EAGER: Anomalous submarine volcanism during glacial terminations: Exploring archives from the global mid-ocean ridge system

GSTDTAP

项目编号	1840886
	EAGER: Anomalous submarine volcanism during glacial terminations: Exploring archives from the global mid-ocean ridge system
	David Lund
主持机构	University of Connecticut
项目开始年	2018
	2018-08-01
项目结束日期	2019-07-31
资助机构	US-NSF
项目类别	Standard Grant
项目经费	49939(USD)
国家	美国
语种	英语
英文摘要	Knowledge about how and why climate has changed in the past is important for understanding the sensitivity of the climate system and the potential for future climate change. There are many natural processes that are linked to climate and associated sea level changes. Continental glaciation draws down sea levels as ice sheets grow, and raises sea levels when ice sheets recede. The release of volatiles, especially carbon dioxide (CO2), from submarine volcanoes along the ~50,000 miles of mid-ocean ridges is also thought to play a role in modulating climate. Sea level changes and volatile release are linked through changes in pressure on the sea floor and underlying Earth's mantle. It is hypothesized that a reduction in pressure (through a drop in sea level) can trigger increased mantle melting and eruption of lava onto the seafloor, and consequent degassing of magmatic CO2 that can raise the CO2 content of the atmosphere and cause global warming. Warming in turn results in increased glacial ice melt, which provides a negative feedback to the process. Recently published work from the Pacific-Antarctic Ridge in the Southeast Pacific suggests that a recent glacial termination was characterized by anomalous mid-ocean ridge volcanism at that location. However, it is not clear if this is simply a coincidence or a global event. This research seeks to address this question. To do this, eleven sediment cores from existing collections will be examined. Cores were selected on the basis of mid-ocean ridge axial proximity, water depth, and core length. These characteristics are necessary for recording volcanic fallout from ridge volcanic eruptions that would indicate active magmatism. The research involves, intensive geochemical and microscopic study of the sediments, the use of oxygen isotopes to determine core stratigraphy and coherence, and quantitative estimates of volcanic ash content. If successful, the work could have implications for our understanding of climate and rates of climate change. Broader impacts also include the training of undergraduate and graduate students at the University of Connecticut. This research builds on a preliminary study of a single site in which a relationship appeared to exist between the waxing of continental glaciation and the increased incidence of mid-ocean ridge magmatism followed by rapid glacial melting. This research tests the researcher's novel and controversial hypothesis by expanding the observations to multiple locations on three major mid-ocean ridge spreading centers: the Mid Atlantic Ridge, the East Pacific Rise, and the Central Indian Ridge. A set of sediment cores are available for study through NSF-supported seafloor sample repositories. These cores have essential criteria needed to shed light on the research question: a location that is close enough to a mid-ocean ridge that volcanic ash and ejecta from eruptions therein are likely to be components of the sediment, length such that cores span multiple continental glacial cycles, and water depth. Goals of the project are to determine whether the results found on the Pacific Antarctic Ridge are representative of conditions of glacial terminations at mid-ocean ridges worldwide. Sediments from the cores will be processed to separate foraminifera that will be analyzed for oxygen isotopes to determine their stratigraphy and ages at high resolution. Sediments will also be examined for evidence of ash, ash layers, and other volcanic ejecta; the total amount of volcanic material; and volcanic particle morphology and grain size. Geochemical analyses on the sediments will take place to look for indicators of basaltic particles, usually evident from the weight percent of titanium in the samples. These data will be compared to the known timing of periods of continental glaciation to see if there is a correlation between the increase and decline of glaciation and corresponding seafloor magmatic activity. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/72932
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	David Lund.EAGER: Anomalous submarine volcanism during glacial terminations: Exploring archives from the global mid-ocean ridge system.2018.