Post-collisional potassic magmatism in the eastern Lhasa terrane, South Tibet: Products of partial melting of melanges in a continental subduction channel

doi:10.1016/j.gr.2015.11.007

CORC > 地质与地球物理研究所 > 中国科学院地质与地球物理研究所 > 中国科学院新生代地质与环境重点实验室

	Post-collisional potassic magmatism in the eastern Lhasa terrane, South Tibet: Products of partial melting of melanges in a continental subduction channel
	Zhang, Lihong 1,2; Guo, Zhengfu 1; Zhang, Maoliang 1,2; Cheng, Zhihui 1,2; Sun, Yutao 1,2
刊名	GONDWANA RESEARCH
	2017
卷号	41 页码:9-28
关键词	Post-collisional Potassic Magmatism Zircon U-pb Dating Assimilation And Fractional Crystallization (Afc) Indian Melanges South Tibet
ISSN号	1342-937X
DOI	10.1016/j.gr.2015.11.007
文献子类	Article
英文摘要	Post-collisional, potassic magmatic rocks widely distributed in the eastern Lhasa terrane provide significant information for comprehensive understanding of geodynamic processes of northward subduction of the Indian lithosphere and uplift of the Tibetan Plateau. A combined dataset of whole-rock major and trace elements, Sr-Nd-Pb isotopes, and in situ zircon U-Pb dating and Hf-O isotopic analyses are presented for the Yangying potassic volcanic rocks (YPVR) in the eastern part of the Lhasa terrane, South Tibet. These volcanic rocks consist of trachytes, which are characterized by high K2O (5.46-9.30 wt.%), SiO2 (61.34-68.62 wt.%) and Al2O3 (15.06-17.36 wt.%), and relatively low MgO (0.47-2.80 wt.%) and FeOt (1.70-4.90 wt.%). Chondrite-normalized rare earth elements (REE) patterns display clearly negative Eu anomalies. Primitive mantle-normalized incompatible trace elements diagrams exhibit strong enrichment in large ion lithophile elements (LILE) relative to high field strength elements (HFSE) and display significantly negative Nb-Ta-Ti anomalies. Initial isotopic compositions indicate relatively radiogenic Sr [(Sr-87/Sr-86)(i) = 0.711978-0.712090)] and unradiogenic Nd [(Nd-143/Nd-144)(i) = 0.512121-0.512148]. Combined with their Pb isotopic compositions [(Pb-206/Pb-204)(i) = 18.615-18.774, (Pb-207/Pb-204)(i) = 15.708-15.793, (Pb-208/Pb-204)(i) = 39.274-39.355)], these data are consistent with the involvement of component from subducted continental crustal sediment in their source region. The whole-rock Sr-Nd-Pb isotopic compositions exhibit linear trends between enriched mantle-derivedmafic ultrapotassicmagmas and relatively depleted crustal contaminants from the Lhasa terrane. The enrichment of the upper mantle below South Tibet is considered to result from the addition of components derived from subducted Indian continental crust to depleted MORB-source mantle during northward underthrusting of the Indian continental lithosphere beneath the Lhasa terrane since India-Asia collision at similar to 55 Ma. Secondary Ion Mass Spectrometry (SIMS) U-Pb zircon analyses yield the eruptive ages of 10.61 +/- 0.10 Ma and 10.70 +/- 0.18 Ma (weighted mean ages). Zircon Hf isotope compositions [epsilon(Hf)(t) = -4.79 to -0.17], combined with zircon O isotope ratios (5.51-7.22 parts per thousand), imply an addition of crustal material in their petrogenesis. Clinopyroxene-liquid thermobarometer reveals pressure (2.5-4.1 kbar) and temperature (1029.4-1082.9 degrees C) of clinopyroxene crystallization, suggesting that depth of the magma chamber was 11.6-16.4 km. Energy-constrained assimilation and fractional crystallization (EC-AFC) model calculation indicates depth of assimilation and fractional crystallization in the region of 14.40-18.75 km underneath the Lhasa terrane, which is in consistent with depth of the magma chamber as suggested by clinopyroxene-liquid thermobarometer. Based on the whole-rock major and trace elements and Sr-Nd-Pb isotope compositions, combined with EC-AFC modeling simulations and zircon Hf-O isotope data, we propose that the YPVR resulted from assimilation and fractional crystallization (AFC) process of the K-rich mafic primitive magmas, which were caused by partial melting of the Indian continental subduction-induced melange rocks. (C) 2015 International Association for Gondwana Research. Published by Elsevier B.V.
WOS关键词	ZIRCON U-PB ; INDIA-ASIA COLLISION ; MIOCENE ULTRAPOTASSIC ROCKS ; NORTH CHINA CRATON ; LINZIZONG VOLCANIC SUCCESSIONS ; ND ISOTOPIC CONSTRAINTS ; THICKENED LOWER CRUST ; RICH MAFIC MAGMATISM ; SLAB BREAK-OFF ; GEOCHEMICAL CONSTRAINTS
WOS研究方向	Geology
语种	英语
出版者	ELSEVIER SCIENCE BV
WOS记录号	WOS:000397873300002
资助机构	Chinese Academy of Sciences(XDB03010600) ; Chinese Academy of Sciences(XDB03010600) ; Chinese Academy of Sciences(XDB03010600) ; Chinese Academy of Sciences(XDB03010600)
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/53007]
专题	地质与地球物理研究所_中国科学院新生代地质与环境重点实验室
通讯作者	Guo, Zhengfu
作者单位	1.Chinese Acad Sci, Inst Geol & Geophys, Key Lab Cenozo Geol & Environm, Beijing 100029, Peoples R China 2.Univ Chinese Acad Sci, Beijing 100049, Peoples R China
推荐引用方式 GB/T 7714	Zhang, Lihong,Guo, Zhengfu,Zhang, Maoliang,et al. Post-collisional potassic magmatism in the eastern Lhasa terrane, South Tibet: Products of partial melting of melanges in a continental subduction channel[J]. GONDWANA RESEARCH,2017,41:9-28.
APA	Zhang, Lihong,Guo, Zhengfu,Zhang, Maoliang,Cheng, Zhihui,&Sun, Yutao.(2017).Post-collisional potassic magmatism in the eastern Lhasa terrane, South Tibet: Products of partial melting of melanges in a continental subduction channel.GONDWANA RESEARCH,41,9-28.
MLA	Zhang, Lihong,et al."Post-collisional potassic magmatism in the eastern Lhasa terrane, South Tibet: Products of partial melting of melanges in a continental subduction channel".GONDWANA RESEARCH 41(2017):9-28.