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Helium, neon and argon in alkaline basalt-related corundum megacrysts: Implications for their origin and forming process

文献类型：期刊论文

作者Guo, Wei1,2; He, Huaiyu1,2,5; Qiao, Lei3,4; Liu, Ziheng1,2; Su, Fei1,2; Li, Jiannan1,2; Shi, Guanghai4; Zhu, Rixiang1,2
刊名GEOCHIMICA ET COSMOCHIMICA ACTA
出版日期2022-04-01
卷号322页码:71-93
关键词Noble gases Corundum megacrysts Sapphires Continental alkaline basalts Eastern Asia and Australia
ISSN号0016-7037
DOI10.1016/j.gca.2022.01.016
英文摘要Corundum megacrysts from Cenozoic alkaline basaltic fields, notably in eastern Asia and Australia, are economically important but poorly understood in their genesis. Here we present new crushing noble gas (He, Ne and Ar) data of alkali basalt-related corundum and some other mineral megacrysts from several localities worldwide to better constrain their ultimate fluid (material) source and forming process. Markedly, the corundum megacrysts have widespread mid ocean ridge basalts (MORB)-like He-3/He-4 ratios (8 +/- 1 R-A, where R-A is atmospheric He-3/He-4 ratio of 1.39 x 10(-6)) in each locality, although lower than MORB (3) He/(4) He ratios also occur in some cases. The latter could be interpreted as the addition of ingrowth He-4 but not reflect the initially trapped compositions. The initially MORB-like (3) He/(4) He and high Ar-40/Ar-36 isotopic ratios, combined with major element and fluid inclusion data, support that the asthenosphere-derived melts/fluids are the primary source for their formation, which is genetically related to the generation of the Cenozoic continental alkaline basalts and mafic megacrysts like clinopyroxene and garnet. Elemental fractionation between helium and argon, enriched in helium compared to the current mantle production value, was observed in most blue-green-yellow (BGY) sapphires, notably for the samples from Changle, eastern China and Ban Huai Sai, Laos. However, the blue sapphires from Wenchang, China do not show such an enrichment. The elevated He-4/Ar-40* (Ar-40* is radiogenic Ar corrected for atmospheric Ar) ratios are interpreted as a solubility-controlled fractionation during magma degassing. Based on the degree of fractionation, the degassing scheme is most likely to be a single-stage process in closed systems (e.g., in a magma chamber), and the original volatile (assuming pure CO2) content of the parental melts before vesiculation is estimated to be similar to 3.5 wt.% in minimum. The degassing process may have caused a sudden Al-saturation of the parental magma and facilitated the crystallization of sapphires by losing alkalis from the magma and decreasing the system's temperature. However, the ``degassing" model, so far, has limitations to interpret the Wenchang data. After crystallization of the BGY sapphires at depths of deep to middle crust levels, a new pulse of alkaline basaltic melt carries them to the surface. (C) 2022 Elsevier Ltd. All rights reserved.
WOS关键词NOBLE-GAS SOLUBILITIES ; LATE CENOZOIC BASALTS ; MIDOCEAN RIDGE ; GEM-CORUNDUM ; TRACE-ELEMENT ; OXYGEN-ISOTOPE ; DIFFUSIVE FRACTIONATION ; LIQUID IMMISCIBILITY ; CONTINENTAL BASALTS ; MANTLE INTERACTION
资助项目National Key Research and Development Program[2016YFC0600105] ; China's National Natural Science Foundation[41903011]
WOS研究方向Geochemistry & Geophysics
语种英语
WOS记录号WOS:000808062900005
出版者PERGAMON-ELSEVIER SCIENCE LTD
资助机构National Key Research and Development Program ; National Key Research and Development Program ; National Key Research and Development Program ; National Key Research and Development Program ; China's National Natural Science Foundation ; China's National Natural Science Foundation ; China's National Natural Science Foundation ; China's National Natural Science Foundation ; National Key Research and Development Program ; National Key Research and Development Program ; National Key Research and Development Program ; National Key Research and Development Program ; China's National Natural Science Foundation ; China's National Natural Science Foundation ; China's National Natural Science Foundation ; China's National Natural Science Foundation ; National Key Research and Development Program ; National Key Research and Development Program ; National Key Research and Development Program ; National Key Research and Development Program ; China's National Natural Science Foundation ; China's National Natural Science Foundation ; China's National Natural Science Foundation ; China's National Natural Science Foundation ; National Key Research and Development Program ; National Key Research and Development Program ; National Key Research and Development Program ; National Key Research and Development Program ; China's National Natural Science Foundation ; China's National Natural Science Foundation ; China's National Natural Science Foundation ; China's National Natural Science Foundation
源URL[http://ir.iggcas.ac.cn/handle/132A11/106062]  
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Guo, Wei; He, Huaiyu
作者单位1.Chinese Acad Sci, Innovat Acad Earth Sci, Beijing 100029, Peoples R China
2.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China
3.Testing Ctr Gold & Jewelry Jiangsu Prov, Nanjing 210016, Peoples R China
4.China Univ Geosci, Sch Gemol, Beijing 100083, Peoples R China
5.Univ Chinese Acad Sci, Beijing 100049, Peoples R China
推荐引用方式
GB/T 7714		 Guo, Wei,He, Huaiyu,Qiao, Lei,et al. Helium, neon and argon in alkaline basalt-related corundum megacrysts: Implications for their origin and forming process[J]. GEOCHIMICA ET COSMOCHIMICA ACTA,2022,322:71-93.
APA Guo, Wei.,He, Huaiyu.,Qiao, Lei.,Liu, Ziheng.,Su, Fei.,...&Zhu, Rixiang.(2022).Helium, neon and argon in alkaline basalt-related corundum megacrysts: Implications for their origin and forming process.GEOCHIMICA ET COSMOCHIMICA ACTA,322,71-93.
MLA Guo, Wei,et al."Helium, neon and argon in alkaline basalt-related corundum megacrysts: Implications for their origin and forming process".GEOCHIMICA ET COSMOCHIMICA ACTA 322(2022):71-93.

入库方式： OAI收割

来源：地质与地球物理研究所

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