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Article: Geochemistry and petrogenesis of Laojungou and Mengtonggou granites in western Sichuan, China: Constraints on the nature of Songpan-Ganzi basement

TitleGeochemistry and petrogenesis of Laojungou and Mengtonggou granites in western Sichuan, China: Constraints on the nature of Songpan-Ganzi basement
Authors
KeywordsGranites
Nature Of The Basement
Nd Model Ages
Part-Melting Of The Lower Crust
Songpan-Ganzi Terrane
Source Composition
Underplating
Issue Date2007
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, 2007, v. 23 n. 5, p. 995-1006 How to Cite?
AbstractThe Mesozoic Laojungou and Mengtonggou granitic plutons in the eastern part of the Songpan-Ganzi terrane represent products of a major orogenic granitic magmatism and contain important information about the nature of the basement. These granites are intermediate- to high-K calc-alkaline, with intermediate to high SiO 2 (63.9-75.0 wt%) and metaluminous to mildly peraluminous characteristics (ACNK =0.86-1.08). Rocks of the Laojungou pluton contain high Al 2O 3 (14.2-16.0wt%) and K 2O(2.88-4.36 wt%)but low MgO (0.38-1.98wt%). The Laojungou pluton has relatively high Sr (307-697 ppm) and low Y (12.2-21.0 ppm) with fractionated REE ((La/ Yb) N > 10) and relatively high Sr/Y ratios (22-55), and resembles adakitic crustal melts. The Mengtonggou pluton is quite similar to the Laojungou pluton in most major and trace element characteristics, except for its relatively low Sr (110-397 ppm), high Y (12.2-21.0 ppm) and strikingly low Sr/Y ratios (5-32). The two plutons all exhibit crustal Nd-Sr isotope compositions (s Nd (T) = -6.02 - -3.11; I Sr = 0.7053-0.7075), indicating that these granites were not mantle-derived, but most likely resulted from partial melting of lower crustal materials in the garnet stability field. The high Rb (106-202 ppm), Cs (3.79-25.6 ppm) contents and intermediate to high K O/Na 2 O ratios (0.56-1.12) of both plutons are consistent with their generation from dehydration of biotite. The relatively high temperature for biotite dehydration precludes shear-heating as the cause for the genesis of these plutons, and requires an underplating or intraplating scheme of mantle-derived magma to fuse the crustal materials. The two plutons possess similar, Mid-proterozoic T DM ages (T DM(II) = 1.23-1.44 Ga), which together with their geochemical compositions, indicate that the Songpan-Ganzi terrane is underlain with the Yangzi-type basement.
Persistent Identifierhttp://hdl.handle.net/10722/151226
ISSN
2015 Impact Factor: 1.234
2015 SCImago Journal Rankings: 0.892
References

 

DC FieldValueLanguage
dc.contributor.authorZhao, YJen_US
dc.contributor.authorYuan, Cen_US
dc.contributor.authorZhou, MFen_US
dc.contributor.authorYan, DPen_US
dc.contributor.authorLong, XPen_US
dc.contributor.authorLi, JLen_US
dc.date.accessioned2012-06-26T06:18:59Z-
dc.date.available2012-06-26T06:18:59Z-
dc.date.issued2007en_US
dc.identifier.citationActa Petrologica Sinica, 2007, v. 23 n. 5, p. 995-1006en_US
dc.identifier.issn1000-0569en_US
dc.identifier.urihttp://hdl.handle.net/10722/151226-
dc.description.abstractThe Mesozoic Laojungou and Mengtonggou granitic plutons in the eastern part of the Songpan-Ganzi terrane represent products of a major orogenic granitic magmatism and contain important information about the nature of the basement. These granites are intermediate- to high-K calc-alkaline, with intermediate to high SiO 2 (63.9-75.0 wt%) and metaluminous to mildly peraluminous characteristics (ACNK =0.86-1.08). Rocks of the Laojungou pluton contain high Al 2O 3 (14.2-16.0wt%) and K 2O(2.88-4.36 wt%)but low MgO (0.38-1.98wt%). The Laojungou pluton has relatively high Sr (307-697 ppm) and low Y (12.2-21.0 ppm) with fractionated REE ((La/ Yb) N > 10) and relatively high Sr/Y ratios (22-55), and resembles adakitic crustal melts. The Mengtonggou pluton is quite similar to the Laojungou pluton in most major and trace element characteristics, except for its relatively low Sr (110-397 ppm), high Y (12.2-21.0 ppm) and strikingly low Sr/Y ratios (5-32). The two plutons all exhibit crustal Nd-Sr isotope compositions (s Nd (T) = -6.02 - -3.11; I Sr = 0.7053-0.7075), indicating that these granites were not mantle-derived, but most likely resulted from partial melting of lower crustal materials in the garnet stability field. The high Rb (106-202 ppm), Cs (3.79-25.6 ppm) contents and intermediate to high K O/Na 2 O ratios (0.56-1.12) of both plutons are consistent with their generation from dehydration of biotite. The relatively high temperature for biotite dehydration precludes shear-heating as the cause for the genesis of these plutons, and requires an underplating or intraplating scheme of mantle-derived magma to fuse the crustal materials. The two plutons possess similar, Mid-proterozoic T DM ages (T DM(II) = 1.23-1.44 Ga), which together with their geochemical compositions, indicate that the Songpan-Ganzi terrane is underlain with the Yangzi-type basement.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.subjectGranitesen_US
dc.subjectNature Of The Basementen_US
dc.subjectNd Model Agesen_US
dc.subjectPart-Melting Of The Lower Crusten_US
dc.subjectSongpan-Ganzi Terraneen_US
dc.subjectSource Compositionen_US
dc.subjectUnderplatingen_US
dc.titleGeochemistry and petrogenesis of Laojungou and Mengtonggou granites in western Sichuan, China: Constraints on the nature of Songpan-Ganzi basementen_US
dc.typeArticleen_US
dc.identifier.emailYuan, C: yuanchao@HKUCC-COM.hku.hken_US
dc.identifier.emailZhou, MF: mfzhou@hkucc.hku.hk-
dc.identifier.emailYan, D: yandanping_99@yahoo.com-
dc.identifier.emailLong, X: longxp@gig.ac.cn-
dc.identifier.authorityZhou, MF=rp00844en_US
dc.identifier.authorityZhou, MF=rp00844-
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.scopuseid_2-s2.0-35948938473en_US
dc.identifier.hkuros144269-
dc.identifier.hkuros167295-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-35948938473&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume23en_US
dc.identifier.issue5en_US
dc.identifier.spage995en_US
dc.identifier.epage1006en_US
dc.publisher.placeChinaen_US
dc.identifier.scopusauthoridZhao, YJ=14013151400en_US
dc.identifier.scopusauthoridYuan, C=35241599200en_US
dc.identifier.scopusauthoridZhou, MF=7403506005en_US
dc.identifier.scopusauthoridYan, DP=36683417500en_US
dc.identifier.scopusauthoridLong, XP=14012199100en_US
dc.identifier.scopusauthoridLi, JL=26643194200en_US

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