CSEDI: Understanding the structure of the continental upper mantle through the use of magnetotelluric and seismic observations

CSEDI：通过使用大地电磁和地震观测了解大陆上地幔的结构

基本信息

批准号：
1160932
负责人：
Shun-ichiro Karato
金额：
$ 12万
依托单位：
Yale University
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：
2012-09-01 至 2014-02-28
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1160932&HistoricalAwards=false
关键词：
CSEDI Understanding structure continental upper

项目摘要

In this project, we will use geophysically inferred electrical conductivity distribution of the Earth's upper mantle to infer the physical and chemical conditions of the upper mantle. The distribution of water in the mantle reflects the processes by which the upper mantle has evolved. Unlike the oceanic upper mantle, evolution of the continental upper mantle is poorly understood. Consequently, we will focus our attention to the distribution of water in the continental upper mantle from which we infer the evolution of continents. Based on the series of experimental (and theoretical) studies, Karato and his co-workers have shown that water (hydrogen) enhances electrical conductivity of upper mantle minerals dramatically. These experimental studies established the functional relationship between electrical conductivity, water content, temperature, oxygen fugacity etc. These relationships are well established and show that the influence of water is much stronger than other parameters. 'Other parameters' that affect electrical conductivity modestly (major element composition, temperature, oxygen fugacity etc.) can be inferred from other observations (temperature and major element composition from mantle samples, for example). Consequently, we can infer the water distribution from the inferred electrical conductivity distribution through the integration of these observations.Dr. Kate Selway has extensive experience in analyzing the MT data to construct three-dimensional conductivity distributions from the observations of electromagnetic induction. She has recently obtained new data set from Tanzania, but we will also use the data from other regions including South Africa and North America. Given the knowledge of 'other factors' listed above, we will establish the methodology to map out water distribution by comparison to MT data. Both forward and inverse modeling approaches will be used in this study. For this study, we will have a better understanding of water distribution in the continental upper mantle that will shed important insights into how continents might have grown.

在这个项目中，我们将利用地球物理推断的地球上地幔的电导率分布来推断上地幔的物理和化学状况。地幔中水的分布反映了上地幔的演化过程。与海洋上地幔不同，我们对大陆上地幔的演化知之甚少。因此，我们将重点关注大陆上地幔中水的分布，并从中推断大陆的演化。基于一系列的实验（和理论）研究，卡拉托和他的同事们表明，水（氢）可以显着增强上地幔矿物的电导率。这些实验研究建立了电导率、含水量、温度、氧逸度等之间的函数关系。这些关系得到很好的建立，并表明水的影响比其他参数强得多。适度影响电导率的“其他参数”（主要元素成分、温度、氧逸度等）可以从其他观测结果（例如地幔样本的温度和主要元素成分）中推断出来。因此，我们可以通过整合这些观测结果，从推断的电导率分布来推断水的分布。 Kate Selway 在分析 MT 数据以根据电磁感应观测结果构建三维电导率分布方面拥有丰富的经验。她最近获得了来自坦桑尼亚的新数据集，但我们还将使用来自南非和北美等其他地区的数据。鉴于上面列出的“其他因素”的知识，我们将建立通过与 MT 数据比较来绘制水分布的方法。本研究将使用正向和逆向建模方法。通过这项研究，我们将更好地了解大陆上地幔中的水分布，这将为了解大陆如何生长提供重要见解。