Triple Oxygen Isotope Investigation of Mantle Materials

GSTDTAP

项目编号	1903852
	Triple Oxygen Isotope Investigation of Mantle Materials
	Zachary Sharp (Principal Investigator)
主持机构	University of New Mexico
项目开始年	2019
	2019-06-15
项目结束日期	2022-05-31
资助机构	US-NSF
项目类别	Standard Grant
项目经费	356983(USD)
国家	美国
语种	英语
英文摘要	The mantle composes 67% of Earth by weight, but is overlain by a 5-10 km oceanic crust or 30-50 km continental crust, making direct sampling of the most abundant material on the planet impossible. However, samples have reached the Earth?s surface in various volcanic rocks or by plate tectonic activity. It is the purpose of this study to apply the new geochemical tool of triple oxygen isotope geochemistry to these rocks in order to better constrain the origin of mantle rocks and the degree of recycling of crustal material back into the mantle. It is ultimately the transfer of volatile compounds between the mantle and crust/atmosphere that is responsible for changes in the long-term climate of the planet. Furthermore, high temperature hydrothermal alteration of oceanic lithospheric material, which includes the shallow mantle, has been shown to be a potentially important repository for sequestration of atmospheric CO2. The triple isotope work proposed in this study will better constrain the natural conditions of alteration of the lithosphere as it incorporates volatiles, including CO2 and water. In addition to these scientific impacts, this project will support a first-generation graduate student, and several undergraduate students. There have been dozens of studies that use the traditional ratio of the two common isotopes of oxygen, 18-O and 16-O, to place constraints on the origin and temperature of formation of mantle samples. Because there is only one isotope ratio being measured (18-O/16-O), the analyses are often ambiguous. By adding the third rare 17-O isotope to the mix, the amount of information available is significantly greater. Preliminary work shows remarkable instances of equilibrium or disequilibrium that would not be identified with the 18-O/16-O data alone. Ultimately, it is envisioned that the triple isotope research in mantle materials will be an important component of broad-based studies of mantle-derived rocks. As such, it is necessary to provide a foundation for future work, in order to make the concept tractable and applicable to the general community. This work will define the boundary conditions, such as the triple isotope composition of "pristine mantle" and unaltered mid-ocean ridge basalts, the range of triple isotope values of altered oceanic crust and provide standards to the broader geological community. 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/213552
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Zachary Sharp .Triple Oxygen Isotope Investigation of Mantle Materials.2019.