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Article: Triassic granitoids in the eastern Songpan Ganzi Fold Belt, SW China: Magmatic response to geodynamics of the deep lithosphere

TitleTriassic granitoids in the eastern Songpan Ganzi Fold Belt, SW China: Magmatic response to geodynamics of the deep lithosphere
Authors
Keywordsadakite
convective thinning
lithospheric flexure
low-degree partial melting
shoshonite
Songpan Ganzi Fold Belt
Issue Date2010
PublisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/epsl
Citation
Earth And Planetary Science Letters, 2010, v. 290 n. 3-4, p. 481-492 How to Cite?
AbstractThe Songpan Ganzi Fold Belt (SGFB), SW China, was developed from a passive continental margin into an orogenic belt with the consumption of the Paleo-Tethys. During the evolution of the SGFB, numerous Late Triassic granitic plutons formed and exhibited a progressive development from adakite/I-type granite, high Ba-Sr granite, A-type granite and monzonite. Representative Late Triassic plutons were studied to unravel the bewildering evolution of the eastern SGFB. The Menggu Pluton (224 ± 3 Ma) consists of granites with high alkali (K 2O+Na 2O = 7.85-10.4 wt.%) and adakitic characteristics (Sr/Y = 19-38). The εNd T values (- 2.77 to - 5.03), initial 87Sr/ 86Sr ratios (0.7050-0.7063) and low Nb/Ta ratios (8-10) are indicative of an origin by partial melting of amphibolitic lower crust. Rocks from the Niuxingou Pluton (215 ± 3 Ma) are richer in K than Na (K 2O/Na 2O = 1.1-1.5) and contain high Sr (1006-1662 ppm) and Ba (1277-2009 ppm), typical of shoshonite and high Ba-Sr granite. They have less enriched εNd T values (+ 0.08 to - 2.04) and less radiogenic 87Sr/ 86Sr i ratios (0.7047-0.7048), and formed from a mixed melt derived from upwelling asthenosphere and the overlying metasomatised lithospheric mantle. The Taiyanghe Pluton (205 ± 3 Ma) consists of monzonites, with high Al 2O 3 (> 20 wt.%), but low MgO (0.94-1.39 wt.%). The rocks are richer in Na than K (K 2O/Na 2O < 0.7), contain high large ion lithophile element (LILE) (681-834 ppm Sr and 2142-9453 ppm Ba) and display strongly fractionated REE patterns ((La/Yb) N = 35-63). These features, together with their enriched Nd-Sr isotopic compositions (εNd T = - 4.78 to - 6.50; 87Sr/ 86Sr i = 0.7074-0.7090), suggest that the monzonite probably formed from low degrees of partial melting of metasomatised lithospheric mantle. Although a continuous compressional regime during the Mid- and Late Triassic has been invoked for the SGFB, the generation of crustally derived adakitic and shoshonitic plutons reflect thickening in response to an arc-continental collision accompanied by fracturing of the lithosphere and an extensional regime in the deep lithosphere in the Late Triassic. The 205 Ma Taiyanghe Pluton was emplaced simultaneously with a rapid uplift of the lithosphere, when surface deposits changed from deep-water turbidite to tidal flat sediments. It was therefore generated during decompression, probably related to the rapid removal of the overthickened lithospheric mantle. The Triassic magmatism in the eastern SGFB is therefore important for probing geodynamic processes in the deep lithosphere. © 2010 Elsevier B.V. All rights reserved.
Persistent Identifierhttp://hdl.handle.net/10722/129158
ISSN
2015 Impact Factor: 4.326
2015 SCImago Journal Rankings: 3.628
ISI Accession Number ID
Funding AgencyGrant Number
CASKZCX2-YW-Q08-3-6
NSFC40721063
40572043
CAS/SAFEA
Hong Kong RGC
Funding Information:

We thank Ms. Xiao Fu and Mr. Liang Qi for their help with the geochemical analyses. The authors benefited from discussions with Drs. Guochun Zhao, Hongfu Zhang and Chunming Wu. This work was supported by a Knowledge Innovation Project of CAS (KZCX2-YW-Q08-3-6), NSFC Projects 40721063 and 40572043, and CAS/SAFEA International Partnership Program for Creative Research Teams, and grants from the Hong Kong RGC scheme. This is contribution No. IS-1154 from GISCAS.

References

 

DC FieldValueLanguage
dc.contributor.authorYuan, Cen_HK
dc.contributor.authorZhou, MFen_HK
dc.contributor.authorSun, Men_HK
dc.contributor.authorZhao, Yen_HK
dc.contributor.authorWilde, Sen_HK
dc.contributor.authorLong, Xen_HK
dc.contributor.authorYan, Den_HK
dc.date.accessioned2010-12-23T08:33:11Z-
dc.date.available2010-12-23T08:33:11Z-
dc.date.issued2010en_HK
dc.identifier.citationEarth And Planetary Science Letters, 2010, v. 290 n. 3-4, p. 481-492en_HK
dc.identifier.issn0012-821Xen_HK
dc.identifier.urihttp://hdl.handle.net/10722/129158-
dc.description.abstractThe Songpan Ganzi Fold Belt (SGFB), SW China, was developed from a passive continental margin into an orogenic belt with the consumption of the Paleo-Tethys. During the evolution of the SGFB, numerous Late Triassic granitic plutons formed and exhibited a progressive development from adakite/I-type granite, high Ba-Sr granite, A-type granite and monzonite. Representative Late Triassic plutons were studied to unravel the bewildering evolution of the eastern SGFB. The Menggu Pluton (224 ± 3 Ma) consists of granites with high alkali (K 2O+Na 2O = 7.85-10.4 wt.%) and adakitic characteristics (Sr/Y = 19-38). The εNd T values (- 2.77 to - 5.03), initial 87Sr/ 86Sr ratios (0.7050-0.7063) and low Nb/Ta ratios (8-10) are indicative of an origin by partial melting of amphibolitic lower crust. Rocks from the Niuxingou Pluton (215 ± 3 Ma) are richer in K than Na (K 2O/Na 2O = 1.1-1.5) and contain high Sr (1006-1662 ppm) and Ba (1277-2009 ppm), typical of shoshonite and high Ba-Sr granite. They have less enriched εNd T values (+ 0.08 to - 2.04) and less radiogenic 87Sr/ 86Sr i ratios (0.7047-0.7048), and formed from a mixed melt derived from upwelling asthenosphere and the overlying metasomatised lithospheric mantle. The Taiyanghe Pluton (205 ± 3 Ma) consists of monzonites, with high Al 2O 3 (> 20 wt.%), but low MgO (0.94-1.39 wt.%). The rocks are richer in Na than K (K 2O/Na 2O < 0.7), contain high large ion lithophile element (LILE) (681-834 ppm Sr and 2142-9453 ppm Ba) and display strongly fractionated REE patterns ((La/Yb) N = 35-63). These features, together with their enriched Nd-Sr isotopic compositions (εNd T = - 4.78 to - 6.50; 87Sr/ 86Sr i = 0.7074-0.7090), suggest that the monzonite probably formed from low degrees of partial melting of metasomatised lithospheric mantle. Although a continuous compressional regime during the Mid- and Late Triassic has been invoked for the SGFB, the generation of crustally derived adakitic and shoshonitic plutons reflect thickening in response to an arc-continental collision accompanied by fracturing of the lithosphere and an extensional regime in the deep lithosphere in the Late Triassic. The 205 Ma Taiyanghe Pluton was emplaced simultaneously with a rapid uplift of the lithosphere, when surface deposits changed from deep-water turbidite to tidal flat sediments. It was therefore generated during decompression, probably related to the rapid removal of the overthickened lithospheric mantle. The Triassic magmatism in the eastern SGFB is therefore important for probing geodynamic processes in the deep lithosphere. © 2010 Elsevier B.V. All rights reserved.en_HK
dc.languageengen_US
dc.publisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/epslen_HK
dc.relation.ispartofEarth and Planetary Science Lettersen_HK
dc.subjectadakiteen_HK
dc.subjectconvective thinningen_HK
dc.subjectlithospheric flexureen_HK
dc.subjectlow-degree partial meltingen_HK
dc.subjectshoshoniteen_HK
dc.subjectSongpan Ganzi Fold Belten_HK
dc.titleTriassic granitoids in the eastern Songpan Ganzi Fold Belt, SW China: Magmatic response to geodynamics of the deep lithosphereen_HK
dc.typeArticleen_HK
dc.identifier.emailZhou, MF:mfzhou@hkucc.hku.hken_HK
dc.identifier.emailSun, M:minsun@hku.hken_HK
dc.identifier.authorityZhou, MF=rp00844en_HK
dc.identifier.authoritySun, M=rp00780en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1016/j.epsl.2010.01.005en_HK
dc.identifier.scopuseid_2-s2.0-75149175956en_HK
dc.identifier.hkuros177736en_US
dc.identifier.hkuros177745-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-75149175956&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume290en_HK
dc.identifier.issue3-4en_HK
dc.identifier.spage481en_HK
dc.identifier.epage492en_HK
dc.identifier.isiWOS:000275306200023-
dc.publisher.placeNetherlandsen_HK
dc.identifier.scopusauthoridYuan, C=35241599200en_HK
dc.identifier.scopusauthoridZhou, MF=7403506005en_HK
dc.identifier.scopusauthoridSun, M=25932315800en_HK
dc.identifier.scopusauthoridZhao, Y=49061635000en_HK
dc.identifier.scopusauthoridWilde, S=35254758600en_HK
dc.identifier.scopusauthoridLong, X=14012199100en_HK
dc.identifier.scopusauthoridYan, D=36683417500en_HK
dc.identifier.citeulike6611161-

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