Towards Characterizing the Nitrogen Isotope Systematics of the Oceanic Mantle

描述大洋地幔氮同位素系统学特征

• 批准号: 2015789
• 负责人: Peter Barry
• 金额: $ 47.87万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-06-01 至 2023-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2015789&HistoricalAwards=false
• 关键词: Towards; Characterizing; Nitrogen; Isotope; Systematics

Nitrogen is far more abundant in the Earth’s atmosphere than in the mantle. Therefore, nitrogen can reflect interactions between Earth’s interior and exterior. However, few studies have investigated the nature of nitrogen in basalts that form as the mantle melts. The difficulty in measuring nitrogen in basalts is because of analytical challenges and the difficulty in obtaining representative samples. This is an important gap in knowledge because basalts make up the ocean crust that underlies two-thirds of the Earth's surface. This project will measure nitrogen isotopes from key mantle-derived samples. The samples were obtained from the main environments of basaltic magmatism in the world's oceans. The project thus aims to produce the best measure, to date, of the global nitrogen cycle over Earth history. The study will establish Woods Hole Oceanographic Institution as a key USA-based laboratory. The unique capability of the laboratory is the measure of high-precision nitrogen isotopes on extremely low concentration samples. Findings from the study will address many broader questions pertaining to the origin of the most abundant gas in our atmosphere. The recycling of this gas is tied to the evolution of the Earth and the solar system.Measurements of oceanic basalts from the Lau Basin, Manus Basin, Alarcon Basin, Galapagos and Mid-Atlantic Ridge Popping Rocks will allow us, for the first time, to define the scale of delta-N-15 variability in the oceanic mantle by targeting samples with high 3He/4He values (plume-influenced mantle) as well as other glasses with 3He/4He values within the nominal range of depleted MORB mantle (DMM). Given the well characterized geochemistry of these samples – including radiogenic isotopes (Sr-Nd-Pb), noble gases and major volatiles (He-Ne-Ar-CO2-H2O) –the relationship between delta-N-15 and petrogenetic tracers will be assessed to distinguish between mantle source features and secondary controls (e.g., degassing fractionation and/or surficial contamination). All samples will allow scrutiny of δ15N-3He/4He relationships and further characterization of the variability of delta-N-15 in the oceanic mantle from the perspective of different sampling media and regional controls. As a proof of concept, mafic crystals and xenoliths from the Canary Islands hotspot will also be measured, however this task is significantly more challenging due to extremely low N abundances in mafic crystals. Studies on mafic crystals will define limits for sample N-contents required for analysis, potentially leading to a significant increase in the sample base amenable to delta-N-15 studies. All results will provide important constraints on modeling the evolution of the DMM vs. plume-influenced mantle, and the advent of plate tectonics over Earth history. Specifically, N isotope data generated in the proposed study will be incorporated into a newly developed forward model that couples observations from N and other volatiles species (i.e., heavy noble gases) to understand the relative recycling efficiency of different volatile species.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

氮在地球大气中比在地幔中更丰富。因此，氮可以反映地球内部和外部之间的相互作用。然而，很少有研究研究以地幔融化形成的玄武岩中氮的性质。测量玄武岩中氮的困难是由于分析挑战和获得代表性样本的困难。这是知道的重要差距，因为玄武岩构成了构成地球表面三分之二的海角。该项目将从关键地幔衍生的样品中测量氮同位素。样品是从世界海洋中玄武岩岩浆岩的主要环境中获得的。因此，该项目的目的是迄今为止在地球历史上生产全球氮循环的最佳测量。这项研究将建立伍兹孔海洋学机构作为基于美国的关键实验室。实验室的独特能力是测量极低浓度样品上的高精度氮同位素。研究结果将解决与我们大气中最丰富气体的起源有关的许多更广泛的问题。这种气体的回收与地球和太阳系的进化有关。海洋玄武岩的测量是Lau盆地，Manus Basin，Manus Basin，Alarcon Basin，Galapagos，Galapagos和Mid-Atlantic Ridge弹出的岩石的测量，这将使我们首次通过Delta-N-15变异性范围来定义Delta-N-15变异性的尺度，以定义Delta-N-15变异性的范围。 （受羽状地幔）以及其他在耗尽的MORB地幔（DMM）标称范围内的玻璃杯。鉴于这些样品的地球化学特征良好 - 包括放射原同位素（SR-ND-PB），高贵的气体和主要挥发物（He-ne-ar-ar-ar-CO2-H2O） - Delta-N-15与岩石发生示踪剂之间的关系将得到评估，以区分地幔源特征和次要对照（例如，或言语），或效果。从不同的采样培养基和区域控制的角度来看，所有样品将允许审查Δ15N-3HE/4HE关系，并进一步表征海洋套中delta-n-15的变异性。作为概念的证明，也将测量来自加那利群岛的镁铁质晶体和异种石，但是由于镁铁质晶体的n含量极低，因此该任务面临更大的挑战。关于镁铁质晶体的研究将定义分析所需的样品N-符号的限制，这可能导致可与Delta-N-15研究相提并论的样品基础显着增加。所有结果都将为建模DMM与羽流影响的地幔的演变以及板块构造的发展而在地球历史上的发展提供重要限制。具体而言，拟议研究中生成的n同位素数据将被纳入新开发的前向模型中，该模型将N和其他挥发物物种（即重量贵重的气体）的观察结果融合在一起，以了解不同波动性物种的相对回收效率。该奖项颁发了NSF的法定任务，并通过评估范围来反映了Crakia cr Infectia and Iffectia and Fundial and Foundation and Foundation的支持。

项目成果

Recycling of nitrogen and light noble gases in the Central American subduction zone: Constraints from 15N15N

中美洲俯冲带氮气和轻惰性气体的回收：来自15N15N的限制

• DOI: 10.1016/j.epsl.2021.117112
• 发表时间: 2021
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: Labidi, J.;Young, E.D.;Fischer, T.P.;Barry, P.H.;Ballentine, C.J.;de Moor, J.M.
• 通讯作者: de Moor, J.M.

Subduction-Driven Volatile Recycling: A Global Mass Balance

• DOI: 10.1146/annurev-earth-071620-055024
• 发表时间: 2021-01-01
• 期刊: ANNUAL REVIEW OF EARTH AND PLANETARY SCIENCES, VOL 49, 2021
• 作者: Bekaert, D. V.;Turner, S. J.;Barry, P. H.
• 通讯作者: Barry, P. H.

Nitrogen and noble gases reveal a complex history of metasomatism in the Siberian lithospheric mantle

氮气和稀有气体揭示了西伯利亚岩石圈地幔复杂的交代作用历史

• DOI: 10.1016/j.epsl.2020.116707
• 发表时间: 2021
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: Barry, Peter H.;Broadley, Michael W.
• 通讯作者: Broadley, Michael W.

Hydrothermal 15N15N abundances constrain the origins of mantle nitrogen

• DOI: 10.1038/s41586-020-2173-4
• 发表时间: 2020-04-16
• 期刊: NATURE
• 影响因子: 64.8
• 作者: Labidi, J.;Barry, P. H.;Young, E. D.
• 通讯作者: Young, E. D.