Sediment Recycling in Southern Cascadia: Insights From Seafloor Sediment and Mafic Volcanic Rock Geochemistry

GSTDTAP

项目编号	1524596
	Sediment Recycling in Southern Cascadia: Insights From Seafloor Sediment and Mafic Volcanic Rock Geochemistry
	Emily Johnson
主持机构	New Mexico State University
项目开始年	2015
	2015-07-15
项目结束日期	2018-06-30
资助机构	US-NSF
项目类别	Continuing grant
项目经费	35831(USD)
国家	美国
语种	英语
英文摘要	This project will investigate the contribution of seafloor sediments and other components to magmas erupted in the southern Cascades. In subduction zone plate boundaries like Cascadia, an oceanic plate sinks, or 'subducts', into the mantle beneath a continental plate. The subducted plate material, which includes oceanic crust and some portion of the overlying seafloor sediments, is then recycled into the mantle and incorporated into the magmas that erupt at volcanoes like those in the Cascades. This research will use the chemical compositions of both magmas erupted in the southern Cascades (from northern California through central Oregon) and the seafloor sediments and oceanic crust offshore of the southern Cascades to model the contributions of sediments, and other components, to the magmas. The estimates of sediment recycling provided in this research will be important to a range of scientists studying the Cascadia subduction zone: such recycling can impact the explosivity of volcanic eruptions and slip during future earthquakes at the Cascadia plate boundary. This project will address three key questions about recycling of subducted material in the southern Cascades: 1) What is the contribution of subducted seafloor sediment to magmas erupted in the southern Cascades?, 2) What is the quantity of subducted material (oceanic crust, sediment) added to the mantle, and what is the nature of that subducted material (fluid and/or melt)?, and 3) How do these and other important parameters (mantle compositions, extents of mantle melting, etc.) vary along the arc? To answer these questions, detailed analyses of the geochemical compositions (major and trace elements, isotopes) of seafloor sediments and crust from the Gorda plate offshore of the southern Cascades and basaltic arc magmas (including volatile contents) will be obtained and used to model the contributions of each potential component to the magmas. Currently, the compositions of sediments offshore of southern Cascadia are unknown, making direct assessment of their contributions to the magmas impossible. As a result of this research, there will be a complete and continuous dataset of the geochemistry of magmas and their origins and the compositions of offshore seafloor sediments for ~450 km of Cascadia. Thus, when combined with previous work on magmas and their sources in other portions of the Cascades, this will be one of the best-studied arcs worldwide, making large-scale along-arc assessments of subduction and magmatic parameters possible.
来源学科分类	Geosciences - Earth Sciences
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/68252
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Emily Johnson.Sediment Recycling in Southern Cascadia: Insights From Seafloor Sediment and Mafic Volcanic Rock Geochemistry.2015.