scholarly journals Improvement in the Analytical Capabilities of LA-ICP-MS for High Spatial Resolution U-Pb Dating of Zircon Using Mixed-Gas Plasma

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Liu Shenghua ◽  
Wang Xin ◽  
Shi Huixia ◽  
Zhang Hui ◽  
Liu Bingbing
Keyword(s):  
Mass Spectrometry ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Spot Size ◽  
Ionization Mass ◽  
Plasma Condition ◽  
Mixed Gas ◽  
Spot Diameter ◽  
Icp Ms ◽  
Ethanol Vapours

In this work, a novel method for high spatial resolution U-Pb dating of zircon by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) at 10–16 μm spot diameter has been proposed. This was achieved by introducing 2% (v/v) water-ethanol vapours into ICP in combination with the shielded torch system to increase the sensitivity and suppress the isotopic fractionation effect. Precise and accurate concordant U-Pb ages for Plešovice, GJ-1, and 91500 zircons were obtained using the proposed method, and the results agreed well with the isotope dilution-thermal ionization mass spectrometry (ID-TIMS) and LA-ICP-MS within 2σ, except for the ages obtained using dry plasma at 10 μm spot diameter. Additionally, the effects of plasma condition (dry plasma or 2% (v/v) ethanol plasma) and spot size (10, 16, 24, or 32 μm) on precision (RSD), accuracy (RE), and uncertainty (2σ) of the 206Pb/238U ages have been studied. The results indicated that increasing the spot diameter and introducing 2% (v/v) water-ethanol vapours into ICP significantly improved the precision, accuracy, and uncertainty for small spot diameters (10 and 16 μm), while it exhibited little influence for intermediate spot diameters (24 and 32 μm). Furthermore, the effects of spot size and plasma condition on the precision, accuracy, and uncertainty strongly depended on the sensitivity of analytes.

scholarly journals Baddeleyite microtextures and U-Pb discordance: insights from the Spread Eagle Intrusive Complex and Cape St. Mary’s sills, Newfoundland, Canada

2020 ◽  
Author(s):  
Johannes E. Pohlner ◽  
Axel K. Schmitt ◽  
Kevin R. Chamberlain ◽  
Joshua H. F. L. Davies ◽  
Anne Hildenbrand ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Precision ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Relative Sensitivity ◽  
Ionization Mass Spectrometry ◽  
Ionization Mass ◽  
Intrusive Complex ◽  
Weighted Mean ◽  
Additional Reference

Abstract. Baddeleyite (ZrO2) is widely used in U-Pb geochronology, but different patterns of discordance often hamper accurate age interpretations. This is also the case for baddeleyite from the Spread Eagle Intrusive Complex (SEIC) and Cape St. Mary’s sills (CSMS) from Newfoundland, which we investigated combining high precision and high spatial resolution methods. Literature data and our own observations suggest that at least seven different types of baddeleyite–zircon intergrowths can be distinguished in nature, among which we describe xenocrystic zircon inclusions in baddeleyite for the first time. Baddeleyite 207Pb/206Pb dates from secondary ionization mass spectrometry (SIMS) and isotope dilution thermal ionization mass spectrometry (ID-TIMS) are in good agreement with each other and with stratigraphic data, but some SIMS sessions of grain mounts show reverse discordance. This suggests that matrix differences between references and unknowns biased the U-Pb relative sensitivity calibration, possibly due to crystal orientation effects, or due to alteration of the baddeleyite crystals, which is indicated by unusually high common Pb contents. ID-TIMS data for SEIC and CSMS single baddeleyite crystals reveal normal discordance as linear arrays with decreasing 206Pb/238U dates, indicating that their discordance is dominated by recent Pb loss due to fast pathway or volume diffusion. Hence, 207Pb/206Pb dates are more reliable than 206Pb/238U dates even for Phanerozoic baddeleyite. Negative lower intercepts of baddeleyite discordias and direct correlations between ID-TIMS 207Pb/206Pb dates and degree of discordance indicate preferential 206Pb loss, possibly due to 222Rn mobilization. In such cases, the most reliable crystallization ages are concordia upper intercept dates or weighted means of the least discordant 207Pb/206Pb dates. We regard the best estimates of the intrusion ages to be 498.7 ± 4.5 Ma (2σ; ID-TIMS upper intercept date for one SEIC dike) and 439.4 ± 0.8 Ma (ID-TIMS weighted mean 207Pb/206Pb date for one sill of CSMS). Sample SL18 of the Freetown Layered Complex, Sierra Leone (associated with the Central Atlantic Magmatic Province) was investigated as an additional reference. For SL18, we report a revised 201.07 ± 0.64 Ma intrusion age, based on a weighted mean 207Pb/206Pb date of previous and new baddeleyite ID-TIMS data, agreeing well with corresponding SIMS data. Increasing discordance with decreasing crystal size in SL18 indicates that Pb loss affected baddeleyite rims more strongly than cores. Employment of SIMS or mechanical abrasion prior to ID-TIMS analysis may therefore produce more concordant baddeleyite data. We emphasize that the combination of high precision and high spatial resolution dating, along with detailed microscale imaging of baddeleyite, is powerful for extracting reliable age information from baddeleyite from rocks with a complex post-magmatic evolution.

High spatial resolution quantitative elemental imaging of foraminifer by laser ablation-inductively coupled plasma-mass spectrometry

2019 ◽  
Vol 11 (16) ◽  
pp. 2129-2137 ◽  
Author(s):  
Yuqiu Ke ◽  
Jianzong Zhou ◽  
Lei Qiao ◽  
Muhui Zhang ◽  
Wei Guo ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Laser Ablation ◽  
Spatial Resolution ◽  
Inductively Coupled Plasma ◽  
High Spatial Resolution ◽  
Elemental Imaging ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Plasma Mass Spectrometry

A methodology for high spatial resolution quantitative elemental imaging of foraminifer by LA-ICP-MS was developed.

scholarly journals High spatial resolution analysis of Pb and U isotopes for geochronology by laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS)

2009 ◽  
Vol 81 (1) ◽  
pp. 99-114 ◽  
Author(s):  
Bernhard Bühn ◽  
Márcio M. Pimentel ◽  
Massimo Matteini ◽  
Elton L. Dantas
Keyword(s):  
Mass Spectrometry ◽  
Laser Ablation ◽  
Spatial Resolution ◽  
Inductively Coupled Plasma ◽  
High Spatial Resolution ◽  
Isotopic Ratios ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Isotopic Analyses ◽  
Plasma Mass Spectrometry

Age determinations using the 235U and 238U radioactive decay series to the daughter isotopes 207Pb and 206Pb, respectively, using the mineral zircon (ZrSiO4), are widely used to decipher geological processes. A new method developed in the last couple of years, the laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS), overcomes previous laborious sample preparation, and yields isotopic ratios and age data with a high spatial resolution of ten of microns. The present study describes the analytical set-up and data reduction process as presently applied at the Laboratory for Geochronology of the University of Brasília. It explores the precision and accuracy of the method by cross-analysing three international zircon standards. We arrive at a precision of 1.9 to 3.7% (2σ SD) and an accuracy of 0.6 to 3.8% (2σ SD) for and U isotopic ratios of the standards. We also apply the method to two natural zircon samples, which have previously been dated by other analytical methods. A comparison of the results show a good conformity of the age data,being whitin the error limits. The data demonstrate the great analytical potential of the method for rapid, precise and accurate U-Pb isotopic analyses on the micron scale.

Validation of Sr isotopes in otoliths by laser ablation multicollector inductively coupled plasma mass spectrometry (LA-MC-ICPMS): opening avenues in fisheries science applications

2005 ◽  
Vol 62 (11) ◽  
pp. 2425-2430 ◽  
Author(s):  
Rachel Barnett-Johnson ◽  
Frank C Ramos ◽  
Churchill B Grimes ◽  
R Bruce MacFarlane
Keyword(s):  
Mass Spectrometry ◽  
Laser Ablation ◽  
Spatial Resolution ◽  
Inductively Coupled Plasma ◽  
High Spatial Resolution ◽  
Fish Growth ◽  
Ionization Mass ◽  
Sr Isotopes ◽  
Inductively Coupled ◽  
Plasma Mass Spectrometry

Advances in probe-based mass spectrometry allow for high spatial resolution of elemental and isotopic signatures in fish otoliths that can be used to address fundamental questions in fisheries ecology. Analyses of Chinook salmon (Oncorhynchus tshawytscha) otoliths from two river populations yield identical 87Sr/86Sr ratios using laser ablation multicollector inductively coupled plasma mass spectrometry (LA-MC-ICPMS) and thermal ionization mass spectrometry (TIMS). Results were obtained from freshwater otoliths with low Sr concentrations (300–800 ppm) using high spatial resolution (50 µm) corresponding to temporal histories of ~12 days fish growth. Low natural variation in 87Sr/86Sr among otoliths from the same rivers allows for conservative estimates of external precision of techniques. Thus, we demonstrate that Sr isotope ratios obtained by LA-MC-ICPMS can be accurate and precise, bypassing the time-intensive sample preparation required by microdrilling and TIMS. This technique opens the use of Sr isotopes for broader ecological questions requiring large sample sizes to characterize nursery habitats, metapopulation dynamics, and stock discrimination similar to studies that focus on elemental concentrations, thereby providing a more robust tool for some freshwater and diadromous fishes.

scholarly journals The Detection of Elemental Signatures of Microbes in Martian Mudstone Analogs Using High Spatial Resolution Laser Ablation Ionization Mass Spectrometry

Astrobiology ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 1224-1235 ◽  
Author(s):  
Andreas Riedo ◽  
Coen de Koning ◽  
Adam H. Stevens ◽  
Charles S. Cockell ◽  
Alison McDonald ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Laser Ablation ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Ionization Mass Spectrometry ◽  
Ionization Mass
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