权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Geochronology using Nucleogenic Neon

使用核生成氖进行地质年代学

基本信息

批准号：
1144500
负责人：
Kenneth Farley
金额：
$ 30.27万
依托单位：
California Institute of Technology
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2012
资助国家：
美国
起止时间：
2012-02-01 至 2015-01-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1144500&HistoricalAwards=false
关键词：
Geochronology using Nucleogenic Neon

项目摘要

This project will support the development of a new method for determining the formation ages of minerals, especially those that cannot currently be dated with existing techniques. The method is based on the ingrowth of a rare isotope of neon - 21Ne - from the decay of uranium and thorium. This technique should be especially useful for dating of iron oxide minerals such as hematite and magnetite, and will likely be applicable to understanding the timing and origin of economically significant ore deposits produced by both sedimentary and hydrothermal processes.Several important aspects of this dating system will be investigated. First, a set of experiments will be performed to determine the nuclear cross sections for the reaction 18O(&#945;, n) 21Ne, which produces the daughter isotope. These experiments will involve implantation of a known dose of &#945; particles of known energies into various target materials, followed by direct measurement of the 21Ne produced by isotope dilution mass spectrometry. Additional experiments will caharcterize the diffusivity of neon in likely minerals to be dated, which will establish under what temperature conditions neon retention is to be expected. Such data are necessary for accurate interpretation of the measured ages. A final set of experiments will be designed to identify the typical levels of uranium and thorium, as well as non-radiogenic neon, in minerals of interest for dating. These data will provide insight to what types of minerals are promising targets for the dating method.

这个项目将支持开发一种确定矿物形成年龄的新方法，特别是那些目前无法用现有技术确定年代的矿物。该方法是基于铀和钍衰变产生的稀有同位素氖- 21Ne的向内生长。这项技术对于氧化铁矿物（如赤铁矿和磁铁矿）的定年特别有用，并且可能适用于了解沉积和热液过程产生的具有经济意义的矿床的时间和起源。我们将研究这一测年系统的几个重要方面。首先，将进行一系列实验来确定反应18O(α, n) 21Ne的核截面，该反应会产生子同位素。这些实验将包括植入已知剂量的&amp；将已知能量的粒子放入各种目标材料中，然后通过同位素稀释质谱法直接测量产生的21Ne。额外的实验将表征氖在可能被测定年代的矿物中的扩散，这将确定在什么温度条件下氖将被保留。这些数据对于准确地解释所测量的年龄是必要的。最后一组实验将被设计用于确定矿物中铀和钍以及非放射性氖的典型含量。这些数据将帮助我们了解哪些类型的矿物是测年方法的有希望的目标。