Development of a simple elemental analysis method for pumices derived from the 2021 Fukutoku-Oka-no-Ba submarine eruption using μ-XRF. Implications to earth science

Micro Energy-dispersive X-ray fluorescence spectroscopy (μED-XRF), one of the X-ray fluorescence spectroscopy (XRF), can analyze samples in a non-destructive and non-contact. It also has the advantage of being able to analyze small amount of samples. In geoscience, it is required to analyze the elemental composition of the pumice generated at Fukutoku-Oka-no-Ba, which erupted in August 2021, and to estimate the source. The μED-XRF technique is utilized to analyze major element composition of pumices. Pumice is a volcanic rock consisting of highly vesicular volcanic glass due to rapid cooling of magma. Since its chemical compositions reflect magma composition and volcanoes produce erupted materials with characteristic chemical composition, specification of volcano source that erupted pumices may be possible by analyzing the elemental composition of pumices. Pumice stones originated from submarine eruption could be eroded as they drift for long time and become microscopic in size. The μED-XRF can be powerful tool for analysis of these pumices, as it can analyze small amounts of samples. In this study, we investigated an analytical method that can measure pumice samples easily using μED-XRF. With improved method, we analyzed 37 pumice samples collected from coastal area in Japan and Thailand to identify whether pumices were originated from the Fukutoku Oka-no-Ba submarine volcano eruption in August 2021. Possible drifted patterns are also proposed. (author)