Trace element analysis of olivine: High precision analytical method for JEOL JXA-8230 electron probe microanalyser

doi:10.1016/j.chemgeo.2015.10.042

Chemical Geology

Volume 419, 25 December 2015, Pages 149-157

https://doi.org/10.1016/j.chemgeo.2015.10.042 Get rights and content

Highlights

Electron probe microanalysis of Ni, Mn, Ca, Al, Cr, Co, Ti, Zn, P, Na in olivine by WDS, precision better than 10 ppm (2 σ).
•
Simultaneous with trace elements, analysis of Fe, Mg and Si in olivine by EDS, precision for Fo better than 300 ppm (2 σ).
•
Analytical volume is a half-sphere with a diameter of approximately 7 μm for most elements.

Abstract

Olivine compositions provide critical information on the composition and origin of primary mantle-derived melts and their sources. The minor and trace elements (Ni, Mn, Ca, Al, Cr, Co, Ti, Zn, P, Na), which are present at concentrations over 10 ppm, are especially informative and can be determined by electron probe microanalysis (EPMA). Here we report a new analytical method to analyse these elements with unprecedented precision for an electron microprobe.

The method was developed using the new JEOL JXA 8230 EPMA at ISTerre, UJF, Grenoble, France. The facility has a tungsten source gun and is equipped with five wavelength-dispersive spectrometers (WDS) and one silicon drift detector energy-dispersive spectrometer (SDD, EDS). It is placed in an environment with closely controlled temperature (+/− 0.5 °C) and humidity (+/− 4%).

The analytical conditions are as follows: acceleration voltage 25 kV, 900 nA beam current; WDS detection for trace elements (Ni, Mn, Ca, Al, Cr, Co, Ti, Zn, P, Na) and EDS detection for Si, Mg and Fe; total counting time 12 min; ZAF correction. The analysed volume is a half-sphere with a diameter of approximately 7 μm for most elements or a cylinder with a diameter of 7 μm and depth of approximately 2 μm for Al and Na. Instrumental drift during analytical sessions was monitored by repeated measurements of olivine standards. For trace elements, the method yields detection limits from 4 to 10 ppm and similar precision of individual analyses (2 standard errors). The detectable amount of an element is down to 2 ∗ 10^− 15 g and the precision for Fo in olivine is 200–300 ppm (2 standard errors).

Comparison of data obtained using the EPMA with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for a large range of olivine compositions confirms the accuracy of the EPMA which is similar to the precision noted above.

Introduction

Olivine comprises more than 50% of the upper mantle of the Earth and is the most common mineral in many ultramafic and basaltic volcanic rocks, mantle peridotites and inclusions in diamond. Recent studies have shown that olivine is one of the principal sources of petrological and geochemical information on magma formation and mantle geodynamics (e.g. Sobolev et al., 2005, Sobolev et al., 2007, De Hoog et al., 2010). Especially informative are the concentrations of minor and trace elements in olivine such as Ni, Mn, Ca, Al, Cr, Co, Ti, Zn, P and Na. The range in concentrations of these elements usually varies from 10 to several thousand ppm. Laser ablation inductively coupled mass spectroscopy (LA-ICP-MS) and secondary ion mass spectroscopy (SIMS) are widely applied to the analysis of trace elements in olivine but the spatial resolution of these methods (20–100 μm) is not sufficient to resolve the fine zoning that is commonly observed in olivine phenocrysts from volcanic rocks (Fig. 1). Only the electron microprobe can provide high-precision analysis of trace elements in olivine with a spatial resolution of 1–5 μm. The high-precision EPMA method developed earlier by Sobolev et al. (2007) allowed the analysis of a range of elements – Ni, Mn, Ca, Al, Cr, and Co – in olivine with a precision of 15–30 ppm (2 standard errors). However, elements such as Na, P, Zn and Ti could not be analysed precisely using this method. The purpose of this contribution is to describe an analytical method for high-precision trace-element analyses in olivine, using the new JEOL JXA-8230 electron probe microanalyser at the Institute des Sciences de la Terre (ISTerre), University Grenoble-Alpes, France, which produces analyses of all the elements mentioned above with a precision better than 10 ppm (2 standard errors). The method has been developed and tested by analysing the well-certified San Carlos olivine standard USNM 111312/444 (Jarosewich et al., 1980, De Hoog et al., 2010; Hauri et al., personal communication), an internal laboratory olivine standard (XEN), and a large set of olivines with a wide range of trace element contents from different types of basalts that have been analysed by LA-ICP-MS at the Max-Planck Institute in Mainz, Germany.

Section snippets

Hardware of the electron probe microanalyser in ISTerre

The JEOL JXA-8230 EPMA was installed at ISTerre in 2012. It employs a tungsten (W) filament that provides a very stable beam current (0.05%/h and 0.3%/12 h) even at high (1 microampere) currents. A stable beam current is an essential requirement for precise trace element analyses because of the long counting time needed for signal accumulation on peak and background positions. The central column (40° X-Ray take-off angle) is surrounded by five wavelength-dispersive spectrometers (WDS) and a

Detection limit and counting statistics

EPMA is widely used to measure trace elements in monazite (e.g. Jercinovic and Williams, 2005, Jercinovic et al., 2008, Jercinovic et al., 2012), quartz (e.g. Rusk et al., 2006, Wark and Watson, 2006, Donovan et al., 2011), olivine (e.g. Sobolev et al., 2005, Sobolev et al., 2007, Sobolev et al., 2009 ) and sulphides (e.g. Gervilla et al., 2004). The current challenge when making such measurements is to decrease the detection limit (minimum detectable concentration) and to improve analytical

Analytical precision and accuracy of microprobe analysis of olivine: comparison with LA-ICP-MS.

Routine EPMA procedure includes monitoring of instrumental drift. To do this we run the San Carlos olivine standard as an unknown, three times for every 30–40 measurement points. All measurements of major and trace elements are corrected for deviation from San Carlos olivine reference values (Table 2) if the deviation is higher than 2 sigma errors.

The analytical precision (reproducibility) of olivine analyses, established by repeated measurement of olivine standards, is 200–300 ppm (2 standard

Advantages and precautions during the use of the high-current olivine method

The reported analytical method significantly increases the precision of in-situ analysis of olivine for elements such as Ni, Ca, Al, Cr, Mn, Co, P, and Ti; for the first time trace elements such as Zn and Na by EPMA can be analysed. This opens new perspectives in the study of geochemical and petrological processes involving olivine, including the development of tracers of mantle source composition and particularly the presence of olivine-free mantle lithologies produced by recycled crust. In

Conclusions

A new analytical method for high-precision measurements of 10 trace elements in olivine, together with major elements, was developed on the JEOL JXA-8230 EPMA. The analytical conditions of analysis are: accelerating voltage 25 kV, probe beam current 900 nA, 12 minutes total measurement time for a single analysis. All elements are analysed simultaneously, trace elements by WDS and major elements (Si, Mg, Fe) by EDS. Linear background interpolation methods with background position measurements on

Acknowledgements

Installation and running of JEOL JXA-8230 in ISTerre was supported by the Chair of Excellence grant of Agence nationale de la recherche, France, (ANR-09-CEXC-003-01) and partly by CNRS and Labex OSUG2020 to AVS. The study was partly supported by grants from Russian Science Foundation 14-17-00491 to AVS and VB and Russian Foundation for Basic Research grants 13-05-00640 to VB and 13-05-12110 to AVS.

We acknowledge K.-P. Jochum, B. Stoll and U. Weis for their help with the LA-ICP-MS and K.

References (39)

L.A. Coogan et al.
Aluminum-in-olivine thermometry of primitive basalts: evidence of an anomalously hot mantle source for large igneous provinces
Chem. Geol.
(2014)
J.C.M. De Hoog et al.
Trace-element geochemistry of mantle olivine and application to mantle petrogenesis and geothermobarometry
Chem. Geol.
(2010)
M.J. Jercinovic et al.
In-situ trace element analysis of monazite and other fine-grained accessory minerals by EPMA
Chem. Geol.
(2008)
V. Le Roux et al.
Mineralogical heterogeneities in the Earth's mantle. Constraints from Mn, Co, Ni and Zn partitioning during partial melting. Earth Planet
Sci. Lett.
(2011)
J. Philibert
A method for calculating the absorption correction in electron probe analysis
J. Prytulak et al.
TiO₂ enrichment in ocean island basalts
Earth Planet. Sci. Lett.
(2007)
N.V. Sobolev et al.
Petrogenetic significance of minor elements in olivines from diamonds and peridotite xenoliths from kimberlites of Yakutia
Lithos
(2009)
M. Ancey et al.
Applications of statistical methods in microanalysis
V.G. Batanova et al.
Consequences of channelised and diffuse melt transport in supra-subduction mantle: evidence from Voykar ophiolite (Polar Urals)
J. Petrol.
(2011)
J.J. Donovan et al.
An improved mean atomic number background correction for quantitative microanalysis
J. Microsc. Microanal.
(1996)

J.J. Donovan et al.

Improved electron probe microanalysis of trace elements in quartz

Am. Miner.

(2011)

D.A. Gedcke

How counting statistics controls detection limits and peak precision, AN59: http://www.ortec-online.com

(2001)

F. Gervilla et al.

Platinum-group element distribution in some ore deposits: results of EPMA and Micro-PIXE analyses

Microchim. Acta

(2004)

J. Goldstein et al.

Scanning Electron Microscopy and X-Ray Microanalysis

(2007)

C. Herzberg

Petrology and thermal structure of the Hawaiian plume from Mauna Kea volcano

Nature

(2006)

E.J. Jarosewich et al.

Reference samples for electron microprobe analysis

Geostand. Newslett.

(1980)

R. Jenkins et al.

Practical X-ray Spectrometry

(1982)

M.J. Jercinovic et al.

Analytical perils (and progress) in electron microprobe trace element analysis applied to geochronology: background acquisition, interferences, and beam irradiation effects

Am. Miner.

(2005)

M.J. Jercinovic et al.

Trace analysis in EPMA: Emas 2011: 12th European Workshop on modern developments in microbeam

Analysis

(2012)

Cited by (103)

High-precision measurement of chlorine in sphalerite by electron probe microanalysis: Method and application
2024, Ore Geology Reviews
The halogen Cl is one of the sensitive indicators for the origin of ore-forming fluids. However, accurate analysis of trace Cl in minerals or glasses remains a challenge. Here, we establish an electron probe microanalysis (EPMA) method for determination of Cl in sphalerite by investigating the key parameters such as accelerating voltage, analytical crystals, beam current, peak counting time, primary calibration standards, and secondary fluorescence effects. Detection limit (3σ) for Cl can be lowered to 14 ppm. The proposed method was used to analyze Cl and other minor/trace elements such as Fe and Ge in sphalerite from the Shanshulin Mississippi Valley type Zn-Pb deposit in the southwestern China. EPMA mapping and profile analyses show that Cl is heterogenous (from below detection limit to 869 ppm) in sphalerite with zoning patterns. Random point analyses show the highest Cl content in the studied sphalerite is 2730 ppm. No correlation of Cl with sphalerite color, Fe, Ge, S, and Zn indicates that Cl behaves differently from other elements. Considering detectable and various Cl contents in sphalerite at the grain scale, between samples, and between deposits, Cl together with other elements can be used to constrain the ore genesis.
Structure characterization of aged automobile exhaust catalysts using electron probe microanalysis
2024, Analytica Chimica Acta
Driven by emission regulations, the technology of emission control catalysts has been under increasing need for development. Understanding the deactivation mechanism of aged or spent automobile exhaust catalysts is the key to extending their service lifetime. However, the lack of comprehensive microstructural characterization results in an incomplete understanding of their physicochemical properties. Deactivation mechanism of automobile exhaust catalysts is a considerably complex phenomenon, it can be classified into three groups based on its origin: thermal sintering, chemical poisoning and mechanical deactivation.
In this study, an aged high-mileage automobile exhaust catalyst with Pd and Rh active phases supported on a cerium zirconium oxide doped alumina coating on cordierite was analysed; six consecutive monolithic blocks along the inlet to the outlet of the aged catalyst were extracted, and the corresponding metallographic samples were fabricated using the vacuum impregnation resin method. The purpose of this study was to accurately characterize the different regions of the monolith via electron probe microanalysis and to infer potential causes of catalyst deactivation. Two major causes of deactivation were found: (1) aggregation and alloying of precious-metal particles caused by thermal sintering and (2) chemical poisoning caused by sulphur and phosphorus. Other mechanisms, such as mechanical degradation, which mainly manifests as the loss or wear of the washed coating, were also found to be involved in deactivation. Additionally, the catalytic activity tests showed a considerable decrease in the aged catalyst. The poison concentration trends in the washcoat indicated that P is detrimental to CO oxidation, while S accumulation affects propane oxidation.
This analysis method can be of substantial practical significance in developing advanced washcoat materials. Meanwhile, it has great potential in the washcoat analysis of honeycomb-shaped monolithic catalyst, such as natural gas catalyst, diesel vehicle oxidation catalyst and other honeycomb catalysts applied in chemical industry.
Low Ni and Co olivine in Chang'E-5 basalts reveals the origin of the young volcanism on the Moon
2023, Science Bulletin
Mare basalts returned by the Chang’E-5 (CE5) mission extend the duration of lunar volcanism almost one billion years longer than previously dated. Recent studies demonstrated that the young volcanism was related neither to radiogenic heating nor to hydrous melting. These findings beg the question of how the young lunar volcanism happened. Here we perform high-precision minor element analyses of olivine in the CE5 basalts, focusing on Ni and Co. Our results reveal that the CE5 basalt olivines have overall lower Ni and Co than those in the Apollo low-Ti basalts. The distinctive olivine chemistry with recently reported bulk-rock chemistry carries evidence for more late-stage clinopyroxene-ilmenite cumulates of the lunar magma ocean (LMO) in the CE5 mantle source. The involvement of these Fe-rich cumulates could lower the mantle melting temperature and produce low MgO magma, inhibiting Ni and Co partitioning into the magma during lunar mantle melting and forming low Ni and Co olivines for the CE5 basalts. Moreover, the CE5 olivines show a continuous decrease of Ni and Co with crystallization proceeding. Fractional crystallization modeling indicates that Co decreasing with crystallization resulted from CaO and TiO₂ enrichment (with MgO and SiO₂ depletion) in the CE5 primary magma. This further supports the significant contribution of late-stage LMO cumulates to the CE5 volcanic formation. We suggest that adding easily melted LMO components resulting in mantle melting point depression is a key pathway for driving prolonged lunar volcanism. This study highlights the usefulness of olivine for investigating magmatic processes on the Moon.
Behavior of critical metals in cumulates of alkaline ultramafic magmas in the Siberian large igneous province: Insights from melt inclusions in minerals
2023, Ore Geology Reviews
Ultramafic-alkaline-carbonatite complexes (UACC), which are formed from mantle-derived carbonated alkali-ultramafic melts in large igneous provinces (LIPs), are important resources of Fe, Ti, U, Th, Nb, rare earth elements (REEs), Cu, Ni and platinum group elements (PGEs). Concentration of these metals and ore formation is assumed to be largely controlled by magmatic differentiation and post-magmatic hydrothermal processes. Although basic patterns of the metals’ partitioning during formation of the UACCs are constrained by geochemical and mineralogical features of the rocks, including in experimental studies, our understanding of their pathway “from primitive melt to ore deposit” is far from complete. In order to further constrain the metals’ behavior during differentiation of a carbonated alkali-ultramafic melt, we studied multiphase inclusions in olivine, chromite, perovskite, pyroxene and magnetite in the ultramafic rocks from three UACCs (Guli, Bor-Uryakh and Odikhincha), located in the Siberian LIP. Examination of both unheated and experimentally heated and quenched inclusions reveals a variety of compositions from melanephelinitic through to highly differentiated nephelinitic to alkali-rich carbonatitic. In addition, sulfide minerals, which turn into immiscible sulfide liquids during heating experiments, are widely distributed in the inclusions’ assemblages. We consider these inclusions to be snapshots of intercumulus melts, which were entrained into olivine-rich cumulate mush, and use their compositions to delineate plutonic differentiation of a carbonated alkali-ultramafic melt. Highly differentiated silicate melts, entrapped in Fe-rich chromite (Guli dunites), were rich in U, Th and Nb and crystallized Os-Ir-Ru phases in proximity to the host chromite. Concentrations of U, Th, Nb and REEs in alkali-rich carbonatite liquids, which were present in the intercumulus of Odikhincha and Bor-Uryakh peridotites, approached levels similar to mineralized carbonatites and support the concentration of these metals in an immiscible alkali-carbonatite fraction, which was enriched in S, P and Cl. Minor sulfide liquids, which are closely associated with these carbonatite fractions, were strongly enriched in Cu and Ni, thus explaining the origin of the Phalaborwa-like sulfide ores in carbonatites as a result of magmatic differentiation. Finally, our study provides insights into the formation of peridotite-hosted types of mineralization (perovskite-magnetite ores, mineralized carbonatite veins and PGE-bearing chromitites) and shows that these ore-bearing assemblages can be formed due to the infiltration of the metal-bearing intercumulus melts through the ultramafic matrix.
Secondary fluorescence effect quantification of EPMA analyses of olivine grains embedded in basaltic glass
2023, Chemical Geology
Trace element analysis of olivine is challenging but vital, since trace elements in olivine can potentially record crystallization conditions and, correspondingly, conditions of magma generation, evolution, and transport dynamics. Electron microprobe analysis (EPMA) is one of the most widely used methods for trace element analysis in olivine for many reasons including but not limited to high-spatial resolution and high precision. EPMA protocols with high-beam currents and long-counting times provide accurate trace element concentrations with low-detection limits. However, these protocols neglect the effect of secondary fluorescence (SF) across phase boundaries, which may lead to fictitious analytical results when analyses are performed near other phases. In these cases, obtaining accurate EPMA data requires correction of SF effects from the adjacent or surrounding phase. In this study, the contents of olivine trace elements Ca, Ni, Mn, Ti, Cr, and Al have been measured in run products of experimental high-temperature studies on mafic magmatic systems consisting of olivine grains embedded in basaltic glass. Olivine grain fragments with known composition, were embedded in basaltic powder, and heated to 1250 °C in 1-atm vertical gas-mixing furnace for a few minutes and quenched. EPMA analyses of the olivine grains before and after the experiments were used to quantify the effect of SF, which was found to be most significant for Ca and Ti, and to a lesser extend for Al, and to depend on the distance from the interface, olivine grain geometry, accelerating voltage, and olivine and glass compositions. By combining our experimental results with systematic SF calculations performed with the Monte Carlo simulation program PENEPMA, analytical expressions that give the apparent Ca, Ti, and Al concentrations due to SF in equant olivine grains embedded in basaltic glass were derived. These equations, which allow for a rapid correction of SF effects, are used to assess the average overestimation due to SF of olivine analyses included in current experimental databases, which might be the source of major discrepancies observed in petrological tools utilizing trace element contents in olivine.
Accurate analyses of key petrogenetic minor and trace elements in olivine by electron microprobe
2022, Chemical Geology
Abundances of minor and trace elements in olivine are increasingly used as petrogenetic indicators for mantle source lithologies, mantle metasomatism history, mantle potential temperatures, and magmatic differentiation. As it is common for olivine to be complexly zoned on a fine-scale, high precision analytical methods for EPMA (electron microprobe microanalyzer, or Electron Microprobe) trace element analysis under high spatial resolution have been developed. However, previous studies have focused more on analytical precision with fewer efforts in examining the accuracy of the data. In this study, we used the Cameca SXFive field emission (FE) EPMA to fully evaluate the effects of beam settings, background offsets and background regression models, and primary calibration standards on the data accuracy of 10 key petrogenetic elements (Na, Al, P, Ca, Ti, Cr, Mn, Co, Ni, and Zn) using MongOlSh11–2 olivine as a reference material. Our results indicate that high voltage, high beam current and long counting time not only improve data precision, but also improve data accuracy, especially on elements with low P/B (peak/background) ratios such as Zn and Cr. Importantly, careful background offsets and background regression models need to be obtained via high resolution WDS relative scans or step scans on each target element. Special care needs to be paid to Co element analysis to avoid or correct for peak interference of Fe Kβ. Among 10 minor and trace elements, exponential background regression models need to be applied to Al, Mn, and Ti elements, whereas other elements require linear background regression. Furthermore, to avoid Al and Zn surface contamination due to alumina polishing or brass presence, ultrasonic cleaning between each intermediate polishing steps and plasma cleaning immediately prior to EPMA experiments is highly recommended. Micro-inclusions such as chromite and spinel in olivine or adjacent Ca-rich phases need to be avoided to minimize primary or secondary fluorescence-related contamination on Al, Cr, or Ca. As a volatile element, Na element needs to be analyzed first with appropriate counting time to minimize the Na loss under high beam conditions. It needs mentioning that major elements (Mg, Fe, and Si) are best analyzed using MongOlSh11–2 or San Carlos olivine as primary standards for calibrations, which can yield more accurate data for both major elements and trace elements because of the improved matrix-corrections. Using our recommended analytical protocols, we have successfully discriminated “depleted” mantle olivine cores from an EMORB in northern East Pacific Rise (EPR) via Ca, Ti, Ni, Co, and Mn abundances. Our olivine data from Siqueiros Transform and the nearby 8°20′ N seamounts also help reveal a metasomatized peridotite mantle beneath the northern EPR. Overall, the protocols proposed in this study can serve as a guide for accurate EPMA olivine trace element analyses, which potentially contributes to the efforts of fostering a comparable olivine database worldwide.

View all citing articles on Scopus

View full text

Trace element analysis of olivine: High precision analytical method for JEOL JXA-8230 electron probe microanalyser

Highlights

Abstract

Introduction

Section snippets

Hardware of the electron probe microanalyser in ISTerre

Detection limit and counting statistics

Analytical precision and accuracy of microprobe analysis of olivine: comparison with LA-ICP-MS.

Advantages and precautions during the use of the high-current olivine method

Conclusions

Acknowledgements

Chem. Geol.

Chem. Geol.

Chem. Geol.

Sci. Lett.

Earth Planet. Sci. Lett.

Lithos

Applications of statistical methods in microanalysis

Consequences of channelised and diffuse melt transport in supra-subduction mantle: evidence from Voykar ophiolite (Polar Urals)

J. Petrol.

An improved mean atomic number background correction for quantitative microanalysis

J. Microsc. Microanal.

Improved electron probe microanalysis of trace elements in quartz

Am. Miner.

How counting statistics controls detection limits and peak precision, AN59: http://www.ortec-online.com

Platinum-group element distribution in some ore deposits: results of EPMA and Micro-PIXE analyses

Microchim. Acta

Scanning Electron Microscopy and X-Ray Microanalysis

Petrology and thermal structure of the Hawaiian plume from Mauna Kea volcano

Nature

Reference samples for electron microprobe analysis

Geostand. Newslett.

Practical X-ray Spectrometry

Analytical perils (and progress) in electron microprobe trace element analysis applied to geochronology: background acquisition, interferences, and beam irradiation effects

Am. Miner.

Trace analysis in EPMA: Emas 2011: 12th European Workshop on modern developments in microbeam

Analysis