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Monazite record of assimilation and differentiation processes in the petrogenesis of Himalayan leucogranites

文献类型：期刊论文

作者Liu, Zhi-Chao1; Wu, Fu-Yuan2; Ji, Wei-Qiang2; Liu, Xiao-Chi2; Wang, Jian-Gang2
刊名CHEMICAL GEOLOGY
出版日期2023-11-20
卷号639页码:17
ISSN号0009-2541
关键词Himalayan leucogranite Monazite In-situ analyses Nd isotope Assimilation Fractional crystallization
DOI10.1016/j.chemgeo.2023.121700
英文摘要The Himalayan leucogranites have received particular attention as they record the continental crust-building processes of a collisional orogenic system. Deciphering the magmatic evolution processes and potential sour-ces is essential for understanding the origin of the Himalayan leucogranites. In-situ monazite Th-Pb ages, trace element geochemistry, and Nd isotope ratios have been determined with whole-rock geochemical data for the leucogranites and their country rocks in the Yadong area, southern Tibet. Monazites in most of the studied leucogranites are marked by multiple age populations with variable REE ratios and wide ranges of Nd isotope ratios, reflecting a complex history of magmatic processes. Abundant inherited monazites are identified in the Yadong leucogranites, and most of them are excluded from the source regions due to their distinguished Nd isotope compositions from the magmatic monazites. The inherited monazites share close affinities in geochro-nological dates and geochemical compositions with those in the country rocks, strongly suggesting a major origin of the country-rock contamination. This highlights the contamination-assimilation processes in the genesis of the Yadong leucogranites. It is worth noting that xenocrystal monazites from the metasedimentary country rock are less preserved in the leucogranites than those from the granitoid country rock, which probably reflects the different assimilation reactions for different types of country rock. Assimilation of the metapelitic rocks released low content of xenocrystic monazite and high volume of partial melt into the leucogranites, whereas assimilation of the granitoid rocks released high content of xenocrystic monazite. In addition to the contamination -assimilation processes, the uniform Nd isotope data with large variations in REE ratios for magmatic mona-zites in some leucogranite samples suggest a subsequent closed-system fractional crystallization process during the magma evolution. Besides, some magmatic monazites in the muscovite granites show a significant tetrad effect in the Chondrite-normalized REE patterns, indicating that the magma system has evolved into an aqueous fluid-available environment. This supports an important role of the magmatic differentiation process in the formation of the Yadong leucogranites. Taken together, a petrogenic model involving AFC (assimilation and fractional crystallization) processes is proposed, and the geochemical variations of the Yadong leucogranites are mainly attributed to the post-source processes. It is suggested that the rock geochemistry of the Himalayan leucogranites often dose not directly reflect the nature and the petrogenetic processes in the source regions.
WOS关键词ND-ISOTOPE DISEQUILIBRIUM ; CRUSTAL ANATEXIS ; LU-HF ; U-PB ; GEOCHEMICAL CONSTRAINTS ; FRACTIONATION PROCESSES ; ACCESSORY MINERALS ; TECTONIC EVOLUTION ; GRANITIC-ROCKS ; EASTERN NEPAL
资助项目NSF of China[41888101] ; NSF of China[42372088] ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP)[2019QZKK0802]
WOS研究方向Geochemistry & Geophysics
语种英语
出版者ELSEVIER
WOS记录号WOS:001095679600001
资助机构NSF of China ; NSF of China ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; NSF of China ; NSF of China ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; NSF of China ; NSF of China ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; NSF of China ; NSF of China ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP)
源URL[http://ir.iggcas.ac.cn/handle/132A11/110695]  
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Liu, Zhi-Chao
作者单位1.Sun Yat Sen Univ, Sch Earth Sci & Geol Engn, Guangzhou 510275, Peoples R China
2.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China
推荐引用方式
GB/T 7714		 Liu, Zhi-Chao,Wu, Fu-Yuan,Ji, Wei-Qiang,et al. Monazite record of assimilation and differentiation processes in the petrogenesis of Himalayan leucogranites[J]. CHEMICAL GEOLOGY,2023,639:17.
APA Liu, Zhi-Chao,Wu, Fu-Yuan,Ji, Wei-Qiang,Liu, Xiao-Chi,&Wang, Jian-Gang.(2023).Monazite record of assimilation and differentiation processes in the petrogenesis of Himalayan leucogranites.CHEMICAL GEOLOGY,639,17.
MLA Liu, Zhi-Chao,et al."Monazite record of assimilation and differentiation processes in the petrogenesis of Himalayan leucogranites".CHEMICAL GEOLOGY 639(2023):17.

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来源：地质与地球物理研究所

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