scholarly journals High-precision isotopic analyses of uranium and plutonium by total sample volatilization and signal integration

1991 ◽  
Vol 103 (2-3) ◽  
pp. 93-105 ◽  
Author(s):  
E.L. Callis ◽  
R.M. Abernathey
Keyword(s):  
High Precision ◽  
Total Sample ◽  
Signal Integration ◽  
Isotopic Analyses

Forming an economic industrial mineral resource in a volcanic arc environment: timescales, fluids and thermal drivers of Europe’s largest bentonite resource

2020 ◽  
Author(s):  
A. Jo Miles ◽  
Simon R. Tapster ◽  
Jonathan Naden ◽  
Simon J. Kemp ◽  
Dan N. Barfod ◽  
...  
Keyword(s):  
High Precision ◽  
Isotope Analysis ◽  
Volcanic Edifice ◽  
Geothermal System ◽  
Volcanic Stratigraphy ◽  
Geological Evidence ◽  
Volcanic Arc ◽  
Steam Heating ◽  
Isotopic Analyses ◽  
Volcanic Pile

<p>Volcanoes in island arcs can undergo edifice evolution that includes submarine and subaerial volcanism. This provides a dynamic environment of magmatic heat and volatiles that drives hydrothermal fluid flow with potential inputs from sea and/or meteoric waters. This, in turn, can generate significant hydrothermal alteration that can result in economic deposits of industrial minerals such as bentonite and kaolinite. The island of Milos is Europe’s largest and actively mined calcium bentonite resource, with production capacities exceeding 400,000 tons per year. Here, we use the Milos island example to understand how magmatism, volcanic edifice evolution and hydrothermal activity interact to generate important bentonite mineralisation. We integrate field relationships of volcanic stratigraphy and alteration zones, with clay mineralogy (XRD), stable (S, O and H) isotope analysis and high precision geochronology (CA-ID-TIMS zircon U-Pb, and alunite Ar-Ar) to elucidate the timescales, thermal drivers and fluid components that lead to the development of a globally important bentonite resource.</p><p>A vertical transect through bentonite-altered volcanic stratigraphy indicates multiple magmatic pulses initiated at ca. 2.8 Ma with a submarine andesitic cryptodome and accompanying hyaloclastite carapace that display quenched and peperitic contacts. Cumulative volcanic and sub-volcanic processes occurred over ca. 170 kyrs, resulting in a volcanic pile exceeding 80 m. This period included an episode of magmatic quiescence and diatomite formation in a shallow submarine environment and is overlain by a silicic pyroclastic flow. In this upper unit, a pervasive alunite-kaolinite alteration assemblage was developed. Stable isotopic analyses of bentonite (> 85% montmorillonite) indicate a hydrothermal origin at around 125°C with the fluid being sourced from sea and meteoric waters. The timing of formation is defined by a maximum duration of ca. 170 kyrs, with clear geological evidence that a significant period of alteration occurred within <20 kyrs at ca. 2.64 Ma. Sulfur isotope analysis on alunite indicates a steaming ground origin that could be interpreted as the oxidised, shallower level counterpart to a boiling geothermal system linked to development of extensive bentonite. However, the timing of alunite can be clearly resolved to > 1 Ma after bentonite formation to 1.2 Ma, supporting a later overprint origin due to relatively recent steam heating of groundwater after emergence.</p><p>This study identifies new key parameters that have resulted in the formation of an economic-scale bentonite resource on the emergent island of Milos. In addition to the requisite appropriate protolith, we conclude that in an emergent volcanic arc setting the hydrology needed to form a bentonite deposit is not constrained to the marine environment and can be connected to emergent parts of the volcanic edifice. High precision geochronology indicates bentonite development happens on volcanic timescales (10 to 100 kyrs). A cumulative volcanic and sub-volcanic pile coeval with the formation of bentonite suggests multiple magmatic episodes over narrow timeframes provide and sustain the thermal driver for significant bentonite development. Once the volcanic edifice has completely emerged and developed a groundwater system, the steam heating of groundwater is deleterious to grade and results in the development of alunite-kaolinite overburden.</p>

Forming an economic bentonite resource in a volcanic arc environment: Milos island, Greece

2021 ◽  
Author(s):  
A. Jo Miles ◽  
Simon R. Tapster ◽  
Jonathan Naden ◽  
Simon J. Kemp ◽  
Dan N. Barfod ◽  
...  
Keyword(s):  
High Precision ◽  
Isotope Analysis ◽  
Dynamic Environment ◽  
Volcanic Edifice ◽  
Geothermal System ◽  
Volcanic Stratigraphy ◽  
Geological Evidence ◽  
Steam Heating ◽  
Isotopic Analyses ◽  
Volcanic Pile

<p>Volcanoes in island arcs can undergo edifice evolution that includes submarine and subaerial volcanism, providing a dynamic environment of magmatic heat and volatiles that drives hydrothermal fluid flow with potential inputs from sea and/or meteoric water. This, in turn, can generate significant hydrothermal alteration that can result in economic deposits of industrial minerals. One example includes bentonite, a smectitic rock composed dominantly of montmorillonite.</p><p>Economically viable bentonite deposits are typically only 0.5 – 5 meters thick and<strong> </strong>although Wyoming-type bentonites comprise 70% of the world’s known deposits, they are commonly no thicker than 8 m. The island of Milos is Europe’s largest and actively mined calcium bentonite resource from volcanic piles exceeding 80 m thickness. Here, we use the Milos island example to understand how magmatism, volcanic edifice evolution and hydrothermal activity interact. We integrate field relationships of volcanic stratigraphy and alteration zones, with clay mineralogy (XRD), stable (S, O and H) isotope analysis and high precision geochronology (CA-ID-TIMS zircon U-Pb, and alunite Ar-Ar) to elucidate the timescales, thermal drivers and fluid components that lead to the development of a globally important bentonite resource.</p><p>A vertical transect through bentonite-altered volcanic stratigraphy indicates multiple magmatic pulses ca. 2.8 Ma with a submarine andesitic cryptodome and accompanying pepperitic hyaloclastite. Cumulative volcanic and sub-volcanic processes occurred over ca. 170 kyrs, resulting in a vertically and laterally extensive volcanic pile overlain by an episode of magmatic quiescence and brackish-water diatomaceous sediments. It is overlain by a silicic pyroclastic flow host to pervasive silica-alunite-kaolinite alteration. Stable isotopic analyses of bentonite indicate a hydrothermal origin at around 70°C with the fluid being sourced from sea and meteoric waters. The timing of formation is defined by a maximum duration of ca. 170 kyrs, with clear geological evidence that a significant period of alteration occurred within < 20 kyrs at ~ 2.64 Ma. Alunite sulfur isotope compositions reflect steaming ground activity that could be interpreted as the oxidised, shallower level counterpart to a boiling geothermal system linked to development of extensive bentonite. However, the timing of alunite can be clearly resolved to > 1.5 myrs after bentonite formation to ~ 1.0 Ma, supporting a later overprint origin due to relatively recent steam heating of groundwater after emergence of the submarine system.</p><p>This study identifies key parameters that have resulted in the formation of an economic-scale bentonite resource on the emergent island of Milos. We conclude that the hydrology needed to form a bentonite deposit is not constrained to the marine environment and can be connected to emergent parts of the volcanic edifice. High precision geochronology indicates bentonite development happens on volcanic timescales (10 to 100 kyrs). A cumulative volcanic and sub-volcanic pile coeval with the formation of bentonite suggests multiple magmatic episodes over narrow timeframes provide and sustain the thermal driver for significant bentonite development. After emergence and development of a groundwater system, the subsequent steam heating is deleterious to grade and results in the development of alunite-kaolinite overburden.</p>

Optimization of mixed Pb–Tl solutions for high precision isotopic analyses by MC-ICP-MS

2004 ◽  
Vol 19 (9) ◽  
pp. 1262-1267 ◽  
Author(s):  
George D. Kamenov ◽  
Paul A. Mueller ◽  
Michael R. Perfit
Keyword(s):  
High Precision ◽  
Icp Ms ◽  
Isotopic Analyses

Recent developments and applications of triple oxygen isotope measurements by secondary ion mass spectrometry

2020 ◽  
Author(s):  
Yves Marrocchi ◽  
Johan Villeneuve ◽  
Paula Peres ◽  
Firmino Fernandes
Keyword(s):  
Mass Spectrometry ◽  
Oxygen Isotope ◽  
High Precision ◽  
Oxygen Isotopes ◽  
Primary Beam ◽  
Isotopic Analyses ◽  
Oxygen Isotopic ◽  
Secondary Ion ◽  
Isotopic Measurements ◽  
Isotope Measurements

<p>Oxygen isotopes are powerful proxies that are commonly used to decipher the formation of terrestrial and extraterrestrial rocks. Most of modern scientific approaches imply the determination of the oxygen isotopic composition at the mineral scale, thus requiring instruments enable to perform in situ, multi-collection, isotopic analyses in complex mineralogical assemblages and zoned minerals. Among them, large-geometry secondary ion mass spectrometer (LG-SIMS) is the most versatile with unique advantages such as (i) high spatial resolution (10–20 μm beam diameter and 1–2 μm depth); (ii) high sensitivity (detection limits below the ppm level for most elements) and (iii) high mass-resolution analysis allowing to remove most isobaric interferences (Villeneuve et al., 2019). Thanks to these capabilities, analytical uncertainties were significantly reduced for oxygen isotopes and reproducibilities much better that 1 ‰ on d<sup>17</sup>O and d<sup>18</sup>O are commonly obtained (e.g., Vacher et al. 2016; Marrocchi et al., 2018). Reaching such precisions is, however, linked to the use of 10<sup>11 </sup>Ω Faraday Cups (FCs) that require minimum count rates of > 10<sup>6</sup> cp/s for reaching permil precisions. This implies performing measurements with relatively large primary beam (i.e., 15-20 μm) that limits the minerals that can be targeted, especially in extraterrestrial samples (e.g., chondrule olivine crystals, Marrocchi et al., 2019).</p><p>Latest generation LG-SIMS instruments have been recently equipped with 10<sup>12 </sup>Ω FCs that enable isotopic measurements to be performed at count rates significantly lower (i.e., 3 × 10<sup>5</sup> cp/s) while maintaining good precision. This implies that high-precision oxygen isotopic measurements can be now performed with a less intense and smaller primary beam (~1 nA; 5 μm), In this contribution, we will report the specific characteristics of measurements using 10<sup>12 </sup>Ω FCs and the reproducibilities obtained for oxygen isotope measurements. Few scientific examples where the use of 10<sup>12 </sup>Ω FCs can represent a significant beakthrough will also be presented.</p><p>Marrocchi Y., Bekaert D.V. & Piani L. (2018). Origin and abundance of water in carbonaceous asteroids. Earth and Planetary Science Letters 482, 23-32.</p><p>Marrocchi Y., Euverte R., Villeneuve J., Batanova V., Welsch B., Ferrière L. & Jacquet E. (2019) Formation of CV chondrules by recycling of amoeboid olivine aggregate-like precursors. Geochimica et Cosmochimica Acta 247C, 121-141.</p><p>Villeneuve J., Chaussidon M., Marrocchi Y., Deng Z. & Watson B.E. (2019). High-precision silicon isotopic analyses by MC-SIMS in olivine and low-Ca pyroxene. Rapid Communication in Mass Spectrometry 33, 1589-1597.</p><p>Vacher L.G., Marrocchi Y., Verdier-Paoletti M., Villeneuve J. & Gounelle M. (2016) Inward radial mixing of interstellar water ices in the solar protoplanetary disk. The Astrophysical Journal Letters, 826, 1-6.</p><p> </p>

High precision isotopic analyses of lead ores from New Mexico by MC-ICP-MS: implications for tracing the production and exchange of Pueblo IV glaze-decorated pottery

2013 ◽  
Vol 40 (7) ◽  
pp. 3067-3075 ◽  
Author(s):  
Alyson M. Thibodeau ◽  
Judith A. Habicht-Mauche ◽  
Deborah L. Huntley ◽  
John T. Chesley ◽  
Joaquin Ruiz
Keyword(s):  
New Mexico ◽  
High Precision ◽  
Icp Ms ◽  
Isotopic Analyses

scholarly journals Rapid Extraction Chemistry Using a Single Column for 230Th/U Dating of Quaternary Hydrothermal Sulfides

Minerals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 983
Author(s):  
Li-Sheng Wang ◽  
Ye-Jian Wang ◽  
Jun Ye ◽  
Xue-Feng Wang ◽  
Ju-Le Xiao ◽  
...  
Keyword(s):  
High Precision ◽  
Total Sample ◽  
Secular Equilibrium ◽  
Single Column ◽  
Sample Dissolution ◽  
The Matrix ◽  
Hydrothermal Sulfides ◽  
Simplified Procedure ◽  
Age Constraints ◽  
238U Activity

230Th/U dating can provide high-precision age constraints on Quaternary hydrothermal sulfides. However, low content of U and Th often involves extraction chemistry for the separation and enrichment of U and Th, but these chemical processes are very complex. We developed a simplified procedure consisting of total sample dissolution and single-column extraction chemistry, which can reduce the time and improve the accuracy of the dating. Concentrated HCl-HF followed by HNO3 was added to ensure complete dissolution. A single column filled with 0.4 mL of AG 1-X8 anion resin was used, then 8 M HNO3, 8 M HCl and 0.1 M HNO3 were used to elute most of the matrix metals, Th and U. This process provided more than 95% recoveries for U and Th, and negligible blanks. Meanwhile, Pb and Bi interferences were tested and showed no effect on the U and Th isotope ratio. The 230Th/238U activity of the Geological Survey of Japan geochemical reference material JZn-1 in secular equilibrium was determined and showed a radioactive equilibrium (1.00 ± 0.01, n = 5, all errors 2σ) and an in-house standard QS-1 was consistent to 0.0078 ± 0.0001 (n = 8, ±2σ) with an average age of 705 ± 10 yrs BP (n = 8, ±2σ). The technique greatly shortens the sample preparation time and allows more concise and effective analysis of U-Th isotopes. It is ideally suited for the high-precision 230Th/U dating of Quaternary submarine hydrothermal sulfides and sulfides from other settings.

On-Line High-Precision Stable Hydrogen Isotopic Analyses on Nanoliter Water Samples

2001 ◽  
Vol 73 (15) ◽  
pp. 3570-3575 ◽  
Author(s):  
J. Morrison ◽  
T. Brockwell ◽  
T. Merren ◽  
F. Fourel ◽  
A. M. Phillips
Keyword(s):  
High Precision ◽  
Water Samples ◽  
Isotopic Analyses ◽  
On Line

Magmatic development of an intra-oceanic arc: High-precision U-Pb zircon and whole-rock isotopic analyses from the accreted Talkeetna arc, south-central Alaska

2007 ◽  
Vol 119 (9-10) ◽  
pp. 1168-1184 ◽  
Author(s):  
M. Rioux ◽  
B. Hacker ◽  
J. Mattinson ◽  
P. Kelemen ◽  
J. Blusztajn ◽  
...  
Keyword(s):  
High Precision ◽  
South Central ◽  
Isotopic Analyses

Automatic measurement of SAED patterns from asbestos minerals

1988 ◽  
Vol 46 ◽  
pp. 846-847
Author(s):  
J. C. Russ ◽  
T. Taguchi ◽  
P. M. Peters ◽  
E. Chatfield ◽  
J. C. Russ ◽  
...  
Keyword(s):  
Diffraction Pattern ◽  
High Precision ◽  
Diffraction Data ◽  
Automatic Measurement ◽  
Automatic Method ◽  
Important Method ◽  
X Ray ◽  
Integrated Intensity ◽  
Asbestiform Minerals ◽  
True Center

Conventional SAD patterns as obtained in the TEM present difficulties for identification of materials such as asbestiform minerals, although diffraction data is considered to be an important method for making this purpose. The preferred orientation of the fibers and the spotty patterns that are obtained do not readily lend themselves to measurement of the integrated intensity values for each d-spacing, and even the d-spacings may be hard to determine precisely because the true center location for the broken rings requires estimation. We have implemented an automatic method for diffraction pattern measurement to overcome these problems. It automatically locates the center of patterns with high precision, measures the radius of each ring of spots in the pattern, and integrates the density of spots in that ring. The resulting spectrum of intensity vs. radius is then used just as a conventional X-ray diffractometer scan would be, to locate peaks and produce a list of d,I values suitable for search/match comparison to known or expected phases.

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