Collaborative research: Water stratigraphy of the oceanic lithosphere using mantle xenoliths from Hawaii

Jacobs Technology Inc., Houston TX

Investigators

Abstract

The funded project provides the first set of measurements of the H2O content of the oceanic mantle and involves collaboration between an academic institution and a private sector firm that has a unique capability to measure H2O in igneous minerals (high-resolution FTIR). The importance of this work lies in the fact that small differences in mantle H2O content can have profound effects on mantle rheology and seismic structure, both of which can impact magma generation and crustal movement and have implications for our understanding and prediction of geohazards. Because the mantle is not directly accessible, the investigators implemented a clever approach in which H2O will be measured in minerals coming from pieces of mantle rock (i.e., xenoliths) that were ripped up during the eruption and upward migration of magma of Hawaiian volcanoes. Using compositional relations of mineral pairs that indicate the depth at which the minerals formed, the depth of origin of the various xenoliths that are to be studied can be determined. Using these, the H2O content of the minerals will be examined by Fourier Transform Infra Red (FTIR) spectroscopy. Xenoliths distributed over 300 km along the Hawaiian Island chain and mantle depths to up to 100 km will be analyzed. Broader impacts of the work are robust and multifaceted. A major impact of the project is the provision of essential data that is needed to better interpret the seismic structure of the ocean crust, which will impact our ability to better model the source areas of geohazards like volcanoes and subduction zone earthquakes. The work also supports collaboration between a public university in an EPSCoR state and private industry. It also has a significant component of in-service teacher training where high school teachers in South Carolina work in the laboratory of the lead PI during the summer, getting a chance to engage in frontline research with academic scientist. The teacher?s research will form the basis for classroom and K-12 instructional materials. Workforce training will be carried through the involvement of graduate and undergraduate students in state-of-the-art geochemical analytical techniques. The Program notes that the graduate student is from a group under-represented in the science.