Non-destructive, safe removal of conductive metal coatings from fossils: a new solution

Jones, David R.; Hartley, Jennifer M.; Frisch, Gero; Purnell, Mark A.; Darras, Laurent

doi:10.26879/303

Cited by 18 publications

(19 citation statements)

References 21 publications

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“…Prior to EPMA, epoxy mounts were coated with a 20‐nm carbon layer (former gold coat was removed by dissolution following the procedure described in Jones et al . 2012). For each element, acquisition times were 10 s on peak and 10 s total on two background positions (5 s each).…”

Section: Methodsmentioning

confidence: 99%

In Situ Oxygen Isotope Determination in Serpentine Minerals by SIMS: Addressing Matrix Effects and Providing New Insights on Serpentinisation at Hole BA1B (Samail ophiolite, Oman)

Scicchitano

Spicuzza

Ellison

et al. 2020

Geostandard Geoanalytic Res

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The ability to constrain the petrogenesis of multiple serpentine generations recorded at the microscale is crucial for estimating the extent and conditions of modern versus fossil serpentinisation in ophiolites. To address matrix bias effects during oxygen isotope analysis by SIMS, we present the first investigation analysing antigorite in the compositional range Mg# = 77.5–99.5 mole %, using a CAMECA IMS‐1280 secondary ion mass spectrometer. Spot‐to‐spot homogeneity is ≤ 0.5‰ (2s) for the new antigorite reference materials. The relative bias between antigorite reference materials with different Mg/Fe ratios is described by a second‐order polynomial, and a maximum difference in bias of ~ 1.8‰ was measured for Mg# ~ 78 to 100. We observed a bias up to ~ 1.0‰ between lizardite and antigorite attributed to their different crystal structures. Orientation effects up to ~ 1‰ were observed in chrysotile. The new analytical protocol allowed the identification of oxygen isotope zoning up to ~ 7‰ in serpentine minerals from two serpentinites recovered from an area of active serpentinisation in the Samail ophiolite. Thus, in situ analysis is capable of resolving isotopic heterogeneity that may directly reflect changes in the physical and chemical conditions of multiple serpentinisation events in the Samail ophiolite.

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Section: Methodsmentioning

confidence: 99%

In Situ Oxygen Isotope Determination in Serpentine Minerals by SIMS: Addressing Matrix Effects and Providing New Insights on Serpentinisation at Hole BA1B (Samail ophiolite, Oman)

Scicchitano

Spicuzza

Ellison

et al. 2020

Geostandard Geoanalytic Res

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“…After SIMS analysis, the gold coating was removed from samples by chemical dissolution of gold using a saturated solution of potassium iodide (Jones et al 2012). The gold-removing solution is a 0.02 mol/L solution of iodine in ethaline.…”

Section: Gold-coat Removal and Sem Imagingmentioning

confidence: 99%

Questioning the biogenicity of Neoproterozoic superheavy pyrite by SIMS

Cui

Kitajima

Spicuzza

et al. 2018

American Mineralogist

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The Neoproterozoic sulfur isotope (δ 34 S) record is characterized by anomalously high δ 34 S pyrite values. Many δ 34 S pyrite values are higher than the contemporaneous δ 34 S sulfate (i.e., δ 34 S pyrite > δ 34 S sulfate ), showing reversed fractionation. This phenomenon has been reported from the Neoproterozoic post-glacial strata globally and is called "Neoproterozoic superheavy pyrite." The commonly assumed biogenic genesis of superheavy pyrite conflicts with current understanding of the marine sulfur cycle. Various models have been proposed to interpret this phenomenon, including extremely low concentrations of sulfate in seawaters or pore waters, or the existence of a geographically isolated and geochemically stratified ocean. Implicit and fundamental in all these published models is the assumption of a biogenic origin for pyrite genesis, which hypothesizes that the superheavy pyrite is syngenetic (in the water column) or early diagenetic (in shallow marine sediments) in origin and formed via microbial sulfate reduction (MSR). In this study, the Cryogenian Datangpo Formation in South China, which preserves some of the highest δ 34 S pyrite values up to +70‰, is studied by secondary ion mass spectrometry (SIMS) at unprecedented spatial resolutions (2 μm). Based on textures and the new sulfur isotope results, we propose that the Datangpo superheavy pyrite formed via thermochemical sulfate reduction (TSR) in hydrothermal fluids during late burial diagenesis and, therefore, lacks a biogeochemical connection to the Neoproterozoic sulfur cycle. Our study demonstrates that SEM-SIMS is an effective approach to assess the genesis of sedimentary pyrite using combined SEM petrography and micrometer-scale δ 34 S measurements by SIMS. The possibility that pervasive TSR has overprinted the primary δ 34 S pyrite signals during late diagenesis in other localities may necessitate the reappraisal of some of the δ 34 S pyrite profiles associated with superheavy pyrite throughout Earth's history.

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“…Further, attention must be paid to the potential window, as gold is much easier to oxidise in many ionic liquids compared to conventional electrolytes. 68 It is possible that the formal potential of the redox couple under investigation could be more positive than the gold stripping potential.…”

Section: Study Of the Electrochemical Behaviourmentioning

confidence: 99%

Voltammetric and spectroscopic study of ferrocene and hexacyanoferrate and the suitability of their redox couples as internal standards in ionic liquids

Frenzel

Hartley

Frisch

2017

Phys. Chem. Chem. Phys.

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Ionic liquids and deep eutectic solvents have great potential in metallurgical applications as specialised solvents. In order to design ionometallurgical electrowinning and electrorefining processes, it is essential to characterise the electrochemical behaviour of metal complexes and compare potentials between relevant solvents. For such investigations, a universal reference redox couple would be desirable. In this study we investigate the speciation and electrochemical behaviour of ferrocenium/ferrocene and hexacyanoferrate(iii/ii) as possible reference couples for 15 different ionic media on platinum (Pt), glassy carbon (GC) and gold (Au) working electrodes. Amongst other parameters, formal electrode potentials, charge transfer coefficients, and rate constants were calculated. It was found that neither ferrocene nor hexacyanoferrate are universally suitable as redox standards in the liquids investigated. Nevertheless, hexacyanoferrate exhibits clear advantages in most of the strongly coordinating ionic liquids studied here.

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Non-destructive, safe removal of conductive metal coatings from fossils: a new solution

Cited by 18 publications

References 21 publications

In Situ Oxygen Isotope Determination in Serpentine Minerals by SIMS: Addressing Matrix Effects and Providing New Insights on Serpentinisation at Hole BA1B (Samail ophiolite, Oman)

In Situ Oxygen Isotope Determination in Serpentine Minerals by SIMS: Addressing Matrix Effects and Providing New Insights on Serpentinisation at Hole BA1B (Samail ophiolite, Oman)

Questioning the biogenicity of Neoproterozoic superheavy pyrite by SIMS

Voltammetric and spectroscopic study of ferrocene and hexacyanoferrate and the suitability of their redox couples as internal standards in ionic liquids

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