| 项目编号: | 1733641
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| 项目名称: | Collaborative Research: Tracking Middle-late Paleozoic Global-ocean Redox Conditions Using U Isotopes in Marine Carbonates |
| 作者: | Jennifer Morford
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| 承担单位: | Franklin and Marshall College
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| 批准年: | 2017
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| 开始日期: | 2017-09-01
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| 结束日期: | 2020-08-31
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| 资助金额: | 102615
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| 资助来源: | US-NSF
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| 项目类别: | Standard 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: | u isotope
; marine animal life
; well-dated succession
; uranium isotope
; global-ocean redox curve
; unique geologic time interval
; global-ocean redox condition
; funded proposal
; multiple primary school science teacher
; first-generation college student
; marine carbonate
; marine anoxia
; u-isotope composition
; relative amount
; icehouse climate
; multiple large positive 13c excursion
; ~
; ocean circulation
; devonian-mississippian marine carbonate
; year study interval
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| 英文摘要: | The goal of the funded proposal is to determine the relative amounts of oxygen dissolved in ancient oceans during a unique geologic time interval (300 to 420 million years ago) when three major mass extinctions occurred and the Earth was significantly warmer than today. Understanding the history of oxygen levels in ancient oceans is important because oxygen concentrations influence all marine animal life, control the formation and preservation of petroleum and many economic mineral deposits, and affect important biochemical reactions in the oceans and atmosphere. This project utilizes the relatively new geochemical tool of uranium isotopes to develop the most detailed history of changing ocean oxygen concentrations to date. The funding supports the training of the next generation of Earth scientists, will provide hands-on field and laboratory experience for first-generation college students, and will support multiple primary school science teachers to conduct real-world science to gain confidence and provide new ideas for their own classrooms.
The project goal is to develop a global-ocean redox curve using U isotopes from Devonian-Mississippian marine carbonates. The ~100 million year study interval, which bridges the transition between poorly oxygenated Precambrian-Early Paleozoic oceans and well-oxygenated Late Paleozoic-Recent oceans, is important because of: 1) a doubling of atmospheric pO2 levels, 2) a transition from greenhouse to icehouse climate and intensifying ocean circulation, 3) the occurrence of three mass extinctions, two of which are attributed to marine anoxia, and 4) multiple large positive 13C excursions. The U-isotope composition of marine carbonates has the potential to record mean global-ocean redox conditions owing to the long residence time (~500 thousand years) of U in seawater. Samples will be collected from biostratigraphically well-dated successions in Nevada and Utah at spacings ranging from ~100 thousand years/sample to <20 thousand years/sample through specific event intervals. To assess samples for local redox influences, we will analyze redox-sensitive metals, Fe-speciation, and Corg:P ratios. To verify the global nature of the composite curve, we will sample and compare to selected shorter stratigraphic intervals on other continents.
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| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/89017
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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: | |
Jennifer Morford. Collaborative Research: Tracking Middle-late Paleozoic Global-ocean Redox Conditions Using U Isotopes in Marine Carbonates. 2017-01-01.
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