Study on the chemical state of the Earth's deep interior based on chemical and isotopic compositions of kimberlites and mantle materials

基于金伯利岩和地幔物质的化学和同位素组成研究地球内部深处的化学状态

• 批准号: 15340183
• 负责人: KANEOKA Ichiro
• 金额: $ 10.18万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15340183/
• 关键词: Kimberlite; Helium isotope ratio; West Greenland; Lower mantle; Volatile elements; Tungsten isotope ratio; Mantle xenolith; Ocean-island basalt; ^3He; ^4He比; W同位体比; ハワイ諸島; モーリシャス島; マントル; 化学的環境; 3He; 4He比; 還元的; 核; 希ガス; ^4He; 過剰^<129>Xe

In this study, we aimed to reveal the chemical state of the Earth's deep interior by analyzing kimberlites and various mantle-related materials and examine some models on the chemical structure of the Earth's interior. To collect in-situ kimberlites, we performed sampling in China and Brazil, but found them to have been much altered. We could get a knowledge that fresh kimberlites might have been only found in a limited place where kimberlite magmas were intruded at a depth like sills. By analyzing noble gases in fresh kimberlites from West Greenland, which we had got from foreign investigators, we have revealed that their magma sources are similar to those of ocean-island basalts and probably derived from the lower mantle based on their high ^3He/^4He ratios. Since kimberlites are enriched in volatile elements and show unfractionated platinum-group element patterns relative to those of chondrites, it can be inferred that the lower mantle might have been less degassed and more reduced … More state compared to the upper mantle. However, we could not identify the difference in tungsten isotope ratios between kimberlites and mantle-related materials of the upper mantle origin.On the other hand, we observed ^3He/^4He ratios lower than that of the air in mantle xenoliths from Far Eastern Russia, which suggests the effect of subducted slabs to the mantle in that area. For xenoliths of lower crust and upper mantle origin from the Indian Ocean area, we observed ^3He/^4He ratios similar to those of MORBs and ^<40>Ar/^<36>Ar ratios affected by the air. Furthermore, we have revealed that basalts of less than 1 Ma from Mauritius Island, which belongs to the Reunion hotspot, show Sr, Nd and Pb isotope ratios which are closer to MORB values than those of older basalts. This can be explained by increasing of the effect of plume magmas by the upper mantle materials of MORB types with time. Such tendency can also be observed in noble gas isotopes in alkaline basalts taken from the ocean floor around the Hawaiian Islands and it suggests a possibility that upper mantle materials might have been affected by the ocean-island basalts. Less

在这项研究中，我们的目标是通过分析金伯利岩和各种地幔相关物质来揭示地球深部的化学状态，并检查地球内部化学结构的一些模型。为了收集原地金伯利岩，我们在中国和巴西进行了取样，但发现它们已经发生了很大的变化。我们可以了解到，新鲜金伯利岩可能只在有限的地方发现，金伯利岩岩浆侵入的深度像窗台。通过分析我们从外国调查人员那里获得的西格陵兰新鲜金伯利岩中的惰性气体，我们揭示了它们的岩浆来源与洋岛玄武岩相似，并且可能来自下地幔，因为它们的^3 He/^4 He比率很高。由于金伯利岩富含挥发性元素，相对于辉长岩而言，表现出未分馏的铂族元素模式，因此可以推断下地幔的脱气程度可能更低，还原程度更高 ...更多信息 与上地幔相比。然而，我们不能确定金伯利岩和上地幔起源的地幔相关物质之间的钨同位素比值的差异，另一方面，我们观察到俄罗斯远东地区地幔捕虏体中的^3He/^4He比值低于空气，这表明该地区俯冲板片对地幔的影响。对于来自印度洋地区的下地壳和上地幔捕虏体，我们观测到了类似于MORB的^3He/^4He比值和受空气影响的^<40>Ar/^<36>Ar比值。此外，我们已经发现，来自毛里求斯岛，这属于留尼汪热点小于1马的玄武岩，显示Sr，Nd和Pb同位素比值更接近MORB值比那些老的玄武岩。这可能是由于MORB型上地幔物质对地幔柱岩浆的作用随时间的增加而增强。这种趋势也可以在取自夏威夷群岛周围洋底的碱性玄武岩的惰性气体同位素中观察到，这表明上地幔物质可能受到洋岛玄武岩的影响。少

项目成果

Modified ion exchange separation for tungsten isotopic measurements from kimberlite samples using multi-collector inductively coupled plasma mass spectrometry

使用多接收器电感耦合等离子体质谱法从金伯利岩样品中进行改进的离子交换分离测量钨同位素

• 发表时间: 2006
• 期刊: Analyst 131
• 作者: Sahoo;Y;Nakai;S.;Ali;A.
• 通讯作者: A.

Ocean-island basalt-like source of kimberlite magmas from West Greenland revealed by high ^3He/^4He ratios

高 ^3He/^4He 比率揭示了来自西格陵兰岛的类似海岛玄武岩的金伯利岩岩浆源

• 发表时间: 2006
• 期刊: Geology 34・4
• 作者: Tachibana;Y.;I.Kaneoka;A.Gaffry;B.Upton
• 通讯作者: B.Upton

Meteoric ^<10>Be in volcanic materials and its behavior during acid-leaching.

火山材料中的流星^<10>Be及其在酸浸过程中的行为。

• 发表时间: 2004
• 期刊: Nuclear Instruments and Methods in Physics Research (NIM), Section B 223/224
• 作者: Shimaoka;A.;M.Sakamoto;H.Hiyagon;H.Matsuzaki;I.Kaneoka;M.Imamura
• 通讯作者: M.Imamura

Kumagai, H., H.J.B.Dick, I.Kaneoka: "Noble gas signatures of abyssal gabbros and periodotites at an Indian Ocean core complex."G-cubed. 4(12). 1-16 (2003)

Kumagai, H.、H.J.B.Dick、I.Kaneoka：“印度洋核心复合体中深海辉长岩和周期岩的惰性气体特征。”G 立方。

The OIB-like source of kimberlite magmas from west Greenland revealed by high ^3He/^4He ratios

高 ^3He/^4He 比率揭示了来自格陵兰岛西部的类似 OIB 的金伯利岩岩浆源

• 发表时间: 2006
• 期刊: Geology (in press)
• 作者: Tachibana;Y.;I.Kaneoka;A.Gaffney;B.Upton
• 通讯作者: B.Upton