In situ element quantification in the hydrothermal diamond anvil cell using synchrotron x-ray fluorescence with applications toward subduction zone processes
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2020-03-26 |
| Authors | S. Maglio |
| Institutions | University of Nevada, Las Vegas |
Abstract
Section titled āAbstractāYttrium is used in geochemical investigations of arc volcanics and metamorphic geothermometers. The ability to use Y as a geochemical tool is predicated on an understanding of the mobility of Y during fluid-saturated conditions attending metamorphic and igneous processes. The goal of this work was to use the hydrothermal diamond anvil cell (HDAC) and synchrotron radiation X-ray fluorescence to quantify, in situ, the concentration of Y in aqueous fluids at 2-5 GPa and 650 - 800 Ā°C; conditions likely at the oceanic lithosphere - mantle wedge interface in subduction zones. Previous studies have used modified diamond anvils which limits their maximum pressure to ~2 GPa. I used unmodified diamond anvils to extend this range to greater pressure, hence simulating greater depth (about 80-140 km), where significant dehydration of the subducting oceanic lithosphere is hypothesized to occur. With the detectors oriented 10Ā° relative to forward scattering geometry, Rayleigh scattering of the diamond anvils was sufficiently reduced to observe Y fluorescence within the HDAC. However, I observed a non-linear relationship between concentration and fluorescence. The new technique offers great promise, and future work to increase sensitivity, perhaps by increasing counting times, is warranted.