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Partial melting of lower crust at 10-15 kbar: constraints on adakite and TTG formation

文献类型：期刊论文

作者Qian, Qing1,2; Hermann, Joerg2
刊名CONTRIBUTIONS TO MINERALOGY AND PETROLOGY
出版日期2013-06-01
卷号165期号:6页码:1195-1224
关键词Partial melting experiment Lower continental crust Adakite TTG Trace element
ISSN号0010-7999
DOI10.1007/s00410-013-0854-9
文献子类Article
英文摘要The pressure-temperature (P-T) conditions for producing adakite/tonalite-trondhjemite-granodiorite (TTG) magmas from lower crust compositions are still open to debate. We have carried out partial melting experiments of mafic lower crust in the piston-cylinder apparatus at 10-15 kbar and 800-1,050 A degrees C to investigate the major and trace elements of melts and residual minerals and further constrain the P-T range appropriate for adakite/TTG formation. The experimental residues include the following: amphibolite (plagioclase + amphibole +/- A garnet) at 10-15 kbar and 800 A degrees C, garnet granulite (plagioclase + amphibole + garnet + clinopyroxene + orthopyroxene) at 12.5 kbar and 900 A degrees C, two-pyroxene granulite (plagioclase + clinopyroxene + orthopyroxene +/- A amphibole) at 10 kbar and 900 A degrees C and 10-12.5 kbar and 1,000 A degrees C, garnet pyroxenite (garnet + clinopyroxene +/- A amphibole) at 13.5-15 kbar and 900-1,000 A degrees C, and pyroxenite (clinopyroxene + orthopyroxene) at 15 kbar and 1,050 A degrees C. The partial melts change from granodiorite to tonalite with increasing melt proportions. Sr enrichment occurs in partial melts in equilibrium with < 20 wt% plagioclase, whereas depletions of Ti, Sr, and heavy rare earth elements (HREE) occur relative to the starting material when the amounts of residual amphibole, plagioclase, and garnet are > 20 wt%, respectively. Major elements and trace element patterns of partial melts produced by 10-40 wt% melting of lower crust composition at 10-12.5 kbar and 800-900 A degrees C and 15 kbar and 800 A degrees C closely resemble adakite/TTG rocks. TiO2 contents of the 1,000-1,050 A degrees C melts are higher than that of pristine adakite/TTG. In comparison with natural adakite/TTG, partial melts produced at 10-12.5 kbar and 1,000 A degrees C and 15 kbar and 1,050 A degrees C have elevated HREE, whereas partial melts at 13.5-15 kbar and 900-1,000 A degrees C in equilibrium with > 20 wt% garnet have depressed Yb and elevated La/Yb and Gd/Yb. It is suggested that the most appropriate P-T conditions for producing adakite/TTG from mafic lower crust are 800-950 A degrees C and 10-12.5 kbar (corresponding to a depth of 30-40 km), whereas a depth of > 45-50 km is unfavorable. Consequently, an overthickened crust and eclogite residue are not necessarily required for producing adakite/TTG from lower crust. The lower crust delamination model, which has been embraced for intra-continental adakite/TTG formation, should be reappraised.
WOS关键词NORTH-CHINA-CRATON ; LOWER CONTINENTAL-CRUST ; RARE-EARTH-ELEMENTS ; HIGH-FIELD-STRENGTH ; ARCHEAN TECTONOMAGMATIC PROCESSES ; TRONDHJEMITE-GRANODIORITE TTG ; UNDERPLATED BASALTIC CRUST ; SUBDUCTING OCEANIC-CRUST ; THICKENED LOWER CRUST ; LOW-K THOLEIITE
WOS研究方向Geochemistry & Geophysics ; Mineralogy
语种英语
WOS记录号WOS:000319009600009
出版者SPRINGER
资助机构Australian Research Council ; Australian Research Council ; National Natural Science Foundation of China(41172065 ; National Natural Science Foundation of China(41172065 ; Chinese Academy of Sciences(XDB03010201) ; Chinese Academy of Sciences(XDB03010201) ; 90914008 ; 90914008 ; 41023009 ; 41023009 ; 40872057) ; 40872057) ; Australian Research Council ; Australian Research Council ; National Natural Science Foundation of China(41172065 ; National Natural Science Foundation of China(41172065 ; Chinese Academy of Sciences(XDB03010201) ; Chinese Academy of Sciences(XDB03010201) ; 90914008 ; 90914008 ; 41023009 ; 41023009 ; 40872057) ; 40872057) ; Australian Research Council ; Australian Research Council ; National Natural Science Foundation of China(41172065 ; National Natural Science Foundation of China(41172065 ; Chinese Academy of Sciences(XDB03010201) ; Chinese Academy of Sciences(XDB03010201) ; 90914008 ; 90914008 ; 41023009 ; 41023009 ; 40872057) ; 40872057) ; Australian Research Council ; Australian Research Council ; National Natural Science Foundation of China(41172065 ; National Natural Science Foundation of China(41172065 ; Chinese Academy of Sciences(XDB03010201) ; Chinese Academy of Sciences(XDB03010201) ; 90914008 ; 90914008 ; 41023009 ; 41023009 ; 40872057) ; 40872057)
源URL[http://ir.iggcas.ac.cn/handle/132A11/87198]  
专题中国科学院地质与地球物理研究所
通讯作者Qian, Qing
作者单位1.Chinese Acad Sci, Inst Geol & Geophys, Key Lab Mineral Resources, Beijing 100029, Peoples R China
2.Australian Natl Univ, Res Sch Earth Sci, Canberra, ACT 0200, Australia
推荐引用方式
GB/T 7714		 Qian, Qing,Hermann, Joerg. Partial melting of lower crust at 10-15 kbar: constraints on adakite and TTG formation[J]. CONTRIBUTIONS TO MINERALOGY AND PETROLOGY,2013,165(6):1195-1224.
APA Qian, Qing,&Hermann, Joerg.(2013).Partial melting of lower crust at 10-15 kbar: constraints on adakite and TTG formation.CONTRIBUTIONS TO MINERALOGY AND PETROLOGY,165(6),1195-1224.
MLA Qian, Qing,et al."Partial melting of lower crust at 10-15 kbar: constraints on adakite and TTG formation".CONTRIBUTIONS TO MINERALOGY AND PETROLOGY 165.6(2013):1195-1224.

入库方式： OAI收割

来源：地质与地球物理研究所

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