Composition of the Tarim mantle plume: Constraints from clinopyroxene antecrysts in the early Permian Xiaohaizi dykes, NW China

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	Composition of the Tarim mantle plume: Constraints from clinopyroxene antecrysts in the early Permian Xiaohaizi dykes, NW China
	Wei, Xun 1,2; Xu, Yi-Gang 1; Luo, Zhen-Yu 1; Zhao, Jian-Xin 3; Feng, Yue-Xing 3
刊名	LITHOS
	2015-08-01
卷号	230 期号:2015 页码:69-81
关键词	Clinopyroxene macrocryst Xiaohaizi dyke Antecryst Tarim large igneous province Assimilation and fractional crystallization
英文摘要	Numerous alkaline basaltic dykes crosscut the Early Permian Xiaohaizi wehrlite in drill-cores and syenite intrusion in the Tarim large igneous province, NW China. One basaltic dyke contains abundant clinopyroxene macrocrysts with strong resorption textures. Such a textural disequilibrium is consistent with their contrasting chemistry between the macrocrysts (Mg# = 80-89) and the host dyke (Mg# = 39, corresponding to Mg# = 73 of clinopyroxene in equilibrium with the dyke), indicating that they are not phenocrysts. The clinopyroxene macrocrysts are characterized by low TiO2 (026-1.09 wt.%), Al2O3 (1.15-3.10 wt.%) and Na2O (0.16-0.37 wt.%), unlike those in mantle peridotites but resembling those in layered mafic intrusions in the same area. The clinopyroxene macrocrysts and the clinopyroxenes from the Xiaohaizi cumulate wehrlites define a coherent compositional trend and have identical trace element patterns, pointing to a comagmatic origin for these crystals. Accordingly, the macrocrysts cannot be xenoaysts foreign to the magmatic system. Rather they are antecrysts that crystallized from progenitor magmas and have been reincorporated into the host dyke before intrusion. The Sr-87/Sr-86(i) (0.7035-0.7037) and epsilon Nd-i (4.5-4.8) of the clinopyroxene macrocrysts with high Mg# (80-89) are apparently lower and higher than their respective ratios of the clinopyroxenes in the wehrlites (Mg# = 75-84, Sr-87/Sr-86(i) = 0.7038-0.7041, epsilon Nd-i = 1.0-1.9). This difference in isotopes can be accounted for by assimilation and fractional crystallization (AFC) process operated during the formation of the Xiaohaizi intrusion. In this sense, the clinopyroxene macrocrysts record the composition of the uncontaminated Tarim plume-derived melts. (C) 2015 Elsevier B.V. All rights reserved.
收录类别	SCI
语种	英语
WOS记录号	WOS:000357839000005
内容类型	期刊论文
源URL	[http://ir.qdio.ac.cn/handle/337002/49206]
专题	海洋研究所_海洋地质与环境重点实验室
作者单位	1.Chinese Acad Sci, Guangzhou Inst Geochem, State Key Lab Isotope Geochem, Guangzhou 510640, Guangdong, Peoples R China 2.Chinese Acad Sci, Inst Oceanol, Key Lab Marine Geol & Environm, Qingdao 266071, Peoples R China 3.Univ Queensland, Sch Earth Sci, Radiogenic Isotope Facil, Brisbane, Qld 4072, Australia
推荐引用方式 GB/T 7714	Wei, Xun,Xu, Yi-Gang,Luo, Zhen-Yu,et al. Composition of the Tarim mantle plume: Constraints from clinopyroxene antecrysts in the early Permian Xiaohaizi dykes, NW China[J]. LITHOS,2015,230(2015):69-81.
APA	Wei, Xun,Xu, Yi-Gang,Luo, Zhen-Yu,Zhao, Jian-Xin,&Feng, Yue-Xing.(2015).Composition of the Tarim mantle plume: Constraints from clinopyroxene antecrysts in the early Permian Xiaohaizi dykes, NW China.LITHOS,230(2015),69-81.
MLA	Wei, Xun,et al."Composition of the Tarim mantle plume: Constraints from clinopyroxene antecrysts in the early Permian Xiaohaizi dykes, NW China".LITHOS 230.2015(2015):69-81.