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Underplating generated A- and I-type granitoids of the East Junggar from the lower and the upper oceanic crust with mixing of mafic magma: Insights from integrated zircon U-Pb ages, petrography, geochemistry and Nd-Sr-Hf isotopes

文献类型：期刊论文

作者Liu, Wei1; Liu, Xiu-Jin1,2; Liu, Li-Juan1
刊名LITHOS
出版日期2013-10-01
卷号179页码:293-319
关键词A-type Granite I-type Granitoid East Junggar Oceanic Crust Magma Mixing Underplating
DOI10.1016/j.lithos.2013.08.009
文献子类Article
英文摘要Whole rock major and trace element, Nd-Sr and zircon Hf isotopic compositions and secondary-ion mass spectrometry zircon U-Pb ages of eleven granitoid intrusions and dioritic rocks from the East Junggar (NW China) were analyzed in this study. The East Junggar granitoids were emplaced during terminal Early to Late Carboniferous (325-301 Ma) following volcanic eruption of the Batamayi Formation. Zircons from the East Junggar granitoids yielded 210 concordant Pb-206/U-238 ages which are all younger than 334 Ma and exhibit epsilon(Hf)(t) values distinctly higher than Devonian arc volcanic-rocks. Seismic P-wave velocities of deep crust of the East Junggar proper resemble those of oceanic crust (OC). These characteristics suggest absence of volcanic rock and volcano-sedimentary rock of Devonian and Early Carboniferous from the source region. The East Junggar granitoids show epsilon(Nd)(t) and initial Sr-87/Sr-86 values substantially overlapping those of the Armantai ophiolite in the area. The Early Paleozoic OC with seamount-like composition as the Zhaheba-Armantai ophiolites remained in the lower crust and formed main source rock of the East Junggar granitoids. Based on petrography and geochemistry, the East Junggar granitoids are classified into peralkaline A-type in the northern subarea, I-type (I-1 and I-2 sub-groups) mainly in the north and A-type in the south of the southern subarea. The perthitic or argillated core and oligoclasic rim with an argillated boundary of feldspar phenocrysts and inclusion of perthites or its over-growth by matrix plagioclase, in the monzogranites (northern subarea), suggest mixing of peralkaline granitic magma with mafic magma. In the north of the southern subarea, the presence of magmatic microdioritic enclaves (MMEs) in the I-1 subgroup granitoids, transfer of plagioclase phenocrysts and hornblendes between host granodiorite and the MME across the boundary and a prominent resorption surface in the plagioclase phenoctysts indicate mixing of crustal magma (I-2 subgroup granitoids) with mafic magma. Magma mixing shifted (Sr-87/Sr-86)(i) of the I-1 subgroup granitoids towards the mantle array. Two generations of hornblende with zonal distribution and similar mineral and geochemical compositions of quartz monzodiorite and hosted MME with unfractionated rare earth elements (REE) suggest extended magma mixing with onset probably at or near source region. These observations imply concurrency of mantle input and the crustal melting and, hence, a causal relationship between underplating/intraplating and the lower OC/upper OC melting. The I-type granitoids experienced plagioclase and hornblende fractionations, whereas fractionated phases of the two groups of A-type granites were alkali feldspar and albite-oligoclase with significant involvement of F--rich fluid. Granodioritic parent magmas of the I-2 subgroup granitoids stemmed from the hydrous upper OC. Parent magmas of the two A-type groups possess syenogranitic or quartz syenitic compositions. The peralkaline A-type granites stemmed from the lower OC, whereas the A-type granites from dehydrated upper OC left behind after extensive partial melting and extraction of I-type granitoids.
WOS关键词A-TYPE GRANITES ; CARBONIFEROUS VOLCANIC-ROCKS ; CONTINENTAL GROWTH ; NW CHINA ; SUBDUCTION-ACCRETION ; MELTING EXPERIMENTS ; SEDIMENTARY SYSTEM ; RIDGE SUBDUCTION ; DEPLETED-MANTLE ; NATURAL SYSTEMS
WOS研究方向Geochemistry & Geophysics ; Mineralogy
语种英语
WOS记录号WOS:000328592900019
资助机构Natural Science Foundation of China(41273019 ; Natural Science Foundation of China(41273019 ; Chinese State 973 Program(2007CB411302) ; Chinese State 973 Program(2007CB411302) ; Chinese Academy of Sciences(KZCX2-YW-JS109) ; Chinese Academy of Sciences(KZCX2-YW-JS109) ; 40972053 ; 40972053 ; 41230207) ; 41230207) ; Natural Science Foundation of China(41273019 ; Natural Science Foundation of China(41273019 ; Chinese State 973 Program(2007CB411302) ; Chinese State 973 Program(2007CB411302) ; Chinese Academy of Sciences(KZCX2-YW-JS109) ; Chinese Academy of Sciences(KZCX2-YW-JS109) ; 40972053 ; 40972053 ; 41230207) ; 41230207)
源URL[http://ir.iggcas.ac.cn/handle/132A11/62645]  
专题地质与地球物理研究所_中国科学院矿产资源研究重点实验室
作者单位1.Chinese Acad Sci, Inst Geol & Geophys, Key Lab Mineral Resources, Beijing 100029, Peoples R China
2.Grad Univ Chinese Acad Sci, Beijing 100049, Peoples R China
推荐引用方式
GB/T 7714		 Liu, Wei,Liu, Xiu-Jin,Liu, Li-Juan. Underplating generated A- and I-type granitoids of the East Junggar from the lower and the upper oceanic crust with mixing of mafic magma: Insights from integrated zircon U-Pb ages, petrography, geochemistry and Nd-Sr-Hf isotopes[J]. LITHOS,2013,179:293-319.
APA Liu, Wei,Liu, Xiu-Jin,&Liu, Li-Juan.(2013).Underplating generated A- and I-type granitoids of the East Junggar from the lower and the upper oceanic crust with mixing of mafic magma: Insights from integrated zircon U-Pb ages, petrography, geochemistry and Nd-Sr-Hf isotopes.LITHOS,179,293-319.
MLA Liu, Wei,et al."Underplating generated A- and I-type granitoids of the East Junggar from the lower and the upper oceanic crust with mixing of mafic magma: Insights from integrated zircon U-Pb ages, petrography, geochemistry and Nd-Sr-Hf isotopes".LITHOS 179(2013):293-319.

入库方式： OAI收割

来源：地质与地球物理研究所

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