An Improved Electron Microprobe Method for the Analysis of Halogens in Natural Silicate Glasses

Flemetakis, Stamatis; Berndt, Jasper; Klemme, Stephan; Genske, Felix; Cadoux, Anita; Louvel, Marion; Rohrbach, Arno

doi:10.1017/s1431927620013495

Cited by 15 publications

(11 citation statements)

References 46 publications

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“…Our study agrees with this line of reasoning and provides a mechanism by which F can be transferred from antigorite to chlorite and HGM, i.e., chondrodite and humite, that are known to accommodate high amounts of F (Evans and Trommsdorff 1983;Lopez Sánchez-Vizcaíno et al 2005). We also surmise that F-saturated antigorites will be discovered in the near future, especially as improved analytical techniques (e.g., Zhang et al 2016;Flemetakis et al 2020) now allow the quantitative analysis of F with the electron microprobe. 2) indicate the P-T conditions at which antigorite breaks down to olivine and orthopyroxene in systems with low F-concentrations (i.e., 2 wt%, reaction 3), and to chlorite and HGM in F-rich systems (i.e., 5 wt%, reactions 4 and 5).…”

Section: Recycling Of H 2 O and F In Subduction Zonesmentioning

confidence: 89%

“…Pulse Height Analysis (PHA) has been used to eliminate the MgKα peak overlap in the F analysis (Zhang et al 2016). We used the method described by Flemetakis et al (2020) to correct for the spectral overlap of the FeLα peak on the FΚα peak. The acceleration voltage was 15 kV and the beam current was 15 nA with a 5-μm beam size.…”

Section: Scanning Electron Microscopy and Electron Microprobe Analysesmentioning

confidence: 99%

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The stability of antigorite in subduction zones revisited: the effect of F on antigorite stability and its breakdown reactions at high pressures and high temperatures, with implications for the geochemical cycles of halogens

Flemetakis

Tiraboschi

Rohrbach

et al. 2022

Contrib Mineral Petrol

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We present new experimental data on the effect of F on the stability of antigorite and its breakdown products at high pressures (2–6 GPa) and high temperatures (570–850 °C). The experiments show that F does not affect the stability of antigorite, but addition of F to the system affects which minerals are formed when antigorite breaks down. In a F-free system and in a system with intermediate F contents (2 wt% F), antigorite breaks down to olivine and orthopyroxene, but in a F-rich system (5 wt% F), antigorite breaks down to other hydrous and F-bearing mineral assemblages which include chlorite, clinohumite and humite-group minerals (HGM). Since the latter mineral phases are stable at higher pressures and temperatures, and contain more F than antigorite, significant amounts of F and potentially other halogens can be retained in the subducting slab and transported deep into the mantle and possibly even into the Earth’s transition zone.

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Section: Recycling Of H 2 O and F In Subduction Zonesmentioning

confidence: 89%

Section: Scanning Electron Microscopy and Electron Microprobe Analysesmentioning

confidence: 99%

The stability of antigorite in subduction zones revisited: the effect of F on antigorite stability and its breakdown reactions at high pressures and high temperatures, with implications for the geochemical cycles of halogens

Flemetakis

Tiraboschi

Rohrbach

et al. 2022

Contrib Mineral Petrol

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“…2016), except for one low value (167 ± 19 μg g −1 ; Flemetakis et al . 2020) (Table 3). The F content of BCR‐2G varied significantly among laboratories (167–448 μg g ‐1 ; Table 3 and Figure 7a), possibly because of glass F heterogeneity among different fragments analysed by different laboratories.…”

Section: Resultsmentioning

confidence: 99%

“…2016, Flemetakis et al . 2020). Due to the ease of access to EPMA instruments in many geoscience institutes, their high spatial resolution and relatively low analytical costs, EPMA has become the preferred method for the determination of F and Cl mass fractions in geological materials.…”

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confidence: 99%

Electron Probe Microanalysis measurement of F‐Cl‐Nb‐P for Geological Glasses

Zhang

Zeng

Zhang

et al. 2022

Geostandard Geoanalytic Res

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Quantitative in situ electron probe microanalysis (EPMA) was applied to determine the F, Cl, Nb and P contents of glass materials. Using reference glasses with low FeO T (< 10% m/m) mass fractions to construct a F calibration line to correct the Fe interference on the F peaks, is unsuitable for analysing natural Fe-rich melt inclusions with up to 21% m/m FeO T , which commonly occur in picritic, nephelinitic and basanitic samples. For this reason, this study presents a series of seven F-free glasses, which show a wider range of FeO T (1-20% m/m) that were synthesised to improve the overlap correction of Fe on F. Using this improved method, reference glasses of USGS and glasses synthesised from powders of other rock RMs were analysed to evaluate well-known reference materials (RMs) as quality control materials for EPMA measurement of F, Cl, Nb and P mass fractions. The results show that amongst the tested RMs, USGS BHVO-2G is the most appropriate RM for F-Cl determination because different pieces of this glass RM analysed by different laboratories yielded results that agree within uncertainty.

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“…This has been shown to be an issue for Ordovician Kbentonites before [5,27]. In particular, problems of accurately quantifying Cl and F concentrations in geological samples, including apatites, using EPMA has been well documented [33,34]. Thus, offsets of data points and data point clusters caused by analytical differences can have a significant impact on the correct identification and correlation of individual K-bentonite beds.…”

Section: Evaluation Of the ML Models Based On Geochemical Data Of Apatite Phenocrystsmentioning

confidence: 99%

Machine Learning Applied to K-Bentonite Geochemistry for Identification and Correlation: The Ordovician Hagan K-Bentonite Complex Case Study

et al. 2021

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Altered tephras (K-bentonites) are of great importance for calibration of the geologic time scale, for local, regional, and global correlations, and paleoenvironmental reconstructions. Thus, definitive identification of individual tephras is critical. Single crystal geochemistry has been used to differentiate tephra layers, and apatite is one of the phenocrysts commonly occurring in tephras that has been widely used. Here, we use existing and newly acquired analytical datasets (electron probe micro-analyzer [EPMA] data and laser ablation ICP-MS [LA-ICP-MS] data, respectively) of apatite in several Ordovician K-bentonites that were collected from localities about 1200 km apart (Minnesota/Iowa/Wisconsin and Alabama, United States) to test the use of machine-learning (ML) techniques to identify with confidence individual tephra layers. Our results show that the decision tree based on EPMA data uses the elemental concentration patterns of Mg, Mn, and Cl, consistent with previous studies that emphasizes the utility of these elements for distinguishing Ordovician K-bentonites. Differences in the experimental setups of the analyses, however, can lead to offsets in absolute elemental concentrations that can have a significant impact on the correct identification and correlation of individual K-bentonite beds. The ML model using LA-ICP-MS data was able to identify several K-bentonites in the southern Appalachians and establish links to K-bentonites samples from the Upper Mississippi Valley. Furthermore, the ML model identified individual layers of multiphase eruptions, thus illustrating very well the great potential of applying ML techniques to tephrochronology.

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An Improved Electron Microprobe Method for the Analysis of Halogens in Natural Silicate Glasses

Abstract: Abstract

Cited by 15 publications

References 46 publications

The stability of antigorite in subduction zones revisited: the effect of F on antigorite stability and its breakdown reactions at high pressures and high temperatures, with implications for the geochemical cycles of halogens

The stability of antigorite in subduction zones revisited: the effect of F on antigorite stability and its breakdown reactions at high pressures and high temperatures, with implications for the geochemical cycles of halogens

Electron Probe Microanalysis measurement of F‐Cl‐Nb‐P for Geological Glasses

Machine Learning Applied to K-Bentonite Geochemistry for Identification and Correlation: The Ordovician Hagan K-Bentonite Complex Case Study

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