Near Continent Intraplate Magmatism in the Atlantic: Implications for Mantle Dynamics and Melting

GSTDTAP

项目编号	1802012
	Near Continent Intraplate Magmatism in the Atlantic: Implications for Mantle Dynamics and Melting
	Esteban Gazel
主持机构	Cornell University
项目开始年	2017
	2017-09-01
项目结束日期	2019-03-31
资助机构	US-NSF
项目类别	Continuing grant
项目经费	276249(USD)
国家	美国
语种	英语
英文摘要	The processes that result in volcanism away from active plate boundaries are not explained by the current plate tectonics theory, and thus remain a missing piece in our understanding of the internal dynamics and evolution of our planet. Localized upwelling of hot mantle known as "mantle plumes" successfully explains locations like Hawaii and Yellowstone. However, there are many other sites worldwide like Cape Verde and the Canaries islands that require further research to understand the mechanisms behind volcanic activity. The team's goal is to elucidate the mechanisms that produce volcanoes away from plate margins using a collaborative approach that combines data from geochemical and geodynamical studies. The investigators, including international collaborators, will collect new geochemical data including volatiles (C, H, S, etc.) from Cape Verde and the Canaries, using these locations as natural laboratories to study the deep Earth. They will use melt inclusions contained within the host crystals to collect volatile data to answer the proposed fundamental questions. These results can also be incorporated in assessment of volcanic hazards. Additionally, they will provide new CO2 and H2O data that will help constrain volatile output for intraplate magmatism, and especially increase our understanding of the deep Earth carbon cycle. The results from this project will flow directly into the teaching of the principal investigator, and will be disseminated to a broad audience through outreach activities at the Geosciences Museum at Virginia Tech, the Virginia Science Festival, and through different media sources to the public. The goal of this project is to integrate petrological and geochemical data from Cape Verde and the Canaries with geodynamic models to broaden our understanding of the composition and dynamical processes in the mantle that can give rise to intraplate magmatism. The mantle plume model has generally been accepted as a plausible mechanism for intraplate volcanism, but not all locations that are considered "hotspots" have the seismic and geochemical signatures to back up a deep-rooted source. Small-scale convection (e.g., edge-driven convection, EDC) has been proposed as an alternative mechanism for a subset of near continent locations. The investigators propose to test mantle plume vs. EDC as mechanisms for intraplate volcanism using Cape Verde and the Canaries as natural laboratories. These locations were selected for their position near a continental margin but away from plate boundaries, making them ideal to test our working hypotheses. Also, these locations provide easy access to abundant primitive tephras to be used for melt-inclusion studies and volatile determinations, which are necessary for an improved determination of melting conditions. Finally, Cape Verde and the Canaries are the only two oceanic settings where carbonatites have been reported. Preliminary work on Cape Verde and the Canaries suggest that some samples (including the carbonatites) from these locations melted from a carbonated mantle source, indicating the importance of intraplate volcanism for mantle outgassing, a missing link in the deep global water and carbon cycles. Thereby, the team will address these fundamental questions: 1) How do the dynamics of mantle upwelling control the melting behavior of the source through the effects of temperature and upwelling rate? 2) What is the source composition of these Atlantic hotspots, and how does it affect the dynamics of mantle upwelling as well as petrological determinations of source temperatures, the size of the swell and the seismic expression of mantle upwelling? 3) What are the volatile budgets of intraplate magmas and their role in the global water and carbon cycles, and how do volatiles modulate mantle dynamics by reducing viscosity? 4) What are the diagnostic geochemical and petrological signatures of the plume model vs. EDC?
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/71805
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Esteban Gazel.Near Continent Intraplate Magmatism in the Atlantic: Implications for Mantle Dynamics and Melting.2017.