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Article: Geochemistry and U-Pb detrital zircon dating of Paleozoic graywackes in East Junggar, NW China: insights into subduction-accretion processes in the southern Central Asian Orogenic Belt

TitleGeochemistry and U-Pb detrital zircon dating of Paleozoic graywackes in East Junggar, NW China: insights into subduction-accretion processes in the southern Central Asian Orogenic Belt
Authors
KeywordsCentral asian orogenic belt
Detrital zircons
Junggar
Provenance
Tectonics
Issue Date2012
PublisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/jcr
Citation
Gondwana Research, 2012, v. 21 n. 2-3, p. 637-653 How to Cite?
AbstractThe southern Central Asian Orogenic Belt (CAOB) is characterized by multiple and linear accretionary orogenic collages, including Paleozoic arcs, ophiolites, and accretionay wedges. A complex history of subduction-accretion processes makes it difficult to distinguish the origin of these various terranes and reconstruct the tectonic evolution of the southern CAOB. In order to provide constraints on the accretionary history, we analyzed major and trace element compositions of Paleozoic graywackes from the Huangcaopo Group (HG) and Kubusu Group (KG) in East Junggar. The HG graywackes have relatively low Chemical Index of Alteration (CIA) values (50 to 66), suggesting a source that underwent relatively weak chemical weathering. The identical average Index of Compositional Variability (ICV) values (1.1) for both the KG and HG samples point to an immature source for the Paleozoic graywackes in East Junggar, which is consistent with an andesitic-felsic igneous source characterized by low La/Th ratios and relatively high Hf contents. These graywackes are geochemically similar to continental island arc sediments and therefore were probably deposited at an active continental margin. U-Pb dating of detrital zircons from the lower subgroup of the HG yielded a young age peak at 440Ma, indicating a post-Early Silurian depositional age. However, the youngest populations of detrital zircons from the KG graywackes and the upper subgroup of the HG yielded 206Pb/ 238U ages of 346Ma and 355Ma, respectively, which suggest a post-Early Carboniferous depositional age. Because of similarities of rock assemblages, these two units should be incorporated into the Early Carboniferous Nanmingshui Formation. The detrital zircon age spectrum of the Early Paleozoic HG graywackes resembles that of the Habahe sediments in the Chinese Altai, which suggests that the ocean between East Junggar and the Chinese Altai was closed before the deposition of the sediments and that the Armantai ophiolite was emplaced prior to the Early Devonian. The differences in age spectra for detrital zircons from the post-Early Carboniferous graywackes in East Junggar and the Harlik arc indicate that the emplacement of the Kalamaili ophiolite postdates the Early Carboniferous. Therefore, a long-lasting northward subduction-accretion process is suggested for the formation of East Junggar and the reconstruction of the Early Paleozoic evolution of the southern CAOB. © 2011 International Association for Gondwana Research.
Persistent Identifierhttp://hdl.handle.net/10722/151356
ISSN
2015 Impact Factor: 8.743
2015 SCImago Journal Rankings: 4.949
ISI Accession Number ID
Funding AgencyGrant Number
National Basic Research Program of China2007CB411308
National Natural Science Foundation of ChinaNSFC 40803009
40725009
40721063
Hong Kong RGCHKU704307P
Funding Information:

We are very grateful to R.D. Nance and the three reviewers, whose polishing work and constructive comments have greatly improved the manuscript This study was supported by the National Basic Research Program of China (2007CB411308), the National Natural Science Foundation of China (NSFC 40803009, 40725009 and 40721063) and the Hong Kong RGC (HKU704307P). We express our appreciation to KJ. Hou, Y. Liu and XL Tu for their laboratory assistance. This is contribution No. IS-1345 from GIGCAS.

References

 

DC FieldValueLanguage
dc.contributor.authorLong, Xen_US
dc.contributor.authorYuan, Cen_US
dc.contributor.authorSun, Men_US
dc.contributor.authorSafonova, Ien_US
dc.contributor.authorXiao, Wen_US
dc.contributor.authorWang, Y-
dc.date.accessioned2012-06-26T06:21:04Z-
dc.date.available2012-06-26T06:21:04Z-
dc.date.issued2012en_US
dc.identifier.citationGondwana Research, 2012, v. 21 n. 2-3, p. 637-653en_US
dc.identifier.issn1342-937Xen_US
dc.identifier.urihttp://hdl.handle.net/10722/151356-
dc.description.abstractThe southern Central Asian Orogenic Belt (CAOB) is characterized by multiple and linear accretionary orogenic collages, including Paleozoic arcs, ophiolites, and accretionay wedges. A complex history of subduction-accretion processes makes it difficult to distinguish the origin of these various terranes and reconstruct the tectonic evolution of the southern CAOB. In order to provide constraints on the accretionary history, we analyzed major and trace element compositions of Paleozoic graywackes from the Huangcaopo Group (HG) and Kubusu Group (KG) in East Junggar. The HG graywackes have relatively low Chemical Index of Alteration (CIA) values (50 to 66), suggesting a source that underwent relatively weak chemical weathering. The identical average Index of Compositional Variability (ICV) values (1.1) for both the KG and HG samples point to an immature source for the Paleozoic graywackes in East Junggar, which is consistent with an andesitic-felsic igneous source characterized by low La/Th ratios and relatively high Hf contents. These graywackes are geochemically similar to continental island arc sediments and therefore were probably deposited at an active continental margin. U-Pb dating of detrital zircons from the lower subgroup of the HG yielded a young age peak at 440Ma, indicating a post-Early Silurian depositional age. However, the youngest populations of detrital zircons from the KG graywackes and the upper subgroup of the HG yielded 206Pb/ 238U ages of 346Ma and 355Ma, respectively, which suggest a post-Early Carboniferous depositional age. Because of similarities of rock assemblages, these two units should be incorporated into the Early Carboniferous Nanmingshui Formation. The detrital zircon age spectrum of the Early Paleozoic HG graywackes resembles that of the Habahe sediments in the Chinese Altai, which suggests that the ocean between East Junggar and the Chinese Altai was closed before the deposition of the sediments and that the Armantai ophiolite was emplaced prior to the Early Devonian. The differences in age spectra for detrital zircons from the post-Early Carboniferous graywackes in East Junggar and the Harlik arc indicate that the emplacement of the Kalamaili ophiolite postdates the Early Carboniferous. Therefore, a long-lasting northward subduction-accretion process is suggested for the formation of East Junggar and the reconstruction of the Early Paleozoic evolution of the southern CAOB. © 2011 International Association for Gondwana Research.en_US
dc.languageengen_US
dc.publisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/jcren_US
dc.relation.ispartofGondwana Researchen_US
dc.subjectCentral asian orogenic belten_US
dc.subjectDetrital zirconsen_US
dc.subjectJunggaren_US
dc.subjectProvenanceen_US
dc.subjectTectonicsen_US
dc.titleGeochemistry and U-Pb detrital zircon dating of Paleozoic graywackes in East Junggar, NW China: insights into subduction-accretion processes in the southern Central Asian Orogenic Belten_US
dc.typeArticleen_US
dc.identifier.emailLong, X: longxp@gig.ac.cnen_US
dc.identifier.emailYuan, C: yuanchao@gig.ac.cn-
dc.identifier.emailSun, M: minsun@hku.hk-
dc.identifier.authoritySun, M=rp00780en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1016/j.gr.2011.05.015en_US
dc.identifier.scopuseid_2-s2.0-84856213411en_US
dc.identifier.hkuros205441-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-84856213411&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume21en_US
dc.identifier.issue2-3en_US
dc.identifier.spage637en_US
dc.identifier.epage653en_US
dc.identifier.isiWOS:000301087300025-
dc.publisher.placeNetherlandsen_US
dc.identifier.scopusauthoridWang, Y=37762225700en_US
dc.identifier.scopusauthoridXiao, W=7202456615en_US
dc.identifier.scopusauthoridSafonova, I=7003902437en_US
dc.identifier.scopusauthoridSun, M=25932315800en_US
dc.identifier.scopusauthoridYuan, C=35241599200en_US
dc.identifier.scopusauthoridLong, X=14012199100en_US

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