Dehydroxylation of muscovite: study of quenched samples

Heller-Kallai, L.; Lapides, I.

doi:10.1007/s00269-015-0767-4

Cited by 28 publications

(12 citation statements)

References 33 publications

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“…An additional mechanism that has frequently been suggested to be operative during thermal treatment of other Fe-free hydrous minerals is the dehydroxylation reaction 2(OH) -↔ H 2 O + O 2-(e.g., Vedder and Wilkins 1969;Gonzalez-Carreño et al 1988). In a recent study on dehydroxylation of muscovite, Heller-Kallai and Lapides (2015) suggested that this Sample thickness 88 μm. Sinusoidal baseline variation is caused by interference fringes Fig.…”

Section: Infrared Spectroscopymentioning

confidence: 97%

Thermal stability of extended clusters in dravite: a combined EMP, SREF and FTIR study

2016

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Section: Infrared Spectroscopymentioning

confidence: 97%

Thermal stability of extended clusters in dravite: a combined EMP, SREF and FTIR study

2016

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“…3b). This strong OH stretching band is well known from multiple spectroscopic studies of muscovite (Beran, 2002;Tokiwai and Nakashima, 2010a, b;Heller-Kallai and Lapides, 2015).…”

Section: Ir Plate Thickness and Oh Absorbance Determinationsmentioning

confidence: 99%

Synchrotron FTIR imaging of OH in quartz mylonites

et al. 2017

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Abstract. Previous measurements of water in deformed quartzites using conventional Fourier transform infrared spectroscopy (FTIR) instruments have shown that water contents of larger grains vary from one grain to another. However, the non-equilibrium variations in water content between neighboring grains and within quartz grains cannot be interrogated further without greater measurement resolution, nor can water contents be measured in finely recrystallized grains without including absorption bands due to fluid inclusions, films, and secondary minerals at grain boundaries.Synchrotron infrared (IR) radiation coupled to a FTIR spectrometer has allowed us to distinguish and measure OH bands due to fluid inclusions, hydrogen point defects, and secondary hydrous mineral inclusions through an aperture of 10 µm for specimens > 40 µm thick. Doubly polished infrared (IR) plates can be prepared with thicknesses down to 4-8 µm, but measurement of small OH bands is currently limited by strong interference fringes for samples < 25 µm thick, precluding measurements of water within individual, finely recrystallized grains. By translating specimens under the 10 µm IR beam by steps of 10 to 50 µm, using a software-controlled x − y stage, spectra have been collected over specimen areas of nearly 4.5 mm 2 . This technique allowed us to separate and quantify broad OH bands due to fluid inclusions in quartz and OH bands due to micas and map their distributions in quartzites from the Moine Thrust (Scotland) and Main Central Thrust (Himalayas).Mylonitic quartzites deformed under greenschist facies conditions in the footwall to the Moine Thrust (MT) exhibit a large and variable 3400 cm −1 OH absorption band due to molecular water, and maps of water content corresponding to fluid inclusions show that inclusion densities correlate with deformation and recrystallization microstructures. Quartz grains of mylonitic orthogneisses and paragneisses deformed under amphibolite conditions in the hanging wall to the Main Central Thrust (MCT) exhibit smaller broad OH bands, and spectra are dominated by sharp bands at 3595 to 3379 cm −1 due to hydrogen point defects that appear to have uniform, equilibrium concentrations in the driest samples. The broad OH band at 3400 cm −1 in these rocks is much less common. The variable water concentrations of MT quartzites and lack of detectable water in highly sheared MCT mylonites challenge our understanding of quartz rheology. However, where water absorption bands can be detected and compared with deformation microstructures, OH concentration maps provide information on the histories of deformation and recovery, evidence for the introduction and loss of fluid inclusions, and water weakening processes.

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“…3b). This strong OH stretching band is well known from multiple spectroscopic studies of muscovite (Beran, 2002;Tokiwai and Nakashima, 2010a, b;Heller-Kallai and Lapides, 2015).…”

Section: Ir Plate Thickness and Oh Absorbance Determinationsmentioning

confidence: 62%

Synchrotron FTIR imaging of OH in quartz mylonites

Kronenberg¹,

Hasnan²,

Holyoke³

et al. 2017

Preprint

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Abstract. Methods of measuring OH absorption bands of fluid inclusions and hydrogen defects in deformed quartz rocks at high spatial resolution are described, using synchrotron infrared IR radiation coupled with a Fourier transform infrared FTIR microscope, and applied to imaging OH in mylonites of the Moine Thrust (from the Stack of Glencoul, NW Scotland Caledonides) and the Main Central Thrust (from the Himalayan front, Sutlej Valley, NW India). Previous measurements of water in deformed quartzites using conventional FTIR instruments, through apertures of 50–100 μm for specimens ~ 100 μm in thickness have shown that water contents of larger grains vary from one grain to another. However, the non-equilibrium variations in water content between neighboring grains and within quartz grains cannot be interrogated further without greater measurement resolution, nor can water contents be measured in finely recrystallized grains without including absorption bands due to fluid inclusions, films, and secondary minerals at grain boundaries. Synchrotron IR radiation is brighter and more collimated than offered by conventional FTIR globar light sources, and we have been able to distinguish and measure OH bands due to fluid inclusions, hydrogen point defects, and secondary hydrous mineral inclusions through an aperture of 10 μm for specimens > 40 μm thick. Doubly polished IR plates can be prepared with thicknesses down to 4–8 μm, but measurement of small OH bands is currently limited by strong interference fringes for samples

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Dehydroxylation of muscovite: study of quenched samples

Cited by 28 publications

References 33 publications

Thermal stability of extended clusters in dravite: a combined EMP, SREF and FTIR study

Thermal stability of extended clusters in dravite: a combined EMP, SREF and FTIR study

Synchrotron FTIR imaging of OH in quartz mylonites

Synchrotron FTIR imaging of OH in quartz mylonites

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