An alternative data acquisition and evaluation strategy for improved isotope ratio precision using LA-MC-ICP-MS applied to stable and radiogenic strontium isotopes in carbonates

Fietzke, Jan; Liebetrau, Volker; Günther, Detlef; Gürs, K.; Hametner, Kathrin; Zumholz, Karsten; Hansteen, Thor H.; Eisenhauer, Anton

doi:10.1039/b717706b

Cited by 115 publications

(128 citation statements)

References 25 publications

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“…We have also assessed an alternative data evaluation strategy suggested by Fietzke et al [51]. These authors extracted the average isotope ratio directly from the slope of a linear fit of the simultaneously collected signal intensities (e.g., 28 Si vs. 30 Si) including the signals of the background measured before and after laser ablation.…”

Section: Data Acquisition and Evaluationmentioning

confidence: 99%

Testing the limits of micro-scale analyses of Si stable isotopes by femtosecond laser ablation multicollector inductively coupled plasma mass spectrometry with application to rock weathering

Schuessler

Blanckenburg

2014

Spectrochimica Acta Part B: Atomic Spectroscopy

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Abstract. An analytical protocol for accurate in-situ Si stable isotope analysis has been established on a new second-generation custom-built femtosecond laser ablation system. The laser was coupled to a multicollector inductively coupled plasma mass spectrometer (fsLA-MC-ICP-MS). We investigated the influence of laser parameters such as spot size, laser focussing, energy density and repetition rate, and ICP-MS operating conditions such as ICP mass load, spectral and nonspectral matrix effects, signal intensities, and data processing on precision and accuracy of Si isotope ratios. We found that stable and reproducible ICP conditions were obtained by using He as aerosol carrier gas mixed with Ar/H2O before entering the plasma. Precise  29 Si and  30 Si values (better than ±0.23‰, 2SD) can be obtained if the area ablated is at least 50 x 50 µm; or, alternatively, for the analysis of geometric features down to the width of the laser spot (about 20 µm) if an equivalent area is covered. Larger areas can be analysed by rastering the laser beam, whereas small single spot analyses reduce the attainable precision of  30 Si to ca. ±0.6 ‰, 2SD, for <30 µm diameter spots. It was found that focussing the laser beam beneath the sample surface with energy densities between 1 and 3.8 J/cm² yields optimal analytical conditions for all materials investigated here. Using pure quartz (NIST 8546 aka. NBS-28) as measurement standard for calibration (standard-sample-bracketing) did result in accurate and precise data of international reference materials and samples covering a wide range in chemical compositions (Si single crystal IRMM-017, basaltic glasses KL2-G, BHVO-2G and BHVO-2, andesitic glass ML3B-G, rhyolitic glass ATHO-G, diopside glass JER, soda-lime glasses NIST SRM 612 and 610, San Carlos olivine). No composition-dependent matrix effect was discernible within uncertainties of the method. The method was applied to investigate the Si isotope signature of rock weathering at the micro-scale in a corestone sampled from a highly weathered roadcut profile in the tropical Highlands of Sri Lanka. The results show that secondary weathering products accumulated in cracks and grain boundaries are isotopically lighter than their unweathered plagioclase host, consistent with isotopically heavy dissolved Si found in rivers.

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Section: Data Acquisition and Evaluationmentioning

confidence: 99%

Testing the limits of micro-scale analyses of Si stable isotopes by femtosecond laser ablation multicollector inductively coupled plasma mass spectrometry with application to rock weathering

Schuessler

Blanckenburg

2014

Spectrochimica Acta Part B: Atomic Spectroscopy

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“…In-situ Sr isotope analyses including data reduction using the linear regression slope (LRS) method followed a previously published procedure initially developed for carbonates (Fietzke et al, 2008). For barite, the former method had to be modified slightly with respect to cup configuration and correction of isobaric interferences.…”

Section: Samplementioning

confidence: 99%

“…Analyses and data reduction using a LRS (linear regression slope) method followed the approach described by Fietzke et al (2008).…”

Section: In Situ Laser Ablation Analysismentioning

confidence: 99%

Precipitation and growth of barite within hydrothermal vent deposits from the Endeavour Segment, Juan de Fuca Ridge

Jamieson

Hannington

Tivey

et al. 2016

Geochimica et Cosmochimica Acta

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Hydrothermal vent deposits form on the seafloor as a result of cooling and mixing of hot hydrothermal fluids with cold seawater. Amongst the major sulfide and sulfate minerals that are preserved at vent sites, barite (BaSO 4 ) is unique because it requires the direct mixing of Ba-rich hydrothermal fluid with sulfate-rich seawater in order for precipitation to occur. Because of its extremely low solubility, barite crystals preserve geochemical fingerprints associated with conditions of formation. Here, we present data from petrographic and geochemical analyses of hydrothermal barite from the Endeavour Segment of the Juan de Fuca Ridge, northeast Pacific Ocean, in order to determine the physical and chemical conditions under which barite precipitates within seafloor hydrothermal vent systems. Petrographic analyses of 22 barite-rich samples show a range of barite crystal morphologies: dendritic and acicular barite forms near the exterior vent walls, whereas larger bladed and tabular crystals occur within the interior of chimneys. A two component mixing model based on Sr concentrations and 87 Sr/ 86 Sr of both seawater and hydrothermal fluid, combined with 87 Sr/ 86 Sr data from whole rock and laser-ablation ICP-MS analyses of barite crystals indicate that barite precipitates from mixtures containing as low as 17% and as high as 88% hydrothermal fluid component, relative to seawater. Geochemical modelling of the relationship between aqueous species concentrations and degree of fluid mixing indicates that Ba 2+ availability is the dominant control on mineral saturation. Observations combined with model results support that dendritic barite forms from fluids of less than 40% hydrothermal component and with a saturation index greater than $0.6, whereas more euhedral crystals form at lower levels of supersaturation associated with greater contributions of hydrothermal fluid. This document is a U.S. government work and is not subject to copyright in the United States.from cyclical oscillations in hydrothermal fluid flux. Barite chemistry and morphology can be used as a reliable indicator for past conditions of mineralization within both extinct seafloor hydrothermal deposits and ancient land-based volcanogenic massive sulfide deposits.

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“…The reproducibility of the analytical procedure was better than 0.2%0 for sulphur, carbon and oxygen. For strontium isotope analysis, equatorial sections of two small sub-spherical nodules were measured for 87Sr/86Sr using LA-MC-ICP-MS across two continuous profiles from the edge to the centre of the samples according to the internal protocol of the IFM-GEOMAR Laboratory detailed in Fietzke et al (2008).…”

Section: Laboratory Analysesmentioning

confidence: 99%

Ferromanganese nodules and micro-hardgrounds associated with the Cadiz Contourite Channel (NE Atlantic): Palaeoenvironmental records of fluid venting and bottom currents

et al. 2012

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An alternative data acquisition and evaluation strategy for improved isotope ratio precision using LA-MC-ICP-MS applied to stable and radiogenic strontium isotopes in carbonates

Cited by 115 publications

References 25 publications

Testing the limits of micro-scale analyses of Si stable isotopes by femtosecond laser ablation multicollector inductively coupled plasma mass spectrometry with application to rock weathering

Testing the limits of micro-scale analyses of Si stable isotopes by femtosecond laser ablation multicollector inductively coupled plasma mass spectrometry with application to rock weathering

Precipitation and growth of barite within hydrothermal vent deposits from the Endeavour Segment, Juan de Fuca Ridge

Ferromanganese nodules and micro-hardgrounds associated with the Cadiz Contourite Channel (NE Atlantic): Palaeoenvironmental records of fluid venting and bottom currents

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