Hyperspectral cathodoluminescence

MacRae, Colin M.; Wilson, Nicholas C.; Torpy, Aaron

doi:10.1007/s00710-013-0272-8

Cited by 33 publications

(21 citation statements)

References 37 publications

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“…A potential (semi-) quantitative estimation of REE trace elements via luminescence intensity needs a broad range of carefully calibrated analytical conditions, e.g., standard material, system stability, and system response (Barbarand and Pagel, 2001;Habermann, 2002;Richter et al, 2003;Edwards et al, 2007;MacRae et al, 2012MacRae et al, , 2013. Xian et al (2004), for instance, proposed to use absolute intensities of Raman spectral features of zircon to differentiate between rock types of mafic, granitic, and metamorphic origin.…”

Section: Zirconmentioning

confidence: 99%

Laser-induced REE3+ photoluminescence of selected accessory minerals — An “advantageous artefact” in Raman spectroscopy

et al. 2015

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Keywords:Zircon Xenotime Monazite Titanite Laser-induced REE photoluminescence Raman artefact Laser-induced photoluminescence of trivalent rare-earth elements (REEs), which is obtained as analytical artefacts in Raman spectra of selected accessory minerals, was studied. Spectra of natural titanite, monazite-(Ce), xenotime-(Y), and zircon samples from various geological environments were compared with emission spectra of synthetic, flux-grown analogues doped with REEs. The latter is of great importance to identify potentially mistakable bands as either Raman or PL signal, and to assign them to certain REE centres. In the samples investigated, various REE centres are excited selectively using 473, 514, 532, 633, and 785 nm laser excitation. Their assignment was verified by photoluminescence-excitation experiments. Luminescence spectral patterns of zircon and titanite vary in dependence of trace-REE concentrations, hence reflecting geochemical growth conditions. "REE artefacts" in Raman spectra of accessory minerals may be used as fingerprint tool for mineral phaseidentification. The distribution of REE emission-intensities, revealed by hyperspectral mapping, opens up the opportunity to visualise mineral textures, complementary to cathodoluminescence imaging-techniques.

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Section: Zirconmentioning

confidence: 99%

Laser-induced REE3+ photoluminescence of selected accessory minerals — An “advantageous artefact” in Raman spectroscopy

et al. 2015

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“…In this case, spatial resolution of CL imaging is similar to that of EPMA mapping (e.g. MacRae et al 2013).…”

Section: Discussionmentioning

confidence: 63%

Visualization of trace-element zoning in fluorapatite using BSE and CL imaging, and EPMA and μPIXE/μPIGE mapping

et al. 2016

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In this paper, zonation patterns of trace elements in fluorapatite are discussed that were visualized using four analytical techniques, namely back-scattered electrons (BSE) and cathodoluminescence (CL) imaging, electron probe micro-analysis (EPMA), and micro-proton-induced X-ray/ gamma ray emission (μPIXE/μPIGE) mapping. Each method demonstrates the in-grain compositional variations in a slightly different way. Both BSE and CL provide qualitative data, and the internal textures are displayed in most detail. Additionally, CL points to specific elements enriched in certain growth zones. Qualitative EPMA maps show detailed zonation patterns for specific elements (with high spatial resolution), which are in general correspondence with the patterns observed in BSE and CL images. The μPIXE/μPIGE maps are fully quantitative and the detection limits are relatively low compared to EPMA mapping. In present spot measurements μPIXE demonstrates lower detection limits than EPMA, however, the latter could be considerably improved by extending the acquisition times. There is no significant overlap of REE (rare earth elements) peaks in the acquired μPIXE energy spectra, however, when multiple REEs are present with sufficiently high concentrations, peak deconvolution may pose some difficulties. Spatial resolution of μPIXE/μPIGE images is not sufficiently high to reflect minor textural features, which also result from the greater interaction depth of the proton beam. However, major growth zones are distinguishable. Even though each method has their advantages and limitations, when applied together, they provide an almost complete characterization of compositional variability in trace-element-bearing minerals.

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“…This detector is sensitive in the range 300-650 nm. Hyperspectral CL maps (MacRae et al, 2013) were acquired in one sample using a JEOL 8500F electron microprobe equipped with an ocean optics QEPro spectrometer tuned to collect from 200-960nm. The sample for hyperspectral CL mapping was polished with colloidal silica, coated with 15nm of carbon and 25 analyzed at 20kV accelerating voltage, 30nA beam current, dwell time of 40 ms per pixel, and a defocused beam and pixel size of 2 µm.…”

Section: Previous Temperature Constraints On Alpine Fault Deformationmentioning

confidence: 99%

Constraints on Alpine Fault (New Zealand) Mylonitization Temperatures and Geothermal Gradient from Ti-in-quartz Thermobarometry

Kidder¹,

Toy²,

Prior³

et al. 2018

Preprint

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Abstract.We constrain the thermal state of the central Alpine Fault using approximately 750 Ti-in-quartz SIMS analyses from a 10 suite of variably deformed mylonites. Ti-in-quartz concentrations span more than an order of magnitude from 0.24 to ~5 ppm, suggesting recrystallization of quartz over a 300° range in temperature. Most Ti-in-quartz concentrations in mylonites, protomylonites, and the Alpine Schist protolith are between 2 and 4 ppm and do not vary as a function of grain size or bulk rock composition. Analyses of 30 large, inferred-remnant quartz grains (>250 µm), as well as late, cross-cutting, chlorite-bearing quartz veins also reveal restricted Ti concentrations of 2-4 ppm. These results indicate that the vast majority of Alpine Fault 15 mylonitization occurred within a restricted zone of pressure-temperature conditions where 2-4 ppm Ti-in-quartz concentrations are stable. This constrains the deep geothermal gradient from the moho to about 8 km to a slope of 5 °/km. In contrast, the small grains (10-40 µm) in ultramylonites have lower Ti concentrations of 1-2 ppm, indicating a deviation from the deeper pressuretemperature trajectory during the latest phase of ductile deformation. These constraints suggest an abrupt, order of magnitude change in the geothermal gradient to an average of about 60 °/km at depths shallower than about 8 km, i.e. within the 20 seismogenic zone. Anomalously, the lowest-Ti quartz (0.24-0.7 ppm) occurs away from the fault in protomylonites, suggesting that the outer fault zone experienced minor plastic deformation late in the exhumation history when more fault-proximal parts of the fault were deforming exclusively by brittle processes.

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Hyperspectral cathodoluminescence

Cited by 33 publications

References 37 publications

Laser-induced REE3+ photoluminescence of selected accessory minerals — An “advantageous artefact” in Raman spectroscopy

Laser-induced REE3+ photoluminescence of selected accessory minerals — An “advantageous artefact” in Raman spectroscopy

Visualization of trace-element zoning in fluorapatite using BSE and CL imaging, and EPMA and μPIXE/μPIGE mapping

Constraints on Alpine Fault (New Zealand) Mylonitization Temperatures and Geothermal Gradient from Ti-in-quartz Thermobarometry

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