An improved analytical method for Re-Os isotope analysis and its application to GSJ geochemical reference materials, JCu-1 and JZn-1

2021 ◽  
Author(s):  
Mizuki Ogasawara ◽  
Junichiro Ohta ◽  
Mizuki Ishida ◽  
Moei Yano ◽  
Kazutaka Yasukawa ◽  
...  
Keyword(s):  
Reference Materials ◽  
Analytical Method ◽  
Isotope Analysis ◽  
Age Determination ◽  
Radiometric Dating ◽  
Earth Planet ◽  
Aqua Regia ◽  
Icp Ms ◽  
Geochemical Reference Materials ◽  
Os Isotope

<p>The Re-Os isotope system is an effective tool in geological studies, especially in radiometric dating. Since both Re and Os are highly siderophile and chalcophile elements, they tend to be concentrated in various sulfide minerals. Therefore, the Re-Os geochronology has been employed for direct age determination of sulfide mineralization [1, 2]. However, conventional analytical methods for the Re-Os dating are complex and consume much time and cost.</p><p>Here we present an improved analytical method for Re-Os in sulfides combined with acid digestion using HClO<sub>4</sub> [3] and sparging introduction of Os [4]. In our method, 0.4 g of powdered sulfide was digested by 1 mL of HClO<sub>4</sub> in addition to 4 mL of inverse aqua regia in Carius tube, and then the Re and Os isotope ratios were measured by MC-ICP-MS. We applied this method to the GSJ geochemical reference materials JCu-1 (copper ore from Kamaishi mine, northeastern Japan) and JZn-1 (zinc ore from Kamioka mine, central Japan). The Re-Os concentrations of JCu-1 and JZn-1 were 255-280 ppt and 4622-4828 ppt for Re, and 39.7-41.7 ppt and 21.7-30.0 ppt for Os, respectively. Furthermore, the analytical results (Re-Os concentrations, <sup>187</sup>Os/<sup>188</sup>Os, and <sup>187</sup>Re/<sup>188</sup>Os) of separated chalcopyrite from Kamaishi mine showed good agreements with those by the conventional method digesting 0.5 g of sample by 10 mL of inverse aqua regia and measured with N-TIMS.</p><p>The new method, using less total volume of acids for sample digestion, enables MC-ICP-MS analysis of sulfides with relatively lower Re and Os concentrations. In addition, for Os isotopes, a sparging method using MC-ICP-MS [4] can be utilized as a simplified analytical procedure. This simplified and improved method may be useful for dating a wider range of sulfide deposits efficiently.</p><p> </p><p>1: Nozaki, T. et al. (2013) Sci. Rep. 3, 1889.</p><p>2: Kato, Y. et al. (2009) Earth Planet. Sci. Lett., 278, 40-49.</p><p>3: Gao, B. et al. (2019) Microchem. J. 150, 104165.</p><p>4: Nozaki, T. et al. (2012) Geostand. Geoanal. Res. 36, 131-148.</p>

scholarly journals Using 87Sr/86Sr LA-MC-ICP-MS Transects within Modern and Ancient Calcite Crystals to Determine Fluid Flow Events in Deep Granite Fractures

Geosciences ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 345 ◽  
Author(s):  
Henrik Drake ◽  
Ellen Kooijman ◽  
Melanie Kielman-Schmitt
Keyword(s):  
Fluid Flow ◽  
Spatial Resolution ◽  
Inductively Coupled Plasma ◽  
High Spatial Resolution ◽  
Isotope Analysis ◽  
Growth Zone ◽  
Water Infiltration ◽  
Radiometric Dating ◽  
Fracture Networks ◽  
Icp Ms

The strontium isotope signature (87Sr/86Sr) of calcite precipitated in rock fractures and faults is a frequently used tool to trace paleofluid flow. However, bedrock fracture networks, such as in Precambrian cratons, have often undergone multiple fracture reactivations resulting in complex sequences of fracture mineral infillings. This includes numerous discrete calcite crystal overgrowths. Conventional 87Sr/86Sr analysis of dissolved bulk samples of such crystals is not feasible as they will result in mixed signatures of several growth zonations. In addition, the zonations are too fine-grained for sub-sampling using micro-drilling. Here, we apply high spatial resolution 87Sr/86Sr spot analysis (80 µm) in transects through zoned calcite crystals in deep Paleoproterozoic granitoid fractures using laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) to trace discrete signs of paleofluid flow events. We compare the outermost calcite growth zone with 87Sr/86Sr values of the present-day groundwater sampled in the same boreholes to distinguish potential modern precipitates. We then connect our results to previously reported radiometric dating and C and O isotope signatures to understand the temporal history and physicochemical evolution of fluid flow within the fractures. Comparisons of modern calcite precipitated in a borehole over a period of 17 years with modern waters prove the concept of using 87Sr/86Sr as a marker for fluid origin in this environment and for how 87Sr/86Sr changed during marine water infiltration. Intermittent calcite precipitation over very long time spans is indicated in calcite of the currently open fractures, showing an evolution of 87Sr/86Sr from ~0.705–0.707—a population dated to ~1.43 billion years—to crystal overgrowth values at ~0.715–0.717 that overlap with the present-day groundwater values. This shows that high spatial resolution Sr isotope analysis of fine-scaled growth zonation within single calcite crystals is applicable for tracing episodic fluid flow in fracture networks.

In situ measurement of Os isotopic ratios in sulfides calibrated against ultra-fine particle standards using LA-MC-ICP-MS

2016 ◽  
Vol 31 (7) ◽  
pp. 1414-1422 ◽  
Author(s):  
Lüyun Zhu ◽  
Yongsheng Liu ◽  
Tingting Ma ◽  
Jie Lin ◽  
Zhaochu Hu ◽  
...  
Keyword(s):  
Fine Particle ◽  
Isotope Analysis ◽  
In Situ Measurement ◽  
Isotopic Ratios ◽  
New Approach ◽  
Icp Ms ◽  
Ultra Fine Particle ◽  
Os Isotope

The spiked in-house standards provide a new approach for in situ Os isotope analysis of sulfides.

High precision cadmium isotope analysis of geological reference materials by double spike MC-ICP-MS

2021 ◽  
Author(s):  
Huan Peng ◽  
Dong He ◽  
Rui Guo ◽  
Xing Liu ◽  
Nicholas S. Belshaw ◽  
...  
Keyword(s):  
High Precision ◽  
Reference Materials ◽  
Isotope Analysis ◽  
Icp Ms

The effect of the DS ratio is evaluated and a correction approach is proposed to improve the accuracy and robustness of the proposed DS Cd isotope analysis.

scholarly journals The use of ASH-15 flowstone as a matrix-matched reference material for laser-ablation U − Pb geochronology of calcite

Geochronology ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 35-47
Author(s):  
Perach Nuriel ◽  
Jörn-Frederik Wotzlaw ◽  
Maria Ovtcharova ◽  
Anton Vaks ◽  
Ciprian Stremtan ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Laser Ablation ◽  
Reference Material ◽  
Reference Materials ◽  
Inductively Coupled Plasma ◽  
Age Determination ◽  
Ionization Mass ◽  
Icp Ms ◽  
Carbonate Material

Abstract. Latest advances in laser ablation inductively coupled plasma mass spectrometer (LA-ICPMS) allow for accurate in situ U−Pb dating of carbonate material, with final age uncertainties usually >3 % 2σ. Cross-laboratory reference materials (RMs) used for sample-bracketing are currently limited to WC1 calcite with an age of 254.4±6.5 (2σ). The minimum uncertainty on any age determination with the LA-ICPMS method is therefore ≥2.5 %, and validation by secondary RMs is usually performed on in-house standards. This contribution presents a new reference material, ASH-15, a flowstone that is dated here by isotope dilution (ID) thermal ionization mass spectrometry (TIMS) analysis using 37 sub-samples, 1–7 mg each. Age results presented here are slightly younger compared to previous ID isotope ratio mass spectrometry (IRMS) U−Pb dates of ASH-15 but within uncertainties and in agreement with in situ analyses using WC1 as the primary RM. We provide new correction parameters to be used as primary or secondary standardization. The suggested 238U∕206Pb apparent age, not corrected for disequilibrium and without common-lead anchoring, is 2.965±0.011 Ma (uncertainties are 95 % confidence intervals). The new results could improve the propagated uncertainties on the final age with a minimal value of 0.4 %, which is approaching the uncertainty of typical ID analysis on higher-U materials such as zircon. We show that although LA-ICPMS spot analyses of ASH-15 exhibit significant scatter in their isotopic ratios, the down-hole fractionation of ASH-15 is similar to that of other reference materials. This high-U (≈1 ppm) and low-Pb (<0.01 ppm) calcite is most appropriate as a reference material for other speleothem-type carbonates but requires more-sensitive ICP-MS instruments such as the new generation of single-collector and multi-collector ICP-MS. Reference materials with high-Pb and low-U or both low-U and low-Pb compositions are still needed to fully cover the compositional range of carbonate material but may introduce analytical challenges.

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