Deciphering the Complex Mineralogy of River Sand Deposits through Clustering and Quantification of Hyperspectral X-Ray Maps

Torpy, Aaron; Wilson, Nick; MacRae, Colin M.; Pownceby, Mark I.; Biswas, Pradip Kumar; Rahman, Aminur; Zaman, Mohammad Nazim

doi:10.1017/s143192762000135x

Cited by 15 publications

(8 citation statements)

References 48 publications

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“…Wavelength-and energy-dispersive spectrometry were acquired in parallel with spectral cathodoluminescence (CL) using a grating spectrometer (MacRae et al, 2013). Extraction of elemental maps, CL maps, and the extraction of X-ray and CL spectra were performed using in-house software Chimage (Torpy et al, 2020). Microanalysis of silicate glass was performed with a 12 kV accelerating voltage, 15 nA beam current, and spot size was at least 1 µm to minimize migration under the electron beam.…”

Section: Methodsmentioning

confidence: 99%

CHOS gas/fluid‐induced reduction in ureilites

Langendam

Tomkins

Evans

et al. 2021

Meteorit & Planetary Scien

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Ureilite meteorites contain regions of localized olivine reduction to Fe metal widely accepted to have formed by redox reactions involving oxidation of graphite, a process known as secondary smelting. However, the possibility that other reductants might be responsible for this process has largely been ignored. Here, 17 ureilite samples are investigated to assess whether, instead of smelting involving only solid reactants, a CHOS gas/fluid could have caused much of the smelting. Features consistent with gas‐ or supercritical fluid‐driven reduction were found to be abundant in all ureilites, such as fracture‐focused smelting, plume‐like reaction fronts, and addition of sulfur. Many of these are developed away from graphite. In some ureilites, it is clear that the redox process coincided with annealing, and we suggest that this was caused by enhanced diffusion facilitated by a higher density gas or fluid, rather than slow cooling, which requires elevated pressure. The C‐CO and CH4‐C‐H2O buffers were modeled to examine their relative potential to drive reduction. This modeling showed that a CH4‐rich fluid is able to produce the observed mineral compositions at elevated pressures. This result, coupled with the observed textures, is used to develop a likely series of reactions. We suggest that at higher pressures, a H2‐CH4‐H2S‐S2‐bearing fluid‐like phase, and at lower pressures, an equivalent gas, were able to infiltrate grain boundaries and fine fractures. Sulfidation to form troilite may have acted to maintain highly reduced gas/fluid conditions. The presence of hydrocarbons in ureilites supports a role for reduction driven by CHOS gas/fluid.

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Section: Methodsmentioning

confidence: 99%

CHOS gas/fluid‐induced reduction in ureilites

Langendam

Tomkins

Evans

et al. 2021

Meteorit & Planetary Scien

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“…Wavelength dispersive spectrometers, energy dispersive spectrometers and spectral cathodoluminescence signals were all collected in parallel (MacRae et al 2013). Mapping data were analyzed using Chimage X in-house software (Harrowfield et al 1993, Torpy et al 2020).…”

Section: Epma Mappingmentioning

confidence: 99%

Supplemental Material: How carbonate dissolution facilitates sediment-hosted Zn-Pb mineralization

Liu¹,

al.²

2021

Preprint

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“…A benefit of hyperspectral data collection is that these data sets are amenable to post-hoc examination to find unexpected phases (x-ray data) and defects or centres (CL data) within a sample. There are number of approaches that can be used to examine hyperspectral data sets, and in this work, we have used clustering algorithms to partition and organise the hyperspectral data [8,9].…”

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confidence: 99%