmatism in the South Tianshan orogenic belt

TitleGeochemistry of the ~ 430-Ma Jingbulake mafic-ultramafic intrusion in Western Xinjiang, NW China: Implications for subduction related magmatism in the South Tianshan orogenic belt
Authors
KeywordsMafic-Ultramafic Intrusion
Nw China
South Tianshan Orogenic Belt
Subduction
Issue Date2009
PublisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/lithos
Citation
Lithos, 2009, v. 113 n. 1-2, p. 259-273 How to Cite?
AbstractThe South Tianshan orogenic belt, the southwestern extension of the Central Asian orogenic belt, separates the Yili-Central Tianshan block to the north from the Tarim block to the south. This belt is marked by a Proterozoic metamorphic complex, ophiolites, granitoids, mafic intrusions and younger high-pressure and low-temperature metamorphic rocks. The Jingbulake mafic intrusion in this belt is a zoned body composed of pyroxene diorite, olivine gabbro and wehrlite. Pyroxenite locally intrudes all of these rocks but is most abundant along the boundaries between pyroxene diorite and olivine gabbro. Both the olivine gabbro and wehrlite contain disseminated sulfide mineralization, and a sulfide rich orebody intrudes the pyroxenite. The pyroxene diorite has a SHRIMP zircon U-Pb isotope age of 431 ± 6 Ma. All the rocks have nearly flat chondrite-normalized rare earth element patterns and show negative Nb-Ta and P-Ti anomalies on mantle-normalized trace element diagrams. They have positive εNd values (+ 1.6 to + 4.0), and low (87Sr/86Sr)i ratios (0.7039-0.7048), indicative of a depleted mantle source. The rocks all have low Th/Nb ratios, narrow isotopic variations, and slightly negative Zr-Hf anomalies, suggesting insignificant crustal contamination. They are enriched in large ion lithophile elements, such as Cs, Rb, Ba, Pb and Sr, and have constant but radiogenic Pb isotopic ratios of 206Pb/204Pb (18.159-18.250), 207Pb/204Pb (15.599-15.633) and 208Pb/204Pb (37.978-38.250), consistent with the involvement of subduction-related fluids and sediments in the source region. The Jingbulake intrusion, together with other mafic intrusions in the belt, suggests subduction of the South Tianshan oceanic lithosphere beneath the Yili-Central Tianshan block. The subduction-related fluids and sediments not only metasomatized the mantle wedge above the subduction zone, but also triggered the melting of the mantle due to the addition of water. © 2009 Elsevier B.V. All rights reserved.
Persistent Identifierhttp://hdl.handle.net/10722/151292
ISSN
2015 Impact Factor: 3.723
2015 SCImago Journal Rankings: 2.920
ISI Accession Number ID
Funding AgencyGrant Number
Research Grants Council of Hong Kong, ChinaHKU 7058/08P
973 key national basic research program of China2007CB411308
University of Hong Kong
Funding Information:

This work was jointly supported by a grant from the Research Grants Council of Hong Kong, China (HKU 7058/08P), a 973 key national basic research program of China (2007CB411308) and a 973 project matching grant of the University of Hong Kong. We thank Jibing Zhou, Yongfeng Gao and Deyi Kong of the 9th geology team of Xinjiang for providing drill hole samples and assistance in the field, and jianfeng Gao for the zircon SHRIMP dating and the Sr-Nd-Pb isotope analyses. Ying Liu assisted with the ICP-AES analyses, Liang QJ with the analysis of SiO<INF>2</INF> and Xiaoping Xia with the ICP-MS analyses. We thankJunhong Zhao and Weihua Sun for reviewing an earlier draft of this manuscript. An anonymous reviewer, Paul I Robinson and Yildirim Dilek provided constructive criticism and are gratefully acknowledged.

References

 

DC FieldValueLanguage
dc.contributor.authorYang, SHen_US
dc.contributor.authorZhou, MFen_US
dc.date.accessioned2012-06-26T06:20:12Z-
dc.date.available2012-06-26T06:20:12Z-
dc.date.issued2009en_US
dc.identifier.citationLithos, 2009, v. 113 n. 1-2, p. 259-273en_US
dc.identifier.issn0024-4937en_US
dc.identifier.urihttp://hdl.handle.net/10722/151292-
dc.description.abstractThe South Tianshan orogenic belt, the southwestern extension of the Central Asian orogenic belt, separates the Yili-Central Tianshan block to the north from the Tarim block to the south. This belt is marked by a Proterozoic metamorphic complex, ophiolites, granitoids, mafic intrusions and younger high-pressure and low-temperature metamorphic rocks. The Jingbulake mafic intrusion in this belt is a zoned body composed of pyroxene diorite, olivine gabbro and wehrlite. Pyroxenite locally intrudes all of these rocks but is most abundant along the boundaries between pyroxene diorite and olivine gabbro. Both the olivine gabbro and wehrlite contain disseminated sulfide mineralization, and a sulfide rich orebody intrudes the pyroxenite. The pyroxene diorite has a SHRIMP zircon U-Pb isotope age of 431 ± 6 Ma. All the rocks have nearly flat chondrite-normalized rare earth element patterns and show negative Nb-Ta and P-Ti anomalies on mantle-normalized trace element diagrams. They have positive εNd values (+ 1.6 to + 4.0), and low (87Sr/86Sr)i ratios (0.7039-0.7048), indicative of a depleted mantle source. The rocks all have low Th/Nb ratios, narrow isotopic variations, and slightly negative Zr-Hf anomalies, suggesting insignificant crustal contamination. They are enriched in large ion lithophile elements, such as Cs, Rb, Ba, Pb and Sr, and have constant but radiogenic Pb isotopic ratios of 206Pb/204Pb (18.159-18.250), 207Pb/204Pb (15.599-15.633) and 208Pb/204Pb (37.978-38.250), consistent with the involvement of subduction-related fluids and sediments in the source region. The Jingbulake intrusion, together with other mafic intrusions in the belt, suggests subduction of the South Tianshan oceanic lithosphere beneath the Yili-Central Tianshan block. The subduction-related fluids and sediments not only metasomatized the mantle wedge above the subduction zone, but also triggered the melting of the mantle due to the addition of water. © 2009 Elsevier B.V. All rights reserved.en_US
dc.languageengen_US
dc.publisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/lithosen_US
dc.relation.ispartofLithosen_US
dc.subjectMafic-Ultramafic Intrusionen_US
dc.subjectNw Chinaen_US
dc.subjectSouth Tianshan Orogenic Belten_US
dc.subjectSubductionen_US
dc.titleGeochemistry of the ~ 430-Ma Jingbulake mafic-ultramafic intrusion in Western Xinjiang, NW China: Implications for subduction related magmatism in the South Tianshan orogenic belten_US
dc.typeArticleen_US
dc.identifier.emailZhou, MF: mfzhou@hkucc.hku.hken_US
dc.identifier.authorityZhou, MF=rp00844en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1016/j.lithos.2009.07.005en_US
dc.identifier.scopuseid_2-s2.0-70350244844en_US
dc.identifier.hkuros177711-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-70350244844&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume113en_US
dc.identifier.issue1-2en_US
dc.identifier.spage259en_US
dc.identifier.epage273en_US
dc.identifier.isiWOS:000272370500015-
dc.publisher.placeNetherlandsen_US
dc.identifier.scopusauthoridYang, SH=35101062300en_US
dc.identifier.scopusauthoridZhou, MF=7403506005en_US
dc.identifier.citeulike5331981-

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