241-9 Energy Dispersive Spectroscopy (EDS) as a quantitative analytical tool for petrologic studies.

Session: Petrology, Volcanology, and Mantle Plumes across the Solar System, Part I

Presenting Author:

Penny Wieser

Authors:

Wieser, Penny Elaine¹, Shi, Sarah², Gleeson, Matthew³, Bawankule, Natasha⁴, Ruth, Dawn Catherine Sweeney⁵, Lynn, Kendra Janell⁶, Downs, Drew⁷, Martin, Celine Alix⁸, Kuehn, Stephen C.⁹, Moore, Lowell¹⁰

(1) UC Berkeley, Earth and Planetary Sciences, Berkeley, CA, USA, (2) UC Berkeley, Berkeley, USA, (3) Univ of California Berkeley, Earth and Planetary Sci, Berkeley, CA, USA, (4) UC Berkeley, Berkeley, CA, USA, (5) USGS, Moffett Field, CA, USA, (6) USGS Hawaiian Volcano Observatory, Hilo, HI, USA, (7) US Geological Survey, Hilo, HI, USA, (8) American Museum of Natural History, New York, NY, USA, (9) Concord University, Physical and Environmental Sciences, Athens, WV, USA, (10) Virginia Tech Department of Geosciences, Blacksburg, VA, USA,

Abstract:

Traditionally, glass and mineral compositions have been measured using wavelength-dispersive spectroscopy (WDS) on an Electron Probe Microanalyzer (EPMA). However, EPMA instruments are expensive, have restricted use outside of the Earth Sciences, and typically require specialized and extensive technical support. This makes it difficult for many Earth Science departments and volcano observatories to operate one sustainably. In contrast, Scanning Electron Microscopes (SEM) are less expensive and simpler to use, and can be far more versatile given the number of different compatible detector types. Thus, SEMs can generate revenue from a larger pool of users and disciplines, so universities are far more likely to have access to an SEM than an EPMA. There have been great technological advances in the speed and quality of chemical data collected using Energy Dispersive Spectroscopy (EDS) detectors in recent years, accompanied by suggestions that EDS-SEM systems can yield quantitative analyses comparable to, and in some cases provide advantages over, traditional EPMA analyses. Here, we critically evaluate the performance of SEM-based EDS analyses for determining major and minor-element chemical data on mineral and glass compositions from igneous rocks. We assess the accuracy of standard-based EDS at UC Berkeley by comparing these results to EPMA measurements made on silicate glass and a variety of mineral species (e.g. pyroxene, amphibole, feldspar, olivine, oxide, apatite) at AMNH, USGS Moffett Field, Concord University, and Virginia Tech. We also assess ways to optimize precision while maintaining accuracy in different materials by changing EDS process time, beam current, and acquisition times.  Our results emphasize the faster analytical and setup times of EDS, and comparable precision and accuracy to EPMA measurements. The lower cost and wider accessibility of EDS means that it is a very powerful technique for rapid-response applications during volcanic eruptions (e.g. quantifying mineral chemistry, mineral zoning). As an example, we assess the quality and speed of EDS transects across olivine crystals from Kīlauea volcano and compare these against EPMA data. Our results suggest that EDS has great promise for rapid determination of mineral populations and diffusion timescales during eruptive crises to help with hazard assessment and mitigation.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

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