Tracing magma mixing and crystal-melt segregation in the genesis of syenite with mafic enclaves: Evidence from in situ zircon Hf-O and apatite Sr-Nd isotopes

doi:10.1016/j.lithos.2019.03.011

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	Tracing magma mixing and crystal-melt segregation in the genesis of syenite with mafic enclaves: Evidence from in situ zircon Hf-O and apatite Sr-Nd isotopes
	Sun, Jin-Feng 1; Zhang, Ji-Heng 1; Yang, Jin-Hui 2; Yang, Yue-Heng 2; Chen, Shi 1
刊名	LITHOS
	2019-06-01
卷号	334 页码:42-57
关键词	Syenite Mafic enclave High-silica porphyritic K-feldspar granite In situ isotopic analysis Magma mixing Crystal-melt segregation
ISSN号	0024-4937
DOI	10.1016/j.lithos.2019.03.011
英文摘要	Alkaline rocks contain essential information on post-collisional/intraplate extensional magmatic processes within the continental lithosphere. The Erhulai syenitic pluton in the Liaodong Peninsula, North China Craton, consists of quartz syenite, mafic enclaves, and porphyritic K-feldspar granite. Field observations and zircon U-Pb dating reveal that the quartz syenite and the hosted mafic enclaves were coeval (with identical emplacement ages of 129-126 Ma), and slightly older than the porphyritic K-feldspar granite (ca. 123 Ma). The mafic enclaves have relatively low SiO2 and high MgO contents (up to 3.0%), and lack Ba or Eu anomalies. Whole-rock analyses of the mafic enclaves and accessory minerals in the enclaves show relatively low initial Sr-87/Sr-86 ratios (0.7056 to 0.7078) and variable epsilon(Nd)(t) ( -11.2 to -2.0) and epsilon(Hf)(t) ( -15.8 to -5.5) values. Large proportion of zircons from the mafic enclaves possess mantle-like delta O-18 values. These geochemical features suggest an enriched mantle source, with the addition of crustal material. The quartz syenites have relatively high SiO2 and low CaO and MgO contents, as well as significantly positive K, Ba, and Eu anomalies. All the quartz syenites show variable (Sr-87/(86))(i) ratios (0.7073 to 0.7081) and epsilon(Nd)(t) values ( -10.4 to -8.6) for the whole-rocks and apatites, epsilon(Hf)(t) values of -12.4 to -3.6 for the zircons, and zircon delta O-18 values of +4.4%0 to +7.0%. (mainly greater than +5.3%.). All these features can be isotopically produced by the partial melting of ancient crustal material, with the involvement of mantle-derived magma. Crystal fractionation process, such as K-feldspar crystallization and accumulation, played an important role in the formation of the quartz syenite. The porphyritic K-feldspar granites possess relatively evolved geochemical compositions with high silica contents (SiO2 > 69 wt%) and remarkable negative Ba and Eu anomalies, which are chemically complementary to the quartz syenite. A crystal mush model was employed to establish the genetic link between the porphyritic K-feldspar granite and the quartz syenite, with the granite representing the interstitial melt extracted from the crystal mush and the quartz syenite representing the residual accumulation of crystals. The variable isotopic compositions of the quartz syenite and the porphyritic granite were mainly the result of extensive interaction of isotopes between mantle- and crust-derived magmas during magma mixing. In situ analyses of the Sr, Nd, Hf, and O isotopes of accessory minerals, coupled with field observations and whole-rock geochemical data for the Erhulai syenitic pluton, indicate a complex multi-stage magmatic process involving magma mixing, crystal-melt segregation, and wall-rock assimilation. Our study also shows that in situ isotopic analyses of accessory minerals provide unique information on, and are powerful geochemical tracers of, mantle-crust interactions and magmatic processes. (C) 2019 Elsevier B.V. All rights reserved.
资助项目	Ministry of Science and Technology of the People's Republic of China[2016YFC0600109] ; National Natural Science Foundation of China[41202046]
WOS关键词	NORTH CHINA CRATON ; LACHLAN FOLD BELT ; A-TYPE GRANITE ; U-PB ; TECTONIC EVOLUTION ; CONTINENTAL-CRUST ; ALKALINE COMPLEX ; RHYOLITE SUITE ; VOLCANIC-ROCKS ; HYBRID MAGMA
WOS研究方向	Geochemistry & Geophysics ; Mineralogy
语种	英语
出版者	ELSEVIER SCIENCE BV
WOS记录号	WOS:000468720900004
资助机构	Ministry of Science and Technology of the People's Republic of China ; Ministry of Science and Technology of the People's Republic of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; Ministry of Science and Technology of the People's Republic of China ; Ministry of Science and Technology of the People's Republic of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; Ministry of Science and Technology of the People's Republic of China ; Ministry of Science and Technology of the People's Republic of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; Ministry of Science and Technology of the People's Republic of China ; Ministry of Science and Technology of the People's Republic of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/92127]
专题	地质与地球物理研究所_岩石圈演化国家重点实验室
通讯作者	Sun, Jin-Feng
作者单位	1.Univ Chinese Acad Sci, Key Lab Computat Geodynam, 19A Yuquanlu, Beijing 100049, Peoples R China 2.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, POB 9825, Beijing 100029, Peoples R China
推荐引用方式 GB/T 7714	Sun, Jin-Feng,Zhang, Ji-Heng,Yang, Jin-Hui,et al. Tracing magma mixing and crystal-melt segregation in the genesis of syenite with mafic enclaves: Evidence from in situ zircon Hf-O and apatite Sr-Nd isotopes[J]. LITHOS,2019,334:42-57.
APA	Sun, Jin-Feng,Zhang, Ji-Heng,Yang, Jin-Hui,Yang, Yue-Heng,&Chen, Shi.(2019).Tracing magma mixing and crystal-melt segregation in the genesis of syenite with mafic enclaves: Evidence from in situ zircon Hf-O and apatite Sr-Nd isotopes.LITHOS,334,42-57.
MLA	Sun, Jin-Feng,et al."Tracing magma mixing and crystal-melt segregation in the genesis of syenite with mafic enclaves: Evidence from in situ zircon Hf-O and apatite Sr-Nd isotopes".LITHOS 334(2019):42-57.