| 项目编号: | 1624587
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| 项目名称: | Tungsten and Ruthenium Isotopic Study of the Chemical Evolution of Earth |
| 作者: | Richard Walker
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| 承担单位: | University of Maryland College Park
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| 批准年: | 2016
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| 开始日期: | 2016-07-15
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| 结束日期: | 2019-06-30
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| 资助金额: | 302125
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| 资助来源: | US-NSF
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| 项目类别: | Continuing grant
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| 国家: | US
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| 语种: | 英语
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| 特色学科分类: | Geosciences - Earth Sciences
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| 英文关键词: | earth
; isotopic composition
; study
; prior study
; isotopic heterogeneity
; domain
; cosmochemical precursor
; earth?s mantle
; early chemical fractionation
; tungsten isotopic variation
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| 英文摘要: | The Earth was likely built as a result of a series of a series of collisions of increasingly larger planetesimals, during the first 50 million years of Solar System history. Growth of the planet largely terminated after a final, giant impact that led to melting of much of the Earth and the creation of the Moon. Surprisingly, there is strong evidence present in the isotopic compositions of some elements in both ancient and young rocks that domains were created within the Earth?s mantle during the primary construction period of the Earth before the giant impact, and these domains have been somehow preserved to the present. This study will examine the tungsten and ruthenium isotopic compositions of rocks derived from these domains to provide new insights to processes occurring within the Earth as it grew, as well as help to constrain the genetic origins of the building blocks of our planet.
Small variations in the abundance of 182-tungsten in terrestrial rocks likely reflects the decay of 182-hafnium, coupled with very early chemical fractionations of the two elements within the silicate portion of the Earth. Prior studies have suggested that modest variations in 182-tungsten among some primitive rocks may reflect processes occurring in early-formed magma oceans. This study will seek to more fully establish the causes of the isotopic heterogeneities, and assess why convective stirring of the mantle has not mixed away the heterogeneities in more than 4.5 billion years. The isotopic composition of Ru varies among planetary bodies in our Solar System as a result of the incorporation of diverse mixtures of nucleosynthetic components. Hence, if the Earth was built from genetically diverse materials, early-formed mantle domains identified by tungsten isotopic variations, may contain ruthenium that is isotopically distinguishable from the dominant composition of the mantle today. If so, the particular building block identified may be tied to a specific type of cosmochemical precursor. |
| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/91786
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| Appears in Collections: | 全球变化的国际研究计划
科学计划与规划
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| Recommended Citation: | |
Richard Walker. Tungsten and Ruthenium Isotopic Study of the Chemical Evolution of Earth. 2016-01-01.
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