In Situ Multi-Element Analysis of the Mount Pinatubo Quartz-Hosted Melt Inclusions by NIR...

In Situ Multi-Element Analysis of the Mount PinatuboQuartz-Hosted Melt Inclusions by NIR Femtosecond LaserAblation-Inductively Coupled Plasma-Mass Spectrometry

Vol. 32 — N° 2 p . 2 0 9 - 2 2 9

Microscopic melt inclusions found in magmaticminerals are undoubtedly one of the most importantsources of information on the chemical compositionof melts. This paper reports on the successful application of near-infrared (NIR) femtosecond laserablation (LA) - inductively coupled plasma-massspectrometry to in situ determination of incompatible trace elements (Li, Rb, Sr, Y, Zr, Nb, Cs,Ba, REE, Ta, Th, U) and ore metals (As, Mo, Pb) inindividual melt inclusions hosted in quartz from theMount Pinatubo dacites, Philippines. The determinedelements cover a concentration range of five ordersof magnitude. Femtosecond LA-ICP-MS analyses of twenty-eight individual melt inclusions demonstrate the efficiency of the microanalyticaltechnique and suggests a spectacular homogeneityof the entrapped melt, at least with respect to thefollowing incompatible trace elements: Rb, Sr, Nb,Cs, Ba, La, Ce, Pr, Nd, Pb, Th. The analytical precision (1s) for Na, Ca, Rb, Sr, Y, Nb, Ba and LREE ranged from 3 to 20%. Comparison of trace element concentrations in Mt. Pinatubo melt inclusions determined by femtosecond LA-ICP-MSwith those of melt inclusions previously analysed bysecondary ion mass spectrometry analysis (SIMS)and those of matrix glasses previously determinedby nanosecond LA-ICP-MS showed an agreementtypically within 30-40%. The homogeneity of traceelement concentrations of the Mt. Pinatubo meltinclusions and the matrix glasses is consistent withthe melt inclusion origin as homogeneous rhyoliticmelt that was trapped in quartz phenocrysts at thefinal crystallisation stages of the host adakite (dacite) magma.

Les inclusions vitreuses microscopiques présentesdans les minéraux d'origine magmatique sont sans aucun doute l'une des plus importantessources d'information sur la composition chimiquedes magmas. Cet article porte sur l'utilisation d'un système d'ablation laser femtoseconde travaillantdans l'infra rouge proche (NIR), couplé avec unspectromètre de masse à plasma inductif, pour analyser in situ les éléments en trace incompatibles(Li, Rb, Sr, Y, Zr, Nb, Cs, Ba, REE, Ta, Th, U) et lesmétaux (As, Mo, Pb) dans des inclusions vitreuses.Les inclusions analysées ici proviennent de quartz présents dans la dacite du Mont Pinatubo(Philippines). Les éléments analysés ont des concentrations couvrant 5 ordres de grandeur. Lesanalyses par LA-ICP-MS (femtoseconde) de vingthuit inclusions individuelles montrent l'efficacité decette technique de micro analyse et met en évidencel'homogénéité impressionnante des liquides piégéspour les éléments en trace suivants : Rb, Sr, Nb, Cs,Ba, La, Ce, Pr, Nd, Pb, Th. La précision des analysesde Na, Ca, Rb, Sr, Y, Nb, Ba et les Terres Rareslégères (LREE) varie de 3 à 20%. La comparaisonentre ces données et, d'une part celles obtenuesprécédemment par sonde ionique (SIMS), d'autrepart, celles obtenues par LA-(nanoseconde)-ICP-MSsur des verres de la matrice, montre que toutes sonten accord à 30-40% près. L'homogénéité desconcentrations en éléments en trace dans les inclusions vitreuses et les verres de la matrice est enaccord avec le modèle de genèse des inclusionsvitreuses à partir d'un liquide rhyolitique piégédans les phénocristaux de quartz lors des stagesfinaux de cristallisation du magma adakitique(dacitique) hôte.

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Anastassia Yu. Borisova (1, 2)*, Rémi Freydier (1), Mireille Polvé (1), Stefano Salvi (1), Frederic Candaudap (1) and Thierry Aigouy (1)

(1) Laboratoire des Mécanismes et Transferts en Géologie, LMTG, Université de Toulouse III, CNRS - IRD - OMP, 14 Avenue E. Belin, 31400 Toulouse, France

(2) Geological Department, Lomonosov Moscow State University, Leninskie Gory, 119899, Moscow, Russia* Corresponding author. e-mail: [email protected]

© 2008 The Authors. Journal compilation © 2008 International Association of Geoanalysts

GEOSTANDARDS and

RESEARCHGEOANALYTICAL

Primary melt inclusions form when small volumes ofmelt are trapped by a mineral during its growth in amagma (Roedder 1984). At room temperature theycan contain a combination of glass, gaseous and crys-talline phases. Melt inclusions have been describedin a wide range of igneous rocks (cf. Schiano andClocchiatti 1994, Veksler 2006, Webster and Thomas2006) and can provide very important information onmagma origin (e.g., Sobolev and Shimizu 1993), frac-tionation processes (e.g., Borisova et al. 2001, 2006),lithosphere contamination (e.g., Borisova et al. 2002),degassing and eruptive mechanisms (e.g., Borisova etal. 2005). Indeed, it is difficult to assess melt composi-tions via bulk-rock analysis because of the complexityof magmatic processes, such as phenocryst accumula-tion, magma mixing and assimilation, fractional crystal-lisation, not to mention post-magmatic processes suchas hydrothermal al terat ion and weathering (e .g. ,Borisova et al. 1996, 1997, Borisova 2001). Melt inclu-sions are probably the best material through whichone can reconstruct the composition of primary melts.Given the frequent occurrence of melt inclusions in vol-canic rocks, development of a rapid high-precisionmethod for their in situ analysis (EMPA, SIMS, LA-ICP-MS, LA-MC-ICP-MS, EXAFS) is necessary.

The majority of previous analytical laser ablationstudies are based on nanosecond pulsed lasers (e.g.,Taylor et al. 1997, Günther et al. 1999, 2000, Pettke2006). Nowadays, femtosecond lasers are findingwidespread use in many applications (e.g., Fernándezet al. 2007, Mateo et al. 2007) because of their abilityto ablate well-defined craters with minimal thermalheating of the area around the crater (Russo et al.2002a), thus reducing the risk of elemental fractiona-tion (Du et al. 1994, Stuart et al. 1996, , Russo et al.2002b, Poitrasson et al. 2003, Freydier et al. 2008).Therefore, femtosecond laser has been suggested asan alternative for laser-ablation based chemical analy-sis. Preliminary research using femtosecond laser foranalytical spectroscopy has only recently been repor-ted (Margetic et al. 2000, 2001a, b, Le Drogoff et al.2001, Ye and Grigoropoulos 2001). These studiesaddress chemical analysis in the laser induced break-down spectroscopy (LIBS). The real “breakthrough” of

the femtosecond laser application into the LA-ICP-MStechnique starts with the work of Russo et al. (2002a),who investigated the effect of laser fluence on elemen-tal fractionation and in particular, on Pb/U ratios.Poitrasson et al. (2003) compared analytical precision,repeatability and accuracy of nanosecond versus fem-tosecond LA-ICP-MS (fs-LA-ICP-MS) determinationsusing reference glasses and natural minerals. Horn etal. (2006) performed in situ Fe-isotope ratio determina-tions in minerals using ultraviolet (UV) femtosecond LA-MC-ICP-MS. González et al. (2006) worked on repea-tabi l i ty of glass microanalyses and Mozná et al .(2006) performed quanti tative analysis of Fe-richsamples using UV femtosecond and nanosecond LA-ICP-MS (ns-LA-ICP-MS). Freydier et al. (2008) studiedthe influence of pulse duration and wavelength on theinternal precision, reproducibility and accuracy of LAquadrupole ICP-MS measurements.

This paper reports on a successful application of fs-LA-ICP-MS to the quantitative geochemical analysis ofthermally homogenised melt inclusions from the Mt.Pinatubo, with particular emphasis on the determina-tion of ore metal (Cu, Zn, As, Mo, Sb, Pb) and incom-patible trace element (Li, Rb, Sr, Y, Zr, Nb, Cs, Ba, REE,Ta, Th, U) concentrations. The impact of our new dataas petrogenetic tools for the understanding of adakiticmagma genesis is important (e.g. , Borisova et al .2006). This analytical technique couples the advan-tages of in situ micro-sampling using a laser ablationmicroprobe with the low detection limits and highsensitivity for many elements provided by the ICP-MStechnique. Internal precision, accuracy of the successivemicroanalyses of natural and standard glasses by fs-LA-ICP-MS and trace element homogeneity of the meltinclusions are evaluated in this study.

Materials and methods

Materials

The samples used in this study consisted of meltinclusions from Mt. Pinatubo that have been the subjectof previous microanalytical studies of volatile and traceelement contents (Borisova et al. 2005, 2006). These

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GEOSTANDARDS and



Keywords: near-infrared femtosecond laser, LA-ICP-MS,rhyolitic melt inclusions, analytical precision, accuracy,MPI-DING reference glasses.

Mots-clés : laser femto seconde dans l'infra rougeproche, LA-ICP-MS, inclusions de liquide rhyolitique,précision analytique, justesse, verres de référence MPI-DING.

Received 20 Sep 07 — Accepted 30 Apr 08

https://www.researchgate.net/publication/9010424_Comparison_of_Ultraviolet_Femtosecond_and_Nanosecond_Laser_Ablation_Inductively_Coupled_Plasma_Mass_Spectrometry_Analysis_in_Glass_Monazite_and_Zircon?el=1_x_8&enrichId=rgreq-2a22978f-ea5f-4232-8a85-74d9f5ad0f75&enrichSource=Y292ZXJQYWdlOzIyOTU5NjgwNztBUzo5ODY1NDIyODU4MjQxMEAxNDAwNTMyNDA5ODg0

https://www.researchgate.net/publication/244553895_Evaluation_of_Infrared_Femtosecond_Laser_Ablation_for_the_Analysis_of_Geomaterials_by_ICP-MS?el=1_x_8&enrichId=rgreq-2a22978f-ea5f-4232-8a85-74d9f5ad0f75&enrichSource=Y292ZXJQYWdlOzIyOTU5NjgwNztBUzo5ODY1NDIyODU4MjQxMEAxNDAwNTMyNDA5ODg0

inclusions occur in quartz phenocrysts from fresh daciteco l lec ted a f te r the erupt ion o f June 15 th, 1991.Although the laser ablation ICP-MS technique provideslaser-induced homogenisation of melt or fluid inclu-sions (e.g., Taylor et al . 1997), the investigated meltinclusions had been previously thermally homogenisedby placing the samples in internally- and externally-heated pressure vessels at 760-780 °C and 185-200MPa for 20 to 24 hours. Run duration was dictated bythe diffusion rate of H2O and CO2 in silicate glasses,in order to obtain homogeneous glasses with respectto major (cf. Borisova et al. 2005) and trace elements.The temperature diapason of 760-780 °C was consi-dered to correspond to the host quartz crystallisationand the quartz-hosted inclusion entrapment (Borisovaet al. 2005). Detailed descriptions of the melt inclu-sions before and after homogenisation experiments aswell as of the experimental procedures can be foundin Borisova et al. (2005), along with major elementdata on the included glass and crystalline phases. Themelt inclusions range in size from 30 to 150 μm (withan average size of 60 μm) and contain homogeneousglasses (homogenised melt inclusions) or glasses withgaseous bubbles (partially homogenised melt inclu-s ions) ; however, only inclusions with minor or nobubble(s) were selected for this study (Figure 1). Afterthe homogenisation experiments, the quartz grainswere mounted in epoxy (Teflon slides, 1 inch diameter)and were hand polished using 3 μm, 1 μm and 0.5μm diamond pastes (Hyprez, Liquid Diamond) asdetailed in Borisova et al. (2005).

Analytical techniques

Laser ablation techniques use a focused laserbeam to ablate a sample confined in a closed cell. Inour system, the ablated material was carried in a flowof helium gas which was mixed with argon in thetransporting tube connected to an ICP-MS. The instru-ment used in this study was a quadrupole-based Elan6000 ICP-MS (Perkin-Elmer SCIEX). We used a femto-second Ti:Sapphire type laser (Pulsar 10, AmplitudeTechnologies) that could provide 55 fs pulse duration,at a wavelength of 800 nm NIR and had a maximumoutput of 12 mJ/pulse (cf. Freydier et al. 2008). Thelaser was fired at a repetition rate of 5 Hz. The laserGaussian beam was then focused, using a x15 objec-tive (reflective) or x1.75 silica lens (Table 1), onto aNIST SRM 612 glass sample placed in a cell locatedon a manual X-Y-Z mechanical stage. Such focusingyielded ablation pits of 50 μm (x15 objective, first andthird ablation sessions) to 200 μm (x1.75 silica lens,

first ablation session) in size on inclusions and glassesanalysed in single-point mode (Table 1). Pulse energyof 1.3 mJ/pulse (using the x15 objective for inclusions)to 7.5 mJ/pulse (using the silica lens for referenceglass) was applied during the first ablation session.Pulse energy of 2 mJ/pulse (with the objective) wasused for the analysis of melt inclusions during thesecond session. Pulse energy of 1.5 mJ/pulse (with theobjective) was used to analyse reference glasses in thethird ablation session. Thirty-four elements (thirty-six dif-ferent masses) were measured with dwell times of 10ms (see list in Table 1). The total acquisition time forone complete analysis was about 2 minutes. PlasmaRF power was set at 1300 W, and other operatingconditions and acquisition parameters of the Perkin

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GEOSTANDARDS and



Figure 1. Photomicrographs of two melt inclusions in

quartz from the Mt. Pinatubo dacite pumice (15th June

1991 eruption), before analysis: (top) homogenised

(Hom 2a:34, Table 2) and (below) partly homogenised

(Hom 2a:42). Melt inclusion classification and inclusion

types are discussed in Borisova et al. (2005).


https://www.researchgate.net/publication/222017492_In_situ_silicate_melt_inclusions_by_laser_ablation_microprobe-inductively_coupled_plasma-mass_spectrometry_LAM-1CP-MS?el=1_x_8&enrichId=rgreq-2a22978f-ea5f-4232-8a85-74d9f5ad0f75&enrichSource=Y292ZXJQYWdlOzIyOTU5NjgwNztBUzo5ODY1NDIyODU4MjQxMEAxNDAwNTMyNDA5ODg0

Elmer Elan 6000 ICP-MS were similar to those used byFreydier et al. (2008). The data obtained for all silicateglasses were processed using the GLITTER 4.0 softwarepackage (GEMOC, Macquarie University, Sydney-Australia). International glass certified reference mate-rial NIST SRM 612 was used for external calibration(Pearce et al. 1997), whereas Na and Ca were usedas internal standards. Na2O (for the second ablationsession only) and CaO concentrations in inclusions

were measured at the Insti tute de Sciences de laTerre (ISTO, Orléans, France) using a wavelength-dispersive electron microprobe analysis package(Cameca SX-50) optimised to provide high-precisionanalyses (Borisova et al. 2005). The following analyt-ical protocol was used: from two to five NIST SRM612 glass calibrator ablations, then five to sevenglass analyses, and finally two to five NIST SRM 612glass cal ibrator ablat ions , the cyc le then being

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GEOSTANDARDS and



Table 1.LA-ICP-MS operating conditions

LASERWavelength 800 nmRepetition rate 5 HzPulse duration 55 fsLaser fluence* 77 J cm-2 (50 μm, 1.5 mJ/pulse) - 96 J cm-2 (200 μm, 7.5 mJ/pulse)Theoretical laser fluence** 15,500 J cm-2 (3.5 μm, objective, 1.5 mJ/pulse) – 9,500 J cm-2 (10 μm, silica lens, 7.5

mJ/pulse)

Ablation session number 1 (first) 2 (second) 3 (third)

Optical material used for: melt inclusion analysis x 15, objective, f.l. = 13 mm x 15, objective, f.l. = 13 mm -MPI-DING reference glass analysis x 1.75, silica lens, f.l.= 10 cm - x 15, objective, f.l. = 13 mm

Incident pulse energy used for: melt inclusion analysis 1.3 mJ/pulse 2 mJ/pulse -MPI-DING reference glass analysis 7.5 mJ/pulse - 1.5 mJ/pulse

Ablation pit obtained for: melt inclusion analysis 50 μm 70 μm -MPI-DING reference glass analysis 200 μm - 50 μm

ICP-MSModel Elan 6000Forward power 1300 W

Gas flowsPlasma 15 l min-1

Auxiliary 1.2 l min-1

Carrier Ar 0.5 l min-1

Carrier He 0.5 l min-1

Data acquisition parameters:Data acquisition protocol Time resolved analysisScanning mode Peak hopping, 1 point per peakIsotopes determined 7Li, 23Na, 43Ca, 44Ca, 48Ti, 63Cu, 65Cu, 66Zn, 75As, 85Rb, 88Sr, 89Y, 90Zr, 93Nb, 95Mo, 114Cd,

120Sn, 121Sb, 133Cs, 138Ba, 139La, 140Ce, 141Pr, 144Nd, 152Sm, 153Eu, 158Gd, 159Tb, 164Dy, 172Yb, 175Lu, 181Ta, 197Au, 208Pb, 232Th, 238U

Dwell time per isotope 10 msSweeps / readings 1Readings / replicate 490Numbers of replicates 1Blank analysis 10 sAnalysis time 120 s

* The diameter of the ablation crater being typically 50–200 μm as measured using optical and electronic microscopy, an estimation of thelaser fluence based on the crater diameter would yield around 77–96 J cm-2. Craters resulting from femtosecond laser ablation result from a timeintegrated process resulting from the penetration of a beam having a conical shape.

** An estimation of theoretical laser fluence based on the focal spot diameter (3.5 - 10 μm) would yield around 9,500–15,500 J cm-2 on thesample surface (Freydier et al. 2008). The theoretical laser fluence calculated using focal spot diameter is more representative of the energy reallydelivered by the laser system at the onset of the ablation process than when using the ablation crater diameter. Focal spot size is a theoreticalprediction assuming the focusing of the laser is diffraction limited and taking into account an estimate of the diameter of the incident beam onthe lens. Several effects (e.g., geometrical aberrations, focusing below the surface) could increase the size of the spot on the sample surface(Freydier et al. 2008).




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GEOSTANDARDS and



Table 2.Major and trace element composition (in μg g-1) of homogenised and partially homogenised melt inclusions in quartz of the Mount Pinatubo dacite pumices

Inclusion: 22-INCL-1i 24-INCL-3 25-INCL-4 28-INCL-7 29-INCL-8 31-INCL-10 35-INCL-11

Session: 1 1 1 1 1 1 1

Ca (μg g-1) 8471 ± 596 7046 ± 631 7786 ± 636 8052 ± 597 8232 ± 800 5517 ± 1179 8759 ± 974

Li 2.10 ± 0.57 10.98 ± 2.19 9.96 ± 1.94 5.70 ± 1.18 3.69 ± 1.16 9.42 ± 4.29 13.77 ± 3.10

Cu 44.35 ± 4.35 21.77 ± 3.05 84.84 ± 9.03 11.66 ± 1.52 81.24 ± 10.11 d.l. 78.04 ± 11.09

Zn 30.27 ± 8.37 17.92 ± 7.53 26.01 ± 8.87 29.83 ± 9.31 27.93 ± 10.75 d.l. d.l.

As 5.41 ± 1.57 10.26 ± 2.74 7.98 ± 2.28 9.67 ± 2.27 10.98 ± 3.20 d.l. 5.62 ± 2.82

Rb 74.47 ± 6.31 67.34 ± 6.84 71.94 ± 6.91 82.50 ± 7.65 83.81 ± 9.40 53.93 ± 11.01 83.09 ± 10.75

Sr 147.56 ± 12.36 132.57 ± 13.28 136.30 ± 12.92 161.15 ± 14.84 143.72 ± 15.97 114.71 ± 23.19 169.58 ± 21.84

Y 5.14 ± 0.44 4.96 ± 0.54 5.66 ± 0.56 6.48 ± 0.58 5.82 ± 0.68 5.64 ± 1.19 6.34 ± 0.83

Zr 52.90 ± 3.93 38.45 ± 3.60 56.59 ± 4.84 62.75 ± 4.97 59.71 ± 6.05 35.61±7.16 48.57 ± 5.68

Nb 4.49 ± 0.37 4.58 ± 0.49 4.68 ± 0.45 5.08 ± 0.42 5.45 ± 0.61 3.34 ± 0.78 5.57 ± 0.70

Mo 0.64 ± 0.26 2.00 ± 0.55 d.l. 2.23 ± 0.41 1.90 ± 0.57 2.66 ± 1.27 1.57 ± 0.66

Sn 2.95 ± 0.36 1.43 ± 0.29 1.79 ± 0.29 2.26 ± 0.30 1.97 ± 0.38 d.l. 3.21 ± 0.59

Sb 0.63 ± 0.15 1.03 ± 0.25 0.45 ± 0.14 0.78 ± 0.16 1.93 ± 0.43 d.l. 0.75 ± 0.27

Cs 5.57 ± 0.46 5.73 ± 0.59 6.75 ± 0.63 7.33 ± 0.64 7.16 ± 0.79 5.03 ± 1.07 6.89 ± 0.87

Ba 510.45 ± 37.74 496.53 ± 45.17 510.54 ± 43.21 579.49 ± 46.19 603.88 ± 60.54 416.44 ± 81.18 631.72 ± 73.14

La 17.67 ± 1.46 16.90 ± 1.69 19.28 ± 1.81 20.43 ± 1.83 21.63 ± 2.38 14.70 ± 2.98 23.11 ± 2.94

Ce 30.68 ± 2.52 30.38 ± 3.02 31.79 ± 2.97 35.23 ± 3.16 36.88 ± 4.04 25.33 ± 5.12 39.47 ± 5.01

Pr 2.80 ± 0.27 3.07 ± 0.36 2.95 ± 0.33 3.38 ± 0.35 3.19 ± 0.41 2.11 ± 0.48 3.25 ± 0.48

Nd 8.52 ± 0.83 7.83 ± 0.96 8.53 ± 0.97 9.39 ± 0.98 9.01 ± 1.19 6.40 ± 1.49 9.71 ± 1.45

Sm 1.27 ± 0.19 0.71 ± 0.18 1.29 ± 0.23 1.43 ± 0.21 1.44 ± 0.30 1.02 ± 0.48 1.29 ± 0.33

Eu d.l. d.l. d.l. 0.29 ± 0.05 d.l. 0.39 ± 0.21 d.l.

Gd 0.85 ± 0.16 0.71 ± 0.21 0.81 ± 0.18 1.04 ± 0.17 1.05 ± 0.26 d.l. 0.94 ± 0.31

Tb d.l. d.l. d.l. d.l. d.l. 0.39 ± 0.18 d.l.

Dy 0.69 ± 0.14 0.84 ± 0.21 0.94 ± 0.20 1.14 ± 0.19 0.71 ± 0.21 0.94 ± 0.45 1.19 ± 0.32

Yb 0.57 ± 0.14 0.73 ± 0.23 0.39 ± 0.19 0.93 ± 0.19 0.53 ± 0.21 1.17 ± 0.54 0.82 ± 0.30

Lu d.l. d.l. d.l. d.l. d.l. d.l. d.l.

Ta 0.45 ± 0.08 0.35 ± 0.11 0.52 ± 0.11 0.49 ± 0.10 0.43 ± 0.14 0.73 ± 0.33 0.45 ± 0.15

Pb 12.93 ± 1.19 12.14 ± 1.36 13.25 ± 1.39 14.04 ± 1.40 14.78 ± 1.80 13.91 ± 2.96 15.25 ± 2.11

Th 8.85 ± 1.50 9.18 ± 1.70 10.87 ± 2.01 11.27 ± 2.21 11.26 ± 2.37 8.64 ± 2.45 11.81 ± 2.96

U 2.75 ± 0.49 2.84 ± 0.56 3.45 ± 0.68 3.44 ± 0.71 3.87 ± 0.86 2.64 ± 0.80 4.04 ± 1.07

Inclusion: 36-INCL-12 37-INCL-13 39-INCL-15 40-INCL-16 42-INCL-18 Average a

Session: 1 1 1 1 1 1

Ca (μg g-1) 7722 ± 627 7726 ± 694 7206 ± 608 7538 ± 887 7489 ± 746 7646 ± 797

Li 13.69 ± 2.57 15.22 ± 3.01 7.89 ± 1.64 5.75 ± 1.88 5.23 ± 1.49 9.79 ± 5.88

Cu 44.46 ± 5.26 13.98 ± 2.09 33.74 ± 4.26 16.74 ± 3.25 9.08 ± 1.70 d.l.

Zn 23.35 ± 8.81 29.01 ± 11.38 31.97 ± 12.83 d.l. 26.17 ± 12.18 d.l.

As 6.11 ± 1.70 7.90 ± 2.31 6.00 ± 1.68 8.40 ± 3.27 7.64 ± 2.44 8.06 ± 1.91

Rb 81.04 ± 8.65 74.77 ± 8.53 67.97 ± 7.79 65.94 ± 9.28 74.79 ± 9.61 82.33 ± 33.04

Sr 153.97 ± 16.44 151.75 ± 17.3 135.90 ± 15.70 144.11 ± 20.27 154.20 ± 19.97 141.15 ± 20.85

Y 4.67 ± 0.48 4.90 ± 0.55 4.39 ± 0.47 4.91 ± 0.71 7.98 ± 0.97 5.79 ± 1.24

Zr 49.65 ± 4.43 47.29 ± 4.61 47.83 ± 4.50 44.83 ± 5.61 776.4 ± 83.4* 54.40 ± 18.83*

Nb 4.24 ± 0.39 4.59 ± 0.47 3.78 ± 0.35 4.98 ± 0.67 4.51 ± 0.51 4.91 ± 1.26

Mo 1.19 ± 0.29 1.57 ± 0.42 1.11 ± 0.25 1.97 ± 0.68 2.26 ± 0.57 1.90 ± 0.79

Sb 0.59 ± 0.15 0.91 ± 0.22 0.61 ± 0.14 0.36 ± 0.20 0.79 ± 0.23 d.l.

Cs 6.16 ± 0.60 6.12 ± 0.65 5.06 ± 0.52 5.52 ± 0.76 7.01 ± 0.83 6.83 ± 2.42

Ba 587.94 ± 53.13 550.26 ± 53.95 499.40 ± 48.11 498.19 ± 61.97 559.99 ± 61.88 578.23 ± 158.99

La 19.00 ± 1.97 19.39 ± 2.15 15.99 ± 1.78 17.60 ± 2.44 20.07 ± 2.53 19.69 ± 3.90

Ce 31.56 ± 3.27 33.26 ± 3.70 28.09 ± 3.14 30.33 ± 4.20 34.40 ± 4.34 33.83 ± 6.69

Pr 2.74 ± 0.33 3.06 ± 0.40 2.66 ± 0.35 2.62 ± 0.43 3.07 ± 0.46 3.07 ± 0.68

Nd 7.97 ± 0.96 8.22 ± 1.08 6.67 ± 0.87 8.17 ± 1.37 8.33 ± 1.24 8.66 ± 1.82

Sm 1.01 ± 0.17 1.01 ± 0.20 1.22 ± 0.19 1.83 ± 0.41 1.24 ± 0.25 1.29 ± 0.36

Eu 0.31 ± 0.06 d.l. d.l. 0.30 ± 0.11 d.l. d.l.

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Table 2 (continued).Major and trace element composition (in μg g-1) of homogenised and partiallyhomogenised melt inclusions in quartz of the Mount Pinatubo dacite pumices

Inclusion: 36-INCL-12 37-INCL-13 39-INCL-15 40-INCL-16 42-INCL-18 Average a

Session: 1 1 1 1 1 1

Gd 0.92 ± 0.17 0.82 ± 0.19 0.58 ± 0.12 1.03 ± 0.30 0.93 ± 0.22 0.94 ± 0.26

Tb d.l. 0.22 ± 0.05 d.l. 0.21 ± 0.08 d.l. d.l.

Dy 0.48 ± 0.11 0.78 ± 0.18 0.80 ± 0.15 0.56 ± 0.20 1.05 ± 0.24 d.l.

Yb 0.72 ± 0.17 0.64 ± 0.20 0.61 ± 0.15 1.10 ± 0.36 1.62 ± 0.40 d.l.

Lu d.l. d.l. d.l. d.l. 0.40 ± 0.10 d.l.

Ta 0.51 ± 0.11 0.43 ± 0.11 0.39 ± 0.09 0.34 ± 0.14 0.34 ± 0.11 0.46 ± 0.11

Pb 14.75 ± 1.67 13.72 ± 1.67 12.59 ± 1.52 12.77 ± 1.93 14.65 ± 2.00 15.27 ± 5.65

Th 9.97 ± 2.42 11.98 ± 3.00 9.06 ± 2.48 9.50 ± 2.77 12.49 ± 3.67 10.89 ± 2.17

U 3.10 ± 0.79 3.13 ± 0.82 2.73 ± 0.78 3.09 ± 0.95 4.30 ± 1.32 3.44 ± 0.79

Inclusion: Hom2a:27 Hom2a:28 Hom2a:29 Hom2a:30 Hom2a:33 Hom2a:34 Hom2a:36 Hom2a:37

Session: 2 2 2 2 2 2 2 2

Cu (μg g-1) d.l. 12.61 ± 0.98 27.21 ± 2.02 d.l. 12.76 ± 3.55 8.91 ± 1.42 27.46 ± 1.77 d.l.

Zn d.l. 40.20 ± 12.85 d.l. d.l. d.l. d.l. d.l. d.l.

As d.l. d.l. d.l. d.l. d.l. d.l. d.l. 14.56 ± 4.99

Rb 83.06 ± 4.05 76.45 ± 2.56 78.46 ± 2.79 82.98 ± 2.81 121.34 ± 5.41 75.25 ± 2.57 87.52 ± 2.86 70.92 ± 2.50

Sr 157.49 ± 6.49 159.63 ± 6.02 156.09 ± 5.98 136.62 ± 5.19 159.54 ± 6.87 142.74 ± 5.41 140.39 ± 5.27 116.01 ± 4.46

Y 3.69 ± 0.74 5.99 ± 0.32 7.09 ± 0.43 5.02 ± 0.30 3.60 ± 0.57 4.87 ± 0.29 6.48 ± 0.33 3.91 ± 0.29

Nb 4.32 ± 1.15 4.83 ± 0.30 4.85 ± 0.49 4.37 ± 0.33 5.63 ± 0.93 4.90 ± 0.35 5.99 ± 0.34 3.97 ± 0.37

Mo d.l. 3.24 ± 0.77 d.l. 3.12 ± 0.98 d.l. d.l. d.l. d.l.

Ba 570.10 ± 19.05 591.33 ± 19.21 564.89 ± 18.43 520.42 ± 16.93 530.29 ± 18.06 514.32 ± 16.73 624.74 ± 20.25 414.19 ± 13.53

La 18.74 ± 1.02 19.85 ± 0.79 21.45 ± 0.90 19.09 ± 0.77 18.38 ± 1.14 20.11 ± 0.81 21.50 ± 0.82 14.26 ± 0.61

Ce 29.23 ± 1.39 33.97 ± 1.15 37.84 ± 1.33 32.76 ± 1.12 29.80 ± 1.54 33.55 ± 1.14 38.09 ± 1.24 26.55 ± 0.95

Pb 12.95 ± 1.95 15.38 ± 0.71 16.20 ± 0.98 15.95 ± 0.80 d.l. 15.37 ± 0.77 17.01 ± 0.77 12.35 ± 0.79

Th 10.63 ± 0.82 12.75 ± 0.50 14.77 ± 0.63 12.18 ± 0.50 10.40 ± 0.88 11.99 ± 0.49 13.24 ± 0.49 8.51 ± 0.41

U 3.75 ± 0.50 3.85 ± 0.20 4.34 ± 0.25 3.12 ± 0.19 4.78 ± 0.57 3.43 ± 0.19 4.22 ± 0.17 2.41 ± 0.19

Inclusion: Hom2a:38 Hom2a:41 Hom2a:42 Hom2a:43 Hom2a:44 Hom2a:45 Hom2a:46 Hom2a:48 Average

Session: 2 2 2 2 2 2 2 2 2

Cu (μg g-1) 31.42 ± 1.30 23.80 ± 1.60 25.69 ± 1.56 19.03 ± 1.50 14.40 ± 2.45 d.l. 9.53 ± 2.51 27.56 ± 1.98 d.l.

Zn d.l. 40.46 ± 14.76 d.l. d.l. 87.57 ± 32.18 d.l. d.l. d.l. d.l.

As 9.58 ± 1.40 d.l. d.l. d.l. d.l. d.l. d.l. d.l. d.l.

Rb 88.19 ± 2.79 80.93 ± 2.73 88.51 ± 2.90 87.81 ± 2.98 83.29 ± 3.27 74.34 ± 2.54 68.65 ± 2.74 99.35 ± 3.34 84.19 ± 12.57

Sr 160.61 ± 5.99 166.69 ± 6.3 168.38 ± 6.33 160.87 ± 6.10 161.34 ± 6.35 148.15 ± 5.62 114.90 ± 4.55 199.17 ± 7.52 153.04 ± 20.39

Y 5.71 ± 0.25 7.56 ± 0.39 6.74 ± 0.34 6.75 ± 0.37 d.l. 5.17 ± 0.30 3.79 ± 0.36 6.67 ± 0.36 5.19 ± 1.90

Nb 4.79 ± 0.22 5.35 ± 0.34 5.33 ± 0.34 5.07 ± 0.35 5.40 ± 0.59 4.95 ± 0.33 2.97 ± 0.65 6.03 ± 0.44 4.92 ± 0.77

Mo 1.22 ± 0.36 d.l. d.l. 2.01 ± 0.78 d.l. d.l. d.l. d.l. d.l.

Ba 640.76 ± 20.74 636.33 ± 20.68 631.68 ± 20.49 605.78 ± 19.71 605.97 ± 19.93 533.05 ± 17.35 428.36 ± 14.11 698.67 ± 22.71 569.43 ± 76.88

La 20.71 ± 0.78 21.90 ± 0.87 21.93 ± 0.85 20.11 ± 0.82 21.64 ± 1.00 19.20 ± 0.78 14.93 ± 0.72 24.36 ± 0.97 19.89 ± 2.56

Ce 35.36 ± 1.14 37.60 ± 1.27 37.54 ± 1.24 35.36 ± 1.22 35.47 ± 1.37 32.69 ± 1.12 26.3 ± 1.04 41.41 ± 1.40 33.97 ± 4.29

Pb 17.04 ± 0.63 15.68 ± 0.76 18.68 ± 0.80 17.14 ± 0.84 17.51 ± 1.26 15.48 ± 0.78 13.28 ± 1.08 20.04 ± 1.00 16.00 ± 2.08

Th 12.21 ± 0.42 13.17 ± 0.52 13.55 ± 0.51 12.52 ± 0.52 15.78 ± 0.78 11.68 ± 0.48 10.57 ± 0.57 15.61 ± 0.62 12.47 ± 1.94

U 3.67 ± 0.13 4.22 ± 0.22 4.19 ± 0.20 4.21 ± 0.22 6.61 ± 0.45 3.03 ± 0.18 2.91 ± 0.26 4.50 ± 0.24 3.95 ± 0.96

a Average value for every session (12 measurements for the first session and 16 for the second session) with 1s standard deviations (external precision).d.l. Value was below the detection limit. * Anomalously high Zr content is due to a presence of co-entrapped zircon crystal(s) of sub-micrometre size in the inclusion 42-INCL-18 (see section “Trace element homogeneity”). The average Zr concentration for the first session melt inclusions wascalculated without this anomalous value. The average Zr concentrations calculated for the first session melt inclusions without and with the anomalous valuewere 54.40 ± 18.83 μg g-1 and 110 ± 210 μg g-1, respectively, with corresponding RSDs of 17% and 191% (see Figure 4b).

repeated. The standardisation procedure was appliedby averaging external calibrator (NIST SRM 612)measurements. Data were also collected for three refe-rence glasses (MPI-DING) of andesitic, quartz-dioriticand rhyolitic compositions during the first and thethird ablation sessions.

The ICP-MS operating conditions were optimisedusing continuous ablation of NIST SRM 612 to minimi-se oxides. The melt inclusion and reference glass datawere acquired on selected isotopes of up to thirty-fourelements (Tables 2 and 4) using the instrument time-

resolved analysis data acquisition software GLITTER4.0, which reports signal intensity data in counts persecond for each isotope measured by the mass spec-trometer. This data acquisition protocol allowed signalsto be acquired as a function of time (equivalent to theablation depth) and the subsequent examination andselective integration of these signals. Each analysisstarted off with a 10 s measurement of instrumentalbackground (i.e., analysis of dry He + Ar carrier gas,no ablation) followed by an ablation event. For eachelemental analysis in a run, time-resolved signalswere then examined, and the most appropriate signal

2 1 5

GEOSTANDARDS and



Table 3.Comparison of trace element compositions (in μg g-1) of the quartz-hosted melt inclusions measured by femtosecond LA-ICP-MS with those of measuredby SIMS and matrix glasses measured by nanosecond LA-ICP-MS

Element: fs-LA-ICP-MS a fs-LA-ICP-MS fs-LA-ICP-MS b SIMS c SIMS d ns-LA-ICP-MS c ns-LA-ICP-MS d

Features: Melt inclusions Session Detection limit Melt inclusions Relative % Matrix glass Relative %(H2O-poor)

Ca (μg g-1) 7646 ± 797 1 79.1 - - - -Ti 83.0 ± 23.1 1 0.04 - - - -Li 9.79 ± 5.88 1 0.24 - - - -Cu d.l. - 0.19 - - - -Zn d.l. - 2.6 - - - -As 8.06 ± 1.91 1 0.76 - - 10.67 ± 1.91 -32Rb 84.19 ± 12.6 2 0.1 - - 98.57 ± 4.31 -17Sr 153.04 ± 20.4 2 0.06 - - 167.60 ± 6.44 -10Y 5.19 ± 1.90 2 0.04 - - 3.50 ± 0.22 33Zr 54.40 ± 18.80 1 0.06 - - 59.17 ± 3.05 -9Nb 4.92 ± 0.77 2 0.05 - - 5.14 ± 0.28 -4Mo 1.90 ± 0.79 1 0.19 2.1 ± 0.1 -10 3.10 ± 0.90 (-63)Cd d.l. - 0.22 - - d.l. -Sn d.l. - 0.1 - - d.l. -Sb d.l. - 0.08 - - 1.07 ± 0.17 -Cs 6.83 ± 2.42 1 0.04 - - 7.66 ± 0.40 -12Ba 578 ± 159 1 0.03 - - 719.63 ± 26.80 -24La 19.89 ± 2.56 2 0.03 18.8 ± 1.7 5 12.10 ± 0.90 39Ce 33.97 ± 4.29 2 0.03 21.2 ± 2.7 38 30.90 ± 2.10 9Pr 3.07 ± 0.68 1 0.02 1.9 ± 0.3 38 2.30 ± 0.12 25Nd 8.66 ± 1.82 1 0.06 - - 6.94 ± 0.45 20Sm 1.29 ± 0.36 1 0.06 - - 0.89 ± 0.19 31Eu d.l. - 0.04 - - 0.26 ± 0.05 -Gd 0.94 ± 0.26 1 0.07 - - 0.75 ± 0.15 20Tb d.l. - 0.03 - - d.l. -Dy d.l. - 0.06 - - d.l. -Yb d.l. - 0.07 - - 0.48 ± 0.09 -Lu d.l. - 0.03 - - d.l. -Ta 0.46 ± 0.11 1 0.05 - - 0.36 ± 0.04 22Au d.l. - 0.05 - - d.l. -Pb 15.27 ± 5.65 1 0.07 15.7 ± 2.4 -3 16.00 ± 0.60 -5Th 10.89 ± 2.17 1 0.03 - - 7.93 ± 0.35 27U 3.44 ± 0.79 1 0.02 - - 3.88 ± 0.23 -13

a Average trace element contents in glasses of melt inclusions with 1s standard deviations determined in this work by fs-LA-ICP-MS; d.l.values below detection limit. b Detection limits determined for the external calibrator (NIST SRM 612) during the first ablation session x1.75 lens; 7.5 mJ/pulse; 200 μm ablation pit; see Table 1 for details). c Average contents in glasses of melt inclusions with1s standard deviations measured by SIMS and those of matrix measured by ns-LA-ICP-MS (Borisova et al. 2006). d SIMS (relative %)is relative percentage between data measured by fs-LA-ICP-MS on melt inclusions and those of SIMS on H2O-poor melt inclusions; ns-LA-ICP-MS(relative %) is relative percentage between data on melt inclusions measured by fs-LA-ICP-MS and those of matrix glasses measured by ns-LA-ICP-MS.

2 1 6

GEOSTANDARDS and



Tab

le 4

.M

easu

red

and

ref

eren

ce c

omp

ositi

ons

of M

PI-D

ING

gla

sses

RM

:T1

-G (

qua

rtz-

dio

rite

)A

THO

-G (

rhyo

lite)

StH

s6/8

0-G

(a

ndes

ite)

(Ses

sio

n):

Mea

sure

d (

1)

aM

easu

red

(3

)R

efer

ence

bM

easu

red

(1

)M

easu

red

(3

)R

efer

ence

Mea

sure

d (

1)

Mea

sure

d (

3)

Ref

eren

ce[P

oin

ts]:

[3]

[7]

[3]

[6]

[4]

[6]

Li (μ

g g-

1)

21.7

4 ±

2.2

92

4.2

3 ±

3.2

22

0 (1

9.9

)2

8.6

4 ±

3.0

42

8.4

4 ±

3.4

92

8.0

0 (2

8.6

)21

.36

±2

.33

21.8

4 ±

6.5

113

(20

.7)

Cu

16.0

4 ±

1.0

515

.36

±1.

39

21 (1

8.8

)18

.83

±1.

23

18.2

6 ±

1.2

621

(18

.6)

38

.07

±2

.43

34

.80

±7.

7247

(41.

5)

Zn77

.96

±12

.60

63

.90

±6

.75

84

.00

(74

)6

4.0

8 ±

10.7

55

7.4

8 ±

5.6

013

9 (1

41)

75.9

1 ±

13.5

177

.77

±18

.90

65

(67

)A

s0

.96

±0

.41

d.l.

0.7

1 (0

.96

)d.

l.d.

l.1.

2 (1

.4)

2.9

3 ±

0.5

5d.

l.2

.6 (2

.73

)Rb

80

.26

±4

.34

91.3

8 ±

4.0

48

0 (7

9.7

)61

.50

±3

.47

60

.54

±2

.79

63

.8 (6

5.3

)2

9.3

5 ±

1.70

34

.64

±3

.83

29

.9 (3

0.7

)Sr

26

9.2

5 ±

14.4

131

0.7

6 ±

11.6

72

83

(28

4)

89

.38

±5

.00

92

.36

±3

.71

96

.4 (9

4.1

)4

67.

70 ±

26

.74

572

.09

±5

0.8

94

86

(48

2)

Y2

3.9

8 ±

1.17

27.

67

±1.

09

23

.2 (2

3.9

)9

0.9

6 ±

4.6

391

.06

±3

.60

93

.8 (9

4.5

)12

.06

±0

.63

14.7

8 ±

1.5

911

.3 (1

1.4

)Zr

139

.28

±6

.36

157.

72 ±

6.4

214

7 (1

44

)4

57.

92

±21

.83

461

.55

±19

.56

52

4 (5

12)

116

.61

±5

.62

132

.54

±12

.47

120

(118

)N

b7.

99

±0

.36

8.9

0 ±

0.4

59

.10

(8.8

7)

52

.49

±2

.39

53

.94

±2

.50

61.9

(62

.4)

6.1

5 ±

0.2

96

.41

±0

.92

7.1

(6.9

4)

Mo

5.0

4 ±

0.3

45

.22

± 0

.56

5.4

(4.2

0)

28

.92

±1.

7231

.05

±1.

86

6 (4

.8)

1.71

±0

.16

d.l.

2.2

(2.0

0)

Sbd.

l.d.

l.0

.28

(0.2

5)

d.l.

0.2

0 ±

0.0

50

.38

(0.3

2)

0.2

0 ±

0.0

3d.

l.0

.21

(0.2

0)

Cs

2.7

2 ±

0.1

42

.99

±0

.20

2.9

(2.6

9)

4.8

2 ±

0.2

54

.88

±0

.30

1.31

(1.0

8)

1.5

8 ±

0.0

9d.

l.1.

89

(1.7

5)

Ba3

61.4

2 ±

16.7

43

99

.61

±19

.57

38

2 (3

88

)4

85

.22

±2

3.5

251

9.4

6 ±

26

.42

55

3 (5

47)

28

3.2

6 ±

13.9

02

72.4

2 ±

25

.76

30

2 (2

98

)La

70.0

1 ±

3.6

175

.53

±3

.91

69

(70

.4)

55

.06

±2

.97

58

.15

±3

.11

55

.5 (5

5.6

)12

.42

±0

.69

11.9

6 ±

1.3

211

.9 (1

2.0

)C

e12

1.91

±6

.30

130

.46

±7.

2112

7 (1

27

)11

6.2

9 ±

6.2

812

7.0

2 ±

7.2

312

4 (1

21)

26

.12

±1.

45

23

.64

±2

.48

25

.7 (2

6.1

)Pr

12.0

4 ±

0.6

912

.45

±0

.71

12.1

(12

.4)

14.3

3 ±

0.8

615

.39

±0

.88

14.5

(14

.6)

3.1

8 ±

0.2

02

.74

±0

.41

3.1

7 (3

.20

)N

d3

6.4

4 ±

2.0

43

8.7

7 ±

2.1

74

0.7

(41.

4)

54

.11

±3

.15

58

.23

±3

.25

61.3

(60

.9)

11.8

7 ±

0.7

210

.56

±1.

60

12.7

(13

.0)

Sm6

.39

±0

.37

6.7

9 ±

0.4

66

.52

(6.5

7)

14.0

6 ±

0.8

214

.48

±0

.84

14.6

(14

.2)

2.8

7 ±

0.1

82

.98

±0

.82

2.7

9 (2

.78

)Eu

1.13

±0

.07

1.16

±0

.11

1.21

(1.2

1)

2.8

5 ±

0.1

53

.01

±0

.19

2.8

4 (2

.76

)0

.93

±0

.06

d.l.

0.9

7 (0

.95

3)

Gd

5.0

7 ±

0.3

05

.28

±0

.39

5.2

(5.3

1)

14.5

7 ±

0.8

415

.59

±0

.88

15.5

(15

.3)

2.5

9 ±

0.1

7d.

l.2

.64

(2.5

9)

Tb0

.71

±0

.05

0.7

3 ±

0.0

60

.82

(0.7

73)

2.4

0 ±

0.1

52

.53

±0

.15

2.5

2 (2

.51

)0

.37

±0

.03

d.l.

0.3

72 (0

.371

)D

y4

.37

±0

.29

4.5

3 ±

0.3

24

.44

(4.5

)16

.13

±1.

05

16.9

8 ±

0.9

015

.6 (1

6.2

)2

.26

±0

.17

d.l.

2.1

9 (2

.22

)Yb

2.3

7 ±

0.1

92

.51

±0

.25

2.3

2 (2

.38

)10

.30

±0

.79

11.5

9 ±

0.6

510

.1 (1

0.5

)1.

08

±0

.10

d.l.

1.11

(1.1

3)

Lu0

.36

±0

.03

0.3

7 ±

0.0

50

.35

(0.3

54

)1.

54

±0

.13

1.6

2 ±

0.1

01.

52

(1.5

4)

0.1

8 ±

0.0

2d.

l.0

.16

8 (0

.16

8)

Ta0

.44

±0

.04

0.4

1 ±

0.0

50

.45

(0.4

64

)3

.53

±0

.30

3.9

0 ±

0.2

53

.81

(3.9

0)

0.4

0 ±

0.0

4d.

l.0

.418

(0.4

20

)Pb

10.1

9 ±

0.5

911

.01

±1.

26

13.0

0 (1

1.6

)2

.02

±0

.13

2.3

0 ±

0.2

85

.7 (5

.67

)10

.68

±0

.65

8.8

3 ±

1.6

210

.2 (1

0.3

)Th

29

.37

±3

.30

36

.48

±1.

82

30

(31.

3)

7.2

8 ±

0.8

57.

43

±0

.40

7.4

8 (7

.40

)2

.32

±0

.29

2.1

5 ±

0.4

62

.22

(2.2

8)

U1.

57

±0

.19

1.8

9 ±

0.1

51.

67

(1.7

1)

1.78

± 0

.22

1.8

3 ±

0.1

22

.35

(2.3

7)

0.9

5 ±

0.1

3d.

l.1.

03

(1.0

1)

a(N

o.)

is t

he a

naly

tica

l se

ssio

n nu

mb

er,

“Poi

nts”

are

the

num

ber

of

poi

nt p

ar

ana

lyse

s; “

Mea

sure

d”

and

“Re

fere

nce”

are

mea

sure

d v

alu

es d

urin

g t

he f

irst

(1

) a

nd t

hird

(3

) a

bla

tion

sess

ions

and

ref

eren

ce (

orin

form

atio

n) v

alu

es,

resp

ectiv

ely.

Va

lues

non

-ma

rked

are

tho

se w

ith a

naly

tica

l p

reci

sion

bet

ter

tha

n 2

0%

rel

. rel

ativ

e to

the

ref

eren

ce v

alu

es o

f Jo

chum

et

al.

(20

06

). U

nder

lined

va

lues

are

tho

se w

ith a

naly

tica

lp

reci

sion

bet

wee

n 2

0%

rel

. and

35

% r

el. r

ela

tive

to t

he r

efer

ence

va

lues

of

Joch

um e

t a

l.(2

00

6).

Valu

es m

ark

ed i

n ita

lica

re t

hose

with

ana

lytic

al

pre

cisi

on m

ore

tha

n 3

5%

rel

. rel

ativ

e to

the

ref

eren

ce v

alu

es o

fJo

chum

et

al.

(20

06

). d

.l. a

re v

alu

es b

elow

det

ectio

n lim

it.b

Refe

renc

e (o

r in

form

atio

n) v

alu

es a

re a

ccor

din

g t

o Jo

chum

et

al.

(20

00

), b

rack

eted

va

lues

are

ref

eren

ce a

bun

da

nces

acc

ord

ing

to

Joch

um e

t a

l.(2

00

6).

Bol

d u

nder

lined

va

lues

dem

onst

rate

(>

10 r

el.%

) d

iffer

ence

in

the

refe

renc

e (o

r in

form

atio

n) v

alu

es i

n co

mp

ari

son

to t

hose

of

Joch

um e

t a

l. (2

00

6).

Thes

e va

ria

tions

in

refe

renc

e va

lues

are

due

to

(1)

tra

ce e

lem

ent

mic

ro-h

eter

ogen

eitie

s fo

und

for

cha

lcop

hile

el

emen

ts o

r (2

) a

naly

tica

l un

cert

ain

ties

(Joc

hum

et

al.

20

06

).

2 1 7

GEOSTANDARDS and



intervals for the background and ablation were selec-ted for integration. Quartz is an appropriate hostmineral for studying melt inclusions because of theabsence of the boundary layer effect (cf. Borisova etal. 2005), and because it contains low background-level concentrations of trace element, thus eliminatingthe problem of subtracting the host mineral composi-tion from the melt inclusion analysis (e.g., Halter et al.2002). We verified that quartz contained negligible(background-level) concentrations of the determinedtrace elements; therefore accuracy of the results wasnot affected by the ablation of the host quartz duringsampling of buried melt inclusions. Background-cor-rected count rates for each isotope were used for cal-culation of sample concentrations with the GLITTER 4.0software. This software was also used to calculateanalytical precision and detection limit for each ele-ment, by entering the measured background signaland elemental sensitivity data. The obtained detectionlimits for NIST SRM 612 glass analyses ranged bet-ween 0.01 and 0.10 μg g-1 for Ti, Rb, Sr, Y, Zr, Nb, Sn,Sb, Cs, Ba, REE, Ta, Au, Pb, Th, U and between 0.19and 2.60 μg g-1 for Li, Cu, Zn, As, Mo, Cd, and bet-ween 70 and 90 μg g-1 for Na and Ca.

Results and discussion

Ablation patterns and trace element data

Figure 1 shows two representative examples ofthe twenty-eight homogenised and partially homoge-nised melt inclusions in quartz, analysed by fs-LA-ICP-MS. The inclusions were located a few micrometresunder the surface of the quartz sample. No particularproblems were encountered with the ablat ion ofquartz wi th the NIR femtosecond laser. This fac tconfirms an independence of the femtosecond laserf rom the opt ical propert ies of ablated mater ials(González et al. 2006). Figure 2 (A-B) depicts typicalablation craters in the host quartz after ablation ofmelt inclusions. Some fracturing at the sample surfacecould be related to the high laser fluence applied( Tab le 1 ) and t he h igh power and i r rad iance(power/sur face) of the femtosecond laser, whichstrongly affec ted the sample sur face, part icularlywhen using the x15 reflective objective, because ofthe small theoretical focal spot diameter (3.5 μmagainst 10 μm for the x1.75 silica lens). Note that thecraters obtained result f rom the penetrat ion of abeam having a Gaussian shape. Nevertheless, cra-ters made in the host quartz and reference MPI-DING glasses did not have melted ejecta deposited

around the crater, which is a typical feature of nano-second laser ablation (e.g., Poitrasson et al. 2003).The cause for this may be a result of reduced plasmainteraction or thermal effects during the femtosecondlaser ablation (Russo et al. 2002a). The internal textu-re of the reference glasses (MPI-DING), especiallyATHO-G, (produced by melting natural rock chips.Jochum et al . 2000), is revealed around cratersmade during the third ablation session with the x15objective (Table 1). Conversely, the MPI-DING glasssurfaces around craters made during the first abla-tion session with the x1.75 silica lens did not showany evidence of this interaction.

Figure 3 depicts the intensities of the major andtrace element yields for 23Na, 63Cu, 85Rb, 88Sr, 89Y and208Pb, obtained with the x15 objective during thesecond ablation session of melt inclusions. The abla-tion signal from host quartz was similar to that of thebackground. A sudden increase in the intensities of23Na, 63Cu, 85Rb, 88Sr, 89Y and 208Pb indicated pene-tration of the ablation pit into the melt inclusion (Figure3). Table 2 reports major and trace element data forindividual melt inclusions obtained by fs-LA-ICP-MS.Average concentrations of incompatible trace elements(Rb, Sr, Y, Nb, Ba, La, Ce, Pb, Th, U) obtained for meltinclusions during the two sessions were fairly reprodu-cible (Table 2). Trace element results on individual meltinclusions showed an agreement typically within 30-40% with the value obtained by SIMS on H2O-poormelt inclusions (Borisova et al. 2006) and by ns-LA-ICP-MS with 100-140 μm ablation pits on matrix glasses(Table 3). The agreement of trace element concentra-tions of the Mount Pinatubo melt inclusions and matrixglasses is consistent with an origin for the melt inclu-sions as an homogeneous rhyolitic melt entrapped inquartz at the final stages of crystallisation of the hostadakite magma.

The above results indicate that fs-LA-ICP-MS is amore advantageous in situ microanalytical techniquefor the analysis of the rhyolitic melt inclusions thanSIMS and ns-LA-ICP-MS. It permits measurement of upto approximately thirty elements per analysis (compa-red to only seven by SIMS with a Cameca IMS 6f), hashigher laser-pulse energy and signal intensity thanthose obtained with nanosecond lasers, and lowerdetection l imits for most elements (Table 3). As aconsequence, i t al lows analys is of much smal lervolumes of material than by ns-LA-ICP-MS. Anotherimportant advantage is its ability to ablate quartz,even at NIR wavelength diapason.

GEOSTANDARDS and


2 1 8

GEOSTANDARDS and



Figure 2. Secondary electron images (SEI) of craters produced during femtosecond LA-ICP-MS sessions,

obtained on a JEOL JSM-6360 LV electron microscope. (A and B) host quartz after the second ablation

session; (C and D) reference material glass ATHO-G after the third session; (E) reference material glass

ATHO-G after the first session; (F) reference material glass StHs6-80-G after the third session; (G and H)

reference material glass T1-G after the third session. Note that crater borders of reference material

glass ATHO-G suffered much more micro-fracturing than those of glasses StHs6-80-G and T1-G.

2 1 9

GEOSTANDARDS and



Trace element homogeneity

The analyses of the Mount Pinatubo quartz-hostedmelt inclusions revealed spectacular major elementhomogeneity of rhyolitic glasses, in particular, for homo-genised inclusions (Borisova et al. 2005, 2006). Traceelement homogeneity for these melt inclusions isexpressed by their concentrations (Figure 4a) and rela-tive standard deviations (RSD) for two separate sessionsof twelve (first session) and sixteen (second session)fs-LA-ICP-MS analyses (Figure 4b). Most elements (e.g.,Rb, Sr, Nb, Ba, La, Ce, Pb, Th) showed similar RSDvalues, i.e., lower than 10 to 16%, for both sessions. Onthe other hand, elements like Y, Sm, Eu, Gd, Dy, Ta, Uand ore metals such as As and Mo showed higherRSDs (17 to 37%) with a value as high as 191% for Zr.Such elevated RSDs could be caused by the low inten-sity of the signals obtained (≤ 1000 cps for Y, Figure 3).However, a strong increase in RSD from 17-18% to 24-37% for Y and U was observed between the first (1.3mJ/pulse) and second (2 mJ/pulse) sessions, despitethe higher laser energy applied, and correspondinghigher signal intensity (≥ 100 cps), during the secondsession. Moreover, RSD values for Y, Zr and U were toohigh (17-191%) to be explained solely in terms of traceelement homogeneity of the entrapped melt.

Zircon/melt partition coefficients for Y, Zr and Uare very high (e.g., Rubatto and Hermann 2007),

and it has been shown by Borisova et al. (2005)tha t z i rcon mic roc ry s ta l s a re con temporaneousphases to the quar tz phenocrys t s in the MountPinatubo dacite. An absence of micrometre-sizedzircon as the daughter crystals in the Mt. Pinatuboquartz-hosted melt inclusions was demonstrated byBorisova et al. (2005). Therefore, it is possible thatthe high RSDs for Y, Zr, U, as well as Sm, Eu, Gda n d D y ( w h i c h a re c h a ra c t e r i s e d b y h i g hzircon/melt partitioning) are caused by melt hetero-geneities with respect to these elements, inducedby zircon crystall isation. Table 2 (see also Figure4b) con ta ins one anomalous l y h igh RSD va lue(inclusion 42-INCL-18). Because i t is unique, i t islikely that this anomaly is due to micrometre-sizedzircon crystal(s) co-entrapped with the melt into theinclusion.

In conclusion, the analysed quartz-hosted meltinclusions are homogeneous with respect to the follo-wing incompatible trace elements: Rb, Sr, Nb, Cs, Ba,La, Ce, Pr, Nd, Pb and Th. On the other hand, theinclusions have more variable concentrations of Y, Zr,Sm, Eu, Gd, Dy, Ta and U, which is likely a reflection ofmelt heterogeneities induced by zircon crystallisationduring formation of quartz phenocrysts. Locally, zirconmicro-crystals can be co-entrapped into the melt inclu-sions and cause highly anomalous values of RSD forY, Zr and U.

GEOSTANDARDS and


Seconds

Coun

ts p

er s

econ

d

Figure 3. Typical signal for a single melt inclusion (Hom 2a:28, 100 μm in diameter, second session) in quartz

from the Mt. Pinatubo dacite pumice. The growing 23Na, 63Cu, 85Rb, 88Sr, 89Y and 208Pb signals show the start

of the melt inclusion ablation.

2 2 0

GEOSTANDARDS and



GEOSTANDARDS and


Figure 4 (a). Trace element

composition (expressed as

concentrations, μg g-1) of

twelve (first session) and

sixteen (second session)

melt inclusions.

Melt inclusion number

Average concentration (μg g-1)

%RS

DCo

ncen

tra

tion

(μg

g-1)

Session (1) Session (2) (a)

Rb

Sr

Y

Zr

Nb

Cs

Ba

La

Ce

Pr

Nd

Sm

Eu

Dy

YbLu

TaPb

Th

U

1000

100

10

1

0.1

0.1 1 10 100 1000 10000

10

100

Ca

As

Rb

Sr

YZr

Nb

Mo

Zr

Cs

Ba

LaCePr Nd

Sm

Eu

Gd

DyTa

Pb

Th

U SrRb

BaNb

La Ce

Th

U

Pb

Y

(b) Figure 4 (b) Trace element

homogeneity (expressed

as % RSD) of twelve (open

circles - first session) and

sixteen (closed circles -

second session) successive

trace element

determinations of the

quartz-hosted melt

inclusions. High RSD (17 -

191%) for Zr in the first

session could be due to

the presence of zircon

micro-crystals

co-entrapped in the

inclusion 42-INCL-18 (see

text). High RSD for Y and

U in the two sessions

could be due to melt

heterogeneity related to

zircon crystallisation.

2 2 1

GEOSTANDARDS and



Analytical precision

The internal precision of fs-LA-ICP-MS analyses isexpressed as relative standard deviation (RSD) for eachmelt inclusion analysed (Figure 4c). The RSD was bet-ween 3 and 20% for most elements, whereas it rea-ched 30% for elements such as U and Th, and 40% forTa (Figure 4c). The internal precision for most elements(RSD between 3 and 10%) was better for the analysesof the second session, during which an energy of 2mJ/pulse was applied, instead of the 1.3 mJ/pulseenergy applied during the first session (Figure 4c).

Accuracy

It is essential for accurate chemical analyses thatsamples and calibrators behave similarly during thelaser ablation. It is known that the femtosecond laserdisplays less matrix-depended behaviour than thenanosecond lase r ( Po i t ra s son e t a l . 2003) .Nonetheless, in order to test the general applicabilityand accuracy of the analytical technique to melt inclu-sion analysis, we collected fs-LA-ICP-MS data for threeMPI-DING reference glasses: an andesite, a quartz-diorite and a rhyolite. These glasses were selected

because their si l icic composit ions (high SiO2 andAl2O3 contents) resemble the analysed rhyolitic glassesof the melt inclusions. These international referencesamples were analysed repeatedly during the first andthird ablation sessions, and the resulting trace elementconcentrations, together with reference concentrationsobtained by isotope dilution (ID), ICP-MS, LA-ICP-MSand other techniques (Jochum et al. 2000, 2006), arepresented in Table 4 and plotted in Figures 5a and5b. A comparison with these values suggests that thefs-LA-ICP-MS technique is generally efficient for allmeasured elements and can yield accurate results, ata level of ≤ 20%. NIR femtosecond LA-ICP-MS provi-ded accurate results for andesite and quartz dioriteglasses (MPI-DING). Rhyolite reference glass ATHO-Gexhibited less accurate results (> 20%) only for chalco-phile elements such as Zn, Mo and Pb and lithophileelements such as Cs and U, whereas Li, Cu, As, Rb, Sr,Y, Zr, Nb, Ba, REE, Ta and Th were measured accurate-ly (Figure 5b, Table 4). At the time, we could notexplain the high concentrations obtained for Mo andCs in ATHO-G. Molybdenum, Cs(?), W, Pb and U wereintroduced during glass preparation (see Figure 4 inJochum et al. 2000) and are more or less homoge-neously distributed in the glasses (Jochum et al. 2000,

GEOSTANDARDS and


Figure 4 (c). Internal precision

(expressed as % RSD) of

fs-LA-ICP-MS analyses of

each melt inclusion obtained

during the first and second

ablation sessions.

Melt inclusion number

% R

SD

Session (1) Session (2) (c)

10

Rb

Sr

Y

Zr

Nb

Cs

Ba

La

Ce

Pr

NdTa

Pb

Th

U

2 2 2

GEOSTANDARDS and



GEOSTANDARDS and


Figure 5 (a). Accuracy of

fs-LA-ICP-MS analyses

expressed as reference value

of RM glasses (Jochum et al.

2006), plotted against the

relative difference between

these reference values and the

measured values obtained in

this study for quartz-diorite

(T1-G) and andesite

(StHs6/80-G) reference material

glasses during the first and third

ablation sessions. The field of ±

20% accuracy is plotted.

Figure 5 (b). Accuracy of the

fs-LA-ICP-MS analyses for

rhyolite RM glass (ATHO-G)

expressed as reference values

on the glass (Jochum et al.

2006), plotted against the

relative difference between

these values and the measured

values obtained during the first

and third ablation sessions. The

field of ± 20% accuracy and

the calculated average

fractionation index I(F) = 1.00 ±

0.03 for the trace elements in

the field are plotted. I(F) is the

fractionation index calculated

for Zn, Pb and U for these

sessions (see text). Data for

Mo and Cs are excluded (see

Table 4).

Reference value (μg g-1)

Reference value (μg g-1)

(Ref

eren

ce v

alu

e -

mea

sure

d v

alu

e)/r

efer

ence

va

lue

(Ref

eren

ce v

alu

e -

mea

sure

d v

alu

e)/r

efer

ence

va

lue

T1-G quartz diorite (1st session)

T1-G quartz diorite (3rd session)

StHs 6/80-G andesite (1st session)

StHs 6/80-G andesite (3rd session)

As

Tb

Y

MoLi

U Cs

Lu

Sb

Lu

Tb

Ta

Ta

Eu

Cs U

Mo Pr

U EuTh

PrTb

Sm

YbDy

GdSm

NbNb

Pb

Nd

Nd

Cu

Pb

Pr

La

La

Y

Nb

Pb

SmLi

Y Ce

YRb

ThZn Rb

Zn

La

La Rb

Ce

Cu

Nd

Cu NdTh

Rb

Zn

Zr

Sr

Sr

BaCe

Ce

Zr

BaSr

Sr

0.1 1 10 100 1000

0.5

0.4

0.3

0.2

0.1

0

-0.1

-0.2

-0.3

-0.4

-0.5

(a)

1 10 100 1000

-0.5

0

0.5

1

(b)

PbZn

U

Lu

TaTh

Yb

Li

CeTb

Eu

La

Nd

Nb

Sr

Y

CuDy

Gd

Sm

Zr

Ba

IF = 1.00 ± 0.03

1st session

3rd session

IF = 0.98 ± 0.01

IF = 0.95 ± 0.06

IF = 0.88 ± 0.08

IF = 0.97 ± 0.09IF = 1.03 ± 0.03

IF = 1.04 ± 0.03

2 2 3

GEOSTANDARDS and



Figure 5 (c). Time-dependent fractionation indices (from 30 to 150 s for total ablation lengths of 120 s)

ratioed to Ca calculated for reference material glasses NIST SRM 612, ATHO-G, T1-G and StHs6/80-G for the

first session. The field of data within which results for Ti, Rb, Sr, Y, Zr, Nb, Ba, REE, Ta and Th lie is indicated.

Fra

ctio

natio

n in

dex

I FFr

act

iona

tion

ind

ex I F

Figure 5 (d). Time-dependent fractionation indices (from 30 to 150 s for total ablation lengths of 120 s)

ratioed to Ca calculated for reference material glasses NIST SRM 612, ATHO-G, T1-G and StHs6/80-G for

the third session. The field of data within which results for Ti, Rb, Sr, Y, Zr, Nb, Ba, REE, Ta and Th lie is marked.

(c)

NIST SRM 612

ATHO-G

T1-G

StHs 6/80-G

Li Ca Ti Cu Zn As Rb Sr Y Zr Nb Mo Cd Sn Sb Cs Ba La Ce Pr Nd Sm Eu Gd Tb Dy Yb Lu Ta Au Pb Th U

0.8

0.9

1.0

1.1

1.2

Li

Ca

Ti

Cu

Zn

RbSr

YZr

Nb

Mo

Cs

BaLa

Ce Pr Nd

SmEu

Gd

Tb

Dy

Yb

LuTa

Pb

ThU

I(F) = 0.99 ± 0.03

(d)

NIST SRM 612

ATHO-G

T1-G

StHs 6/80-G

Li Ca Ti Cu Zn As Rb Sr Y Zr Nb Mo Cd Sn Sb Cs Ba La Ce Pr Nd Sm Eu Gd Tb Dy Yb Lu Ta Au Pb Th U

0.8

0.9

1.1

1.2

1.3

1.0

Li

CaTi

Cu

Zn

As

Rb

SrY Zr

Nb

Mo

Cd

Sn

Sb

Cs

BaLa

Ce

Pr

NdSm

Eu

GdTb

Dy

Yb

Lu

Ta

Au

Pb

ThU

I(F) = 1.00 ± 0.03

2 2 4

GEOSTANDARDS and



2006). We suggest that very low accuracy for Mo andCs is probably due to (1) rhyolite calibrator contamina-tion with Mo or (2) Mo and Cs(?) heterogeneities causedby their introduction during the reference material pre-paration (Jochum et al. 2000). The lower accuracy forZn, Pb and U are probably due to (1) the rhyolite cali-brator micro-heterogeneities (e.g., Jochum et al. 2000)or (2) an elemental fractionation of Zn, Pb and Uduring the fs-LA-ICP-MS analyses.

Time-dependent elemental fractionation

The concept of elemental fractionation was propo-sed by Fryer et al. (1995) who noticed, for a time-resol-ved signal from one analytical spot, that integrating thefirst and the second half of the signal and normalisingthe resulting intensities to that of Ca did not provide thesame values. Elemental fractionation, at least to someextent, has been observed with all types of laser, inclu-ding the femtosecond laser (e.g., Fryer et al. 1995,Günther et al. 1998, 1999, 2000, Chen 1999, Mankand Mason 1999, Becker et al. 2000, Borisov et al.2000, Guillong and Günther 2002, Russo et al. 2002a,Heinrich et al. 2003, Jochum et al. 2007, Koch andGünther 2007). Although a number of methods havebeen proposed to minimise this effect (e.g., Günther etal. 1998, 1999, Guillong and Günther 2002, Russo etal. 2002a, Heinrich et al. 2003, Jochum et al. 2007), sofar it has proven difficult to identify and separate the dif-ferent parameters that may lead to fractionation, giventhe number of variables involved during processes suchas ablation, transportation and excitation or ionisation inthe ICP-MS. Jochum et al. (2007) demonstrated thattime-dependent elemental fractionation is related to thevolatilisation and condensation processes occurring atthe ablation site, during transport to and within the ICP-MS. Only very recently has it become accepted that pro-cesses in the plasma can also fundamentally affect ove-rall elemental fractionation. These are directly related toparticle size distribution, which in turn influences aerosoltransport phenomena from the ablation crater to theplasma (e.g., Pettke 2006). Different experimental resultsshow evidence that large particles may not be quantita-tively ionised in the ICP-MS (e.g., Kuhn et al. 2004). Forinstance, Guillong and Günther (2002) and Guillong etal. (2003) found that removal of large particles from theaerosol eliminates the elemental fractionation. Mankand Mason (1999) as well as Borisov et al. (2000)found that crater geometry (crater-diameter to crater-depth ratio) may have a significant effect on elementalfractionation, although the exact mechanisms remainpoorly understood.

We calculated the relative fractionation of elements(the fractionation index, I(F)) as the ratio between theintegrated signals obtained from the second part (90to150 s) of a continuous ablation of reference glassessuch as NIST SRM 612, ATHO-G, T1-G and StHs6/80-G, and the signals from the first part (30 to 90 s), allnormalised to Ca as internal standard. Lithophile ele-ments such as Ti, Rb, Sr, Y, Zr, Nb, Ba, REE, Ta and Thdid not display significant elemental fractionationduring analysis (I(F)= 0.99 ± 0.03 during the first ses-s ion and 1.00 ± 0.03 dur ing the th i rd session).Moreover, our data show the occurrence of insignificantelemental fractionation for the chalcophile (Cu, Zn, As,Mo, Cd, Sn, Sb, Au and Pb) and lithophile (Li, Cs andU) elements during fs-LA-ICP-MS analysis of referenceglass NIST SRM 612 (Figures 5c, d). These elementstend to fractionate more during the third ablation ses-sion performed with the x15 objective in comparisonto those of the first session where we used the x1.75silica lens. The elemental fractionation is controlled bythe optical system because of the different crater geo-metries or profiles (the aspect ratio varying from ~ 1.5(x1.75 silica lens) to ~ 6 (x15 objective): crater diame-ter / crater depth (~ 300 μm for NIST SRM 612) is notthe same for two optical systems and is less favou-rable for the reflective objective). This is reflected bythe different features of surface interaction after thefemtosecond laser ablation (Figure 2).

I t seems that NIR and UV femtosecond laserfluences control the elemental fractionation differently(Russo et al. 2002a, Koch et al. 2006). Fractionationindexes obtained (I(F) ≤ 0.95 and I(F) ≥ 1.05) could bedue to the very high laser fluences applied in this workwith the 800 nm NIR femtosecond laser (Table 1). Withthe aim of measuring trace element concentrations, inparticular chalcophile elements, maximum pulse ener-gies and high laser fluences (Table 1) were used inorder to provide the best analytical performance in theanalysis of the quartz-hosted melt inclusions.

As indicated by Jochum et al. (2007), time-depen-dent elemental fractionation is difficult to correct. Weperformed calculations on the trace element concen-trations in ATHO-G glass corrected for the effect ofelemental fractionation, according to the procedureoutlined by Chen et al. (1999). However, the calcula-ted values for Zn (42 μg g-1), Mo (27 μg g-1), Cs (4.5μg g-1), Pb (1.9 μg g-1) and U (1.7 μg g-1) differ fromthe reference as well as the measured concentrations(Table 4). Another question that should be addressedis what elements are more likely to be sensitive to

GEOSTANDARDS and


2 2 5

GEOSTANDARDS and



elemental fractionation during LA-ICP-MS analysis?Günther et al. (1999) demonstrated the dependenceof elemental fractionation on the chemical propertiesof elements according to Goldschmidt’s classification.For example, Chen (1999) investigated elemental frac-tionation and showed a dependence on element ioni-sation energy. Figure 6 illustrates the first ionisationenergy versus accuracy of measurements for the refe-rence glasses analysed. The l i thophi le refrac toryelements such as Ti , Y, Zr, Nb, REE and Th, andalkaline earth elements such as Sr and Ba similar toCa have fractionation indices approaching unity (0.99-1.00 ± 0.03, Figure 5c, d). Volatile elements such as Li,Rb and Cs and the chalcophile elements such as Cu,Zn, As, Mo, Cd, Sn, Sb, Au and Pb have more scatte-red fractionation indices (Figure 5c, d). Thus, volatileand chalcophile elements are likely to be the mostsensitive to elemental fractionation, whereas lithophile

refractory and alkaline earth elements should not frac-tionate relative to Ca during multi-elemental microana-lysis by fs-LA-ICP-MS. Nevertheless, chalcophile (Cu, Zn,As, Mo, Cd, Sn, Sb, Au and Pb) and lithophile (Li, Csand U) elements did not display a strong elementalfractionation in our analyses: their fractionation indicesdid not exceed 1.1 with the silica lens session and1.25 with the objective session (Figure 5c, d). This allo-wed acquisition of rather good quality and valuable insitu data on trace elements (Li, Rb, Sr, Y, Zr, Nb, Cs, Ba,REE, Ta, Th, U) and ore metals (As, Mo, Pb) in thequartz-hosted rhyolitic melt inclusions.

Conclusions

(1) NIR femtosecond LA-ICP-MS is an eff icienttechnique for multi-element analysis of individualmelt inclusions hosted in quartz. Quantitative analysis

GEOSTANDARDS and


Figure 6. Relationship between first ionisation energy (kJ mol-1) and accuracy for the trace elements

determined in this study during the first ablation session. Ionisation energies are from James and Lord

(1992). Data for Mo and Cs in the ATHO-G glass reference material are excluded (see Table 4).

First ionisation energy (kJ mol-1)

Refe

renc

e va

lue

- m

easu

red

va

lue)

/ref

eren

ce v

alu

e

T1-G quartz diorite

ATHO-G rhyolite

StHs 6/80-G andesite

400 500 600 700 800 900

-0.5

0

0.5

1

Pb

Zn

U

Nb Cu

Ta

PbMo

Sb

ZnMoMREE

LREE

HREE

Sr Th

ZrY

Ba

As

CsRb

2 2 6

GEOSTANDARDS and



primarily depends on the focused laser ablation ofthe host minerals by continuous visual observationand on rapid detection of major, minor and traceelements over five orders of magnitude of intensityrange, within the brief period of spectrum acquisitiongenerated by a single melt inclusion. The laser pulseenergy applied during melt inclusion analysis has astrong impact on the quantitative LA-ICP-MS analysisbecause of the larger ablated volume. The use of an800 nm NIR femtosecond laser coupled with anElan 6000 ICP-MS instrument allowed the detailedstudy of a wide spectrum of trace elements. 23Na,43Ca and 44Ca were successfully used as internalstandards for the absolute quantification of elementconcen t ra t i on s , ba sed on t he NaO and CaOcontents that were pre-determined by electron probemicroanalysis.

(2) Quantitative data for most elements in theconcentration range from 0.1 to 10,000 μg g-1, fromnatural melt inclusions of 60 μm average size, showedthat the procedure can be used for in situ micro-analy-tical studies of geological materials, with a typicalinternal precision of ≤ 10% and accuracy of ≤ 20%.Determination of lithophile elements such as Na, Ca,Ti, Rb, Sr, Y, Zr, Nb, Ba, and REE, Ta and Th demonstra-ted very good precision and accuracy, reflecting anabsence of elemental fractionation. Chalcophile ele-ments such as Cu, Zn, As, Mo, Cd, Sn, Sb, Au and Pband lithophile Li, Cs and U in NIST SRM 612 and MPI-DING glasses displayed insignificant time-dependentelemental fractionation during the femtosecond laserablation ICP-MS. The elemental fractionation wascontrolled by the optical system and was less favou-rable for the reflective objective.

(3) The analysed quartz-hosted melt inclusionswere homogeneous, at least with respect to incompa-tible trace elements such as Rb, Sr, Nb, Cs, Ba, La, Ce,Pr, Nd, Pb and Th. On the other hand, Y, Zr, Sm, Eu,Gd, Dy, Ta and U heterogeneity of inclusions was likelydue to (a) melt heterogeneity induced by zircon crystal-lisation and (b) zircon micro-crystals co-entrapped withthe melt into the inclusions. Trace element concentra-tion homogeneity within Mt. Pinatubo melt inclusionsand matrix glasses in the limit of 30-40% was consis-tent with the homogeneity of rhyolitic melt entrappedin quartz phenocrysts at the final stage of crystallisa-tion of the host adakite (dacite) magma.

(4) NIR femtosecond LA-ICP-MS provided accurateresults for andesite, quartz diorite and rhyolite reference

glasses (MPI-DING) for Li, Cu, As, Rb, Sr, Y, Zr, Nb, Ba,REE, Ta and Th. Our data suggest that the accuracy ofPb and U measurements by fs-LA-ICP-MS might beaffected by the heterogeneity of the rhyolite ATHO-Gglass caused by Pb and U introduction during theglass preparation. At this time, we cannot explain theaccuracy problem for Mo and Cs in ATHO-G referencematerial glass.

Acknowledgements

The first author (Dr Anastassia Borisova-Pokrovski)thanks Drs. E. Suc, M. Martinez, their secretariats andworking teams for their enormous assistance in 2007and 2008. Gleb S. Pokrovski is thanked for continuedassistance and discussions. We thank the two anony-mous reviewers and the editor for important sugges-tions that significantly improved the manuscript. Theauthors thank Elena V. Bibikova, Clement Courtieu,Leonid V. Danyushevsky, Michel Grégoire, Klaus PeterJochum, Michel Pichavant, Frank Poitrasson, JacquesSchott and Michel Valladon for discussions and insight-ful suggestions which significantly improved the manus-cript. They thank Fabienne de Parseval for sample pre-paration for the femtosecond LA-ICP-MS. This work wassupported by a post-doctoral fellowship to A.Y. Borisovafrom the French Ministry of Scientific Research (2005-6).

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