Collaborative Research: Tracking middle-late Paleozoic global-ocean redox conditions using uranium isotopes in marine marbonates

GSTDTAP

项目编号	1733991
	Collaborative Research: Tracking middle-late Paleozoic global-ocean redox conditions using uranium isotopes in marine marbonates
	Maya Elrick
主持机构	University of New Mexico
项目开始年	2017
	2017-09-01
项目结束日期	2020-08-31
资助机构	US-NSF
项目类别	Standard Grant
项目经费	318839(USD)
国家	美国
语种	英语
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 uranium 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 oxygen 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 carbon excursions. The uranium-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 uranium in seawater. Samples will be collected from biostratigraphically well-dated successions in Nevada and Utah at spacings that range 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.
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/71833
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Maya Elrick.Collaborative Research: Tracking middle-late Paleozoic global-ocean redox conditions using uranium isotopes in marine marbonates.2017.