Defining the noble gas composition of highly depleted mantle domains

定义高度贫化地幔域的稀有气体成分

• 批准号: 1464484
• 负责人: Sujoy Mukhopadhyay
• 金额: $ 32.59万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-10-01 至 2018-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1464484&HistoricalAwards=false
• 关键词: Defining; noble; gas; composition; highly

The noble gases play an important role in understanding mantle structure and in quantifying mass and volatile fluxes in and out of the mantle. The isotopic composition of non-radiogenic noble gases in the Earth's mantle can constrain the sources of volatile sources on our planet and the mechanisms through which volatiles are incorporated into the solid Earth. Furthermore, the isotopic composition of the noble gases in Earth's mantle can provide important clues to the origin and evolution of the atmosphere. For example, the modern atmosphere was traditionally thought to be secondary, i.e, derived from mantle degassing after the dissipation of a primary atmosphere that the Earth might have acquired during the accretion process. Theories on the origin of the early atmosphere through degassing of the mantle are now being challenged by new noble gas data and neon isotopes. This research will use new developments in noble gas mass spectrometry that allow much higher resolution and precision measurements than previously available to examine a suite of heavy noble gases and their isotopic ratios to determine the composition of the most depleted mantle domains and understand how they relate to normal and enriched Mid Ocean Ridge Basalt sources. Issues such as: (1) the noble gas elemental abundance ratios in depleted, normal and enriched mantle domains, (2) whether isotopic anomalies in argon and xenon in different mantle domains are related to ancient mantle differentiation events or to the on going process of plate subduction and recirculation that introduces atmospheric noble gases into the mantle; (3) the proportion of Pu- to U-derived, fission generated Xe in depleted, normal, and enriched mantle domains; (4) whether there time-constants associated with mantle degassing can be determined; and (5) whether the non-radiogenic isotopic compositions of Xe and Kr are solar, chondritic, or air-like, will be addressed. Answers to these questions will allow determination of the flux of volatiles and material from plumes in the mantle into the mid-ocean ridge basalt (MORB) source and the degree of mixing between MORB and plume sources. It will also provide key insights on Earth structure and mantle flow. In addition, the research seeks to constrain sources of Earth volatiles and the recycling of noble gases between the crust and atmosphere and the mantle, and the formation of Earth's atmosphere. Broader impacts of the work include new analytical method development that will increase the infrastructure for science, use of a an NSF-funded mass spectrometry facility, and student support, including support of a student whose gender is under-represented in the sciences. Additional impacts include incorporation of research results into graduate and undergraduate courses.

贵重气体在理解地幔结构以及量化质量和挥发性通量方面起着重要作用。地球地幔中非放射原质贵重气体的同位素组成可以约束我们行星上挥发性源的来源以及将挥发物纳入实心土的机制。此外，地球地幔中贵重气体的同位素组成可以为大气的起源和演变提供重要的线索。例如，传统上认为，现代气氛是次要的，即源自地幔脱气后，地球散发出来，地球散发出了地球在增生过程中可能获得的原发气氛。现在，新的贵族气体数据和霓虹同位素对早期大气的起源进行了关于早期大气的起源的理论。这项研究将在高贵的气体质谱法中使用新的开发项目，该开发项目允许比以前可用的更高的分辨率和精确测量值，以检查一套重型贵重气体及其同位素比，以确定最耗尽的地幔域的组成，并了解它们与正常和丰富的中海洋ridge Basalt ride Source的相关性。 Issues such as: (1) the noble gas elemental abundance ratios in depleted, normal and enriched mantle domains, (2) whether isotopic anomalies in argon and xenon in different mantle domains are related to ancient mantle differentiation events or to the on going process of plate subduction and recirculation that introduces atmospheric noble gases into the mantle; （3）在耗尽，正常和富集的地幔域中产生的pu衍生，裂变的比例； （4）是否可以确定与地幔脱气相关的时代； （5）XE和KR的非放射原性同位素组合物是否是太阳，软骨或空气样的。 这些问题的答案将允许从地幔中的羽流到中山脊（MORB）来确定挥发物和材料的通量，以及MORB和羽流源之间的混合程度。它还将提供有关地球结构和地幔流的关键见解。此外，该研究试图限制地球挥发物的来源以及地壳与大气与地幔之间贵重气体的回收，以及地球大气的形成。这项工作的更广泛的影响包括新的分析方法开发，该方法将增加科学的基础设施，使用NSF资助的质谱设施以及学生的支持，包括对科学中性别不足的学生的支持。其他影响包括将研究结果纳入研究生和本科课程。